U.S. patent application number 10/837961 was filed with the patent office on 2004-11-25 for soft fibrous structure.
This patent application is currently assigned to The Procter & Gamble Company. Invention is credited to Hernandez-Munoa, Diego Antonio.
Application Number | 20040231812 10/837961 |
Document ID | / |
Family ID | 33416010 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040231812 |
Kind Code |
A1 |
Hernandez-Munoa, Diego
Antonio |
November 25, 2004 |
Soft fibrous structure
Abstract
Fibrous structures, especially to through-air-dried fibrous
structures, that exhibit a Slip Stick coefficient of Friction of
less than about 0.023 and a B Compressibility of from about 15 to
about 50 and/or fibrous structures, especially through-air-dried
fibrous structures, that exhibit a Slip Stick Coefficient of
Friction of less than about 0.0175 are provided.
Inventors: |
Hernandez-Munoa, Diego Antonio;
(Liberty Township, OH) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY
INTELLECTUAL PROPERTY DIVISION
WINTON HILL TECHNICAL CENTER - BOX 161
6110 CENTER HILL AVENUE
CINCINNATI
OH
45224
US
|
Assignee: |
The Procter & Gamble
Company
|
Family ID: |
33416010 |
Appl. No.: |
10/837961 |
Filed: |
May 3, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10837961 |
May 3, 2004 |
|
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|
10429304 |
May 5, 2003 |
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Current U.S.
Class: |
162/109 ;
162/123; 162/158; 162/164.6; 162/179 |
Current CPC
Class: |
D21H 27/00 20130101 |
Class at
Publication: |
162/109 ;
162/123; 162/179; 162/158; 162/164.6 |
International
Class: |
D21H 017/07; D21H
017/45 |
Claims
What is claimed is:
1. A fibrous structure that exhibits a Slip Stick Coefficient of
Friction of less than about 0.0175.
2. The fibrous structure according to claim 1 wherein the fibrous
structure exhibits a Slip Stick Coefficient of Friction of from
about 0.0135 to about 0.0175.
3. The fibrous structure according to claim 1 wherein the fibrous
structure further exhibits a B compressibility of from about 15 to
about 50.
4. The fibrous structure according to claim 3 wherein the fibrous
structure further exhibits a Coefficient of Friction of from about
0.65 to about 0.83.
5. The fibrous structure according to claim 4 wherein the fibrous
structure exhibits a Coefficient of Friction of from about 0.65 to
about 0.81.
6. The fibrous structure according to claim 3 wherein the fibrous
structure exhibits a B Compressibility of from about 20 to about
40.
7. The fibrous structure according to claim 1 wherein the fibrous
structure comprises hardwood fibers.
8. The fibrous structure according to claim 7 wherein the fibrous
structure comprises tropical hardwood fibers.
9. The fibrous structure according to claim 8 wherein the tropical
hardwood fiber comprises Acacia fibers, Eucalyptus fibers and
mixtures thereof.
10. The fibrous structure according to claim 1 wherein the fibrous
structure comprises softwood fibers.
11. The fibrous structure according to claim 1 wherein the fibrous
structure comprises a chemical softener.
12. The fibrous structure according to claim 11 wherein the
chemical softener is selected from the group consisting of:
silicone compounds, quaternary ammonium compounds and mixtures
thereof.
13. The fibrous structure according to claim 12 wherein the
silicone compounds comprise a cationic silicone polymer comprising
one or more polysiloxane units and one or more non-pendant
quaternary nitrogen moieties.
14. The fibrous structure according to claim 13 wherein the
cationic silicone polymer comprises at least 2 or more polysiloxane
units and at least 2 or more quaternary nitrogen moieties.
15. The fibrous structure according to claim 1 wherein the fibrous
structure exhibits a WABY factor of less than about 0.2.
16. The fibrous structure according to claim 1 wherein the fibrous
structure exhibits a smoothness of greater than about 500.
17. A single- or multi-ply sanitary tissue product selected from
the group consisting of facial tissue products, hankies, toilet
tissue products, paper towel products and mixtures thereof,
comprising a fibrous structure according to claim 1.
18. A fibrous structure that exhibits a Slip Stick Coefficient of
Friction of less than about 0.023 and a B Compressibility of from
about 15 to about 50.
19. The fibrous structure according to claim 18 wherein the fibrous
structure further exhibits a WABY factor of less than about
0.2.
20. The fibrous structure according to claim 18 wherein the fibrous
structure exhibits a Coefficient of Friction of from about 0.65 to
about 0.83.
21. The fibrous structure according to claim 18 wherein the fibrous
structure comprises a chemical softener.
22. A single- or multi-ply sanitary tissue product selected from
the group consisting of facial tissue products, hankies, toilet
tissue products, paper towel products and mixtures thereof,
comprising a fibrous structure according to claim 18.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 10/429,304 filed May 5, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates to fibrous structures,
especially to through-air-dried fibrous structures, that exhibit a
Slip Stick Coefficient of Friction of less than about 0.023 and a B
Compressibility of from about 15 to about 50 and/or fibrous
structures, especially through-air-dried fibrous structures, which
exhibit a Slip Stick Coefficient of Friction of less than about
0.0175.
BACKGROUND OF THE INVENTION
[0003] It is well known in the art that the softness of a fibrous
structure or a sanitary tissue product, especially a
through-air-dried sanitary tissue product, incorporating a fibrous
structure is inversely proportional to the total tensile strength
of the fibrous structure or sanitary tissue product. Further, it is
well known in the art that the smoothness of a fibrous structure or
a sanitary tissue product, especially a through-air-dried sanitary
tissue product, incorporating a fibrous structure is inversely
proportional to the caliper of the fibrous structure or sanitary
tissue product.
[0004] Attempts by formulators to overcome the inverse
relationships, especially the softness to total tensile strength
have included adding cationic silicones to sanitary tissue products
and/or fibrous structures making up such products. See for example
U.S. Pat. No. 5,059,282 to Ampulski et al.
[0005] Formulators have deposited various softening agents,
including silicone materials, onto the external surfaces of fibrous
structures to try to deliver the consumer desired softness and/or
smoothness. Such prior art fibrous structures exhibited
Coefficients of Friction of about 0.72 to about 1.07 or Slip Stick
Coefficients of Friction of from at least about 0.0207 or B
Compressibility of less than or equal to 17.
[0006] Prior formulators have failed to develop a fibrous
structure, especially a through-air-dried fibrous structure, which
exhibits a Slip Stick Coefficient of Friction of less than about
0.023 and a B Compressibility of from about 15 to about 50 and/or
fibrous structures, especially through-air-dried fibrous
structures, which exhibit a Slip Stick Coefficient of Friction of
less than about 0.0175. Accordingly, there exists a long felt need
to provide a fibrous structure, especially a through-air-dried
fibrous structure, that exhibits a Slip Stick Coefficient of
Friction of less than about 0.023 and a B Compressibility of from
about 15 to about 50 and/or fibrous structures, especially
through-air-dried fibrous structures, that exhibit a Slip Stick
Coefficient of Friction of less than about 0.0175.
SUMMARY OF THE INVENTION
[0007] The present invention fulfills the need described above by
providing a fibrous structure, especially a through-air-dried
fibrous structure, which exhibits a Slip Stick Coefficient of
Friction of less than about 0.023 and, optionally, a B
Compressibility of from about 15 to about 50.
[0008] In one aspect of the present invention, a fibrous structure
that exhibits a Slip Stick Coefficient of Friction of less than
about 0.023 and/or less than about 0.021 and/or less than about
0.0190 and/or less than about 0.0175 is provided.
