U.S. patent application number 11/027617 was filed with the patent office on 2006-07-06 for softening agent pre-treated fibers.
Invention is credited to Deborah Joy Nickel, Troy Michael Runge.
Application Number | 20060144541 11/027617 |
Document ID | / |
Family ID | 36097171 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060144541 |
Kind Code |
A1 |
Joy Nickel; Deborah ; et
al. |
July 6, 2006 |
Softening agent pre-treated fibers
Abstract
A paper product includes fibers, such as cellulosic fibers, that
are pre-treated with a softening agent. The softening agent is
added to a fiber slurry and then is allowed to cure onto the
fibers, typically by drying. The pre-treated fibers are then
diluted, re-slurried, and incorporated into the fiber stream of a
paper machine to form a fibrous web. The fibrous web can then be
converted into a paper product, such as a personal care paper
product, which exhibits improved softness with minimized
slough.
Inventors: |
Joy Nickel; Deborah;
(Appleton, WI) ; Runge; Troy Michael; (Appleton,
WI) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
US
|
Family ID: |
36097171 |
Appl. No.: |
11/027617 |
Filed: |
December 30, 2004 |
Current U.S.
Class: |
162/158 ;
162/146; 162/164.3; 162/164.6; 162/168.3; 162/175; 162/179;
162/182 |
Current CPC
Class: |
D21H 15/04 20130101;
D21H 11/20 20130101; D21H 21/16 20130101; D21H 21/20 20130101; D21H
27/30 20130101 |
Class at
Publication: |
162/158 ;
162/182; 162/175; 162/164.3; 162/164.6; 162/168.3; 162/179;
162/146 |
International
Class: |
D21H 21/22 20060101
D21H021/22 |
Claims
1. A paper product comprising at least one fibrous web which
comprises pre-treated cellulosic fibers, wherein said pre-treated
cellulosic fibers have been cured with a softening agent prior to
incorporation into said paper product.
2. The paper product of claim 1 comprising about 10% to about 50%
of said pre-treated cellulosic fibers.
3. The paper product of claim 1 wherein said at least one fibrous
web comprises pre-treated cellulosic fibers having a Water
Retention Value below 0.9 g/g.
4. The paper product of claim 1 wherein said at least one fibrous
web has a tensile strength that is reduced by at least 50% compared
to the same fibrous web comprising untreated cellulosic fibers.
5. The paper product of claim 1 wherein said softening agent is
selected from the group consisting of wet strength resins, sizing
agents, latex emulsions, cross-linking agents, and combinations
thereof.
6. The paper product of claim 5 wherein said wet strength resin is
selected from the group consisting of glyoxylated polyacrylamide,
dialdehyde starch, aldehyde containing,
polyamide-polyamine-epichlorohydrin, polyethylenimine resins,
aminoplast, and combinations thereof.
7. The paper product of claim 5 wherein said sizing agent is
selected from the group consisting of alkenyl succinic anhydride,
alkyl ketene dimer, amylopectin starch, and combinations
thereof.
8. The paper product of claim 5 wherein said latex emulsion is a
complex formed from a hydrophobic polymer anionic styrene butadiene
latex emulsion at a solids content of about 50% by weight and a
quaternary amine imidazoline softener at a solids content of about
80% by weight.
9. The paper product of claim 5 wherein said cross-linking agent is
chosen from the group consisting of styrene-butadiene copolymers,
polyvinyl acetate copolymers, vinyl-acetate acrylic copolymers,
ethylene-vinyl chloride copolymers, acrylic polymers, nitrile
polymers, dispersed polyolefins, and combinations thereof.
10. The paper product of claim 1 further comprising a debonding
agent.
11. The paper product of claim 1 wherein said pre-treated
cellulosic fibers are not distributed uniformly throughout said
soft paper product.
12. The paper product of claim 1 wherein said pre-treated
cellulosic fibers are distributed discretely within said soft paper
product.
13. The paper product of claim 1 wherein said pre-treated
cellulosic fibers have a curl index less than 0.2.
14. The paper product of claim 1 wherein said pre-treated
cellulosic fibers comprise substantially hardwood fibers.
15. The paper product of claim 14 wherein said hardwood fibers
comprise Eucalyptus fibers.
16. The paper product of claim 1 wherein said at least one fibrous
web is a multi-layered fibrous web having two outer layers, wherein
at least one of said two outer layers comprises said pre-treated
cellulosic fibers.
17. A method for making a paper product comprising: providing a
fiber slurry comprising water and cellulosic fibers; adding a
softening agent to said cellulosic fibers; allowing said softening
agent to cure with said cellulosic fibers to form pre-treated
fibers; diluting said pre-treated fibers with water; re-slurrying
said pre-treated fibers and water to form a pre-treated fiber
slurry; incorporating said pre-treated fiber slurry into a fiber
stream of a papermaking machine; forming a fibrous web comprising
said pre-treated fibers on said papermaking machine; and converting
said fibrous web into a paper product.
18. The method of claim 17 further comprising adding a debonding
agent to said fiber stream.
19. The method of claim 17 wherein said paper product comprises
about 10% to about 50% of said pre-treated cellulosic fibers.
20. The method of claim 17 wherein said fibrous web further
comprises synthetic fibers.
Description
BACKGROUND
[0001] The invention generally concerns paper products and
properties thereof. More particularly, in the manufacture of
personal care paper products, such as facial tissues, bath tissues,
napkins, wipes, and paper towels, it is often desired to optimize
various aesthetic and performance related properties. For example,
personal care products should generally exhibit a soft feel, low
slough, good bulk, and sufficient strength to perform the desired
functions.
[0002] Unfortunately, when steps are taken to increase one of these
properties, other such properties may also be adversely affected.
For instance, softness is an important aesthetic property of many
personal care paper products, so it is desirable in the art to
develop products which exhibit improved softness. One conventional
method for improving softness in such products is to apply a
chemical debonder to the fiber-water suspension in the wet-end
section of a paper machine. Another conventional method is to spray
such a chemical debonder directly onto the fibrous web in the
forming section of a paper machine. In either case, the chemical
debonder interrupts the bonding which would normally take place
between the fibers, which reduces the overall strength of the
fibrous web. This reduction in strength corresponds directly to an
increase in softness.
[0003] However, this same reduction in strength also leads to an
increase in slough, which is generally undesirable for personal
care products. For example, during processing and/or use, the
loosely bound (i.e., debonded) fibers can be freed from the paper
product, thereby creating airborne fibers and fiber fragments.
Moreover, zones of fibers that are poorly bound to each other but
not to adjacent zones of fibers may be created which can break away
from the paper surface and then can deposit onto other surfaces,
such as human skin or clothing. Therefore, there is a desire for a
paper product which exhibits improved softness while minimizing the
level of slough.
SUMMARY
[0004] The invention concerns a paper product and properties
thereof. More particularly, the invention concerns a soft, low
slough paper product which comprises at least a quantity of
cellulosic fibers which have been pre-treated with a softening
agent, then allowed to cure, and then diluted and incorporated into
a paper machine's fiber stream. In one embodiment, the pre-treated
fibers exhibit a Water Retention Value below 0.9 g/g. In another
embodiment, the fibers have a degree of curl that is less than
1.3.
[0005] The resulting paper product can comprise about 10% to about
100% pre-treated fibers, such as about 10% to about 50% pre-treated
fibers. The paper product can also comprise a single layer or
multiple layers of pre-treated and/or untreated fibers. In one
embodiment, the tensile strength of a fibrous web comprising
pre-treated fibers is reduced by 50% as compared to the same
fibrous web consisting of untreated fibers.
[0006] Numerous other features and advantages of the present
invention will appear from the following description. In the
description, reference is made to the accompanying drawings which
help illustrate exemplary embodiments of the invention. Such
embodiments do not represent the full scope of the invention.
Reference should therefore be made to the claims herein for
interpreting the full scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing and other features, aspects and advantages of
the present invention will become better understood with regard to
the following description, appended claims and accompanying
drawings where:
[0008] FIG. 1 illustrates one embodiment of a dry-lap machine that
can be used for pre-treating fibers with a softening agent;
[0009] FIG. 2 illustrates one embodiment of a paper machine that
can be used to form a fibrous web comprising at least pre-treated
fibers made in accordance with the present invention;
[0010] FIG. 3 illustrates one embodiment of a headbox that can be
used in accordance with the present invention;
[0011] FIG. 4a illustrates an apparatus for testing slough; and
[0012] FIG. 4b is a perspective view of the abrasive spindle of
FIG. 4a.
[0013] Repeated use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present invention.
Definitions
[0014] It should be noted that, when employed in the present
disclosure, the terms "comprises," "comprising" and other
derivatives from the root term "comprise" are intended to be
open-ended terms that specify the presence of any stated features,
elements, integers, steps, or components, and are not intended to
preclude the presence or addition of one or more other features,
elements, integers, steps, components, or groups thereof.
[0015] The terms "additive" and "chemical additive" refer to a
single treatment compound or to a mixture of treatment
compounds.
[0016] The terms "cure," "cured," "curing" and other derivatives of
the term "cure" refer to the drying of fibers that have been
pre-treated with a softening agent of the present invention such
that the softening agent substantially adheres to and retains to
such fibers through a papermaking process and paper converting
process. The dryness required to cure the softening agent(s) onto
the fibers will vary depending on the softening agent(s) utilized.
However, in general, the pre-treated fibers may be dried to a
consistency of at least about 80% by weight.
