Note: Descriptions are shown in the official language in which they were submitted.
I
MODIFIED CELLULOSE FROM CHEMICAL KRAFT FIBER AND
METHODS OF MAKING AND USING THE SAME
TECHNICAL FIELD
[001] This disclosure relates to the chemical modification of cellulose
fiber. More particularly, this disclosure relates to chemically modified
cellulose fiber derived from bleached kraft pulp that exhibits a unique set of
characteristics, improving its performance over standard cellulose fiber
derived from kraft pulp and making it useful in applications that have
heretofore been limited to expensive fibers (e.g., cotton or high alpha
content
sulfite pulp). Specifically, the chemically modified bleached kraft fiber may
exhibit one or more of the following beneficial characteristics, including but
not
limited to, improved odor control, improved compressibility, and/or improved
brightness. The chemically modified bleached kraft fiber may exhibit one or
more of these beneficial characteristics while also maintaining one or more
other characteristics of the non-chemically modified bleached kraft fiber, for
example, maintaining fiber length and/or freeness.
[002] This disclosure further relates to chemically modified cellulose
fiber derived from bleached softwood and/or hardwood kraft pulp that exhibits
a low or ultra low degree of polymerization, making it suitable for use as
fluff
pulp in absorbent products, as a chemical cellulose feedstock in the
production of cellulose derivatives including cellulose ethers and esters, and
in consumer products. As used herein "degree of polymerization" may be
abbreviated "DP." This disclosure still further relates to cellulose derived
from
a chemically modified kraft fiber having a level-off degree of polymerization
of
less than about 80. More specifically, the chemically modified kraft fiber
described herein, exhibiting a low or ultra low degree of polymerization
(herein
referred to as "LDP" or "ULDP"), can be treated by acid or alkaline hydrolysis
to further reduce the degree of polymerization to less than about 80, for
instance to less than about 50, to make it suitable for a variety of
downstream
applications.
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[003] This disclosure also relates to methods for producing the
improved fiber described. This disclosure provides, in part, a method for
simultaneously increasing the carboxylic and aldehydic functionality of kraft
fibers. The fiber, described, is subjected to a catalytic oxidation treatment.
In
some embodiments, the fiber is oxidized with iron or copper and then further
bleached to provide a fiber with beneficial brightness characteristics, for
example brightness comparable to standard bleached fiber. Further, at least
one process is disclosed that can provide the improved beneficial
characteristics mentioned above, without the introduction of costly added
steps for post-treatment of the bleached fiber. In this less costly
embodiment,
the fiber can be treated in a single stage of a kraft process, such as a kraft
bleaching process. Still a further embodiment relates to a five-stage
bleaching process comprising a sequence of DoEl D1 E2D2, where stage four
(E2) comprises the catalytic oxidation treatment.
[004] Finally, this disclosure relates to consumer products, cellulose
derivatives (including cellulose ethers and esters), and microcrystalline
cellulose all produced using the chemically modified cellulose fiber as
described.
BACKGROUND
[005] Cellulose fiber and derivatives are widely used in paper,
absorbent products, food or food-related applications, pharmaceuticals, and in
industrial applications. The main sources of cellulose fiber are wood pulp and
cotton. The cellulose source and the cellulose processing conditions
generally dictate the cellulose fiber characteristics, and therefore, the
fiber's
applicability for certain end uses. A need exists for cellulose fiber that is
relatively inexpensive to process, yet is highly versatile, enabling its use
in a
variety of applications.
[006] Cellulose exists generally as a polymer chain comprising
hundreds to tens of thousands of glucose units. Various methods of oxidizing
cellulose are known. In cellulose oxidation, hydroxyl groups of the glycosides
of the cellulose chains can be converted, for example, to carbonyl groups
such as aldehyde groups or carboxylic acid groups. Depending on the
Date Recue/Date Received 2020-06-04
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oxidation method and conditions used, the type, degree, and location of the
carbonyl modifications may vary. It is known that, certain oxidation
conditions
may degrade the cellulose chains themselves, for example by cleaving the
glycosidic rings in the cellulose chain, resulting in depolymerization. In
most
instances, depolymerized cellulose not only has a reduced viscosity, but also
has a shorter fiber length than the starting cellulosic material. When
cellulose
is degraded, such as by depolymerizing and/or significantly reducing the fiber
length and/or the fiber strength, it may be difficult to process and/or may be
unsuitable for many downstream applications. A need remains for methods of
modifying cellulose fiber that may improve both carboxylic acid and aldehyde
functionalities, which methods do not extensively degrade the cellulose fiber.
This disclosure provides unique methods that resolve one or more of these
deficiencies.
[007] Various attempts have been made to oxidize cellulose to provide
both carboxylic and aldehydic functionality to the cellulose chain without
degrading the cellulose fiber. In traditional cellulose oxidation methods, it
may
be difficult to control or limit the degradation of the cellulose when
aldehyde
groups are present on the cellulose. Previous attempts at resolving these
issues have included the use of multi-step oxidation processes, for instance
site-specifically modifying certain carbonyl groups in one step and oxidizing
other hydroxyl groups in another step, and/or providing mediating agents
and/or protecting agents, all of which may impart extra cost and by-products
to a cellulose oxidation process. Thus, there exists a need for methods of
modifying cellulose that are cost effective and/or can be performed in a
single
step of a process, such as a kraft process.
[008] This disclosure provides novel methods that offer vast
improvements over methods attempted in the prior art. Generally, oxidization
of cellulose kraft fibers, in the prior art, is conducted after the bleaching
process. Surprisingly, the inventors have discovered that it is possible to
use
the existing stages of a bleaching sequence, particularly the fourth stage of
a
five stage bleaching sequence, for oxidation of cellulose fibers. Furthermore,
surprisingly, the inventors have discovered that a metal catalyst,
particularly
Date Recue/Date Received 2020-06-04
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an iron catalyst, could be used in the bleaching sequence to accomplish this
oxidation without interfering with the final product, for example, because the
catalyst did not remain bound in the cellulose resulting in easier removal of
at
least some of the residual iron prior to the end of the bleaching sequence
than
would have been expected based upon the knowledge in the art. Moreover,
unexpectedly, the inventors have discovered that such methods could be
conducted without substantially degrading the fibers.
[009] It is known in the art that cellulose fiber, including kraft pulp, may
be oxidized with metals and peroxides and/or peracids. For instance,
cellulose may be oxidized with iron and peroxide ("Fenton's reagent"). See
Kishimoto et al., Holzforschung, vol. 52, no. 2 (1998), pp. 180-184. Metals
and peroxides, such as Fenton's reagent, are relatively inexpensive oxidizing
agents, making them somewhat desirable for large scale applications, such as
kraft processes. In the case of Fenton's reagent, it is known that this
oxidation method can degrade cellulose under acidic conditions. Thus, it
would not have been expected that Fenton's reagent could be used in a kraft
process without extensive degradation of the fibers, for example with an
accompanying loss in fiber length, at acidic conditions. To prevent
degradation of cellulose, Fenton's reagent is often used under alkaline
conditions, where the Fenton reaction is drastically inhibited. However,
additional drawbacks may exist to using Fenton's reagent under alkaline
conditions. For example, the cellulose may nonetheless be degraded or
discolored. In kraft pulp processing, the cellulose fiber is often bleached in
multi-stage sequences, which traditionally comprise strongly acidic and
strongly alkaline bleaching steps, including at least one alkaline step at or
near the end of the bleaching sequence. Therefore, contrary to what was
known in the art, it was quite surprising that fiber oxidized with iron in an
acidic stage of a kraft bleaching process could result in fiber with enhanced
chemical properties, but without physical degradation or discoloration.
[010] Thus there is a need for a low cost and/or single step oxidation
that could impart both aldehyde and carboxylic functionalities to a cellulose
fiber, such as a fiber derived from kraft pulp, without extensively degrading
the
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cellulose and/or rendering the cellulose unsuitable for many downstream
applications. Moreover, there remains a need for imparting high levels of
carbonyl groups, such as carboxylic acid, ketone, and aldehyde groups, to
cellulose fiber. For example, it would be desirable to use an oxidant under
conditions that do not inhibit the oxidation reaction, unlike the use of
Fenton's
reagent at alkaline pH for instance, to impart high levels of carbonyl groups.
The present inventors have overcome many difficulties of the prior art,
providing methods that meet these needs.
[011] In addition to the difficulties in controlling the chemical structure
of cellulose oxidation products, and the degradation of those products, it is
known that the method of oxidation may affect other properties, including
chemical and physical properties and/or impurities in the final products. For
instance, the method of oxidation may affect the degree of crystallinity, the
hem i-cellulose content, the color, and/or the levels of impurities in the
final
product. Ultimately, the method of oxidation may impact the ability to process
the cellulose product for industrial or other applications.