[0009] In another aspect of the present invention, a fibrous
structure that exhibits a Slip Stick Coefficient of Friction of
less than about 0.023 and a B Compressibility of from about 15 to
about 50.
[0010] In yet another aspect of the present invention, a single- or
multi-ply sanitary tissue product comprising a fibrous structure
according to the present invention is provided.
[0011] Accordingly, the present invention provides a fibrous
structure that exhibits a Slip Stick Coefficient of Friction of
less than about 0.023, a fibrous structure that exhibits a Slip
Stick Coefficient of Friction of less than about 0.023 and a B
Compressibility of from about 15 to about 50, and a single- or
multi-ply sanitary tissue product comprising a fibrous structure
according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] "Fiber" as used herein means an elongate particulate having
an apparent length greatly exceeding its apparent width, i.e. a
length to diameter ratio of at least about 10. More specifically,
as used herein, "fiber" refers to papermaking fibers. The present
invention contemplates the use of a variety of papermaking fibers,
such as, for example, natural fibers or synthetic fibers, or any
other suitable fibers, and any combination thereof. Papermaking
fibers useful in the present invention include cellulosic fibers
commonly known as wood pulp fibers. Applicable wood pulps include
chemical pulps, such as Kraft, especially Northern Softwood Kraft
("NSK"), sulfite, and sulfate pulps, as well as mechanical pulps
including, for example, groundwood, thermomechanical pulp and
chemically modified thermomechanical pulp. Nonlimiting examples of
wood pulps include fibers derived from a fiber source selected from
the group consisting of Acacia, Eucalyptus, Maple, Oak, Aspen,
Birch, Cottonwood, Alder, Ash, Cherry, Elm, Hickory, Poplar, Gum,
Walnut, Locust, Sycamore, Beech, Catalpa, Sassafras, Gmelina,
Albizia, Anthocephalus, Magnolia, Bagasse, Flax, Hemp, Kenaf and
mixtures thereof. 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"), especially tropical
hardwood, and coniferous trees (hereinafter, also referred to as
"softwood") may be utilized. The hardwood and softwood fibers can
be blended, or alternatively, can be deposited in layers to provide
a stratified web. U.S. Pat. No. 4,300,981 and U.S. Pat. No.
3,994,771 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.
[0013] In addition to the various wood pulp fibers, other
cellulosic fibers such as cotton linters, rayon, and bagasse can be
used in this invention. Synthetic fibers, such as polymeric fibers,
can also be used. Elastomeric polymers, polypropylene,
polyethylene, polyester, polyolefin, and nylon, can be used. The
polymeric fibers can be produced by spunbond processes, meltblown
processes, and other suitable methods known in the art. One
exemplary polyethylene fiber that can be utilized is Pulpex.RTM.,
available from Hercules, Inc. (Wilmington, Del.).
[0014] In addition to the above, fibers and/or filaments made from
polymers, specifically hydroxyl polymers may be used in the present
invention. Nonlimiting examples of suitable hydroxyl polymers
include polyvinyl alcohol, starch, starch derivatives, chitosan,
chitosan derivatives, cellulose derivatives, gums, arabinans,
galactans and mixtures thereof.
[0015] An embryonic fibrous web can be typically prepared from an
aqueous dispersion of papermaking fibers, though dispersions in
liquids other than water can be used. The fibers can be dispersed
in the carrier liquid to have a consistency of from about 0.1% to
about 0.3%. It is believed that the present invention can also be
applicable to moist forming operations where the fibers are
dispersed in a carrier liquid to have a consistency less than about
50%, more preferably less than about 10%.
[0016] "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/or hankies), and multi-functional absorbent and cleaning uses
(absorbent towels). The properties and values thereof discussed
herein with respect to the fibrous structures described herein may
also be present in the sanitary tissue products incorporating such
fibrous structures.
[0017] "Weight average molecular weight" as used herein means the
weight average molecular weight as determined using gel permeation
chromatography according to the protocol found in Colloids and
Surfaces A. Physico Chemical & Engineering Aspects, Vol. 162,
2000, pg. 107-121.
[0018] "Ply" or "Plies" as used herein means an individual fibrous
structure optionally to be disposed in a substantially contiguous,
face-to-face relationship with other plies, forming a multiple ply
fibrous structure. It is also contemplated that a single fibrous
structure can effectively form two "plies" or multiple "plies", for
example, by being folded on itself.
[0019] "Caliper" as used herein means the macroscopic thickness of
a sample. Caliper of a sample of fibrous structure and/or sanitary
tissue product according to the present invention are obtained on a
VIR Electronic Thickness Tester Model II available from
Thwing-Albert Instrument Company, Philadelphia, Pa. The caliper
measurement can be repeated and recorded at least five (5) times so
that an average caliper can be calculated. The result is reported
in millimeters.
[0020] "Smoothness" and/or "Physiological Surface Smoothness" as
used herein is a factor (hereinafter the PSS Factor and/or SMD
Factor) derived from scanning machine-direction fibrous structure
and/or sanitary tissue product samples with a profilometer having a
diamond stylus, the profilometer being installed in a surface test
apparatus such as, for example, is described in the 1991
International paper Physics Conference. TAPPI Book 1, article
entitled "Methods for the Measurement of the Mechanical Properties
of Tissue Paper" by Ampulski et al. found at page 19, and/or in
U.S. Pat. No. 5,059,282 issued to Ampulski et al., both of which
are incorporated herein by reference. The smoothness and/or the
inverse of smoothness (i.e., roughness) can also be measured using
a Kato Surface Tester KES-FB4 which is available from Kato Tekko
Co., LTD., Karato-Cho, Nishikiyo, Minami-Ku, Koyota, Japan.
Alternatively, the smoothness of a fibrous structure and/or
sanitary tissue product according to the present invention may be
measured using a Primos Optical Profiler/3D Surface Analyzer
commercially available from GF Messtechnik, Berlin, Germany. It is
desirable that fibrous structures and/or sanitary tissue products
comprising such fibrous structures exhibit a smoothness of greater
than about 500 and/or from about 500 to about 1200 and/or from
about 550 to about 1000 and/or from about 600 to about 950 and/or
from about 650 to about 900.
[0021] "Slip Stick Coefficient of Friction" (S&S COF) is
defined as the mean deviation of the coefficient of friction. Like
the coefficient of friction, it is dimensionless. This test is
performed on a KES-FB4 Surface Analyzer from Kato Tekko Co. with a
modified friction probe. The probe sled is a two centimeter
diameter, 40 to 60 micron glass frit obtained from Ace Glass
Company. The normal force of the probe was 19.6 grams. The details
of the procedure are described in "Methods for the Measurement of
the Mechanical Properties of Tissue Paper" by Ampulski, et. al.,
1991 International Paper Physics Conference, page 19, incorporated
herein by reference.
[0022] In one embodiment, the fibrous structure exhibits a Slip
Stick Coefficient of Friction of from about 0.010 to about 0.021
and/or from about 0.0135 to about 0.0190 and/or from about 0.0135
to about 0.0175.
[0023] "Total Dry Tensile Strength" or "TDT" of a fibrous structure
and/or sanitary tissue product comprising such fibrous structure is
measured as follows. One (1) inch by five (5) inch (2.5
cm.times.12.7 cm) strips of fibrous structure and/or paper product
comprising such fibrous structure are provided. The strip is placed
on an electronic tensile tester Model 1122 commercially available
from Instron Corp., Canton, Mass. in a conditioned room at a
temperature of 73.degree. F..+-.4.degree. F. (about 28.degree. C.
.+-.2.2.degree. C.) and a relative humidity of 50% .+-.10% . The
crosshead speed of the tensile tester is 2.0 inches per minute
(about 5.1 cm/minute) and the gauge length is 4.0 inches (about
10.2 cm). The TDT is the arithmetic total of MD and CD tensile
strengths of the strips.