[0017] The term "nits" refers to fiber/polymer bundles that create
the appearance of white spots within a fibrous web and/or paper
product. These white spots will generally be on the order of one
square millimeter in size or greater. A "nit count" refers to the
number of nits counted in a 7.5 inch by 7.5 inch sample of a
fibrous web and/or paper product made from pre-treated pulp fibers.
The fibrous web and/or paper product should have a nit count of
about 10 or less, more specifically about 5 or less, and still more
specifically about 3 or less.
[0018] The term "personal care paper product" is used herein to
broadly include tissue such as bath tissue, facial tissue, napkins,
wipers, and towels, along with other cellulose structures including
absorbent pads, intake webs in absorbent articles such as diapers,
bed pads, wet wipes, meat and poultry pads, feminine care pads, and
the like made in accordance with any conventional process for the
production of such products. The term "paper" as used herein
includes any fibrous web containing cellulosic fibers alone or in
combination with other fibers, natural or synthetic. A paper
product can be layered or unlayered, creped or uncreped, and can
comprise a single ply or multiple plies. In addition, the paper
product can contain reinforcing fibers for integrity and
strength.
[0019] The term "slough" refers to the loss of paper particles from
the surface of the paper due to surface abrasion. Slough tends to
increase when conventional softening techniques, such as the use of
chemical debonders, are utilized in the wet-end section of a paper
machine. In general, slough is an undesirable property for personal
care paper products. For example, many consumers react negatively
to paper that exhibits a high level of slough. Therefore, it is a
desire to provide a paper product that exhibits a minimal amount of
slough.
[0020] The term "softening agent" refers to chemical additives that
can be incorporated into paper products to provide improved
softness and tactile feel. These chemical additives can also act to
reduce paper stiffness and paper strength, and can act solely to
improve the surface characteristics of tissue, such as by reducing
the coefficient of friction between the paper surface and a
person's hand.
[0021] The term "water" refers to water or a solution containing
water and other treatment additives desired in the papermaking
process.
[0022] These terms may be defined with additional language in the
remaining portions of the specification.
DETAILED DESCRIPTION
[0023] The present invention concerns a paper product, such as a
personal care paper product, and properties thereof. Generally
stated, the present invention is directed to a paper product that,
among other things, exhibits an improved level of softness and
which minimizes slough. In particular, the paper product includes
fibers that are pre-treated with a softening agent wherein the
softening agent has been cured onto the fibers, and wherein the
fibers are then diluted and incorporated into the fiber stream of a
paper machine.
[0024] Personal care paper products can generally be formed in
accordance with the present invention from at least one fibrous
web. For example, in one aspect, the paper product can contain a
single-layered fibrous web formed from a blend of pre-treated and
untreated fibers. In another aspect, the paper product can contain
a multi-layered (i.e., stratified) fibrous web wherein at least one
layer comprises at least pre-treated fibers, and at least one layer
comprises at least untreated fibers. Furthermore, the paper product
itself can be constructed from a single fibrous web or from
multiple fibrous webs. In one particular aspect, at least one
fibrous web in the paper product comprises pre-treated fibers
according to the present invention.
[0025] In general, the basis weight of a fibrous web of the present
invention is less than about 200 grams per square meter (gsm), such
as between about 5 and about 120 gsm or between about 10 and about
70 gsm. Fibers that are suitable for the invention include
cellulosic fibers such as hardwood fibers, softwood fibers,
recycled fibers, and the like, as well as synthetic fibers. Such
fibers can be formed by a variety of pulping processes, including
Kraft, sulfite, mechanical, thermomechanical, and
chemithermomechanical pulping processes, and the like. In one
example, the paper product includes a fibrous web having at least
one layer formed primarily from pre-treated Kraft hardwood
fibers.
[0026] Hardwood fibers such as Eucalyptus, maple, birch, and aspen
typically have an average fiber length of about 0.5 mm to about 1.5
mm and exhibit relatively large diameters (as compared to softwood
fibers). As such, hardwood fibers may be more useful for enhancing
the softness of a fibrous web than softwood fibers. Therefore, it
may be desirable to provide at least one outer surface of a paper
product which comprises substantially hardwood fibers. However,
when conventional methods are utilized to enhance softness, such as
through the addition of a chemical debonder in the wet-end section
of a paper machine, fibrous webs containing hardwood fibers tend to
result in substantially higher levels of slough.
[0027] In contrast, softwood fibers such as northern softwood,
southern softwood, redwood, cedar, hemlock, pine, and spruce
typically have an average fiber length of about 1.5 mm to about 3
mm with relatively small diameters (as compared to hardwood). As
such, softwood fibers may be more useful for enhancing the strength
of a fibrous web than hardwood fibers. However, softwood fibers
substantially reduce the softness of a fibrous web. In addition,
softwood fibers can also result in increased levels of slough when
conventional methods are used to enhance softness. Therefore,
softwood fibers are typically blended with hardwood fibers, or may
be used as an inner layer in a multi-layered fibrous web.
[0028] If desired, secondary fibers obtained from recycled
materials may also be utilized in a paper product of the invention.
Such secondary fibers can be obtained from sources including old
newsprint, reclaimed paperboard, envelopes, and mixed office waste.
Additionally, other natural fibers can be utilized in the present
invention, such as abaca, sabai grass, milkweed floss, pineapple
leaf, and the like. Furthermore, in some instances, synthetic
fibers can also be utilized, such as rayon fibers, ethylene vinyl
alcohol copolymer fibers, polyolefin fibers, polyesters, and the
like.
[0029] Suitable cellulosic fibers for the present invention can
include, for example, ARACRUZ ECF, a Eucalyptus hardwood Kraft pulp
available from Aracruz, a business having offices located in Rio de
Janeiro, RJ, Brazil; LONGLAC-19, a northern softwood Kraft pulp
available from Neenah Paper Incorporated, a business having offices
located in Alpharetta, Ga., U.S.A.; NB 416, a bleached southern
softwood Kraft pulp, available from Weyerhaeuser Co., a business
having offices located in Federal Way, Wash., U.S.A.; CR 54, a
bleached southern softwood Kraft pulp, available from Bowater Inc.,
a business having offices located in Greenville, S.C., U.S.A.;
SULPHATATE HJ, a chemically modified hardwood pulp, available from
Rayonier Inc., a business having offices located in Jesup, Ga.,
U.S.A.; NF 405, a chemically treated bleached southern softwood
Kraft pulp, available from Weyerhaeuser Co.; and CR 1654, a mixed
bleached southern softwood and hardwood Kraft pulp, available from
Bowater Inc.
[0030] As referenced above, a paper product of the present
invention can be formed from one or more fibrous webs, each of
which can be single-layered or multi-layered. For instance, in one
aspect, the paper product can comprise a single-layered paper web
that is formed from a blend of fibers. For example, in some
instances, Eucalyptus and softwood fibers can be homogeneously
blended to form the single-layered paper web. In another aspect,
the paper product can contain a multi-layered paper web that is
formed from a stratified pulp furnish having various principal
layers. In one particular aspect, the fibrous web can comprise
three layers wherein at least one of the outer layers includes
pre-treated Eucalyptus fibers, while at least the inner layer
includes untreated northern softwood Kraft fibers. In another
aspect, the fibrous web can comprise two layers wherein one layer
comprises pre-treated hardwood Kraft fibers, while the remaining
outer layer comprises a blend of untreated northern softwood Kraft
fibers and untreated synthetic fibers. In still another aspect, the
fibrous web can comprise three layers wherein at least one of the
outer layers includes a blend of pre-treated hardwood fibers and
untreated softwood fibers, while the inner layer comprises
untreated recycled fibers. It should be understood that a
multi-layered paper web can include any number of layers and can be
made from various types of fibers.
[0031] In accordance with the present invention, various properties
of a paper product such as described above, can be optimized. For
instance, softness, slough level, strength (e.g., tensile index),
bulk and the like, are some examples of properties which may be
optimized in accordance with the present invention. However, it
should be understood that not every property mentioned above needs
be optimized in every instance. For example, in certain
applications, it may be desired to form a paper product that has
optimized softness without regard to strength.
[0032] For purposes of the invention, the process of pre-treating
fibers with a suitable softening agent can be accomplished by first
adding a softening agent to a slurry or a web of fibers, then
allowing the combination to dry to at least about 80% consistency
such that the softening agent cures onto the fibers, and then
diluting the fibers with water, re-slurrying the fibers, and
incorporating the pre-treated fibers into the fiber stream of a
papermaking process. The result is a paper product which exhibits
an increased level of softness while minimizing the level of
slough. Without being bound by a particular theory, it is believed
that pre-treating fibers with a softening agent in accordance with
the invention results in fibers that can have areas of high
strength while decreasing the overall bonded area between the
fibers. More particularly, it is believed that the overall bonded
area is decreased due to the pre-treated fibers' inability to
conform to neighboring fibers (i.e., less flexibility), thus
creating more voids between the fibers during the papermaking
process.
[0033] Suitable softening agents should have the ability to cure
onto the fibers, and should allow the fibers to be re-slurried
substantially without nits. In some aspects, the softening agent
can decrease the contact angle of the fiber and/or prevent the
fiber from swelling through mechanisms such as cross-linking. In
other aspects, the softening agent can decrease the overall bonding
potential of the fibers without decreasing the surface fiber
tension of the fiber-water suspension. In still other aspects, the
softening agent can decrease the strength of a fibrous web formed
from the pre-treated fibers by at least about 30%, such as at least
about 50%, as compared to a similar web consisting of untreated
fibers. In yet other aspects, fibrous webs comprising pre-treated
fibers can exhibit a Water Retention Value of about 0.9 g/g or
less.