[012] Bleaching of wood pulp is generally conducted with the aim of
selectively increasing the whiteness or brightness of the pulp, typically by
removing lignin and other impurities, without negatively affecting physical
properties. Bleaching of chemical pulps, such as kraft pulps, generally
requires several different bleaching stages to achieve a desired brightness
with good selectivity. Typically, a bleaching sequence employs stages
conducted at alternating pH ranges. This alternation aids in the removal of
impurities generated in the bleaching sequence, for example, by solubilizing
the products of lignin breakdown. Thus, in general, it is expected that using
a
series of acidic stages in a bleaching sequence, such as three acidic stages
in
sequence, would not provide the same brightness as alternating
acidic/alkaline stages, such as acidic-alkaline-acidic. For instance, a
typical
DEDED sequence produces a brighter product than a DEDAD sequence
(where A refers to an acid treatment). Accordingly, a sequence that does not
have an intervening alkaline stage, yet produces a product with comparable
brightness, would not be expected by a person of skill in the art.
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[013] Generally, while it is known that certain bleaching sequences
may have advantages over others in a kraft process, the reasons behind any
advantages are less well understood. With respect to oxidation, no studies
have shown any preference for oxidation in a particular stage of a multi-stage
sequence or any recognition that fiber properties can be affected by post
oxidation stages/treatments. For instance, the prior art does not disclose any
preference for a later stage oxidation over an earlier stage oxidation. In
some
embodiments, the disclosure provides methods uniquely performed in
particular stages (e.g., later stages of a bleaching process) that have
benefits
in the kraft process and that result in fibers having a unique set of physical
and chemical characteristics.
[014] In addition, with respect to brightness in a kraft bleaching
process, it is known that metals, in particular transition metals naturally
present in the pulp starting material, are detrimental to the brightness of
the
product. Thus, bleaching sequences frequently aim to remove certain
transition metals from a final product to achieve a target brightness. For
example, chelants may be employed to remove naturally occurring metal from
a pulp. Thus, because there is emphasis on removing the metals naturally
present in the pulp, a person of skill in the art would generally not add any
metals to a bleaching sequence as that would compound the difficulties in
achieving a brighter product.
[015] With respect to iron, moreover, addition of this material to a pulp
leads to significant discoloration, akin to the discoloration present when,
for
example, burning paper. This discoloration, like the discoloration of burnt
paper, has heretofore been believed to be non-reversible. Thus, it has been
expected that upon discoloring a wood pulp with added iron, the pulp would
suffer a permanent loss in brightness that could not be recovered with
additional bleaching.
[016] Thus, while is known that iron or copper and peroxide can
inexpensively oxidize cellulose, heretofore they have not been employed in
pulp bleaching processes in a manner that achieves a comparable brightness
to a standard sequence not employing an iron or copper oxidation step.
Date Recue/Date Received 2020-06-04
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Generally, their use in pulp bleaching processes has been avoided.
Surprisingly, the inventors have overcome these difficulties, and in some
embodiments, provide a novel method of inexpensively oxidizing cellulose
with iron or copper in a pulp bleaching processes. In some embodiments, the
methods disclosed herein result in products that have characteristics that are
very surprising and contrary to those predicted based on the teachings of the
prior art. Thus, the methods of the disclosure may provide products that are
superior to the products of the prior art and can be more cost-effectively
produced.
[017] For instance, it is generally understood in the art that metals,
such as iron, bind well to cellulose and cannot be removed by normal
washing. Typically, removing iron from cellulose is difficult and costly, and
requires additional processing steps. The presence of high levels of residual
iron in a cellulose product is known to have several drawbacks, particularly
in
pulp and papermaking applications. For instance, iron may lead to
discoloration of the final product and/or may be unsuitable for applications
in
which the final product is in contact with the skin, such as in diapers and
wound dressings. Thus, the use of iron in a kraft bleaching process would be
expected to suffer from a number of drawbacks.
[018] Heretofore, oxidation treatment of kraft fiber to improve
functionality has often been limited to oxidation treatment after the fiber
was
bleached. Moreover, known processes for rendering a fiber more aldehydic
also cause a concomitant loss in fiber brightness or quality. Furthermore,
known processes that result in enhanced aldehydic functionality of the fiber
also result in a loss of carboxylic functionality. The methods of this
disclosure
do not suffer from one or more of those drawbacks.
[019] Kraft fiber, produced by a chemical kraft pulping method,
provides an inexpensive source of cellulose fiber that generally maintains its
fiber length through pulping, and generally provides final products with good
brightness and strength characteristics. As such, it is widely used in paper
applications. However, standard kraft fiber has limited applicability in
downstream applications, such as cellulose derivative production, due to the
Date Recue/Date Received 2020-06-04
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chemical structure of the cellulose resulting from standard kraft pulping and
bleaching. In general, standard kraft fiber contains too much residual hemi-
cellulose and other naturally occurring materials that may interfere with the
subsequent physical and/or chemical modification of the fiber. Moreover,
standard kraft fiber has limited chemical functionality, and is generally
rigid
and not highly compressible.
[020] The rigid and coarse nature of kraft fiber can require the layering
or addition of different types of materials, such as cotton, in applications
that
require contact with human skin, for example, diapers, hygiene products, and
tissue products. Accordingly, it may be desirable to provide a cellulose fiber
with better flexibility and/or softness to reduce the requirement of using
other
materials, for example, in a multi-layered product.
[021] Cellulose fiber in applications that involve absorption of bodily
waste and/or fluids, for example, diapers, adult incontinence products, wound
dressings, sanitary napkins, and/or tampons, is often exposed to ammonia
present in bodily waste and/or ammonia generated by bacteria associated
with bodily waste and/or fluids. It may be desirable in such applications to
use a cellulose fiber which not only provides bulk and absorbency, but which
also has odor reducing and/or antibacterial properties, e.g., can reduce odor
from nitrogenous compounds, such as ammonia (NH3). Heretofore,
modification of kraft fiber by oxidation to improve its odor control
capability
invariably came with an undesirable decrease in brightness. A need exists for
an inexpensive modified kraft fiber that exhibits good absorbency
characteristics and/or odor control capabilities while maintaining good
brightness characteristics.
[022] In today's market, consumers desire absorbent products, for
example, diapers, adult incontinence products, and sanitary napkins, that are
thinner. Ultra-thin product designs require lower fiber weight and can suffer
from a loss of product integrity if the fiber used is too short. Chemical
modification of kraft fiber can result in loss of fiber length making it
unacceptable for use in certain types of products, e.g., ultra-thin products.
More specifically, kraft fiber treated to improve aldehyde functionality,
which is
Date Recue/Date Received 2020-06-04
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associated with improved odor control, may suffer from a loss of fiber length
during chemical modification making it unsuitable for use in ultra-thin
product
designs. A need exists for an inexpensive fiber that exhibits compressibility
without a loss in fiber length which makes it uniquely suited to ultra-thin
designs (i.e., the product maintains good absorbency based upon the amount
of fiber that can be compressed into a smaller space while maintaining
product integrity at lower fiber weights).
[023] Traditionally, cellulose sources that were useful in the
production of absorbent products or tissue were not also useful in the
production of downstream cellulose derivatives, such as cellulose ethers and
cellulose esters. The production of low viscosity cellulose derivatives from
high viscosity cellulose raw materials, such as standard kraft fiber, required
additional manufacturing steps that would add significant cost while imparting
unwanted by-products and reducing the overall quality of the cellulose
derivative. Cotton linter and high alpha cellulose content sulfite pulps,
which
generally have a high degree of polymerization, are generally used in the
manufacture of cellulose derivatives such as cellulose ethers and esters.
However, production of cotton linters and sulfite fiber with a high degree of
polymerization and/or viscosity is expensive due to the cost of the starting
material, in the case of cotton; the high energy, chemical, and environmental
costs of pulping and bleaching, in the case of sulfite pulps; and the
extensive
purifying processes required, which applies in both cases. In addition to the
high cost, there is a dwindling supply of sulfite pulps available to the
market.
Therefore, these fibers are very expensive, and have limited applicability in
pulp and paper applications, for example, where higher DP or higher viscosity
pulps may be required. For cellulose derivative manufacturers these pulps
constitute a significant portion of their overall manufacturing cost. Thus,
there
exists a need for low cost fibers, such as a modified kraft fiber, that may be
used in the production of cellulose derivatives.
[024] There is also a need for inexpensive cellulose materials that can
be used in the manufacture of microcrystalline cellulose. Microcrystalline
cellulose is widely used in food, pharmaceutical, cosmetic, and industrial
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applications, and is a purified crystalline form of partially depolymerized
cellulose. The use of kraft fiber in microcrystalline cellulose production,
without the addition of extensive post-bleaching processing steps, has
heretofore been limited. Microcrystalline cellulose production generally
requires a highly purified cellulosic starting material, which is acid
hydrolyzed
to remove amorphous segments of the cellulose chain. See U.S. Patent No.
2,978,446 to Battista et al. and U.S. Patent No. 5,346,589 to Braunstein et
al.
A low degree of polymerization of the chains upon removal of the amorphous
segments of cellulose, termed the "level-off DP," is frequently a starting
point
for microcrystalline cellulose production and its numerical value depends
primarily on the source and the processing of the cellulose fibers. The
dissolution of the non-crystalline segments from standard kraft fiber
generally
degrades the fiber to an extent that renders it unsuitable for most
applications
because of at least one of 1) remaining impurities; 2) a lack of sufficiently
long
crystalline segments; or 3) it results in a cellulose fiber having too high a
degree of polymerization, typically in the range of 200 to 400, to make it
useful
in the production of microcrystalline cellulose. Kraft fiber having good
purity
and/or a lower level-off DP value, for example, would be desirable, as the
draft fiber may provide greater versatility in microcrystalline cellulose
production and applications.