[0024] "Wet Burst Strength" as used herein is a measure of the
ability of a fibrous structure and/or a paper product incorporating
a fibrous structure to absorb energy, when wet and subjected to
deformation normal to the plane of the fibrous structure and/or
paper product. Wet burst strength may be measured using a
Thwing-Albert Burst Tester Cat. No. 177 equipped with a 2000 g load
cell commercially available from Thwing-Albert Instrument Company,
Philadelphia, Pa. In one embodiment, the fibrous structures of the
present invention and/or sanitary tissue products comprising such
fibrous structures may have a wet burst strength of greater than
about 10 g/cm and/or from about 12 g/cm to about 394 g/cm and/or
from about 13 g/cm to about 197 g/cm and/or from about 15 g/cm to
about 197 g/cm and/or from about 15 g/cm to about 78 g/cm.
[0025] "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 paper 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). 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). In one embodiment, the fibrous structures of the present
invention and/or sanitary tissue products comprising such fibrous
structures have a basis weight of from about 12 g/m.sup.2 to about
120 g/m.sup.2 and/or from about 14 g/m.sup.2 to about 80 g/m.sup.2
and/or from about 17 g/m.sup.2 to about 70 g/m.sup.2 and/or from
about 20 g/m.sup.2 to about 60 g/m.sup.2. Typically, a single ply
of the fibrous structure has a basis weight of from about 12
g/m.sup.2 to about 50 g/m.sup.2.
[0026] "Machine Direction" or "MD" as used herein means the
direction parallel to the flow of the fibrous structure through the
papermaking machine and/or product manufacturing equipment.
[0027] "Cross Machine Direction" or "CD" as used herein means the
direction perpendicular to the machine direction in the same plane
of the fibrous structure and/or paper product comprising the
fibrous structure.
[0028] "Apparent Density" or "Density" as used herein means the
basis weight of a sample divided by the caliper with appropriate
conversions incorporated therein. Apparent density used herein has
the units g/cm.sup.3.
[0029] "Total Dry Tensile Strength" as used herein means the
geometric mean of the machine and cross-machine breaking strengths
in grams per cm of sample width. Mathematically, this is the square
root of the product of the machine and cross-machine direction
breaking strengths in grams per cm of sample width. In one
embodiment, the fibrous structures of the present invention and/or
sanitary tissue products comprising such fibrous structures have a
total dry tensile of greater than about 39 g/cm and/or greater than
about 59 g/cm and/or from about 63 g/cm to about 1575 g/cm and/or
from about 78 g/cm to about 985 g/cm and/or from about 78 g/cm to
about 394 g/cm and/or from about 98 g/cm to about 335 g/cm.
Typically a single ply of the fibrous structure has a total dry
tensile of from about 39 g/cm to about 590 g/cm.
[0030] "Flexibility" as used herein means the slope of the secant
of the graph-curve derived from force vs. stretch % data which
secant passes through the origin (0% stretch, 0 force) and through
the point on the graph-curve where the force per centimeter of
width is 20 grams.
[0031] "Total Flexibility" as used herein means the geometric mean
of the machine-direction flexibility and cross-machine-direction
flexibility. Mathematically, this is the square root of the product
of the machine-direction flexibility and cross-machine-direction
flexibility in grams per cm.
[0032] "WABY Factor" as used herein means the ratio of Total
Flexibility to Total Tensile Strength. The WABY Factor has been
determined to be a factor which characterizes embodiments of the
invention as being strong yet having high bulk softness. This ratio
is hereby dubbed the WABY Factor. For instance, a sample having a
Total Flexibility of 20 g/cm, and a Total Tensile Strength of 154
g/cm has a WABY Factor of 0.13. It is desirable that fibrous
structures and/or sanitary tissue products comprising such fibrous
structures exhibit a WABY factor less than about 0.2 and/or from
about 0.05 to about 0.15 and/or from about 0.06 to about 0.13
and/or from about 0.06 to about 0.11.
[0033] Briefly, tactile perceivable softness of tissue paper is
inversely related to its WABY Factor. Also, note that the WABY
Factor is dimensionless because both Flexibility and Total Tensile
Strength as defined above are in g/cm, their ratio is
dimensionless.
[0034] "B Compressibility" as used herein means the intercept of a
curve generated by plotting weight versus thickness resulting from
a compression test.
[0035] "Lint" as used herein is measured in accordance with the
procedure set forth in commonly assigned U.S. Pat. No. 5,814,188
issued Sep. 29, 1998 to Vinson et al., and incorporated herein by
reference.
[0036] The fibrous structures and/or sanitary tissue products
employing the fibrous structures of the present invention may be
characterized as being within a multi-parametric domain defined by
empirically determined ranges of one or more and/or two or more
and/or three or more of the following parameters: 1) Caliper; 2)
Physiological Surface Smoothness; 3) Slip Stick Coefficient of
Friction; 4) Total Tensile Strength; 5) Flexibility; 6) Basis
Weight; 7) Wet Burst Strength; 8) Coefficient of Friction; 9) WABY
Factor and/or 10) B Compressibility.
[0037] It has surprisingly been found that fibrous structures and
sanitary tissue products incorporating such fibrous structures that
exhibit, in addition to a Slip Stick Coefficient of Friction less
than about 0.023, a Coefficient of Friction of from about 0.65 to
about 0.83 and/or from about 0.65 to about 0.81 and/or from about
0.71 to about 0.81 and/or a B Compressibility of from about 15 to
about 50 and/or from about 20 to about 40 exhibit enhanced softness
and/or smoothness as compared to known fibrous structures.
[0038] As used herein, the articles "a" and "an" when used herein,
for example, "an anionic surfactant" or "a fiber" is understood to
mean one or more of the material that is claimed or described.
[0039] All percentages and ratios are calculated by weight unless
otherwise indicated. All percentages and ratios are calculated
based on the total composition unless otherwise indicated.
[0040] Unless otherwise noted, all component or composition levels
are in reference to the active level of that component or
composition, and are exclusive of impurities, for example, residual
solvents or by-products, which may be present in commercially
available sources.
[0041] Fibrous Structure
[0042] The fibrous structures and/or tissue paper of the present
invention can be made by different methods. Nonlimiting examples of
fibrous structure types and/or tissue paper types include
conventionally pressed and/or felt-pressed tissue paper; pattern
densified tissue paper either with a patterned forming wire and/or
a patterned fabric/resin belt; high-bulk, uncompacted tissue paper
and creped or uncreped tissue paper. The tissue paper may be of a
homogenous and/or single layered or multilayered construction; and
tissue paper products made therefrom may be of a single-ply or
multi-ply construction.
[0043] Further, the fibrous structures of the present invention
and/or sanitary tissue products incorporating the same may be
creped or uncreped.
[0044] Further yet, the sanitary tissue products incorporating the
fibrous structures of the present invention may incorporate dry
fibers via an air laid process and/or latex binding agents via a
wet laid process.
[0045] Conventional converting methods may be used to convert dried
rolls of fibrous structure according to the present invention into
one-ply and/or multi-ply sanitary tissue products. Nonlimiting
examples of such converting methods include embossing including
high pressure embossing, dry creping, ply bonding, calendaring
and/or other mechanical treatments to the fibrous structures.
[0046] The fibrous structure may be made with a fibrous furnish
that produces a single layer embryonic fibrous web or a fibrous
furnish that produces a multi-layer embryonic fibrous web.
[0047] The properties described herein may be for a single ply of
the fibrous structure and/or a single ply sanitary tissue product
and/or for a multi-ply sanitary tissue product that incorporates at
least one ply comprising the fibrous structure of the present
invention.