[0034] Without being held to a particular theory, it is believed
that suitable softening agents used for pre-treating fibers in
accordance with the present invention result in fibers that are
more resilient to compression when wet. This, in turn, can prevent
full bonding of such fibers to neighboring fibers in a fiber-water
suspension, and thus increases softness of a resulting paper
product. Additionally, higher bulk may be obtained in wet-pressed
webs because such pre-treated fibers can resist compression from a
pressure roll on a paper machine. Furthermore, it is believed that
the pre-treated fibers tend not to debond through reduction of
surface tension, thus unretained resin would tend not to have an
adverse effect on other fibers, such as those used for the purpose
of increasing strength.
[0035] Suitable softening agents include wet strength resins,
sizing agents, latex emulsions, cross-linking agents, and
thermoplastics, as well as other additives. In general, wet
strength resins are typically used to impart mechanical strength to
a paper product under wet conditions without adversely affecting
absorbency properties. However, as used in accordance with the
present invention, wet strength resin can result in a personal care
paper product which exhibits improved softness while minimizing
slough. Suitable wet strength resins can be temporary or permanent,
and can be cationic, anionic, or nonionic.
[0036] Examples of suitable temporary wet strength resins include,
but are not limited to, cationic glyoxylated polyacrylamides such
as those under the trade name PAREZ 631 NC and PAREZ 725, available
from Cytec Industries Inc., a business having offices located in
West Paterson, N.J., U.S.A. and HERCOBOND 1366, available from
Hercules Inc., a business having offices located in Wilmington,
Del., U.S.A. Other similar resins are described in U.S. Pat. No.
3,556,932 to Williams et al., herein incorporated by reference in a
manner consistent with the present disclosure. Still other suitable
temporary wet strength resins include dialdehyde starches, such as
those under the trade name COBOND 1000, available from National
Starch and Chemical Company, a business having offices located in
Bridgewater, N.J., U.S.A. as well as those described in U.S. Pat.
No. 6,224,714 to Schroeder et al.; U.S. Pat. No. 6,274,667 to
Shannon et al.; U.S. Pat. No. 6,287,418 to Schroeder et al.; U.S.
Pat. No. 6,365,667 to Shannon et al. U.S. Pat. No. 4,675,394 to
Solarek et al., and Japanese Kokai Tokkyo Koho JP 03,185,197, all
of which are herein incorporated by reference in a manner
consistent with the present disclosure. Still other suitable
temporary wet strength resins include, but are not limited to,
dialdehyde starch, polyethylene imine, mannogalactan gum, glyoxal,
and dialdehyde mannogalactan. Other suitable temporary wet-strength
agents are described in U.S. Pat. No. 3,556,932 to Coscia et al.;
U.S. Pat. No. 5,466,337 to Darlington, et al.; U.S. Pat. No.
3,556,933 to Williams et al.; U.S. Pat. No. 4,605,702 to Guerro et
al.; U.S. Pat. No. 4,603,176 to Bjorkquist et al.; U.S. Pat. No.
5,935,383 to Sun, et al.; and U.S. Pat. No. 6,017,417 to Wendt, et
al., all of which are herein incorporated by reference in a manner
consistent with the present disclosure.
[0037] Examples of suitable permanent wet strength resins include,
but are not limited to, cationic oligomeric or polymeric resins, as
well as those described in U.S. Pat. No. 2,345,543 to Wohnsiedler
et al.; U.S. Pat. No. 2,926,116 to Keim; and U.S. Pat. No.
2,926,154 to Keim. Other suitable permanent wet strength agents
include polyamine-epichlorohydrin, polyamide epichlorohydrin or
polyamide-amine epichlorohydrin resins, which are collectively
termed "PAE resins." These materials have been described in U.S.
Pat. No. 3,700,623 to Keim; U.S. Pat. No. 3,772,076 to Keim; U.S.
Pat. No. 3,855,158 to Petrovich et al.; U.S. Pat. No. 3,899,388 to
Petrovich et al.; U.S. Pat. No. 4,129,528 to Petrovich et al.; U.S.
Pat. No. 4,147,586 to Petrovich et al.; and U.S. Pat. No. 4,222,921
to Van Eenam, all of which are herein incorporated by reference in
a manner that is consistent with this disclosure. Still other
suitable permanent wet strength resins included polyethyenimine
resins and aminoplast resins obtained by reaction of formaldehyde
with melamine or urea. In one example of the present invention
KYMENE 6500, a polyamide-polyamine-epichlorohydrin commercially
available from Hercules Inc. is utilized as the softening agent.
Other commercially available resins include KYMENE 557H and KYMENE
557LX, also from Hercules Inc. In some aspects, it is advantageous
to utilize both permanent and temporary wet strength resins for
pre-treating the fiber.
[0038] As mentioned above, sizing agents can also be utilized as
the softening agent. In general, sizing agents are typically used
in non-absorbent paper products, such as fine paper, to control
excess penetration of coating formulations and ink, reduce
bleed-through for improved print quality, and improve opacity.
However, when used in accordance with the present invention, sizing
agents can result in a personal care paper product which exhibits
improved softness while minimizing slough. Suitable sizing agents
can be natural or synthetic, and can be cationic, anionic, or
nonionic. Suitable natural sizing agents include, but are not
limited to, rosins and modified and unmodified natural starches
such as reserve polysaccharides found in plants (e.g., corn, wheat,
potato and the like) that can have linear (amylose) and/or branched
(amylopectin) polymers of alpha-D-glucopyranosyl units. Suitable
synthetic sizing agents include, but are not limited to, synthetic
copolymers such as polyvinyl alcohol and styrene, as well as other
cellulose-reactive sizes including alkenyl succinic anhydride and
alkyl ketene dimer. In one example of the invention, HERCON 70
sizing agent, an alkyl ketene dimer commercially available from
Hercules Inc., is utilized as the softening agent.
[0039] As mentioned above, latex emulsions can also be utilized as
the softening agent. In general, latex emulsions are typically used
in coatings for fine paper, publication paper and coated paperboard
used in packaging, such as for improved printing performance.
However, when used in accordance with the present invention, latex
emulsions can result in a personal care paper product which
exhibits improved softness while minimizing slough. For purposes of
the present invention, latex emulsions can be used on there own, or
in conjunction with another polymer to form a latex emulsion
complex. Suitable latex emulsions include AIRFLEX 124, AIRFLEX 426,
and AIRFLEX EN1165, all available from Air Products, a business
having offices in Allentown, Pa., U.S.A., and RESYN 225A, available
from National Starch, a business having offices in Chicago, Ill.,
U.S.A. In one example of the present invention, a latex emulsion
complex containing an anionic styrene butadiene latex emulsion at a
solids content of about 50% by weight under the trade name LATRIX
6300, available from Nalco Company, a business having offices in
Naperville, Ill., U.S.A. combined with a quaternary amine
imidazoline softener at a solids content of about 80% by weight
under the trade name PROSOFT TQ-1003, available from Hercules Inc.,
is utilized as the softening agent.
[0040] As mentioned above, cross-linking agents can also be
utilized as the softening agent. In general, cross-linking agents
are typically used to impart high strength in paper products which
may be subjected to rigorous wet conditions, such as filtering
paper. However, when used in accordance with the present invention,
cross-linking agents can result in a personal care paper product
which exhibits improved softness while minimizing slough. Suitable
cross-linking agents include, but are not limited to,
styrene-butadiene copolymers, polyvinyl acetate copolymers,
vinyl-acetate acrylic copolymers, ethylene-vinyl chloride
copolymers, acrylic polymers, nitrile polymers, dispersed
polyolefins, diols, polyols, diamines, polyamines, dicarboxylic
acids, polycarboxylic acids, dialdehydes, polyaldehydes, butandiol,
diethylene triamine, citric acid, glutaric dialdehyde and ethylene
glycol diglycidyl ether, tri-valent or tetra-valent metal ions, and
combinations thereof.
[0041] The amount of softening agent added for pre-treating fibers
in accordance with the present invention will vary depending upon
the softening agent chosen. For example, in one aspect, a wet
strength resin such as KYMENE 6500 can be utilized in an amount
ranging from about 0.1 to about 10 dry kilograms/oven dry
metric-ton (kg/ODMT) of fiber, such about 1 to about 2 dry kg/ODMT
of fiber. Alternatively, the same KYMENE 6500 can be utilized in a
pre-treatment amount which results in about 0.01 to about 5 dry
kg/ODMT, such as about 0.2 to about 1 dry kg/ODMT of KYMENE 6500 on
the treated fibers in the finished product. In another aspect, a
sizing agent such as HERCON 70 can be utilized in an amount ranging
from about 1 to 10 dry kg/ODMT of fiber. In still another aspect, a
latex emulsion complex can be utilized in an amount ranging from
about 1 to 10 dry kg/ODMT of fiber. In yet another aspect, a
cross-linking agent can be utilized in an amount ranging from about
0.1 to 10 dry kg/mt of dry fiber. Additionally combinations of
these agents are considered within the scope of this invention.
[0042] Numerous methods can be utilized for pre-treating fibers
with a softening agent in accordance with the present invention.
Such methods should include the ability for the softening agent to
be cured onto the fibers, such as by drying, and should allow for
the fibers to be diluted with water and re-slurried substantially
without nits. For example, in one aspect, the softening agent can
be added to dry-lap pulp during a dry-lap pulp manufacturing
process either in the wet-end stock or onto the formed sheet such
as before the dryer section. In another aspect, the softening agent
can be added in a side-stream process as part of a papermaking
system where the pre-treated fibers are allowed to dry and then
re-slurried and incorporated into the papermaking fiber system.