[025] In the present disclosure, fiber having one or more of the
described properties can be produced simply through modification of a typical
kraft pulping plus bleaching process. Fiber of the present disclosure
overcomes many of the limitations associated with known modified kraft fiber
discussed above.
BRIEF DESCRIPTION OF THE DRAWINGS
[026] FIGURE 1 shows a chart of final 0.5% capillary CED viscosity as
a function of percent peroxide consumed.
[027] FIGURE 2 shows a chart of wet strength to dry strength ratio
given as a function of wet strength resin level.
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DESCRIPTION
I. Methods
[028] The present disclosure provides novel methods for treating
cellulose fiber. In some embodiments, the disclosure provides a method of
modifying cellulose fiber, comprising providing cellulose fiber, and oxidizing
the cellulose fiber. As used herein, "oxidized," "catalytically oxidized,"
"catalytic oxidation" and "oxidation" are all understood to be interchangeable
and refer to treatment of cellulose fiber with at least a catalytic amount of
at
least one of iron or copper and at least one peroxide, such as hydrogen
peroxide, such that at least some of the hydroxyl groups of the cellulose
fibers
are oxidized. The phrase "iron or copper" and similarly "iron (or copper)"
mean "iron or copper or a combination thereof." In some embodiments, the
oxidation comprises simultaneously increasing carboxylic acid and aldehyde
content of the cellulose fiber.
[029] The cellulose fiber used in the methods described herein may
be derived from softwood fiber, hardwood fiber, and mixtures thereof. In
some embodiments, the modified cellulose fiber is derived from softwood,
such as southern pine. In some embodiments, the modified cellulose fiber is
derived from hardwood, such as eucalyptus. In some embodiments, the
modified cellulose fiber is derived from a mixture of softwood and hardwood.
In yet another embodiment, the modified cellulose fiber is derived from
cellulose fiber that has previously been subjected to all or part of a kraft
process, i.e., kraft fiber.
[030] References in this disclosure to "cellulose fiber" or "kraft fiber"
are interchangeable except where specifically indicated as different or as one
of ordinary skill in the art would understand them to be different.
[031] In at least one embodiment, the method comprises providing
cellulose fiber, and oxidizing the cellulose fiber while generally maintaining
the
fiber length of the cellulose fibers
[032] "Fiber length" and "average fiber length" are used
interchangeably when used to describe the property of a fiber and mean the
length-weighted average fiber length. Therefore, for example, a fiber having
Date Recue/Date Received 2020-06-04
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an average fiber length of 2 mm should be understood to mean a fiber having
a length-weighted average fiber length of 2 mm.
[033] In at least one embodiment, the method comprises providing
cellulose fiber, partially bleaching the cellulose fiber, and oxidizing the
cellulose fiber. In some embodiments, the oxidation is conducted in the
bleaching process. In some embodiments, the oxidation is conducted after
the bleaching process.
[034] In at least one embodiment, the method comprises providing the
cellulose fiber, and oxidizing cellulose fiber thereby reducing the degree of
polymerization of the cellulose fiber.
[035] In at least one embodiment, the method comprises providing
cellulose fiber, and oxidizing the cellulose fiber while maintaining the
Canadian Standard Freeness ("freeness") of that cellulose fiber.
[036] In at least one embodiment, the method comprises providing
cellulose fiber, oxidizing the cellulose fiber, and increasing the brightness
of
that oxidized cellulose fiber over standard cellulose fiber.
[037] As discussed above, in accordance with the disclosure,
oxidation of cellulose fiber involves treating the cellulose fiber with at
least a
catalytic amount of iron or copper and hydrogen peroxide. In at least one
embodiment, the method comprises oxidizing cellulose fiber with iron and
hydrogen peroxide. The source of iron can be any suitable source, as a
person of skill would recognize, such as for example ferrous sulfate (for
example ferrous sulfate heptahydrate), ferrous chloride, ferrous ammonium
sulfate, ferric chloride, ferric ammonium sulfate, or ferric ammonium citrate.
[038] In some embodiments, the method comprises oxidizing the
cellulose fiber with copper and hydrogen peroxide. Similarly, the source of
copper can be any suitable source as a person of skill would recognize.
Finally, in some embodiments, the method comprises oxidizing the cellulose
fiber with a combination of copper and iron and hydrogen peroxide.
[039] In some embodiments, the disclosure provides a method for
treating cellulose fiber, comprising, providing cellulose fiber, pulping the
cellulose fiber, bleaching the cellulose fiber, and oxidizing the cellulose
fiber.
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[040] In some embodiments, the method further comprises oxygen
delignifying the cellulose fiber. Oxygen delignification can be performed by
any method known to those of ordinary skill in the art. For instance, oxygen
delignification may be a conventional two-stage oxygen delignification. It is
known, for example, that oxygen delignifying cellulose fiber, such as kraft
fiber, may alter the carboxylic acid and/or aldehyde content of the cellulose
fiber during processing. In some embodiments, the method comprises
oxygen delignifying the cellulose fiber before bleaching the cellulose fiber.
[041] In at least one embodiment, the method comprises oxidizing
cellulose fiber in at least one of a kraft pulping step, an oxygen
delignification
step, and a kraft bleaching step. In a preferred embodiment, the method
comprises oxidizing the cellulose fiber in at least one kraft bleaching step.
In
at least one embodiment, the method comprises oxidizing the cellulose fiber
in two or more than one kraft bleaching steps.
[042] When cellulose fiber is oxidized in a bleaching step, cellulose
fiber should not be subjected to substantially alkaline conditions in the
bleaching process during or after the oxidation. In some embodiments, the
method comprises oxidizing cellulose fiber at an acidic pH. In some
embodiments, the method comprises providing cellulose fiber, acidifying the
cellulose fiber, and then oxidizing the cellulose fiber at acidic pH. In some
embodiments, the pH ranges from about 2 to about 6, for example from about
2t0 about 5 or from about 2 to about 4.
[043] The pH can be adjusted using any suitable acid, as a person of
skill would recognize, for example, sulfuric acid or hydrochloric acid or
filtrate
from an acidic bleach stage of a bleaching process, such as a chlorine dioxide
(D) stage of a multi-stage bleaching process. For example, the cellulose fiber
may be acidified by adding an extraneous acid. Examples of extraneous
acids are known in the art and include, but are not limited to, sulfuric acid,
hydrochloric acid, and carbonic acid. In some embodiments, the cellulose
fiber is acidified with acidic filtrate, such as waste filtrate, from a
bleaching
step. In some embodiments, the acidic filtrate from a bleaching step does not
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have a high iron content. In at least one embodiment, the cellulose fiber is
acidified with acidic filtrate from a D stage of a multi-stage bleaching
process.
[044] In some embodiments, the method comprises oxidizing the
cellulose fiber in one or more stages of a multi-stage bleaching sequence. In
some embodiments, the method comprises oxidizing the cellulose fiber in a
single stage of a multi-stage bleaching sequence. In some embodiments, the
method comprises oxidizing the cellulose fiber at or near the end of a multi-
stage bleaching sequence. In some embodiments, the method comprises
oxidizing cellulose fiber in at least the fourth stage of a five-stage
bleaching
sequence.
[045] In accordance with the disclosure, the multi-stage bleaching
sequence can be any bleaching sequence that does not comprise an alkaline
bleaching step following the oxidation step. In at least one embodiment, the
multi-stage bleaching sequence is a five-stage bleaching sequence. In some
embodiments, the bleaching sequence is a DEDED sequence. In some
embodiments, the bleaching sequence is a DoE1D1E2D2 sequence. In some
embodiments, the bleaching sequence is a Do(EoP)D1E2D2 sequence. In
some embodiments the bleaching sequence is a Do(E0)D1E2D2.
[046] The non-oxidation stages of a multi-stage bleaching sequence
may include any convention or after discovered series of stages, be
conducted under conventional conditions, with the proviso that to be useful in
producing the modified fiber described in the present disclosure, no alkaline
bleaching step may follow the oxidation step.
[047] In some embodiments, the oxidation is incorporated into the
fourth stage of a multi-stage bleaching process. In some embodiments, the
method is implemented in a five-stage bleaching process having a sequence
of DoE1 D1 E2D2, and the fourth stage (E2) is used for oxidizing kraft fiber.
[048] In some embodiments, the kappa number increases after
oxidation of the cellulose fiber. More specifically, one would typically
expect a
decrease in kappa number across this bleaching stage based upon the
anticipated decrease in material, such as lignin, which reacts with the
permanganate reagent. However, in the method as described herein, the
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kappa number of cellulose fiber may decrease because of the loss of
impurities, e.g., lignin; however, the kappa number may increase because of
the chemical modification of the fiber. Not wishing to be bound by theory, it
is
believed that the increased functionality of the modified cellulose provides
additional sites that can react with the permanganate reagent. Accordingly,
the kappa number of modified kraft fiber is elevated relative to the kappa
number of standard kraft fiber.
[049] In at least one embodiment, the oxidation occurs in a single
stage of a bleaching sequence after both the iron or copper and peroxide
have been added and some retention time provided. An appropriate retention
is an amount of time that is sufficient to catalyze the hydrogen peroxide with
the iron or copper. Such time will be easily ascertainable by a person of
ordinary skill in the art.