[0048] Fiber Furnish
[0049] In one embodiment, the fibrous structure is produced from a
fiber furnish. In another embodiment, the fibrous structure is
produced from a melt blown and/or spun bonded and/or rotary die
process. The fiber furnish of the present invention comprises one
or more fibers and typically one or more optional ingredients.
[0050] Optional Ingredients
[0051] The fibrous structures of the present invention may comprise
an optional ingredient selected from the group consisting of
permanent wet strength resins, chemical softeners, such as
silicones, particularly cationic silicones, and/or quaternary
ammonium compounds, temporary wet strength resins, dry strength
resins, wetting agents, lint resisting agents, absorbency-enhancing
agents, immobilizing agents, especially in combination with
emollient lotion compositions, antiviral agents including organic
acids, antibacterial agents, polyol polyesters, antimigration
agents, polyhydroxy plasticizers, fillers (clays), humectants and
mixtures thereof. Such optional ingredients may be added to the
fiber furnish, the embryonic fibrous web and/or the dried fibrous
structure. Such optional ingredients may be present in the fibrous
structure at any level based on the dry weight of the fibrous
structure.
[0052] The optional ingredients may be applied to the fiber furnish
and/or the embryonic fibrous web and/or the dried fibrous structure
and/or the sanitary tissue product of the present invention.
Further, the optional ingredients, such as other chemical
softeners, more particularly, lotions, especially, transferable
lotions may be applied to the dried fibrous structure and/or
sanitary tissue product after the any cationic silicone, if any,
has been applied thereto.
[0053] The optional ingredients may be present in the fibrous
structure and/or sanitary tissue product of the present invention
at a level of from about 0.001% to about 50% and/or from about
0.001% to about 30% and/or from about 0.001% to about 22% and/or
from about 0.01% to about 5% and/or from about 0.03% to about 3%
and/or from about 0.05 to about 2% and/or from about 0.1% to about
1% by weight, on a dry fibrous structure or sanitary tissue product
basis.
[0054] Chemical Softeners
[0055] Nonlimiting examples of suitable chemical softeners include
silicones, especially cationic silicones, more preferably cationic
silicones that comprise one or more polysiloxane units, preferably
polydimethylsiloxane units of formula
--{(CH.sub.3).sub.2SiO}.sub.c-- having a degree. of polymerization,
c, of from 1 to 1000, preferably of from 20 to 500, more preferably
of from 50 to 300, most preferably from 100 to 200, and
organosilicone-free units comprising at least one diquatemary unit.
In a preferred embodiment of the present invention, the selected
cationic silicone polymer has from 0.05 to 1.0 mole fraction, more
preferably from 0.2 to 0.95 mole fraction, most preferably 0.5 to
0.9 mole fraction of the organosilicone-free units selected from
cationic divalent organic moieties. The cationic divalent organic
moiety is preferably selected from
N,N,N',N'-tetramethyl-1,6-hexanediamronium units.
[0056] The selected cationic silicone polymer can also contain from
0 to 0.95 mole fraction, preferably from 0.001 to 0.5 mole
fraction, more preferably from 0.05 to 0.2 mole fraction of the
total of organosilicone-free units, polyalkyleneoxide amines of the
following formula:
[--Y --O(--C.sub.aH.sub.2aO).sub.b--Y--]
[0057] wherein Y is a divalent organic group comprising a secondary
or tertiary amine, preferably a C.sub.1 to C.sub.8 alkylenamine
residue; a is from 2 to 4, and b is from 0 to 100. The
polyalkyleneoxide blocks may be made up of ethylene oxide (a=2),
propylene oxide (a=3), butylene oxide (a=4) and mixtures thereof,
in a random or block fashion.
[0058] Such polyalkyleneoxide amine--containing units can be
obtained by introducing in the silicone polymer structure,
compounds such as those sold under the tradename Jeffamine.RTM.
from Huntsman Corporation. A preferred Jeffamine is Jeffamine
ED-2003.
[0059] The selected cationic silicone polymer can also contain from
0, preferably from 0.001 to 0.2 mole fraction, of the total of
organosilicone-free units, of --NR.sub.3.sup.+ wherein R is alkyl,
hydroxyalkyl or phenyl. These units can be thought of as
end-caps.
[0060] Moreover the selected cationic silicone polymer generally
contains anions, selected from inorganic and organic anions, more
preferably selected from saturated and unsaturated
C.sub.1-C.sub.20. carboxylates and mixtures thereof, to balance the
charge of the quaternary moieties, thus the cationic silicone
polymer also comprises such anions in a quaternary charge-balancing
proportion.
[0061] Conceptually, the selected cationic silicone polymers herein
can helpfully be thought of as non-crosslinked or "linear" block
copolymers including non-fabric-substantive but surface energy
modifying "loops" made up of the polysiloxane units, and
fabric-substantive "hooks". One preferred class of the selected
cationic polymers (illustrated by Structure 1 hereinafter) can be
thought of as comprising a single loop and two hooks; another, very
highly preferred, comprises two or more, preferably three or more
"loops" and two or more, preferably three or more "hooks"
(illustrated by Structures 2a and 2b hereinafter), and yet another
(illustrated by Structure. 3 hereinafter) comprises two "loops"
pendant from a single "hook".
[0062] Of particular interest in the present selection of cationic
silicone polymers is that the "hooks" contain no silicone and that
each "hook" comprises at least two quaternary nitrogen atoms.
[0063] Also of interest in the present selection of preferred
cationic silicone polymers is that the quaternary nitrogen is
preferentially located in the "backbone" of the "linear" polymer,
in contradistinction from alternate and less preferred structures
in which the quaternary nitrogen is incorporated into a moiety or
moieties which form a "pendant" or "dangling" structure off the
"backbone".
[0064] The structures are completed by terminal moieties which can
be noncharged or charged. Moreover a certain proportion of
nonquaternary silicone-free moieties can be present, for example
the moiety [--Y --O(--C.sub.aH.sub.2aO).sub.b--Y--] as described
hereinabove.
[0065] Of course the conceptual model presented is not intended to
be limiting of other moieties, for example connector moieties,
which can be present in the selected cationic silicone polymers
provided that they do not substantially disrupt the intended
function as tissue benefit agents.
[0066] In more detail, the cationic silicone polymers herein have
one or more polysiloxane units and one or more quaternary nitrogen
moieties, including polymers wherein the cationic silicone polymer
has the formula: 1
[0067] wherein:
[0068] R.sup.1 is independently selected from the group consisting
of: C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl,
aryl, cycloalkyl, and mixtures thereof;
[0069] R.sup.2 is independently selected from the group consisting
of: divalent organic moieties that may contain one or more oxygen
atoms (such moieties preferably consist essentially of C and H or
of C, H and O);
[0070] X is independently selected from the group consisting of
ring-opened epoxides;
[0071] R.sup.3 is independently selected from polyether groups
having the formula:
-M.sup.1(C.sub.aH.sub.2aO).sub.b-M.sup.2
[0072] wherein M.sup.1 is a divalent hydrocarbon residue; M.sup.2
is independently selected from the group consisting of H,
C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl,
cycloalkyl, C.sub.1-22 hydroxyalkyl, polyalkyleneoxide,
(poly)alkoxy alkyl, and mixtures thereof;
[0073] Z is independently selected from the group consisting of
monovalent organic moieties comprising at least one quaternized
nitrogen atom;
[0074] a is from 2 to 4; b is from 0 to 100; c is from 1 to 1000,
preferably greater than 20, more preferably greater than 50,
preferably less than 500, more preferably less than 300, most
preferably from 100 to 200;
[0075] d is from 0 to 100; n is the number of positive charges
associated with the cationic silicone polymer, which is greater
than or equal to 2; and A is a monovalent anion.