[0043] An exemplary process for pre-treating fibers with a
softening agent in accordance with the present invention is
described below. With reference to FIG. 1, dry-lap pulp
manufacturing equipment 20 is illustrated in which a softening
agent can be applied to pulp fibers according to one aspect of the
present invention. A fiber slurry 10 is prepared and thereafter
transferred through suitable conduits (not shown) to the headbox 28
where the fiber slurry 10 is injected or deposited onto a
fourdrinier section 30 thereby forming a wet fibrous web 32. The
wet fibrous web 32 may be subjected to mechanical pressure to
remove process water. It is understood that the process water may
contain process chemicals used in treating the fiber slurry 10
prior to a web formation step.
[0044] In the illustrated example, the fourdrinier section 30
precedes a press section 44, although alternative dewatering
devices such as a nip thickening device, or the like may be used.
The fiber slurry 10 is deposited onto a foraminous fabric 46 such
that the fourdrinier section filtrate 48 is removed from the wet
fibrous web 32. The fourdrinier section filtrate 48 comprises a
portion of the process water. The press section 44 or other
dewatering device known in the art suitably increases the fiber
consistency of the wet fibrous web 32 to about 30% by weight or
greater, such as about 40% by weight or greater, thereby creating a
dewatered web 33. The process water removed as fourdrinier section
filtrate 48 during the web forming step may be used as dilution
water for dilution stages in the pulp processing or may be
discarded.
[0045] The dewatered fibrous web 33 may be further dewatered in
additional press sections or other dewatering devices known in the
art. The suitably dewatered fibrous web 33 may be transferred to a
dryer section 34 where evaporative drying is carried out on the
dewatered fibrous web 33 to a consistency of about 80% by weight or
greater, thereby forming a dried fibrous web (i.e., dry-lap) 36.
The dry-lap 36 is thereafter wound on a reel 37 or slit, or cut
into sheets, and allowed to sufficiently cure before delivery to a
paper machine.
[0046] The softening agent 24 may be added or applied to the
dewatered fibrous web 33 or the dry-lap 36 at a variety of addition
points 35a, 35b, 35c, and 35d as shown in FIG. 1. It is understood
that while only four addition points 35a, 35b, 35c, and 35d are
shown in FIG. 1, the application of the softening agent 24 may
occur at any point between the point of initial dewatering of the
wet fibrous web 32 to the point the dry-lap 36 is wound on the reel
37 or baled for transport to the paper machines. The addition point
35a shows the addition of the softening agent 24 within press
section 44. The addition point 35b shows the addition of the
softening agent 24 between the press section 44 and the dryer
section 34. The addition point 35c shows the addition of the
softening agent in the dryer section 34. The addition point 35d
shows the addition of the softening agent 24 between the dryer
section 34 and the reel 37.
[0047] Once the softening agent has sufficiently cured onto the
fibers, the dry-lap 36 can be diluted with water and re-slurried to
form a softening agent pre-treated fiber slurry. The pre-treated
fiber slurry can then be incorporated into the fiber stream of a
paper machine and processed to form a finished product.
[0048] A paper product made in accordance with the present
invention can generally be formed according to a variety of
papermaking processes known in the art. In fact, any process
capable of making a paper web can be utilized in the present
invention. For example, a papermaking process of the present
invention can utilize wet-pressing, creping, through-air-drying,
creped through-air-drying, uncreped through-air-drying, single
recreping, and double recreping. Also, calendering, embossing, as
well as other steps in processing the paper web may also be
utilized. By way of illustration, various suitable papermaking
processes are disclosed in U.S. Pat. No. 5,667,636 to Engel et al.;
U.S. Pat. No. 5,607,551 to Farrington, Jr. et al.; U.S. Pat. No.
5,672,248 to Wendt et al.; and, U.S. Pat. No. 5,494,554 to Edwards
et al., all of which are herein incorporated by reference in a
manner that is consistent with the present disclosure.
[0049] An exemplary paper making process which could be utilized
for the present invention is described below. In general, one or
more fiber furnishes are provided. For instance, in one aspect, two
fiber furnishes can be utilized. Although other fibers may be
utilized, at least one fiber furnish should comprise pre-treated
fibers. Moreover, by way of example, a second fiber furnish can be
utilized containing pre-treated or untreated softwood fibers. In
still other aspects, by way of example, the second fiber furnish or
a third fiber furnish can contain pre-treated or untreated
hardwood, softwood, recycled fibers, synthetic fibers, or
combinations thereof.
[0050] The above exemplary fiber furnishes can then be fed to
separate pulpers that disperse the fibers into individual fibers.
The pulpers can run continuously or in a batch format to supply
fibers to the papermaking machine. Once the fibers are dispersed,
the furnishes can then, in some embodiments, be pumped to a dump
chest and diluted to about a 3% to about a 4% by weight
consistency. For example, in one aspect, a fiber furnish containing
pre-treated fibers can be transferred to a dump chest. Thereafter,
the fiber furnish can be transferred directly to a clean stock
chest, where it is diluted to a consistency of about 2% to about a
3% by weight. If desired, additional chemical additives can also be
added to the dump chest and/or clean stock chest to improve various
properties of the finished product. The furnish(es) can further be
diluted, if desired, to about 0.1% by weight consistency at the fan
pump prior to entering the headbox of a paper machine.
[0051] With reference to FIG. 2, an exemplary fibrous web forming
process (i.e., papermaking machine) is described. In this example,
a tissue web 64 is formed by feeding a fiber slurry 42 comprising
pre-treated fibers into a 2-layer headbox 50. The headbox 50
deposits the fiber slurry 49 between a forming fabric 52 and a
conventional wet press papermaking (or carrier) felt 56 which wraps
at least partially about a forming roll 54 and a press roll 58 to
create a tissue web 64. The tissue web 64 is then transferred from
the papermaking felt 56 to the Yankee dryer 60 by applying the
vacuum press roll 58. An adhesive mixture is optionally sprayed
using a spray boom 59 onto the surface of the Yankee dryer 60 just
before the application of the tissue web 64 onto the Yankee dryer
60 from the press roll 58. In some aspects, certain additives can
be applied to the paper web as the web traverses over the dryer 60.
A natural gas heated hood (not shown) may partially surround the
Yankee dryer 60, assisting in drying the tissue web 64. The tissue
web 64 can then be removed from the Yankee dryer by a creping
doctor blade 62.
[0052] The fibrous web 64 may optionally be calendered, and is then
wound into a hard roll. The substrate can then be converted using
various means known in the art to produce a paper product, such as
a personal care paper product, which exhibits enhanced softness and
minimized slough due to the retention of the softening agent by the
pre-treated pulp fibers.
[0053] Although the exemplary embodiment discussed above relates to
a multi-layered paper web having two layers, it should be
understood that the paper web can contain any number of layers
greater than or equal to one. For example, FIG. 3 illustrates a
particular aspect wherein a paper machine comprises a 3-layer
headbox. As shown, an endless traveling forming fabric 76, suitably
supported and driven by rolls 78 and 80, receives the layered paper
making stock issuing from the headbox 70. Once retained on the
fabric 76, the fiber suspension passes water through the fabric as
shown by the arrows 82. In one aspect, at least one of the outer
layers 72,74 can contain pre-treated fibers and at least the
inner-layer 73 can contain strength enhancing fibers. Water removal
can then be achieved as described above.
[0054] In addition, it should also be understood that the layers of
the multi-layered paper web can also contain more than one type of
fiber. For example, in some aspects, one of the layers can contain
a blend of pre-treated hardwood fibers and untreated hardwood
fibers, a blend of pre-treated hardwood fibers and untreated
softwood fibers, a blend of untreated hardwood fibers and
pre-treated softwood fibers, a blend of pre-treated hardwood fibers
and recycled fibers, a blend of pre-treated hardwood fibers and
synthetic fibers, and the like.
[0055] It should be further understood that a paper product of the
present invention can comprise single or multiple fibrous webs. At
least one of these webs is formed in accordance with the present
invention. For instance, in one aspect, a two-ply paper product can
be formed. The first and second ply, for example, can be a
multi-layered paper web formed according to the present invention.
The configuration of the plies can also vary. For instance, in one
embodiment, one ply can be positioned such that a layer comprising
pre-treated hardwood fibers can define a first outer surface of the
paper product to provide a soft feel with minimized slough to
consumers. If desired, another ply can also be positioned such that
a layer comprising pre-treated hardwood fibers can define a second
outer surface of the paper product.
[0056] The plies may be similarly configured when more than two
plies are utilized. For example, in some embodiments, when forming
a paper product from three plies, fibrous webs comprising
pre-treated fibers can be positioned to define first and second
outer surfaces of the paper product to provide a soft feel with
minimized slough to consumers. Additionally, a third fibrous web
comprising untreated softwood fibers can be positioned to define an
inner ply to provide enhanced strength of the paper product to
consumers. However, it should also be understood that any other ply
configuration may be utilized in the present invention.
[0057] The present invention may be better understood with
reference to the following examples.
EXAMPLES
Pulpsheets
[0058] Twenty-four grams of oven dry fiber from various dry-lap
samples was used to prepare pulpsheets each having a basis weight
of approximately 460 grams per square meter (gsm). The pulpsheets
were prepared by diluting the fiber with water in a BRITISH PULP
DISINTEGRATOR (commercially available from Lorentzen and Wettre AB,
a business having offices located in Atlanta, Ga., U.S.A.) to a
consistency of 1.2% by weight.