[050] In accordance with the disclosure, the oxidation is carried out for
a time and at a temperature that is sufficient to produce the desired
completion of the reaction. For example, the oxidation may be carried out at a
temperature ranging from about 60 to about 80 degrees C, and for a time
ranging from about 40 to about 80 minutes. The desired time and
temperature of the oxidation reaction will be readily ascertainable by a
person
of skill in the art.
[051] Advantageously, the cellulose fiber is digested to a target kappa
number before bleaching. For example, when the oxidized cellulose is
desired for paper grade or fluff pulp cellulose, the cellulose fiber may be
digested in a two-vessel hydraulic digester with Lo-Solids TM cooking to a
kappa number ranging from about 30 to about 32 before bleaching and
oxidizing the cellulose. Alternatively, if oxidized cellulose is desired for
cellulose derivative applications, for instance in the manufacture of
cellulose
ethers, cellulose fiber may be digested to a kappa number ranging from about
20 to about 24 before bleaching and oxidizing the cellulose according to the
methods of this disclosure. In some embodiments, the cellulose fiber is
digested and delignified in a conventional two-stage oxygen delignification
step before bleaching and oxidizing the cellulose fiber. Advantageously, the
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delignification is carried out to a target kappa number ranging from about 6
to
about 8 when the oxidized cellulose is intended for cellulose derivative
applications, and a target kappa number ranging from about 12 to about 14
when the oxidized cellulose is intended for paper and/or fluff applications.
[052] In some embodiments, the bleaching process is conducted
under conditions to target about 88-90% final ISO brightness, such as ranging
from about 85 to about 95%, or from about 88% to about 90%.
[053] The disclosure also provides a method of treating cellulose fiber,
comprising providing cellulose fiber, reducing the DP of the cellulose fiber,
and maintaining the fiber length of the cellulose fiber. In some embodiments,
the cellulose fiber is kraft fiber. In some embodiments, the DP of the
cellulose
fiber is reduced in a bleaching process. In some embodiments, the DP of the
cellulose fiber is reduced at or near the end of a multi-stage bleaching
sequence. In some embodiments, the DP is reduced in at least the fourth
stage of a multi-stage bleaching sequence. In some embodiments, the DP is
reduced in or after the fourth stage of a multi-stage bleaching sequence.
[054] Alternatively, the multi-stage bleaching sequence may be
altered to provide more robust bleaching conditions prior to oxidizing the
cellulose fiber. In some embodiments, the method comprises providing more
robust bleaching conditions prior to the oxidation step. More robust bleaching
conditions may allow the degree of polymerization and/or viscosity of the
cellulose fiber to be reduced in the oxidation step with lesser amounts of
iron
or copper and/or hydrogen peroxide. Thus, it may be possible to modify the
bleaching sequence conditions so that the brightness and/or viscosity of the
final cellulose product can be further controlled. For instance, reducing the
amounts of peroxide and metal, while providing more robust bleaching
conditions before oxidation, may provide a product with lower viscosity and
higher brightness than an oxidized product produced with identical oxidation
conditions but with less robust bleaching. Such conditions may be
advantageous in some embodiments, particularly in cellulose ether
applications.
Date Recue/Date Received 2020-06-04
17
[055] In some embodiments, the methods of the disclosure further
comprise reducing the crystallinity of cellulose fiber so that it is lower
than the
crystallinity of that cellulose fiber as measured before the oxidation stage.
For
example, in accordance with the methods of the disclosure, the crystallinity
index of the cellulose fiber may be reduced up to 20% relative to the starting
crystallinity index as measured before the oxidation stage.
[056] In some embodiments, the methods of the disclosure further
comprise treating the modified cellulose fiber with at least one caustic or
alkaline substance. For example, in at least one embodiment, a method of
treating cellulose fiber comprises providing an oxidized cellulose fiber of
the
disclosure, exposing the oxidized cellulose fiber to an alkaline or caustic
substance, and then dry laying the cellulose product. Without being bound by
theory, it is believed that the addition of at least one caustic substance to
the
modified cellulose may result in a cellulose fiber having very high
functionality
and very low fiber length.
[057] It is known that cellulose comprising increased aldehyde groups
may have advantageous properties in improving the wet strength of cellulose
fibers. See, For Example, U.S. Patent Nos. 6,319,361 to Smith et al., and
6,582,559 to Thornton et al. Such properties may be beneficial, for example,
in absorbent material applications. In some embodiments, the disclosure
provides a method for improving the wet strength of a product, comprising
providing modified cellulose fiber of the disclosure and adding the modified
cellulose fiber of the disclosure to a product, such as a paper product. For
example, the method may comprise oxidizing cellulose fiber in a bleaching
process, further treating the oxidized cellulose fiber with an acidic or
caustic
substance, and adding the treated fiber to a cellulose product.
[058] In accordance with the disclosure, hydrogen peroxide is added
to the cellulose fiber in acidic media in an amount sufficient to achieve the
desired oxidation and/or degree of polymerization and/or viscosity of the
final
cellulose product. For example, peroxide can be added in an amount of from
about 0.1 to about 4%, or from about 1% to about 3%, or from about 1% to
about 2%, or from about 2% to about 3%, based on the dry weight of the pulp.
Date Recue/Date Received 2020-06-04
18
[059] Iron or copper are added at least in an amount sufficient to
catalyze the oxidation of the cellulose with peroxide. For example, iron can
be added in an amount ranging from about 25 to about 200 ppm based on the
dry weight of the kraft pulp. A person of skill in the art will be able to
readily
optimize the amount of iron or copper to achieve the desired level or amount
of oxidation and/or degree of polymerization and/or viscosity of the final
cellulose product.
[060] In some embodiments, the method further involves adding
steam either before or after the addition of hydrogen peroxide.
[061] In some embodiments, the final DP and/or viscosity of the pulp
can be controlled by the amount of iron or copper and hydrogen peroxide and
the robustness of the bleaching conditions prior to the oxidation step. A
person of skill in the art will recognize that other properties of the
modified
kraft fiber of the disclosure may be affected by the amounts of iron or copper
and hydrogen peroxide and the robustness of the bleaching conditions prior to
the oxidation step. For example, a person of skill in the art may adjust the
amounts of iron or copper and hydrogen peroxide and the robustness of the
bleaching conditions prior to the oxidation step to target or achieve a
desired
brightness in the final product and/or a desired degree of polymerization or
viscosity.
[062] In some embodiments, the disclosure provides a method of
modifying cellulose fiber, comprising providing cellulose fiber, reducing the
degree of polymerization of the cellulose fiber, and maintaining the fiber
length of the cellulose fiber.
[063] In some embodiments, the oxidized kraft fiber of the disclosure
is not refined. Refining of the oxidized kraft fiber may have a negative
impact
on its fiber length and integrity, for instance refining the fiber may cause
the
fiber to fall apart.
[064] In some embodiments, each stage of the five-stage bleaching
process includes at least a mixer, a reactor, and a washer (as is known to
those of skill in the art).
[065] In some embodiments, a kraft pulp is acidified on a D1 stage
Date Recue/Date Received 2020-06-04
19
washer, the iron source is also added to the kraft pulp on the D1 stage
washer, the peroxide is added following the iron source (or copper source) at
an addition point in the mixer or pump before the E2 stage tower, the kraft
pulp is reacted in the E2 tower and washed on the E2 washer, and steam may
optionally be added before the E2 tower in a steam mixer.
[066] In some embodiments, iron (or copper) can be added up until
the end of the D1 stage, or the iron (or copper) can also be added at the
beginning of the E2 stage, provided that the pulp is acidified first (i.e.,
prior to
addition of the iron) at the D1 stage. Steam may be optionally added either
before or after the addition of the peroxide.
[067] In an exemplary embodiment, the method for preparing a low
viscosity modified cellulose fiber may involve bleaching kraft pulp in a multi-
stage bleaching process and reducing the DP of the pulp at or near a final
stage of the multi-stage bleaching process (for example in the 4th stage of a
multi-stage bleaching process, for example in the 4th stage of a 5 stage
bleaching process) using a treatment with hydrogen peroxide in an acidic
media and in the presence of iron. For instance, the final DP of the pulp may
be controlled by the appropriate application of the iron or copper and
hydrogen peroxide, as further described in the Examples section. In some
embodiments, the iron or copper and hydrogen peroxide is provided in
amounts and under conditions appropriate for producing a low DP fiber (i.e., a
fiber having a DPw ranging from about 1180 to about 1830, or a 0.5%
Capillary CED viscosity ranging from about 7 to about 13 mPa.$). In some
exemplary embodiments, the iron or copper and hydrogen peroxide may be
provided in amounts and under conditions appropriate for producing an ultra
low DP fiber (i.e., a fiber having a DPw ranging from about 700 to about 1180,
or a 0.5% 0.5% Capillary CED viscosity ranging from about 3.0 to about 7
mPass).
[068] For example, in some embodiments, the treatment with
hydrogen peroxide in an acidic media with iron or copper may involve
adjusting the pH of the kraft pulp to a pH ranging from about 2 to about 5,
adding a source of iron to the acidified pulp, and adding hydrogen peroxide to
Date Recue/Date Received 2020-06-04
20
the kraft pulp.