[0076] In a preferred embodiment of the Structure 1 cationic
silicone polymers, Z is independently selected from the group
consisting of: 2
[0077] (v) monovalent aromatic or aliphatic heterocyclic group,
substituted or unsubstituted, containing at least one quaternized
nitrogen atom;
[0078] wherein:
[0079] R.sup.12, R.sup.13, R.sup.14 are the same or different, and
are selected from the group consisting of: C.sub.1-22 alkyl,
C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl, cycloalkyl,
C.sub.1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and
mixtures thereof;
[0080] R.sup.15 is --O-- or NR.sup.19;
[0081] R.sup.16 is a divalent hydrocarbon residue;
[0082] R.sup.17, R.sup.18, R.sup.19 are the same or different, and
are selected from the group consisting of: H, C.sub.1-22 alkyl,
C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl, cycloalkyl,
C.sub.1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and
mixtures thereof; and e is from 1 to 6.
[0083] In a highly preferred embodiment, the cationic silicone
polymers herein have one or more polysiloxane units and one or more
quaternary nitrogen moieties, including polymers wherein the
cationic silicone polymer has the formula: (Structure 2a)
[0084] STRUCTURE 2a: Cationic silicone polymer composed of
alternating units of:
[0085] (i) a polysiloxane of the following formula 3
[0086] and
[0087] (ii) a divalent organic moiety comprising at least two
quaternized nitrogen atoms.
[0088] Note that Structure 2a comprises the alternating combination
of both the polysiloxane of the depicted formula and the divalent
organic moiety, and that the divalent organic moiety is
organosilicone-free corresponding to a preferred "hook" in the
above description.
[0089] In this preferred cationic silicone polymer, R.sup.1 is
independently selected from the group consisting of: C.sub.1-22
alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl, cycloalkyl,
and mixtures thereof,
[0090] R.sup.2 is independently selected from the group consisting
of: divalent organic moieties that may contain one or more oxygen
atoms; X is independently selected from the group consisting of
ring-opened epoxides; R.sup.3 is independently selected from
polyether groups having the formula:
-M.sup.1(C.sub.aH.sub.2aO).sub.b-M.sup.2
[0091] wherein M.sup.1 is a divalent hydrocarbon residue; M.sup.2
is independently selected from the group consisting of H,
C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl,
cycloalkyl, C.sub.1-22 hydroxyalkyl, polyalkyleneoxide,
(poly)alkoxy alkyl, and mixtures thereof; a is from 2 to 4; b is
from 0 to 100; c is from 1 to 1000, preferably greater than 20,
more preferably greater than 50, preferably less than 500, more
preferably less than 300, most preferably from 100 to 200; and d is
from 0 to 100.
[0092] In an even more highly preferred embodiment of the Structure
2a cationic silicone polymer, the cationic silicone polymer has the
formula Structure 2b wherein the polysiloxane (i) of the formula
described above in Structure 2a is present with (ii) a cationic
divalent organic moiety is selected from the group consisting of:
4
[0093] (d) a divalent aromatic or aliphatic heterocyclic group,
substituted or unsubstituted, containing at least one quaternized
nitrogent atom; and
[0094] (iii) optionally, a polyalkyleneoxide amine of formula:
[0095] ti [--Y--O(--C.sub.aH.sub.2aO).sub.b--Y--]
[0096] Y is a divalent organic group comprising a secondary or
tertiary amine, preferably a C.sub.1 to C.sub.8 alkylenamine
residue; a is from 2 to 4; b is from 0 to 100; the
polyalkyleneoxide blocks may be made up of ethylene oxide (a=2),
propylene oxide (a=3), butylene oxide (a=4) and mixtures thereof,
in a random or block fashion; and
[0097] (iv) optionally, a cationic monovalent organic moiety, to be
used as an end-group, selected from the group consisting of: 5
[0098] (v) monovalent aromatic or aliphatic heterocyclic group,
substituted or unsubstituted, containing at least one quaternized
nitrogen atom;
[0099] wherein:
[0100] R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9,
R.sup.10, R.sup.11 are the same or different, and are selected from
the group consisting of: C.sub.1-22 alkyl, C.sub.2-22 alkenyl,
C.sub.6-22 alkylaryl, aryl, cycloalkyl, C.sub.1-22 hydroxyalkyl,
polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof, or in
which R.sup.4 and R.sup.6, or R.sup.5 and R.sup.7, or R.sup.8 and
R.sup.10, or R.sup.9 and R.sup.11 may be components of a bridging
alkylene group;
[0101] R.sup.12, R.sup.13, R.sup.14 are the same or different, and
are selected from the group consisting of: C.sub.1-22 alkyl,
C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, C.sub.1-22 hydroxyalkyl,
polyalkyleneoxide, (poly)alkoxy alkyl groups, and mixtures thereof;
and
[0102] R.sup.15 is --O-- or NR.sup.19;
[0103] R.sup.16 and M.sup.1 are the same or different divalent
hydrocarbon residues;
[0104] R.sup.17, R.sup.18, R.sup.19 are the same or different, and
are selected from the group consisting of: H, C.sub.1-22 alkyl,
C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl, cycloalkyl,
C.sub.1-22 hydroxyalkyl, polyalkyleneoxide, (poly)alkoxy alkyl, and
mixtures thereof; and
[0105] Z.sup.1 and Z.sup.2 are the same or different divalent
hydrocarbon groups with at least 2 carbon atoms, optionally
containing a hydroxy group, and which may be interrupted by one or
several ether, ester or amide groups;
[0106] wherein, expressed as fractions on the total moles of the
organosilicone--free moieties, the cationic divalent organic moiety
(ii) is preferably present at of from 0.05 to 1.0 mole fraction,
more preferably of from 0.2 to 0.95 mole fraction, and most
preferably of from 0.5 to 0.9 mole fraction; the polyalkyleneoxide
amine (iii) can be present of from 0.0 to 0.95 mole fraction,
preferably of from 0.001 to 0.5, and more preferably of from 0.01
to 0.2 mole fraction; if present, the cationic monovalent organic
moiety (iv) is present of from 0 to 0.2 mole fraction, preferably
of from 0.001 to 0.2 mole fraction;
[0107] e is from 1 to 6; m is the number of positive charges
associated with the cationic divalent organic moiety, which is
greater than or equal to 2; and A is an anion.
[0108] Note that Structure 2b comprises the alternating combination
of both the polysiloxane of the depicted formula and the divalent
organic moiety, and that the divalent organic moiety is
organosilicone-free corresponding to a preferred "hook" in the
above general description. Structure 2b moreover includes
embodiments in which the optional polyalkyleneoxy and/or end group
moieties are either present or absent.
[0109] In yet another embodiment, the cationic silicone polymers
herein have one or more polysiloxane units and one or more
quaternary nitrogen moieties, and including polymers wherein the
cationic silicone polymer has the formula: (Structure 3) 6
[0110] wherein:
[0111] R.sup.1 is independently selected from the group consisting
of: C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl,
aryl, cycloalkyl, and mixtures thereof;
[0112] R.sup.2 is independently selected from the group consisting
of: divalent organic moieties that may contain one or more oxygen
atoms;
[0113] X is independently selected from the group consisting of
ring-opened epoxides;
[0114] R.sup.3 is independently selected from polyether groups
having the formula:
-M.sup.1(C.sub.aH.sub.2aO).sub.b-M.sup.2
[0115] wherein M.sup.1 is a divalent hydrocarbon residue; M.sup.2
is independently selected from the group consisting of H,
C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22 alkylaryl, aryl,
cycloalkyl, C.sub.1-22 hydroxyalkyl, polyalkyleneoxide,
(poly)alkoxy alkyl, and mixtures thereof;
[0116] X is independently selected from the group consisting of
ring-opened epoxides;
[0117] W is independently selected from the group consisting of
divalent organic moieties comprising at least one quaternized
nitrogen atom;
[0118] a is from 2 to 4; b is from 0 to 100; c is from I to 1000,
preferably greater than 20, more preferably greater than 50,
preferably less than 500, more preferably less than 300, most
preferably from 100 to 200; d is from 0 to 100; n is the number of
positive charges associated with the cationic silicone polymer,
which is greater than or equal to 1; and A is a monovalent anion,
in other words, a suitable counterion.