[0059] Each sample was allowed to soak in the disintegrator for a
total of 5 minutes. After about 2.5 minutes, a particular amount of
desired softening agent was introduced into the fiber-water mixture
and was pulped in the disintegrator for 5 seconds before stopping
and resuming the soaking period. After the soaking period was
completed, the sample was pulped in the disintegrator for 5 minutes
at ambient temperature (i.e., about 25.degree. C.). A control
sample was also made using the same procedure, but eliminating the
step of adding the softening-agent.
[0060] An appropriate amount of the fiber slurry required to make a
460 gsm sheet was measured into a graduated cylinder. The slurry
was then poured from the graduated cylinder into an 9-inch by
9-inch VALLEY handsheet mold, commercially available from Voith
Inc., a business having offices located in Appleton, Wis., U.S.A.)
that had been pre-filled to the appropriate level with water.
[0061] After pouring the slurry into the mold, the mold was then
completely filled with water, including water used to rinse the
graduated cylinder. The slurry was then agitated gently with a
standard perforated mixing plate that was inserted into the slurry
and moved up and down seven times, then removed. A valve was then
opened to allow the water-fiber slurry to drain from the mold
through a 90.times.90 mesh stainless-steel wire cloth with a
14.times.14 mesh backing wire at the bottom of the mold that
retained the fibers to form a fibrous web. The web was allowed to
dewater using the vacuum formed by the water drop of 31.5
inches.
[0062] One 360 gsm reliance grade blotter sheet (commercially
available from Curtis Fine Papers, a business having offices
located in Guardbridge, Scotland) was then placed on top of the web
with the smooth side of the blotter contacting the web. The web was
then couched from the mold wire by using a 10 kg roller and passing
over the sheets several times. The top blotter sheet and fibrous
web were lifted from the screen. The blotter sheet was then
positioned with the fibrous web facing up and was placed on top of
two dry blotter sheets. Two additional dry blotter sheets were then
placed on top of the fibrous web to make a total of five blotter
sheets.
[0063] The stack of blotter sheets, including the fibrous web, was
placed in a VALLEY hydraulic press (commercially available from
Voith, Inc.) and pressed for one minute at a pressure of 100 psi.
The pressed web was then removed from the blotter sheets and dried,
wire-side up, for 2 minutes to absolute dryness using a VALLEY
STEAM HOTPLATE (commercially available from Voith, Inc.) heated
with saturated steam at a pressure of 2 pounds per square inch and
a standard weighted canvas cover having a weighted tube (4.75
pounds) at one end to maintain constant tension.
Handsheets
[0064] Twenty-four grams of oven dry fiber from the pulpsheet
samples described above was used to prepare handsheet strip samples
having a basis weight of 60 grams per square meter (g/m.sup.2). The
twenty-four grams of pulp sheet sample was placed into the BRITISH
PULP DISINTEGRATOR and was diluted with water to a consistency of
1.2% by weight. The pulp fiber sample was again allowed to soak for
5 minutes in the disintegrator, and then was re-slurried in the
disintegrator for 5 minutes at ambient temperature (i.e., about
25.degree. C.).
[0065] An appropriate amount of the fiber slurry required to make a
60 gsm sheet was measured into a graduated cylinder. The slurry was
then poured from the graduated cylinder into the 9-inch by 9-inch
VALLEY handsheet mold (described above) that had been pre-filled to
the appropriate level with water.
[0066] After pouring the slurry into the mold, the mold was then
completely filled with water, including water used to rinse the
graduated cylinder. The slurry was then agitated gently with a
standard perforated mixing plate that was inserted into the slurry
and moved up and down seven times, then removed. A valve was then
opened to allow the water-fiber slurry to drain from the mold
through a 90.times.90 mesh stainless-steel wire cloth with a
14.times.14 mesh backing wire and at the bottom of the mold that
retained the fibers to form a fibrous web. The web was allowed to
dewater using the vacuum formed by the water drop of 31.5
inches.
[0067] One 360 gsm reliance grade blotter sheet (commercially
available from Curtis Fine Papers) was then placed on top of the
web with the smooth side of the blotter contacting the web. The web
was then couched from the mold wire by using a 10 kg roller,
passing over the sheets several times. The top blotter sheet and
fibrous web were lifted from the screen. The blotter sheet was then
positioned with the fibrous web facing up and was placed on top of
two dry blotter sheets. Two additional dry blotter sheets were then
placed on top of the fibrous web to make a total of five blotter
sheets.
[0068] The stack of blotter sheets, including the fibrous web, was
placed in the VALLEY hydraulic press (described above) and pressed
for one minute at a pressure of 100 psi. The pressed web was then
removed from the blotter sheets and dried, wire-side up, for 2
minutes to absolute dryness using the VALLEY STEAM HOTPLATE
(described above) which was heated with saturated steam at a
pressure of 2 pounds per square inch and utilized a standard
weighted canvas cover having a weighted tube (4.75 pounds) at one
end to maintain constant tension. The resulting handsheet was then
conditioned in a humidity controlled room at 23.degree. C. and 50%
relative humidity prior to preparation as a handsheet strip sample
for testing.
Example 1
[0069] ARACRUZ ECF in the form of a 1000 gsm dry-lap sheet were
used to create a first set of pulp sheets, which was used to create
a set of handsheets. The Pulpsheet and Handsheet methods described
above for making the handsheets were utilized. This first set of
comparative handsheets, hereinafter referred to as Control 1,
represents a paper product without any type of chemical treatment
for improving aesthetic properties, such as softness. The
handsheets were then tested for various properties in accordance
with the test procedures set forth below.
Example 2
[0070] ARACRUZ ECF was used to create a set of pulpsheets, which
were then used to create a set of handsheets. The Pulpsheet and
Handsheet methods described above for making comparative handsheets
were again utilized, except that PROSOFT TQ-1003 debonder
(commercially available from Hercules Inc.) was added in an amount
equal to 0.075% on a dry fiber basis during the pulp re-slurrying
step of the Handsheet procedure above. This second set of
comparative handsheets, hereinafter referred to as Control 2,
represents a paper product in which a debonder is added to the
fiber without curing, such as through addition in the wet end of a
paper machine. The handsheets were then tested for various
properties in accordance with the test procedures set forth
below.
Example 3
[0071] ARACRUZ ECF was used to create a set of pulpsheets which
were used to create a set of handsheets. The same procedure was
utilized as in EXAMPLE 2 above, except that the addition of PROSOFT
TQ-1003 debonder was in an amount of 0.15% on a dry fiber basis.
This third set of comparative handsheets, hereinafter referred to
as Control 3, represents a paper product in which a debonder is
added to the fiber without curing, such as through addition in the
wet end of a paper machine. The handsheets were then tested for
various properties in accordance with the test procedures set forth
below.
Example 4
[0072] ARACRUZ ECF was used to create a set of pulp sheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing a polyamide-polyamine-epichlorohydrin (PAE) type
resin under the trade name KYMENE 6500 in an amount equal to 0.2%
on a dry fiber basis. The fibers were then diluted and re-slurried
to form handsheets according to the Handsheet procedure described
above. This first set of pre-treated fibers, hereinafter referred
to as Sample 1, represents fibers which are pre-treated with a
softening agent in the form of a permanent wet strength resin, then
cured, and then diluted with water, re-slurried and incorporated
into the fiber stream for a paper machine to enhance aesthetic
properties such as softness while minimizing slough. The handsheets
were then tested for various properties in accordance with the test
procedures set forth below.
Example 5
[0073] ARACRUZ ECF was used to create a set of handsheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing KYMENE 6500 in an amount equal to 0.5% on a dry
fiber basis. The fibers were then diluted and re-slurried to form
handsheets according to the Handsheet procedure described above.
This second set of pre-treated fibers, hereinafter referred to as
Sample 2, represents fibers which are pre-treated with a softening
agent in the form of a permanent wet strength resin, then cured,
and then diluted with water, re-slurried and incorporated into the
fiber stream for a paper machine to enhance aesthetic properties
such as softness while minimizing slough. The handsheets were then
tested for various properties in accordance with the test
procedures set forth below.
Example 6
[0074] ARACRUZ ECF was used to create a third set of pulpsheets
representing pre-treated fibers of the present invention identical
to Sample 1 above using the Pulpsheet procedure described above.
Additionally, ARACRUZ ECF was used to create a set of comparative
pulpsheets identical to Control 1 above using the Pulpsheet
procedure described above. A 1:1 mixture of the treated and
untreated dried fiber sheets were diluted with water to a
consistency of 1.2% and slurried, and then made into standard
handsheets utilizing the Handsheet procedure described above. This
first set of blended pre-treated/untreated fiber pulp sheets,
hereinafter referred to as Sample 3, represents fibers which are
pre-treated with a softening agent in the form of a permanent wet
strength resin, then cured, and then diluted with water and
re-slurried and incorporated into the fiber stream of a paper
machine to enhance aesthetic properties such as softness while
minimizing slough. The handsheets were then tested for various
properties in accordance with the test procedures set forth
below.