[069] In some embodiments, for example, the method of preparing a
modified cellulose fiber within the scope of the disclosure may involve
acidifying the kraft pulp to a pH ranging from about 2 to about 5 (using for
example sulfuric acid), mixing a source of iron (for example ferrous sulfate,
for
example ferrous sulfate heptahydrate) with the acidified kraft pulp at an
application of from about 25 to about 250 ppm Fe+2 based on the dry weight
of the kraft pulp at a consistency ranging from about 1% to about 15% and
also hydrogen peroxide, which can be added as a solution at a concentration
of from about 1% to about 50% by weight and in an amount ranging from
about 0.1% to about 1.5% based on the dry weight of the kraft pulp. In some
embodiments, the ferrous sulfate solution is mixed with the kraft pulp at a
consistency ranging from about 7% to about 15%. In some embodiments the
acidic kraft pulp is mixed with the iron source and reacted with the hydrogen
peroxide for a time period ranging from about 40 to about 80 minutes at a
temperature ranging from about 60 to about 80 degrees C.
[070] In some embodiments, the method of preparing a modified
cellulose fiber within the scope of this disclosure involves reducing DP by
treating a kraft pulp with hydrogen peroxide in an acidic media in the
presence
of iron (or copper), wherein the acidic, hydrogen peroxide and iron (or
copper)
treatment is incorporated into a multi-stage bleaching process. In some
embodiments, the treatment with iron, acid and hydrogen peroxide is
incorporated into a single stage of the multi-stage bleaching process. In some
embodiments, the treatment with iron (or copper), acid and hydrogen peroxide
is incorporated into a single stage that is at or near the end of the multi-
stage
bleaching process. In some embodiments, the treatment with iron (or
copper), acid and hydrogen peroxide is incorporated into the fourth stage of a
multi-stage bleaching process. For example, the pulp treatment may occur in
a single stage, such as the E2 stage, after both the iron (or copper) and
peroxide have been added and some retention time provided. In some
embodiments, each stage of a five stage bleaching process includes at least a
mixer, a reactor, and a washer (as is known to those of skill in the art), and
Date Recue/Date Received 2020-06-04
21
the kraft pulp may be acidified on the D1 stage washer, the iron source may
also be added to the kraft pulp on the D1 stage washer, the peroxide may be
added following the iron source (or copper source) at an addition point in the
mixer or pump before the E2 stage tower, the kraft pulp may be reacted in the
E2 tower and washed on the E2 washer, and steam may optionally be added
before the E2 tower in a steam mixer. In some embodiments, for example,
iron (or copper) can be added up until the end of the D1 stage, or the iron
(or
copper) could also be added at the beginning of the E2 stage, provided that
the pulp is acidified first (i.e., prior to addition of the iron) at the D1
stage,
extra acid may be added if needed to bring the pH into the range of from
about 3 to about 5, and peroxide may be added after the iron (or copper).
Steam may be added either before or after the addition of the peroxide
[071] For example, in one embodiment, the above-described five
stage bleaching processes conducted with a softwood cellulose starting
material may produce modified cellulose fiber having one or more of the
following properties: an average fiber length of at least 2.2 mm, a viscosity
ranging from about 3.0 mPa.s to less than 13 mPa.s, an S10 caustic solubility
ranging from about 16% to about 20%, an S18 caustic solubility ranging from
about 14% to about 18%, a carboxyl content ranging from about 2 meq/100 g
to about 6 meq/100 g, an aldehyde content ranging from about 1 meq/100 g
to about 3 meq/100 g, a carbonyl content of from about Ito 4, a freeness
ranging from about 700 mls to about 760 mls, a fiber strength ranging from
about 5 km to about 8 km, and a brightness ranging from about 85 to about 95
ISO. For example, in some embodiments, the above-described exemplary
five stage bleaching processes may produce modified cellulose softwood
fibers having each of the afore-mentioned properties.
[072] According to another example, wherein the cellulose fiber is a
softwood fiber, the above-described exemplary five stage bleaching
processes may produce a modified cellulose softwood fiber having an
average fiber length that is at least 2.0 mm (for example ranging from about
2.0 mm to about 3.7 mm, or from about 2.2 mm to about 3.7 mm), a viscosity
that is less than 13 mPa.s (for example a viscosity ranging from about 3.0
Date Recue/Date Received 2020-06-04
22
mPa.s to less than 13 mPa.s, or from about 3.0 mPa.s to about 5.5 mPa.s, or
from about 3.0 mPa.s to about 7 mPa.s, or from about 7 mPa.s to less than
13 mPa.s ), and a brightness of at least 85 (for example ranging from about
85 to about 95).
[073] In some embodiments, the disclosure provides a method for
producing fluff pulp, comprising providing modified kraft fiber of the
disclosure
and then producing a fluff pulp. For example, the method comprises
bleaching kraft fiber in a multi-stage bleaching process, oxidizing the fiber
in
at least the fourth or fifth stage of the multi-stage bleaching process with
hydrogen peroxide under acidic conditions and a catalytic amount of iron or
copper, and then forming a fluff pulp. In at least one embodiment, the fiber
is
not refined after the multi-stage bleaching process.
[074] The disclosure also provides a method for reducing odor, such
as odor from bodily waste, for example odor from urine or blood. In some
embodiments, the disclosure provides a method for controlling odor,
comprising providing a modified bleached kraft fiber according to the
disclosure, and applying an odorant to the bleached kraft fiber such that the
atmospheric amount of odorant is reduced in comparison with the
atmospheric amount of odorant upon application of an equivalent amount of
odorant to an equivalent weight of standard kraft fiber. In some embodiments
the disclosure provides a method for controlling odor comprising inhibiting
bacterial odor generation. In some embodiments, the disclosure provides a
method for controlling odor comprising absorbing odorants, such as
nitrogenous odorants, onto a modified kraft fiber. As used herein,
"nitrogenous odorants" is understood to mean odorants comprising at least
one nitrogen.
[075] In at least one embodiment, a method of reducing odor
comprises providing modified cellulose fiber according to the disclosure, and
applying an odorant, such as a nitrogenous compound, for instance ammonia,
or an organism that is capable of generating a nitrogenous compound to the
modified kraft fiber. In some embodiments, the method further comprises
forming a fluff pulp from modified cellulose fiber before adding an odorant to
Date Recue/Date Received 2020-06-04
23
the modified kraft fiber. In some embodiments, the odorant comprises at least
one bacteria capable of producing nitrogenous compounds. In some
embodiments, the odorant comprises nitrogenous compounds, such as
ammonia.
[076] In some embodiments, the method of reducing odor further
comprises absorbing ammonia onto modified cellulose fiber. In some
embodiments, the method of reducing odor further comprises inhibiting
bacterial ammonia production. In some embodiments, the method of
inhibiting bacterial ammonia production comprises inhibiting bacterial growth.
In some embodiments, the method of inhibiting bacterial ammonia production
comprises inhibiting bacterial urea synthesis.
[077] In some embodiments, a method of reducing odor comprises
combining modified cellulose fiber with at least one other odor reductant, and
then applying an odorant to the modified cellulose fiber combined with odor
reductant.
[078] Exemplary odor reductants are known in the art, and include, for
example, odor reducing agents, odor masking agents, biocides, enzymes, and
urease inhibitors. For instance, modified cellulose fiber may be combined
with at least one odor reductant chosen from zeolites, activated carbons,
diatomaceous earth, cyclodextrins, clay, chelating agents, such as those
containing metal ions, such as copper, silver or zinc ions, ion exchange
resins, antibacterial or antimicrobial polymers, and/or aromatizers.
[079] In some embodiments, the modified cellulose fiber is combined
with at least one super absorbent polymer (SAP). In some embodiments, the
SAP may by an odor reductant. Examples of SAP that can be used in
accordance with the disclosure include, but are not limited to, HysorbTM sold
by the company BASF, Aqua Keep sold by the company Sumitomo, and
FAVOR , sold by the company Evonik.
II. Kraft Fibers
[080] Reference is made herein to "standard," "conventional," or
"traditional," kraft fiber, kraft bleached fiber, kraft pulp or kraft bleached
pulp.
Date Recue/Date Received 2020-06-04
24
Such fiber or pulp is often described as a reference point for defining the
improved properties of the present invention. As used herein, these terms are
interchangeable and refer to the fiber or pulp which is identical in
composition
to and processed in a like manner to the target fiber or pulp without having
been subject to any oxidation, either alone or followed by one or more of
alkaline or acid treatments (i.e., processed in the standard or conventional
manner). As used herein, the term "modified" refers to fiber that has been
subject to an oxidation treatment, either alone or followed by one or more of
alkaline or acid treatments.
[081] Physical characteristics (for example, fiber length and viscosity)
of the modified cellulose fiber mentioned in the specification are measured in
accordance with protocols provided in the Examples section.
[082] The present disclosure provides kraft fiber with low and ultra-low
viscosity. Unless otherwise specified, "viscosity" as used herein refers to
0.5% Capillary CED viscosity measured according to TAPPI T230-0m99 as
referenced in the protocols. Modified kraft fiber of the present invention
exhibits unique characteristics which are indicative of the chemical
modifications that have been made to it. More specifically, fiber of the
present
invention exhibits characteristics similar to those of standard kraft fiber,
i.e.,
length and freeness, but also exhibits some very different characteristics
which are a function of the increased number of functional groups that are
included in the modified fiber. This modified fiber exhibits unique
characteristics when subjected to the cited TAPPI test for measuring
viscosity.