[0119] In preferred cationic silicone polymers of Structure 3, W is
selected from the group consisting of: 7
[0120] (d) a divalent aromatic or aliphatic heterocyclic group,
substituted or unsubstituted, containing at least one quaternized
nitrogent atom; and
[0121] wherein
[0122] R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9,
R.sup.10, R.sup.11 are the same or different, and are selected from
consisting of: C.sub.1-22 alkyl, C.sub.2-22 alkenyl, C.sub.6-22
alkylaryl, aryl, cycloalkyl, C.sub.1-22 hydroxyalkyl,
polyalkyleneoxide, (poly)alkoxy alkyl, and mixtures thereof; or in
which R.sup.4 and R.sup.6, or R.sup.5 and R.sup.7, or R.sup.8 and
R.sup.10, or R.sup.9 and R.sup.11 may be components of a bridging
alkylene group; and
[0123] Z.sup.1 and Z.sup.2 are the same or different divalent
hydrocarbon groups with at least 2 carbon atoms, optionally
containing a hydroxy group, and which may be interrupted by one or
several ether, ester or amide groups.
[0124] The cationic silicone polymer may be applied to the
embryonic fibrous web and/or applied to a dried fibrous structure
and/or before and/or concurrently and/or after converting one or
more dried fibrous structures into a sanitary tissue product.
Nonlimiting examples of suitable processes for applying the
cationic silicone polymer to the fibrous structure include
spraying, including but not limited to using a spraying disk, onto
the embryonic fibrous web and/or dried fibrous structure before it
is wound into a roll of paper, extruding, especially via slot
extrusion, onto the embryonic web and/or dried fibrous structure,
and/or by printing, especially gravure printing, onto the embryonic
fibrous web and/or dried fibrous structure and/or sanitary tissue
product.
[0125] The cationic silicone polymer may be applied to the
embryonic fibrous web and/or dried fibrous structure and/or
sanitary tissue product in a homogeneous and/or patterned and/or
inhomogeneous fashion.
[0126] The cationic silicone polymer can be applied to the
embryonic fibrous web and/or fibrous structure and/or sanitary
tissue product of the present invention as it is being made on a
papermaking machine or the her while it is wet (i.e., prior to
final drying) or dry (i.e., after final drying).
[0127] In one embodiment, an aqueous mixture containing the
cationic silicone polymer is sprayed onto the embryonic fibrous web
and/or fibrous structure and/or sanitary tissue product as it
courses through the papermaking machine: for example, and not by
way of limitation, referring to a papermaking machine of the
general configuration disclosed in U.S. Pat. No. 3,301,746, either
before the predryer, or after the predryer, or even after the
Yankee dryer/creping station although the fibrous structure is
preferably creped after the cationic silicone polymer is
applied.
[0128] The cationic silicone polymer can be applied to the
embryonic fibrous web in an aqueous solution, emulsion, or
suspension. The cationic silicone polymer can also be applied in a
solution containing a suitable, nonaqueous solvent, in which the
cationic silicone polymer dissolves or with which the cationic
silicone polymer is miscible: for example, hexane. The cationic
silicone polymer may be supplied in neat form or, preferably,
emulsified with a suitable surfactant emulsifier. The cationic
silicone polymer can be applied after embryonic fibrous web
formation has been effected. In a typical process, the embryonic
fibrous web is formed and then dewatered prior to cationic silicone
polymer application in order to reduce the loss of cationic
silicone polymer due to drainage of free water. The cationic
silicone polymer can be applied to the wet embryonic fibrous web at
a fiber consistency of greater than about 15% in the manufacture of
conventionally pressed tissue paper; and to a wet embryonic fibrous
web having a fiber consistency of between about 20% and about 35%
in the manufacture of tissue paper in papermaking machines wherein
the newly formed embryonic fibrous web is transferred from a fine
mesh Fourdrinier to a relatively coarse imprinting/carrier fabric
and/or belt.
[0129] Methods of applying the cationic silicone polymer to the
embryonic fibrous web and/or dried fibrous structure and/or
sanitary tissue product include spraying, slot extrusion and
gravure printing. Other methods include deposition of the cationic
silicone polymer onto a forming wire or fabric or belt which is
then contacted by the embryonic fibrous web and/or dried fibrous
structure and/or sanitary tissue product. Equipment suitable for
spraying cationic silicone polymer-containing liquids onto
embryonic fibrous webs and/or dried fibrous structures and/or
sanitary tissue products include external mix, air atomizing
nozzles such as the 2 mm nozzle available from V.I.B. Systems,
Inc., Tucker, Ga. Equipment suitable for printing cationic silicone
polymer-containing liquids onto embryonic fibrous webs and/or dried
fibrous structures and/or sanitary tissue products includes
rotogravure printers.
[0130] The cationic silicone polymer can be applied uniformly to
the embryonic fibrous web and/or dried fibrous structure and/or
sanitary tissue product. A uniform distribution is desirable so
that substantially the entire sheet benefits from the tactile
effect of the cationic silicone polymer. Continuous and patterned
distributions are both within the scope of the invention and meet
the above criteria.
[0131] Application methods described herein for the cationic
silicone polymer can be used with dry or wet embryonic fibrous webs
and/or fibrous structures and/or sanitary tissue products.
[0132] Exemplary art related to the addition of silicone materials
to the fibrous structure during its formation includes U.S. Pat.
No. 5,059,282 issued to Ampulski, et. al. on Oct. 22, 1991
incorporated herein by reference. The Ampulski patent discloses a
process for adding a polysiloxane compound to a wet tissue web
("fibrous structure") (preferably at a fiber consistency between
about 20% and about 35%). Such a method represents an advance in
some respects over the addition of chemicals into the slurry vats
supplying the papermaking machine. For example, such means target
the application to one of the web surfaces as opposed to
distributing the additive onto all of the fibers of the
furnish.
[0133] Considerable art has been devised to apply silicones and/or
other chemical softeners to already-dried paper webs ("fibrous
structures") either at the so-called dry end of the papermaking
machine or in a separate converting operation subsequent to the
papermaking step. Exemplary art from this field includes U.S. Pat.
No. 5,215,626 issued to Ampulski, et. al. on Jun. 1, 1993; U.S.
Pat. No. 5,246,545 issued to Ampulski, et. al. on Sep. 21, 1993;
and U.S. Pat. No. 5,525,345 issued to Warner, et. al. on Jun. 11,
1996, all incorporated herein by reference. The U.S. Pat. No.
5,215,626 discloses a method for preparing soft tissue paper by
applying a polysiloxane to a dry web ("fibrous structure"). The
U.S. Pat. No. 5,246,545 Patent discloses a similar method utilizing
a heated transfer surface. Finally, the Warner Patent discloses
methods of application including roll coating and extrusion for
applying particular compositions to the surface of a dry tissue web
("fibrous structure").
[0134] The cationic silicone may be applied to one or both surfaces
of an embryonic web and/or dried fibrous structure and/or sanitary
tissue product such that one or both external surfaces of a
resulting sanitary tissue product incorporating the fibrous
structure has the cationic silicone polymer present thereon.