[0075] The resulting properties for the Control 1-3 comparative
examples, as well as the Samples 1-3 invention examples are shown
in Table 1 below. TABLE-US-00001 TABLE 1 Pretreated Pulp Properties
with PAE resin Control 1 Control 2 Control 3 Sample 1 Sample 2
Sample 3 Description Pretreated Pretreated 1:1 Euc and Euc w/0.075%
Euc w/0.15% Euc. w/0.2% Euc. w/0.5% Pretreated Physical Properties
Eucalyptus ProSoft ProSoft PAE PAE Euc w/0.2% PAE Tensile Index
8.74 5.71 4.98 2.73 0.67 5.45 Average (Nm/g) Tensile Index 0.37
0.32 0.61 0.10 0.11 0.39 Standard Deviation Caliper Average 6.29
6.46 6.63 7.06 8.09 6.88 (in 10-3) Caliper Standard 0.25 0.29 0.35
0.22 0.39 0.22 Deviation Slough Average (mg) 12.83 17.6 18.23 16.83
too weak 15.2 to test for slough Slough Standard 1.97 1.19 2.48
2.25 n/a 1.2 Deviation * Note, samples that are identified as
"Control #" represent comparative examples, while samples that are
identified as "Sample #" represent examples of the invention.
[0076] The results in Table 1 show that fibers in Samples 1 and 2
that were pre-treated with a polyamide-polyamine-epichlorohydrin
permanent wet strength resin have a substantial debonding effect
compared to Control 1 resulting in a reduced tensile index for the
pre-treated samples, which equates to increased softness (i.e., as
the tensile index decreases, softness increases). In fact the
tensile index reduction for Samples 1 and 2 is significantly
greater for the pre-treated samples than with the PROSOFT debonder
samples of Control 2 and 3. Furthermore, it can be surmised that
the pre-treated fibers show a potential to reduce slough at equal
tensile strengths as compared to a traditional wet-end softener
such as PROSOFT imidazoline debonder. This can be illustrated when
comparing the properties between Control 2, which was prepared with
0.075% PROSOFT debonder and Sample 3, which was prepared using a
1:1 ratio of 0.2% PAE resin treated fiber and untreated fiber.
Additionally, the pre-treated fiber in Sample 3 has higher caliper
and lower slough than Control 2 at approximately the same tensile
index. In general, the increased caliper for each of the
pre-treated samples equates to an increase in bulk for the
resulting paper product.
Example 7
[0077] ARACRUZ ECF was used to create a set of handsheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing HERCON 70 in an amount equal to 0.15% on a dry
fiber basis. The fibers were then diluted and re-slurried to form
handsheets according to the Handsheet procedure described above.
This set of pre-treated handsheets, hereinafter referred to as
Sample 4, represents fibers which are pre-treated with a softening
agent in the form of a sizing agent, then cured, and then diluted
with water, re-slurried and incorporated into the fiber stream of a
paper machine to enhance aesthetic properties such as softness
while minimizing slough. The handsheets were then tested for
various properties in accordance with the test procedures set forth
below.
Example 8
[0078] ARACRUZ ECF was used to create a set of handsheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing HERCON 70 in an amount equal to 0.50% on a dry
fiber basis. The fibers were then diluted and re-slurried to form
handsheets according to the Handsheet procedure described above.
This set of pre-treated handsheets, hereinafter referred to as
Sample 5, represents fibers which are pre-treated with a softening
agent in the form of a sizing agent, then cured, and then diluted
with water, re-slurried and incorporated into the fiber stream of a
paper machine to enhance aesthetic properties such as softness
while minimizing slough. The handsheets were then tested for
various properties in accordance with the test procedures set forth
below.
[0079] The resulting properties for the Control 1-3 comparative
examples, as well as the Samples 4-5 invention examples are shown
in Table 2 below. TABLE-US-00002 TABLE 2 Pretreated Pulp Properties
with AKD sizing agent Control 1 Control 2 Control 3 Sample 4 Sample
5 Description Pretreated Pretreated Euc w/0.075% Euc w/0.15% Euc.
w/0.15% Euc. w/0.5% Physical Properties Eucalyptus ProSoft ProSoft
Hercon Hercon Tensile Index 8.74 5.71 4.98 6.53 3.87 Average (Nm/g)
Tensile Index 0.37 0.32 0.61 0.73 0.08 Standard Deviation Caliper
Average 6.29 6.46 6.63 6.59 6.70 (in 10-3) Caliper Standard 0.25
0.29 0.35 0.34 0.20 Deviation Slough Average (mg) 12.83 17.6 18.23
12.53 16.23 Slough Standard 1.97 1.19 2.48 1.29 1.05 Deviation *
Note, samples that are identified as "Control #" represent
comparative examples, while samples that are identified as "Sample
#" represent examples of the invention.
[0080] The results in Table 2 show that fibers pre-treated with an
alkyl ketene dimer type sizing agent resin have a substantial
debonding effect compared to Control 1 resulting in a reduced
tensile index for the pre-treated samples, which equates to
increased softness (i.e., as the tensile index decreases, softness
increases). Furthermore, it can be surmised that the pre-treated
fibers show a potential to reduce slough at equal tensile strengths
as compared to a traditional wet-end softener such as the PROSOFT
imidazoline debonder used in Control 2 and 3. Additionally, the
increased caliper of the pre-treated samples equates to an increase
in bulk for the resulting paper product.
Example 9
[0081] ARACRUZ ECF was used to create a set of handsheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing a complex of hydrophobic polymer anionic emulsion
and a cationic surfactant at a 2:1 mass ratio in an amount equal to
0.3% on a dry fiber basis. The complex was prepared by mixing
LATRIX 6300 emulsion at a solids content of about 50% by weight
with PROSOFT TQ-1003 at a solids content of about 80% by weight.
The fibers were then diluted and re-slurried to form handsheets
according to the Handsheet procedure described above. This set of
pre-treated handsheets, hereinafter referred to as Sample 6,
represents fibers which are pre-treated with a softening agent in
the form of a polymer emulsion, then cured, and then diluted with
water, re-slurried and incorporated into the fiber stream of a
paper machine to enhance aesthetic properties such as softness
while minimizing slough. The handsheets were then tested for
various properties in accordance with the test procedures set forth
below.
Example 10
[0082] ARACRUZ ECF was used to create a set of handsheets
representing pre-treated fibers of the present invention. The
fibers were treated according to the Pulpsheet procedure described
above utilizing a complex of hydrophobic polymer anionic emulsion
and a cationic surfactant at a 2:1 mass ratio in an amount equal to
1.0% on a dry fiber basis. The complex was prepared by mixing
LATRIX 6300 emulsion at a solids content of about 50% with PROSOFT
TQ-1003 at a solids content of about 80%. The fibers were then
diluted and re-slurried to form handsheets according to the
Handsheet procedure described above. This set of pre-treated
handsheets, hereinafter referred to as Sample 7, represents fibers
which are pre-treated with a softening agent in the form of a latex
emulsion complex, then cured, and then diluted with water,
re-slurried and incorporated into the fiber stream of a paper
machine to enhance aesthetic properties such as softness while
minimizing slough. The handsheets were then tested for various
properties in accordance with the test procedures set forth
below.
[0083] The resulting properties for the Control 1-3 comparative
examples, as well as the Samples 6-7 invention examples are shown
in Table 3 below. TABLE-US-00003 TABLE 3 Pretreated Pulp Properties
with Polymer complex Control 1 Control 2 Control 3 Sample 6 Sample
7 Description Pretreated Pretreated Euc w/0.075% Euc w/0.15% Euc.
w/0.3% Euc. w/1.0% Physical Properties Eucalyptus ProSoft ProSoft
Complex Complex Tensile Index 8.74 5.71 4.98 5.21 4.43 Average
(Nm/g) Tensile Index 0.37 0.32 0.61 0.38 0.41 Standard Deviation
Caliper Average 6.29 6.46 6.63 6.61 6.75 (in 10-3) Caliper Standard
0.25 0.29 0.35 0.41 0.16 Deviation Slough Average (mg) 12.83 17.6
18.23 15.63 10.37 Slough Standard 1.97 1.19 2.48 0.83 1.01
Deviation * Note, samples that are identified as "Control #"
represent comparative examples, while samples that are identified
as "Sample #" represent examples of the invention.
[0084] The results in Table 3 show that fibers pre-treated with the
complex formed from hydrophobic polymer anionic emulsion with a
cationic surfactant at a 2:1 ratio have a substantial debonding
effect compared to the untreated control, which equates to
increased softness (i.e., as the tensile index decreases, softness
increases). Further, the samples containing fibers pre-treated with
the polymer complex exhibit lower slough at equal or lower tensile
strengths compared to the PROSOFT debonder controls. Additionally,
the increased caliper of the pre-treated samples equates to an
increase in bulk for the resulting paper product.
Example 11
[0085] A 90% ARACRUZ ECF Eucalyptus/10% LL-19 northern softwood
pulp sheet was produced on a pilot scale tissue machine at a speed
of 18 feet per minute. The pulp sheet was dried to 85% solids with
a basis weight of 160 grams per square meter. The pulp sheet was
re-slurried for 30 minutes at 120.degree. F. (hereinafter, the
"Untreated Fibers") and used to make a comparative example Control
4.
[0086] A layered fibrous web having a basis weight of about 7.0
pounds per 2880 square feet of oven dried tissue web was then
produced on the pilot scale tissue machine by utilizing a 3 layer
headbox to form a sheet having two outer layers and one inner
layer. The first outer layer comprised 66% ARACRUZ ECF and 34% of
the Untreated Fibers from above. The inner layer comprised 70%
LL-19 and 30% of the Untreated Fibers from above. A 0.1% solution
of strength additive under the tradename HERCOBOND 1366, available
from Hercules Inc., was also added to the center layer to control
the final strength of the layered fibrous web to a geometric mean
tensile of 2.41 Nm/g. The dilute solution of HERCOBOND 1366 was
added continuously through a pump to the stock pipe prior to the
headbox. The remaining outer layer comprised 66% ARACRUZ ECF and
34% of the Untreated Fibers from above. Additionally, a solution of
wet strength additive, under the tradename KYMENE 6500, available
from Hercules Inc., was added to all 3 layers at an amount of 2 dry
kg/dry metric ton of tissue to provide wet strength to the product.