Specifically, the cited TAPPI test treats fiber with a caustic agent as part
of the
test method. The application of caustic to the modified fiber, as described,
causes the modified fiber to hydrolyze differently than standard kraft fiber
thus
reporting a viscosity which is generally lower than the viscosity of standard
kraft fiber. Accordingly, a person of skill in the art will understand that
the
reported viscosities may be affected by the viscosity measurement method.
For purposes of the present invention, the viscosities reported herein as
measured by the cited TAPPI method represent the viscosity of the kraft fiber
used to calculate the degree of polymerization of the fiber.
Date Recue/Date Received 2020-06-04
25
[083] Unless otherwise specified, "DP" as used herein refers to
average degree of polymerization by weight (DPw) calculated from 0.5%
Capillary CED viscosity measured according to TAPPI T230-0m99. See, e.g.
J.F. Cellucon Conference in The Chemistry and Processing of Wood and
Plant Fibrous Materials, p. 155, test protocol 8, 1994 (Woodhead Publishing
Ltd., Abington Hall, Abinton Cambridge CBI 6AH England, J.F. Kennedy et al.
eds.) "Low DP" means a DP ranging from about 1160 to about 1860 or a
viscosity ranging from about 7 to about 13 mPa.s. "Ultra low DP" fibers
means a DP ranging from about 350 to about 1160 or a viscosity ranging from
about 3 to about 7 mPa-s.
[084] Without wishing to be bound by theory, it is believed that the
fiber of the present invention presents an artificial Degree of Polymerization
when DP is calculated via CED viscosity measured according to TAPPI T230-
0m99. Specifically, it is believed that the catalytic oxidation treatment of
the
fiber of the present invention does not break the cellulose down to the extent
indicated by the measured DP, but instead largely has the effect of opening
up bonds and adding substituents that make the cellulose more reactive,
instead of cleaving the cellulose chain. It is further believed that the CED
viscosity test (TAPPI T230-0m99), which begins with the addition of caustic,
has the effect of cleaving the cellulose chain at the new reactive sites,
resulting in a cellulose polymer which has a much higher number of shorter
segments than are found in the fiber's pre-testing state. This is confirmed by
the fact that the fiber length is not significantly diminished during
production.
[085] In some embodiments, modified cellulose fiber has a DP ranging
from about 350 to about 1860. In some embodiments, the DP ranges from
about 710 to about 1860. In some embodiments, the DP ranges from about
350 to about 910. In some embodiments, the DP ranges from about 350 to
about 1160. In some embodiments, the DP ranges from about 1160 to about
1860. In some embodiments, the DP is less than 1860, less than 1550, less
than 1300, less than 820, or less than 600.
Date Recue/Date Received 2020-06-04
26
[086] In some embodiments, modified cellulose fiber has a viscosity
ranging from about 3.0 mPa.s to about 13 mPa.s. In some embodiments, the
viscosity ranges from about 4.5 mPa-s to about 13 mPa.s. In some
embodiments, the viscosity ranges from about 3.0 mPa.s to about 5.5 mPa.s.
In some embodiments, the viscosity ranges from about 3.0 mPa.s to about 7
mPa.s. In some embodiments, the viscosity ranges from about 7 mPa.s to
about 13 mPa.s. In some embodiments, the viscosity is less than 13 mPa.s,
less than 10 mPa.s, less than 8 mPa.s, less than 5 mPa.s, or less than 4
mPa.s.
[087] In some embodiments, the modified kraft fiber of the disclosure
maintains its freeness during the bleaching process. In some embodiments,
the modified cellulose fiber has a "freeness" of at least about 690 mls, such
as
at least about 700 mls, or about 710 mls, or about 720 mls, or about 730 mls.
[088] In some embodiments, modified kraft fiber of the disclosure
maintains its fiber length during the bleaching process.
[089] In some embodiments, when the modified cellulose fiber is a
softwood fiber, the modified cellulose fiber has an average fiber length, as
measured in accordance with Test Protocol 12, described in the Example
section below, that is about 2 mm or greater. In some embodiments, the
average fiber length is no more than about 3.7 mm. In some embodiments,
the average fiber length is at least about 2.2 mm, about 2.3 mm, about 2.4
mm, about 2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8 mm, about 2.9
mm, about 3.0 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4
mm, about 3.5 mm, about 3.6 mm, or about 3.7 mm. In some embodiments,
the average fiber length ranges from about 2 mm to about 3.7 mm, or from
about 2.2 mm to about 3.7 mm.
[090] In some embodiments, when the modified cellulose fiber is a
hardwood fiber, the modified cellulose fiber has an average fiber length from
about 0.75 to about 1.25 mm. For example, the average fiber length may be
at least about 0.85 mm, such as about 0.95 mm, or about 1.05 mm, or about
1.15 mm.
Date Recue/Date Received 2020-06-04
27
[091] In some embodiments, modified kraft fiber of the disclosure has
a brightness equivalent to kraft fiber standard kraft fiber. In some
embodiments, the modified cellulose fiber has a brightness of at least 85, 86,
87, 88, 89, or 90 ISO. In some embodiments, the brightness is no more than
about 92. In some embodiments, the brightness ranges from about 85 to
about 92, or from about 86 to about 90, or from about 87 to about 90, or from
about 88 to about 90.
[092] In some embodiments, modified cellulose fiber of the disclosure
is more compressible and/or embossable than standard kraft fiber. In some
embodiments, modified cellulose fiber may be used to produce structures that
are thinner and/or have higher density than structures produced with
equivalent amounts of standard kraft fiber.
[093] In some embodiments, modified cellulose fiber of the disclosure
may be compressed to a density of at least about 0.21 g/cc, for example
about 0.22 g/cc, or about 0.23 g/cc, or about 0.24 g/cc. In some
embodiments, modified cellulose fiber of the disclosure may be compressed
to a density ranging from about 0.21 to about 0.24 g/cc. In at least one
embodiment, modified cellulose fiber of the disclosure, upon compression at
20 psi gauge pressure, has a density ranging from about 0.21 to about 0.24
g/cc.
[094] In some embodiments, modified cellulose fiber of the disclosure,
upon compression under a gauge pressure of about 5 psi, has a density
ranging from about 0.110 to about 0.114 g/cc. For example, modified
cellulose fiber of the disclosure, upon compression under a gauge pressure of
about 5 psi, may have a density of at least about 0.110 g/cc, for example at
least about 0.112 g/cc, or about 0.113 g/cc, or about 0.114 g/cc.
[095] In some embodiments, modified cellulose fiber of the disclosure,
upon compression under a gauge pressure of about 10 psi, has a density
ranging from about 0.130 to about 0.155 g/cc. For example, the modified
cellulose fiber of the disclosure, upon compression under a gauge pressure of
about 10 psi, may have a density of at least about 0.130 g/cc, for example at
Date Recue/Date Received 2020-06-04
28
least about 0.135 g/cc, or about 0.140 g/cc, or about 0.145 g/cc, or about
0.150 g/cc.
[096] In some embodiments, modified cellulose fiber of the disclosure
can be compressed to a density of at least about 8% higher than the density
of standard kraft fiber. In some embodiments, the modified cellulose fiber of
the disclosure have a density of about 8% to about 16% higher than the
density of standard kraft fiber, for example from about 10% to about 16%
higher, or from about 12% to about 16% higher, or from about 13% to about
16% higher, or from about 14% to about 16% higher, or from about 15% to
about 16% higher.
[097] In some embodiments, modified kraft fiber of the disclosure has
increased carboxyl content relative to standard kraft fiber.
[098] In some embodiments, modified cellulose fiber has a carboxyl
content ranging from about 2 meq/100 g to about 9 meq/100 g. In some
embodiments, the carboxyl content ranges from about 3 meq/100 g to about 8
meq/100 g. In some embodiments, the carboxyl content is about 4 meq/100
g. In some embodiments, the carboxyl content is at least about 2 meq/100 g,
for example, at least about 2.5 meq/100 g, for example, at least about 3.0
meq/100 g, for example, at least about 3.5 meq/100 g, for example, at least
about 4.0 meq/100 g, for example, at least about 4.5 meq/100 g, or for
example, at least about 5.0 meq/100 g.
[099] Modified kraft fiber of the disclosure has increased aldehyde
content relative to standard bleached kraft fiber. In some embodiments, the
modified kraft fiber has an aldehyde content ranging from about 1 meq/100 g
to about 9 meq/100 g. In some embodiments, the aldehyde content is at least
about 1.5 meq/100 g, about 2 meq/100 g, about 2.5 meq/100 g, about 3.0
meq/100 g, about 3.5 meq/100 g, about 4.0 meq/100 g, about 4.5 meq/100 g,
or about 5.0 meq/100 g, or at least about 6.5 meq, or at least about 7.0 meq.
[0100] In some embodiments, the modified cellulose fiber has a ratio of
total aldehyde to carboxyl content of greater than about 0.3, such as greater
than about 0.5, such as greater than about 1, such as greater than about 1.4.