[0135] In one embodiment, the cationic silicone may be applied to
one surface of an embryonic web and/or dried fibrous structure
and/or sanitary tissue product such that the cationic silicone
passes through the embryonic web and/or dried fibrous structure
and/or sanitary tissue product such that both surfaces of an
embryonic web and/or fibrous structure and/or sanitary tissue
product have cationic silicone present thereon.
[0136] The fibrous structure of the present invention and/or
sanitary tissue product incorporating such fibrous structure may
comprise from about 0.0001% to about 10% and/or from about 0.001%
to about 5% and/or from about 0.005% to about 3% and/or from about
0.005% to about 2% and/or from about 0.005% to about 1.5% by dry
weight of the fibrous structure or sanitary tissue product of the
cationic silicone polymer.
[0137] Reference is made to the following patents and patent
applications which do also disclose cationic silicone polymers
suitable for use in the present invention: WO 02/06 403; WO
02/18528, EP 1 199 350; DE OS 100 36 533; WO 00/24853; WO 02/10259;
WO 02/10257 and WO 02/10256.
[0138] Synthesis Example--When not otherwise known or available in
commerce, the cationic silicone polymers herein can be prepared by
conventional techniques as disclosed in WO 02/18528.
[0139] Other silicone compounds besides the cationic silicones
discussed above can be used as chemical softeners. Nonlimiting
examples of such other silicone compounds that are suitable for the
present invention include silicone emulsions, particularly
aminosilicones. Suitable aminosilicones are available under the
tradename AF2130, which is commercially available from Wacker
Silicones.
[0140] Processes of the Present Invention:
[0141] The fibrous structure of the present invention may be made
by any suitable papermaking process.
[0142] A nonlimiting example of a suitable papermaking process for
making the fibrous structure of the present invention is described
as follows.
[0143] In one embodiment, a fiber furnish is prepared by mixing one
or more fibers with water. One or more additional optional
ingredients may be added to the fiber furnish. The fiber furnish
may then be put into a headbox, which may be a layered headbox, of
a papermaking machine. The fiber furnish may then be deposited on a
foraminous surface to form a single layer or a multi-layer
embryonic fibrous web. The cationic silicone polymer and/or
optional ingredients may be added to the embryonic fibrous web by
spraying and/or extruding and/or printing and/or by any other
suitable process known to those of ordinary skill in the art. The
embryonic web may then be transferred to a through-air drying belt
and/or a Yankee dryer such that the embryonic fibrous web is dried
via through-air drying and/or via the Yankee dryer. From the
through-air drying belt, if there is one present, the fibrous
structure may be transferred to a Yankee dryer. From the Yankee
dryer, the fibrous structure may be transferred to a rewinder to
form a roll of dried fibrous structure. During this transfer step,
the cationic silicone polymer and/or optional ingredients may be
applied to the dried fibrous structure. The fibrous structure may
be converted into various paper products, particularly sanitary
tissue products, both in single-ply forms and/or in multi-ply
forms. During the converting step, the cationic silicone polymer
may be applied to the fibrous structure. Accordingly, the cationic
silicone polymer may be applied before and/or concurrently with
and/or after the converting step.
[0144] Test Methods
[0145] A. Coefficient of Friction
[0146] The coefficient of friction is obtained using a KES4BF
surface analyzer with a modified friction probe as described in
"Methods for the Measurement of the Mechanical Properties of Tissue
Paper", Ampulski, et. al., 1991 International Paper Physics
Conference, published by TAPPI press, and incorporated herein by
reference.
[0147] The substrate used for the friction evaluation, as disclosed
herein, is a laboratory prepared handsheet, prepared according to
TAPPI standard T-205 incorporated herein by reference. The friction
is measured on the smooth side of the handsheet (the side which is
dried against a metal plate according to the method).
[0148] The substrate is advanced at 1 mm/sec constant rate for the
measurement and the friction probe is modified from the standard
instrument probe to a two centimeter diameter 40-60 micron glass
frit.
[0149] When using a 19.6 g normal force on the probe and the
heretofore specified translation rate for the substrate, the
coefficient of friction can be calculated by dividing the
frictional force by the normal force. The frictional force is the
lateral force on the probe during the scanning, an output of the
instrument.
[0150] The average of coefficient of friction obtained by a single
scan in the forward direction and a single scan in the reverse
direction is reported as the coefficient of friction for the
specimen.
[0151] B. Physiological Surface Smoothness
[0152] Physiological surface smoothness as used herein is a factor
(hereinafter the PSS Factor) derived from scanning
machine-direction tissue paper samples with a profilometer
(described below) having a diamond stylus, the profilometer being
installed in a surface test apparatus such as, for example, Surface
Tester KES-FB-4 which is available from KATO TECH CO., LTD.,
Karato-Cho, Nishikiyo, Minami-Ku, Koyota, Japan. In this tester, a
sample of tissue is mounted on a motorized drum, and a stylus is
gravitationally biased towards the drum at the 12 o'clock position.
The drum is rotated to provide a sample velocity of one (1)
millimeter per second, and moves the sample 2 cm. with respect to
the probe. Thus, the probe scans a 2 cm length of the sample. The
profilometer comprises means for counterbalancing the stylus to
provide a normal force of 270 mg. Basically, the instrument senses
the up and down displacements (in mm) of the stylus as a 2 cm
length of sample is scanned under the profilometer probe. The
resulting stylus-amplitude vs. stylus-distance-scanned data are
digitized, and then converted to a stylus-amplitude vs. frequency
spectrum by performing a Fourier Transform using the Proc Spectra
standard program available from SAS Institute Inc., Post Office Box
10066, Raleigh, N.C. 27605. This identifies spectral components in
the sample's topography; and the frequency spectral data are then
adjusted for human tactile responsiveness as quantified and
reported by Verrillo (Ronald T. Verrillo, "Effect of Contractor
Area on the Vibrotactile Threshold", The Journal of the Accoustical
Society of America, 35, 1962 (1963)). However, whereas Verrillo's
data are in the time domain (i.e., cycles per second), and
physiological surface smoothness is related to finger-to-sample
velocity, Verrillo-type data are converted to a spatial domain
(i.e., cycles per millimeter) using 65 mm/sec as a standard
finger-to-sample velocity factor. Finally, the data are integrated
from zero (0) to ten (10) cycles per millimeter. The result is the
PSS Factor. Graphically, the PSS Factor is the area under the
Verrillo-adjusted frequency (cycles/mm) vs. stylus amplitude curve
between zero (0) and ten (10) cycles per millimeter. Preferably,
PSS Factors are average values derived from scanning multiple
samples (e.g., ten samples), both forward and backward.
[0153] The profilometer described above comprises, more
specifically, a Gould Surfanalyzer Equipment Controller
#21-1330-20428, Probe #21-3100-465, Diamond stylus tip (0.0127 mm
radius) #21-0120-00 and stylus tip extender #22-0129-00 all
available from Federal Products, Providence, R.I. The profilometer
probe assembly is fitted with a counterbalance, and set up as
depicted in FIG. 22 of U.S. Pat. No. 4,300,981 (referenced
hereinbefore).
[0154] C. Slip Stick Coefficient of Friction
[0155] Slip Stick Coefficient of Friction (hereinafter S&S COF)
is defined as the mean deviation of the coefficient of friction. It
is dimensionless. It may be determined using commercially available
test apparatus such as, for example, the Kato Surface Tester
identified above which has been fitted with a stylus which is
configured and disposed to slide on the surface of the sample being
scanned: for example, a fritted glass disk. When a sample is
scanned as described above, the instrument senses the lateral force
on the stylus as the sample is moved thereunder: i.e., scanned. The
lateral force is called the frictional force; and the ratio of
frictional force to stylus weight is the coefficient of friction,
COF. The instrument then calculates and reports the S&S COF for
each scan of each sample.