The KYMENE 6500 was added in to the pulp storage vat and allowed to
mix for 10 minutes before the pulp was transported to the
headbox.
[0087] The layered fibers were deposited from the headbox onto a
forming fabric and dewatered with vacuum. The tissue web was then
transferred to a papermaking felt which carried the wet web at
approximately 20% solids content from the formic fabric to a press
roll which pressed additional water from the web to approximately a
45% solids content and transferred the web to a Yankee dryer. An
adhesive mixture was sprayed using a spray boom onto the surface of
the Yankee dryer just before the application of the tissue web by
the press roll. The adhesive mixture contained about 40% by weight
polyvinyl alcohol, about 40% by weight polyamide resin and about
20% by weight quaternized polyamido amine, such as disclosed in
U.S. Pat. No. 5,730,839 to Wendt et al. which is herein
incorporated by reference in a manner that is consistent with the
present disclosure. The application rate of the adhesive mixture
was about 6 pounds of dry adhesive per metric ton of oven dry pulp
fiber in the tissue web.
[0088] The sheet was dried on the Yankee dryer which was heated
with 23 psi pressure saturated steam. Additionally, a natural gas
heated hood partially surrounding the Yankee dryer had a supply air
temperature of about 600.degree. F. to assist in drying the tissue
web. The temperature of the tissue web after the application of the
creping doctor was about 225.degree. F. as measured with a handheld
infrared temperature gun. The sheet was creped off of the dryer
using a steel blade with a 10 degree bevel. The blade was held in a
chamber with a 3/4 inch extension, which was pressed against the
dryer with enough force to allow the tissue to be scraped uniformly
from the dryer. The tissue was wound onto a reel that was traveling
27% slower than the Yankee dryer. The machine speed of the 16 inch
wide tissue web was about 50 feet per minute.
[0089] Two rolls of the creped tissue were then rewound and plied
together in a fashion to allow both creped sides to be on the
outside of the 2-ply structure. The plied structures were
calendered at approximately 40 pounds per linear inch, mechanically
crimped on the edges to hold the plies together, and slit on the
edges to achieve a width of approximately 8.5 inches to form a
two-ply facial tissue product. The product was then tested for
various properties in accordance with the test procedures set forth
below. The results can be seen in Table 4.
Example 12
[0090] A 90% ARACRUZ ECF Eucalyptus/10% LL-19 northern softwood
pulp sheet was produced on a pilot scale tissue machine at a speed
of 18 feet per minute. In this example, the fibers were pre-treated
with KYMENE 6500 PAE resin controlled to achieve an addition amount
of 0.1% on a dry fiber basis. The resin treatment involved mixing
the resin with the pulp fibers for 30 minutes pulping time at
120.degree. F. before forming and drying the pulpsheet. The
pulpsheet was dried to 85% solids with a basis weight of 160 grams
per square meter. The pulpsheet was then re-slurried for 30 minutes
at 120.degree. F. (hereinafter, the "Pre-Treated Fibers") and used
as a fiber source to produce Sample 8, a two-ply facial tissue
product produced in the same manner as Control 4 above, with the
exception that the amounts of Untreated Fibers were replaced with
Pre-Treated Fibers made in this example. The product was then
tested for various properties in accordance with the test
procedures set forth below. The results can be seen in Table 4.
TABLE-US-00004 TABLE 4 Two-ply Facial Tissue using PAE resin
pre-treated pulp. Code Control 4 Sample 8 Description Average (Std.
Dev.) Average (Std. Dev.) BW, (gsm) 32.2 (0.15) 31.7 (0.14) Caliper
9.01 (0.12) 9.72 (0.22) (0.001 in) Slough mg 6.78 (0.93) 4.62
(0.72) MD Tensile 3.56 (0.24) 3.36 (0.23) (Nm/g) CD Tensile 1.64
(0.08) 1.61 (0.10) (Nm/g) GMT (Nm/g) 2.42 2.33 * Note, samples that
are identified as "Control #" represent comparative examples, while
samples that are identified as "Sample #" represent examples of the
invention.
[0091] The results in Table 4 show that a tissue product made from
fibers pre-treated with the 20% PAE resin inclusion in the furnish
have, at approximately the same geometric mean tensile strength
(GMT), an increase in caliper with less slough.
Example 13
[0092] Samples were produced in a similar manner as Control 1-3,
and Samples 1-2 and 4-7 above. However, prior to the step of
re-slurrying the samples, the fibers were tested to determine water
retention values using the procedure described below. In the case
of Control 2 and Control 3, the PROSOFT chemistry was added during
the Pulpsheet procedure, rather than during the re-slurrying step
of the Handsheet procedure. The results are shown in Table 5.
Additionally, these same samples were used to measure Length
Weighted Curl Index using the procedure described below. The Curl
Index values are also shown in Table 5. TABLE-US-00005 TABLE 5
Pulpsheet Water Retention Values Water Water Retention Retention
Value Curl Index Value Standard Curl Index Standard Average (g/g)
Deviation Average Deviation Control 1 1.24 0.03 0.087 0.004 Control
2 1.14 0.02 0.083 0.001 Control 3 1.15 0.05 0.086 0.003 Sample 1
0.87 0.04 0.090 0.001 Sample 2 0.82 0.03 0.093 0.002 Sample 4 0.96
0.08 0.087 0.002 Sample 5 0.83 0.01 0.079 0.004 Sample 6 0.86 0.01
0.084 0.002 Sample 7 0.79 0.07 0.082 0.001 * Note, samples that are
identified as "Control #" represent comparative examples, while
samples that are identified as "Sample #" represent examples of the
invention.
[0093] The data in Table 5 suggest a potential mechanism describing
why pulp pre-treatment of the present invention creates a paper
product having increased softness while minimizing slough. Without
being held to a particular theory, it appears that by having low
water retention, an inventive debonding mechanism is created which
differs from the use of typical debonder chemistries. For example,
it is believed that the pre-treated fibers, which have less water
in them, are less flexible and create a lower density fibrous mat
in a wet formation process. It can be surmised that the lower
density fibrous mat diminishes fiber to fiber contact, thus making
the mat weaker. This contrasts with chemical debonders which are
believed to adsorb to fibers and reduce hydrogen bonding of fibers
through covering hydroxyl and carboxyl sites as well as reducing
surface tension which draws fibers together. Therefore, it is
believed that the invention reduces fiber to fiber contact but
allows strong bonds to form where contact is made, whereas
traditional debonder chemistries reduce the strength of all bonds
through adsorption to cellulose.
Test Procedures
Tensile Test
[0094] Unless otherwise specified, tensile strengths were measured
according to TAPPI Test Method T 494 om-88 for tissue, modified in
that the tensile tester used a crosshead speed of 10 inches per
minute. The samples were conditioned at 23.degree. C.+/-1.degree.
C. and 50%+/-2% relative humidity for a minimum of 4 hours. The
handsheets were cut into 1-inch wide strips using a Precision
sample cutter model JDC 15M-10, commercially available from
Thwing-Albert Instruments, a business having offices located in
Philadelphia, Pa., U.S.A.
[0095] Each strip was then placed into the tensile frame at a gauge
length of 5 inches. The tensile frame used in these experiments was
an ALLIANCE RT/1 frame run with TESTWORKS 4 software, available
from MTS Systems Corporation, a business having offices located in
Cary, N.C., U.S.A. Each strip was then subjected to a strain of 0.5
inches per minute and the resulting stress was recorded with an
appropriate load cell.
[0096] The Tensile Index (TI) is a measure of tensile strength
normalized for basis weight of the web tested. The tensile strength
as measured above may be converted to tensile index using the
following formula: Tensile Index=Peak Load (N)/[Sample basis weight
(g/m.sup.2).times.Sample width (m)] where peak load is expressed in
Newtons (N), the sample basis weight is expressed in grams per
square meter (g/m.sup.2), the sample width is expressed in meters
(m), and the tensile index is expressed in Newton meter per gram
(Nm/g).
[0097] The Geometric Mean Tensile (GMT) was also calculated for the
samples to provide an average strength independent of test
direction. The GMT was calculated using the following formula:
GMT=Square Root (MD tensile value.times.CD tensile value)
[0098] The Tensile Test procedure for the tissue samples of Control
4 and Sample 8 was modified slightly. These particular tissue
samples were conditioned at 23.degree. C.+/-1.degree. C. and
50%+/-2% relative humidity for a minimum of 4 hours. The samples
were cut into 3 inch wide strips using the Precision sample cutter
model JDC 15M-10. Two strips, to represent a 2-ply product, were
then placed into the tensile frame at a gauge length of 4 inches.
The tensile frame used in these experiments was the ALLIANCE RT/1
frame run with TESTWORKS 4 software described above. Each strip was
then subjected to a strain of 10 inches per minute and the
resulting stress was recorded with an appropriate load cell. The
Tensile Index and the Geometric Mean Tensile were then calculated
as described above.