In some embodiments, the aldehyde to carboxyl ratio ranges from about 0.3
Date Recue/Date Received 2020-06-04
29
to about 1.5. In some embodiments, the ratio ranges from about 0.3 to about
0.5. In some embodiments, the ratio ranges from about 0.5 to about 1. In
some embodiments, the ratio ranges from about 1 to about 1.5.
[0101] In some embodiments, modified kraft fiber has higher kink and
curl than standard kraft fiber. Modified kraft fiber according to the present
invention has a kink index in the range of about 1.3 to about 2.3. For
instance, the kink index may range from about 1.5 to about 2.3, or from about
1.7 to about 2.3 or from about 1.8 to about 2.3, or from about 2.0 to about
2.3.
Modified kraft fiber according to the present disclosure may have a length
weighted curl index in the range of about 0.11 to about 0.23, such as from
about 0.15 to about 0.2.
[0102] In some embodiments, the crystallinity index of modified kraft
fiber is reduced from about 5% to about 20% relative to the crystallinity
index
of standard kraft fiber, for instance from about 10% to about 20%, or from
about 15% to about 20%.
[0103] In some embodiments, modified cellulose according to the
present disclosure has an R10 value ranging from about 65% to about 85%,
for instance from about 70% to about 85%, or from about 75% to about 85%.
In some embodiments, modified fiber according to the disclosure has an R18
value ranging from about 75% to about 90%, for instance from about 80% to
about 90%, for example from about 80% to about 87%. The R18 and R10
content is described in TAPPI 235. R10 represents the residual undissolved
material that is left extraction of the pulp with 10 percent by weight caustic
and
R18 represents the residual amount of undissolved material left after
extraction of the pulp with an 18% caustic solution. Generally, in a 10%
caustic solution, hemicellulose and chemically degraded short chain cellulose
are dissolved and removed in solution. In contrast, generally only
hemicellulose is dissolved and removed in an 18% caustic solution. Thus, the
difference between the R10 value and the R18 value, (R = R18 - R10),
represents the amount of chemically degraded short chained cellulose that is
present in the pulp sample.
Date Recue/Date Received 2020-06-04
30
[0104] Based on one or more of the above-cited properties, such as the
kink and curl of the fiber, the increased functionality, and the crystallinity
of the
modified kraft fiber, a person of skill in the art would expect the modified
kraft
fiber of the disclosure to have certain characteristics that standard kraft
fiber
does not possess. For instance, it is believed that kraft fiber of the
disclosure
may be more flexible than standard kraft fiber, and may elongate and/or bend
and/or exhibit elasticity and/or increase wicking. Moreover, without being
bound by theory, it is expected that modified kraft fiber may provide a
physical
structure, for example in a fluff pulp, that would either cause fiber
entanglement and fiber/fiber bonding or would entangle materials applied to
the pulp, such that they these materials remain in a relatively fixed spatial
position within the pulp, retarding their dispersion. Additionally, it is
expected,
at least because of the reduced crystallinity relative to standard kraft
fiber, that
modified kraft fiber of the disclosure would be softer than standard kraft
fiber,
enhancing their applicability in absorbent product applications, for example,
such as diaper and bandage applications.
[0105] In some embodiments, modified cellulose fiber has an S10
caustic solubility ranging from about 16% to about 30%, or from about 14% to
about 16%. In some embodiments, modified cellulose fiber has an S18
caustic solubility ranging from about 14% to about 22%, or from about 14% to
about 16%. In some embodiments, modified cellulose fiber has a AR
(difference between S10 and S18) of about 2.9 or greater. In some
embodiments the AR is about 6.0 or greater.
[0106] In some embodiments, modified cellulose fiber strength, as
measured by wet zero span breaking length, ranges from about 4 km to about
km, for instance, from about 5 km to about 8 km. In some embodiments,
the fiber strength is at least about 4 km, about 5 km, about 6 km, about 7 km,
or about 8 km. In some embodiments, the fiber strength ranges from about 5
km to about 7 km, or from about 6 km to about 7 km.
[0107] In some embodiments, modified kraft fiber has odor control
properties. In some embodiments, modified kraft fiber is capable of reducing
the odor of bodily waste, such as urine or menses. In some embodiments
Date Recue/Date Received 2020-06-04
31
modified kraft fiber absorbs ammonia. In some embodiments, modified kraft
fiber inhibits bacterial odor production, for example, in some embodiments,
modified kraft fiber inhibits bacterial ammonia production.
[0108] In at least one embodiment, modified kraft fiber is capable of
absorbing odorants, such as nitrogen containing odorants, for example
ammonia.
[0109] As used herein, the term "odorant" is understood to mean a
chemical material that has a smell or odor, or that is capable of interacting
with olfactory receptors, or to mean an organism, such as a bacteria, that is
capable of generating compounds that generate a smell or odor, for example
a bacteria that produces urea.
[0110] In some embodiments, modified kraft fiber reduces atmospheric
ammonia concentration more than a standard bleached kraft fiber reduces
atmospheric ammonia. For example, modified kraft fiber may reduce
atmospheric ammonia by absorbing at least part of an ammonia sample
applied to modified kraft fiber, or by inhibiting bacterial ammonia
production.
In at least one embodiment, modified kraft fiber absorbs ammonia and inhibits
bacterial ammonia production.
[0111] In some embodiments, modified kraft fiber reduces at least
about 40% more atmospheric ammonia than standard kraft fibers, for example
at least about 50% more, or about 60% more, or about 70% more, or about
75% more, or about 80% more, or about 90% more ammonia than standard
kraft fiber.
[0112] In some embodiments, modified kraft fiber of the disclosure,
after application of 0.12 g of a 50% solution of ammonium hydroxide to about
nine grams of modified cellulose and a 45 minute incubation time, reduces
atmospheric ammonia concentration in a volume of 1.6 L to less than 150
ppm, for example, less than about 125 ppm, for example less than bout 100
ppm, for example, less than about 75 ppm, for example, less than about 50
ppm.
[0113] In some embodiments, modified kraft fiber absorbs from about 5
to about 10 ppm ammonia per gram of fiber. For instance, the modified
Date Recue/Date Received 2020-06-04
32
cellulose may absorb from about 6 to about 10 ppm, or from about 7 to about
ppm, or from about 8 to about 10 ppm ammonia per gram of fibers.
[0114] In some embodiments, modified kraft fiber has both improved
odor control properties and improved brightness compared to standard kraft
fiber. In at least one embodiment, modified cellulose fiber has a brightness
ranging from about 85 to about 92 and is capable of reducing odor. For
example, the modified cellulose may have a brightness ranging from about 85
to about 92, and absorbs from about 5 to about 10 ppm ammonia for every
gram of fiber.
[0115] In some embodiments, modified cellulose fiber has an MEM
Elution Cytotoxicity Test, ISO 10993-5, of less than 2 on a zero to four
scale.
For example the cytotoxicity may be less than about 1.5 or less than about 1.
[0116] It is known that oxidized cellulose, in particular cellulose
comprising aldehyde and/or carboxylic acid groups, exhibits anti-viral and/or
antimicrobial activity. See, e.g., Song et al., Novel antiviral activity of
dialdehyde starch, Electronic J. Biotech., Vol. 12, No. 2, 2009; U.S. Patent
No. 7,019,191 to Looney et al. For instance, aldehyde groups in dialdehyde
starch are known to provide antiviral activity, and oxidized cellulose and
oxidized regenerated cellulose, for instance containing carboxylic acid
groups,
have frequently been used in wound care applications in part because of their
bactericidal and hemostatic properties. Accordingly, in some embodiments,
the cellulose fibers of the disclosure may exhibit antiviral and/or
antimicrobial
activity. In at least one embodiment, modified cellulose fiber exhibits
antibacterial activity. In some embodiments, modified cellulose fiber exhibits
antiviral activity.
[0117] In some embodiments, modified kraft fiber of the disclosure has
a level-off DP of less than 200, such as less than about 100, or less than
about 80, or less than about 75, or less than about 50 or less than or equal
to
about 48. Level-off DP can be measured by methods known in the art, for
example by methods disclosed in Battista, etal., Level-Off Degree of
Polymerization, Division of Cellulose Chemistry, Symposium on Degradation
of Cellulose and Cellulose Derivatives, 127th Meeting, ACS, Cincinnati, Ohio,
Date Recue/Date Received 2020-06-04
33
March-April 1955.
[0118] In some embodiments modified kraft fiber has a kappa number
of less than about 2. For example, modified kraft fiber may have a kappa
number less than about 1.9. In some embodiments modified kraft fiber has a
kappa number ranging from about 0.1 to about 1, such as from about 0.1 to
about 0.9, such as from about 0.1 to about 0.8, for example from about 0.1 to
about 0.7, for instance from about 0.1 to about 0.6, such as from about 0.1 to
about 0.5, or from about 0.2 to about 0.5.
[0119] In some embodiments, modified kraft fiber is kraft fiber bleached
in a multi-stage process, wherein an oxidation step is followed by at least
one
bleaching step. In such embodiments, the modified fiber after the at least one
bleaching step has a "k number", as measured according to TAPPI UM 251,
ranging from about 0.2 to about 1.2. For example, the k number may range
from about 0.4 to about 1.2, or from about 0.6 to about 1.2, or from about 0.8
to about 1.2, or from about 1.0 to about 1.2.