[0156] D. B Compressibility Test
[0157] A circular sample (single ply or multi-ply) of a fibrous
structure and/or a sanitary tissue product to be tested having a
2.5 inch diameter is placed on a Thwing-Albert Compressibility
Tester, commercially available from Thwing-Albert. A weight of up
to 1500 g is placed on the sample at a test speed according to the
Tester.
[0158] The thickness of the sample is measured/recorded at every 1
g of weight. The paired data (weight (X) vs. thickness (Y)) is then
placed in an X-Y graph using Microsoft Excel Program.
[0159] After the X-Y graph is created, a trendline that is
logarithmic which has an equation:
Y=Mln(X)+B
[0160] wherein M is the slope of the curve and B is the intercept.
B is the B Compressibility value of the fibrous structures and/or
sanitary tissue products incorporating such fibrous structures of
the present invention.
NONLIMITING EXAMPLES
[0161] The following nonlimiting examples employ a cationic
silicone polymer in accordance with the present invention. The
cationic silicone polymer is used typically in the form of an
emulsion containing an amine oxide, a nonionic surfactant, ethanol
and water. In one embodiment, the emulsion is formed as follows:
24.39 g of cationic silicone solution (80% cationic silicone
polymer/20% ethanol) is mixed with 6.05 g C12-15 EO3 (4) with a
normal laboratory blade mixer. After 10 minutes, 6.7 g of ethanol
is added. After another 10 minutes, 8.71 g of C12-14 alkyl dimethyl
amineoxide 31% active solution in water (2) is added. After another
10 minutes, 54.2 g of demineralized water are quickly added to the
mixture, under continuous stirring. The pH of the emulsion is
brought to pH 7.5 with 0.8 g 0.1M HCl. The emulsion can be diluted
to about 10-20% cationic silicone polymer concentration.
Example 1
A Nonlimiting Embodiment of a Fibrous Structure, such as a Facial
Tissue, in accordance with the present invention is prepared as
follows.
[0162] An aqueous slurry of Northern Softwood Kraft (NSK) of about
3% consistency is made up using a conventional pulper and is passed
through a stock pipe toward the headbox of the Fourdrinier. A 1%
dispersion of Hercules' Kymene 557 LX is prepared and is added to
the NSK stock pipe at a rate sufficient to deliver about 0.8%
Kymene 557 LX based on the dry weight of the ultimate sanitary
tissue paper. The absorption of the permanent wet strength resin is
enhanced by passing the treated slurry through an in-line mixer. An
aqueous solution of Carboxymethyl cellulose (CMC) dissolved in
water and diluted to a solution strength of 1% is added next to the
NSK stock pipe after the in-line mixer at a rate of about 0.1% CMC
by weight based on the dry weight of the ultimate sanitary tissue
paper. The aqueous slurry of NSK fibers passes through a
centrifugal stock pump to aid in distributing the CMC. An aqueous
dispersion of DiTallow DiMethyl Ammonium Methyl Sulfate (DTDMAMS)
(170.degree. F./76.6.degree. C.) at a concentration of 1% by weight
is added to the NSK stock pipe at a rate of about 0.1% by weight
DTDMAMS based on the dry weight of the ultimate sanitary tissue
paper.
[0163] An aqueous slurry of acacia pulp fibers (from PT
Tel--Indonesia) of about 1.5% by weight is made up using a
conventional repulper and is passed through a stock pipe toward the
headbox of the Fourdrinier. This Acacia furnish joins the NSK
slurry at the fan pump where both are diluted with white water to
about 0.2% consistency.
[0164] An aqueous slurry of Acacia pulp fibers (from PT
Tel--Indonesia) of about 3% by weight is made up using a
conventional repulper. The Acacia slurry passes to the second fan
pump where it is diluted with white water to a consistency of about
0.2%.
[0165] The slurries of NSK/acacia and acacia are directed into a
multi-channeled headbox suitably equipped with layering leaves to
maintain the streams as separate layers until discharged onto a
traveling Fourdrinier wire. A three-chambered headbox is used. The
acacia slurry containing 48% of the dry weight of the ultimate
sanitary tissue paper is directed to the chamber leading to the
layer in contact with the wire, while the NSK/acacia slurry
comprising 52% (27-35% NSK and 17-25% acacia) of the dry weight of
the ultimate paper is directed to the chamber leading to the center
and inside layer. The NSK/acacia and acacia slurries are combined
at the discharge of the headbox into a composite slurry.
[0166] The composite slurry is discharged onto the traveling
Fourdrinier wire and is dewatered assisted by a deflector and
vacuum boxes.
[0167] The embryonic wet web is transferred from the Fourdrinier
wire, at a fiber consistency of about 17% by weight at the point of
transfer, to a patterned, drying fabric. 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 48.times.52 filament, dual layer
mesh. The thickness of the resin cast is about 9 mil above the
supporting fabric. The knuckle area is about 35-50% and the open
cells remain at a frequency of about 10-87 per cm.sup.2.
[0168] Further de-watering is accomplished by vacuum assisted
drainage until the web has a fiber consistency of about 23-27%.
[0169] While remaining in contact with the patterned forming
fabric, the patterned web is pre-dried by air blown through to a
fiber consistency of about 60% by weight.
[0170] The semi-dry web is then adhered to the surface of a Yankee
dryer with a sprayed creping adhesive comprising a 0.250% aqueous
solution of polyvinyl alcohol. The creping adhesive is delivered to
the Yankee surface at a rate of 0.1% adhesive solids based on the
dry weight of the web. The fiber consistency is increased to about
98% before the web is dry creped from the Yankee with a doctor
blade. After the doctor blade, the web is calendared across all its
width with a steel to rubber calendar roll operating at a loading
of 2-3.5 MPa.
[0171] The resulting tissue has a basis weight of about 20-25
g/m.sup.2; a 1-ply total dry tensile between 225 and 300 g/cm, a
1-ply wet burst between 30 and 65 gr/cm and a 2-ply caliper of
about 0.035-0.05 cm. The resulting tissue is then combined with a
like sheet to form a two-ply, creped, pattern-densified tissue so
that the acacia fibers face the outside and it is subjected to
calendaring between two smooth steel calendar rolls. The cationic
silicone polymer emulsion is then slot extruded onto both sides in
contact with a human's skin, at an add-on amount of approximately
0.8-1.0 g/m.sup.2 of emulsion per side, equivalent to a total
add-on level of 0.7-1.0% by weight of silicone per ply, based on
the total weight of fibers. Product is then ply-bonded using a
mechanical plybond wheel to ensure that both plies stay together.
The resulting two-ply tissue has a) a total basis weight of about
39-50 g/m.sup.2; b) a 2-ply total dry tensile between 450 and 550
gr/cm; c) a 2-ply wet burst between 55 and 120 gr/cm; d) a 4-ply
caliper of about 0.05 and 0.09 cm; e) a slip-stick coefficient of
friction (MMD) of about 0.0146-0.0172; f) a Coefficient of Friction
(MIU) of about 0.734-0.742; g) a B Compressibility of 29-31; h) a
calculated WABY factor of about 0.0786-0.0836; i) a PAA of about
720-770; and j) a lint of about 9-12 lint units.
[0172] The resultant tissue paper is judged significantly softer
than an untreated tissue sample by a panel of expert judges.
[0173] All documents cited in the Detailed Description of the
Invention are, in relevant part, incorporated herein by reference;
the citation of any document is not to be considered as an
admission that it is prior art with respect to the present
invention.
[0174] 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.
* * * * *