Caliper Test
[0099] The term "caliper" as used herein refers to the thickness of
a single tissue sheet. Caliper may either be measured as the
thickness of a single tissue sheet or as the thickness of a stack
of ten tissue sheets where each sheet within the stack is placed
with the same side up and dividing the measurement by ten. Caliper
is expressed in microns or 0.001 inches. Caliper was measured in
accordance with TAPPI test methods T402 "Standard Conditioning and
Testing Atmosphere For Paper, Board, Pulp Handsheets and Related
Products" and T411 om-89 "Thickness (caliper) of Paper, Paperboard,
and Combined Board" optionally with Note 3 for stacked tissue
sheets. The micrometer used for carrying out T411 om-89 was a MODEL
49-72-00 BULK MICROMETER (available from TMI Company, a business
having offices located in Amityville, N.Y. U.S.A.) or equivalent
having an anvil diameter of 4 1/16 inches (103.2 millimeters) and
an anvil pressure of 220 grams/square inch (3.3 kiloPascal).
Slough Test
[0100] The Slough Test determines the abrasion resistance or
tendency of the fibers to be rubbed from the web when handled. More
particularly, this test measures the resistance of tissue material
to abrasive action when the material is subjected to a horizontally
reciprocating surface abrader. Each sample was measured by abrading
the tissue specimens via the following method.
[0101] All samples were conditioned at 23+ C.+/-1.degree. C. and
50%+/-2% relative humidity for a minimum of 4 hours. The slough of
each handsheet was measured using a 3-inch wide by 8-inch long
strip fastened by weighted clamps allowing a rough, slow-rotating
mandrel to pass back and forth under the tissue strip for a
pre-determined number of cycles. This instrument was designed by
the Kimberly-Clark Corporation in Neenah, Wis. Weights to the
nearest 0.0001 gram are recorded for each sample strip before and
after testing to determine the amount of sloughing measured in
milligrams.
[0102] With reference to FIG. 4, the abrading spindle 94 contained
a stainless steel rod 96, 0.5'' in diameter with the abrasive
portion 84 having a 0.005'' deep diamond pattern extending 4.25''
in length around the entire circumference of the rod 96. The
spindle 94 was mounted perpendicularly to the face of the
instrument such that the abrasive portion 84 of the rod 96 extends
out its entire distance from the face of the instrument 100. Guide
pins 102,104 with magnetic clamps 86,88 are located on each side of
the spindle 94, one movable 86 and one fixed 88, spaced 4 inches
apart and centered about the spindle 94. The movable clamp 86 and
guide pins 102 were allowed to slide freely in the vertical
direction, providing the means for insuring a constant tension of
the sample over the spindle 94 surface.
[0103] Using a die press with a die cutter, the specimens 92 were
cut into 3+/-0.05 inch wide by 8 inch long strips with two holes
(not shown) at each end of the sample 92 for the guide pins 102,104
to fit through. For the tissue samples 92, the MD direction
corresponds to the longer dimension. Each test strip 92 was then
weighed to the nearest 0.0001 gram. Each end of the sample 92 was
slid onto the guide pins 86,88 and magnetic clamps 86,88 held the
sheet 92 in place. The movable jaw 86 was then allowed to fall
providing constant tension across the spindle 94.
[0104] The spindle 94 was then moved back and forth at an
approximate 15 degree angle from the centered vertical centerline
in a reciprocal horizontal motion 90 against the test strip 92 for
40 cycles (each cycle is a back and forth stroke), at a speed of 80
cycles per minute, removing loose fibers from the web surface.
Additionally, the spindle 94 rotated counter clockwise 98 (when
looking at the front of the instrument) at an approximate speed of
5 RPMs. The magnetic clamps 86,88 were then removed from the sample
92 and the sample 92 was slid off of the guide pins 102,104 and any
loose fibers on the sample 92 surface were removed by blowing
compressed air (approximately 5-10 psi) on the test sample 92. The
test sample 92 was then weighed to the nearest 0.0001 gram and the
weight loss was calculated. Ten test samples per tissue sample were
tested and the average weight loss value in grams (or milligrams)
was recorded.
Water Retention Value
[0105] Each dried pulp sample was disintegrated by diluting in
deionized water to a consistency of 1.2% by weight in a BRITISH
PULP DISINTEGRATOR (described above). The pulp fiber sample was
allowed to soak for 5 minutes before being pulped at 15,000
revolutions for 5 minutes at ambient temperature (i.e., about
25.degree. C.). A sheet of a Whatman No. 1 filter paper (available
from Whatman Inc., a business having offices located in Clifton,
N.J. U.S.A.) used to gravity filter approximately 100 mL of the
fiber suspension was supported on a 50 mesh wire screen in a
plastic centrifuge tube with a drainage hole on the bottom. Four
samples were prepared in this manner and placed into metal
centrifuge tubes with a space of approximately 3 mm to allow water
to drain from the samples. The assembly was placed into a
centrifuge where the samples where accelerated to achieve 900
gravities of centrifugal force on the pulp specimens. The samples
were spun at this speed for 30 minutes after which time the samples
were removed utilizing a dissecting needle.
[0106] The filter papers were quickly separated from the dewatered
fiber samples and each sample was placed onto a pre-weighed drying
dish. Each wet sample was weighed, subtracting the weight of the
dish, recorded as the wet fiber weight (Wwet). The sample was then
dried in an oven at approximately 105 degrees C. for 12 hours and
weighed again with the weighing dish. This dish weight was
subtracted and recorded as the dry fiber weight (Wdry). The water
retention value (WRV) was calculated from the following equation:
WRV=(Wwet-Wdry)/Wdry where Wwet and Wdry are expressed in grams
(g), and WRV is expressed as g water/g fiber. Curl Index
[0107] "Curl" or "curl index" of a fiber is the measure of
fractional shortening of a fiber due to kinks, twists, and/or bends
in the fiber. For the purposes of this invention, a fiber's curl
value is measured in terms of a two-dimensional plane, determined
by viewing the fiber in a two-dimensional plane. To determine the
curl index of a fiber, the projected length of a fiber as the
longest dimension of a two-dimensional rectangle encompassing the
fiber (I), and the actual length of the fiber (L), are both
measured. An image analysis method may be used to measure "L" and
"I". A suitable image analysis method is described in U.S. Pat. No.
4,898,642 to Moore et al., which is incorporated herein by
reference in a manner that is consistent with this disclosure. The
curl value of a fiber can then be calculated from the following
equation: Curl index=(L/l)-1
[0108] The Wet Curl value for fibers was determined by using a
FIBER QUALITY ANALYZER, OPTEST PRODUCT CODE LDA 96, available from
OpTest Equipment Inc., a business having offices located in
Hawkesbury, Ontario, Canada. The sample was placed into a 600
milliliter plastic sample beaker to be used in the Fiber Quality
Analyzer. The fiber sample in the beaker was diluted with tap water
until the fiber concentration in the beaker was about 10 to about
25 fibers per second for evaluation by the Fiber Quality Analyzer.
An empty plastic sample beaker was filled with tap water and placed
in the Fiber Quality Analyzer test chamber. The <System
Check> button of the Fiber Quality Analyzer was then pushed. If
the plastic sample beaker filled with tap water was properly placed
in the test chamber, the <OK> button of the Fiber Quality
Analyzer was then pushed. The Fiber Quality Analyzer then performed
a self-test. If a warning was not displayed on the screen after the
self-test, the machine was ready to test the fiber sample.
[0109] The plastic sample beaker filled with tap water was removed
from the test chamber and replaced with the fiber sample beaker.
The <Measure> button of the Fiber Quality Analyzer was then
pushed. The <New Measurement> button of the Fiber Quality
Analyzer was then pushed. An identification of the fiber sample was
then typed into the Fiber Quality Analyzer. The <OK> button
of the Fiber Quality Analyzer was then pushed. The <Options>
button of the Fiber Quality Analyzer was then pushed. The fiber
count was set at 3,000. The parameters of scaling of a graph to be
printed out was set to automatic. The <Previous> button of
the Fiber Quality Analyzer was then pushed. The <Start>
button of the Fiber Quality Analyzer was then pushed. If the fiber
sample beaker was properly placed in the test chamber, the
<OK> button of the Fiber Quality Analyzer was then
pushed.
[0110] The Fiber Quality Analyzer then began testing and displayed
the fibers passing through the flow cell. The Fiber Quality
Analyzer also displayed the fiber frequency passing through the
flow cell, which was about 10 to about 20 fibers per second. If the
fiber frequency is outside of this range, the <Stop> button
of the Fiber Quality Analyzer should be pushed and the fiber sample
should be diluted or have more fibers added to bring the fiber
frequency within the desired range. If the fiber frequency is
sufficient, the Fiber Quality Analyzer tests the fiber sample until
it has reached a count of 3000 fibers at which time the Fiber
Quality Analyzer automatically stops. The <Results> button of
the Fiber Quality Analyzer was then pushed. The Fiber Quality
Analyzer calculated the Wet Curl value of the fiber sample, which
printed out by pushing the <Done> button of the Fiber Quality
Analyzer.
[0111] It will be appreciated that details of the foregoing
examples, given for purposes of illustration, are not to be
construed as limiting the scope of this invention. Although only a
few exemplary embodiments of this invention have been described in
detail above, those skilled in the art will readily appreciate that
many modifications are possible in the examples without materially
departing from the novel teachings and advantages of this
invention. For example, features described in relation to one
example may be incorporated into any other example of the
invention.
[0112] Accordingly, all such modifications are intended to be
included within the scope of this invention, which is defined in
the following claims and all equivalents thereto. Further, it is
recognized that many embodiments may be conceived that do not
achieve all of the advantages of some embodiments, particularly of
the preferred embodiments, yet the absence of a particular
advantage shall not be construed to necessarily mean that such an
embodiment is outside the scope of the present invention. As
various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all
matter contained in the above description shall be interpreted as
illustrative and not in a limiting sense.
* * * * *