[0120] In some embodiments, the modified cellulose fiber has a copper
number greater than about 2. In some embodiments, the copper number is
greater than 2Ø In some embodiments, the copper number is greater than
about 2.5. For example, the copper number may be greater than about 3. In
some embodiments, the copper number ranges from about 2.5 to about 5.5,
such as from about 3 to about 5.5, for instance from about 3 to about 5.2.
[0121] In at least one embodiment, the hemicellulose content of the
modified kraft fiber is substantially the same as standard unbleached kraft
fiber. For example, the hemicellulose content for a softwood kraft fiber may
range from about 16% to about 18%. For instance, the hemicellulose content
of a hardwood kraft fiber may range from about 18% to about 25%.
Ill. Further Processing - Acid/Alkaline Hydrolysis
[0122] In some embodiments, modified kraft fiber of the disclosure is
suitable for production of cellulose derivatives, for example for production
of
lower viscosity cellulose ethers, cellulose esters, and microcrystalline
cellulose. In some embodiments, modified kraft fiber of the disclosure is
hydrolyzed modified kraft fiber. As used herein "hydrolyzed modified kraft
Date Recue/Date Received 2020-06-04
34
fiber," hydrolyzed kraft fiber" and the like are understood to mean fiber that
has been hydrolyzed with any acid or alkaline treatment know to
depolymerized the cellulose chain. In some embodiments, the kraft fiber
according to the disclosure is further treated to reduce its viscosity and/or
degree of polymerization. For example, the kraft fiber according to the
disclosure may be treated with an acid or a base.
[0123] In some embodiments, the disclosure provides a method of
treating kraft fiber, comprising bleaching kraft fiber according to the
disclosure, and then hydrolyzing the bleached kraft fiber. Hydrolysis can be
by any method known to those of ordinary skill in the art. In some
embodiments, the bleached kraft fiber is hydrolyzed with at least one acid. In
some embodiments, the bleached kraft fiber is hydrolyzed with an acid
chosen from sulfuric acid, mineral acids, and hydrochloric acid
[0124] The disclosure also provides a method for producing cellulose
ethers. In some embodiments, the method for producing cellulose ethers
comprises bleaching kraft fiber in accordance with the disclosure, treating
the
bleached kraft fiber with at least one alkali agent, such as sodium hydroxide
and reacting the fibers with at least one etherying agent.
[0125] The disclosure also provides methods for producing cellulose
esters. In some embodiments, the method for producing cellulose esters
comprises bleaching kraft fiber in accordance with the disclosure, treating
the
bleached kraft fiber with a catalyst, such as sulfuric acid, then treating the
fiber with at least one acetic anhydride or acetic acid. In an alternative
embodiment, the method for producing cellulose acetates comprises
bleaching kraft fiber in accordance with the disclosure, hydrolyzing the
bleached kraft fiber with sulfuric acid, and treating the hydrolyzed kraft
fiber
with at least one acetic anhydride or acetic acid.
[0126] The disclosure also provides methods for producing
microcrystalline cellulose. In some embodiments, the method for producing
microcrystalline cellulose comprises providing bleached kraft fiber according
to the disclosure, hydrolyzing the bleached kraft fiber with at least one acid
until the desired DP is reached or under conditions to arrive at the level-off
Date Recue/Date Received 2020-06-04
35
DP. In a further embodiment, the hydrolyzed bleached kraft fiber is
mechanically treated, for example by grinding, milling, or shearing. Methods
for mechanically treating hydrolyzed kraft fibers in microcrystalline
cellulose
production are known to persons of skill in the art, and may provide desired
particle sizes. Other parameters and conditions for producing microcrystalline
cellulose are known, and are described for example in U.S. Patent Nos.
2,978,446 and 5,346,589.
[0127] In some embodiments, modified kraft fiber according to the
disclosure is further treated with an alkaline agent or caustic agent to
reduce
its viscosity and/or degree of polymerization. Alkaline treatment, a pH above
about 9, causes dialdehydes to react and undergo a beta-hydroxy elimination.
This further modified fiber that has been treated with an alkaline agent, may
also be useful in the production of tissue, towel and also other absorbent
products and in cellulose derivative applications. In more conventional
papermaking, strength agents are often added to the fiber slurry to modify the
physical properties of the end products. This alkaline modified fiber may be
used to replace some or all of the strength adjusting agent used in the
production of tissue and towel.
[0128] As described above, there are three types of fiber products that
can be prepared by the processes described herein. The first type is fiber
that
has been treated by catalytic oxidation, which fiber is almost
indistinguishable
from its conventional counterpart (at least as far as physical and papermaking
properties are concerned), yet it has functionality associated with it that
gives
it one or more of its odor control properties, compressibility, low and ultra
low
DP, and/ or the ability to convert "in-situ" into a low DP/low viscosity fiber
under either alkaline or acid hydrolysis conditions, such as the conditions of
cellulose derivative production, e.g., ether or acetate production. The
physical
characteristics and papermaking properties of this type of fiber make it
appropriate for use in typical papermaking and absorbent product
applications. The increased functionality, e.g., aldehydic and carboxylic, and
the properties associated with that functionality, on the other hand, make
this
fiber more desirable and more versatile than standard kraft fiber.
Date Recue/Date Received 2020-06-04
36
[0129] The second type of fiber is fiber that has been subjected to
catalytic oxidation and then has been treated with an alkaline or caustic
agent.
The alkaline agent causes the fiber to break down at the sites of carbonyl
functionality that were added through the oxidation process. This fiber has
different physical and papermaking properties than the fiber only subjected to
oxidation, but may exhibit the same or similar DP levels since the test used
to
measure viscosity and thereby DP subjects the fiber to a caustic agent. It
would be evident to the skilled artisan that different alkaline agents and
levels
may provide different DP levels.
[0130] The third type of fiber is fiber that has been subjected to catalytic
oxidation and then been treated in an acid hydrolysis step. The acid
hydrolysis results in a breakdown of the fiber, possibly to levels consistent
with its level-off DP.
[0131] Fiber produced as described can, in some embodiments, be
treated with a surface active agent. The surface active agent for use in the
present invention may be solid or liquid. The surface active agent can be any
surface active agent, including by not limited to softeners, debonders, and
surfactants that is not substantive to the fiber, i.e., which does not
interfere
with its specific absorption rate. As used herein a surface active agent that
is
"not substantive" to the fiber exhibits an increase in specific absorption
rate of
30% or less as measured using the pfi test as described herein. According to
one embodiment, the specific absorption rate is increased by 25% or less,
such as 20% or less, such as 15% or less, such as 10% or less. Not wishing
to be bound by theory, the addition of surfactant causes competition for the
same sites on the cellulose as the test fluid. Thus, when a surfactant is too
substantive, it reacts at too many sites reducing the absorption capability of
the fiber.
[0132] As used herein PFI is measured according to SCAN-C-33:80
Test Standard, Scandinavian Pulp, Paper and Board Testing Committee. The
method is generally as follows. First, the sample is prepared using a PFI Pad
Former. Turn on the vacuum and feed approximately 3.01 g fluff pulp into the
Date Recue/Date Received 2020-06-04
37
pad former inlet. Turn off the vacuum, remove the test piece and place it on a
balance to check the pad mass. Adjust the fluff mass to 3.00+ 0.01 g and
record as Massdry. Place the fluff into the test cylinder. Place the fluff
containing cylinder in the shallow perforated dish of an Absorption Tester and
turn the water valve on. Gently apply a 500 g load to the fluff pad while
lifting
the test piece cylinder and promptly press the start button. The Tester will
fun
for 30 s before the display will read 00.00. When the display reads 20
seconds, record the dry pad height to the nearest 0.5 mm (Heightdry). When
the display again reads 00.00, press the start button again to prompt the tray
to automatically raise the water and then record the time display (absorption
time, T). The Tester will continue to run for 30 seconds. The water tray will
automatically lower and the time will run for another 30S. When the display
reads 20 s, record the wet pad height to the nearest 0.5 mm
(Heightwet). Remove the sample holder, transfer the wet pad to the balance
for measurement of Masswet and shut off the water valve. Specific
Absorption Rate (s/g) is T/Massdry. Specific Capacity (g/g) is (Masswet -
Massdry)/Massdry. Wet Bulk (cc/g) is [19.64 cm2 x Heightwet/3]/10. Dry
Bulk is [19.64 cm2 x Heightdry/3]/10. The reference standard for comparison
with the surfactant treated fiber is an identical fiber without the addition
of
surfactant.
[0133] It is generally recognized that softeners and debonders are often
available commercially only as complex mixtures rather than as single
compounds. While the following discussion will focus on the predominant
species, it should be understood that commercially available mixtures would
generally be used in practice. Suitable softener, debonder and surfactants
will
be readily apparent to the skilled artisan and are widely reported in the
literature.
[0134] Suitable surfactants include cationic surfactants, anionic, and
nonionic surfactants that are not substantive to the fiber. According to one
embodiment, the surfactant is a non-ionic surfactant. According to one
embodiment, the surfactant is a cationic surfactant. According to one
embodiment, the surfactant is a vegetable based surfactant, such as a
Date Recue/Date Received 2020-06-04
38
vegetable based fatty acid, such as a vegetable based fatty acid quaternary
ammonium salt. Such compounds include DB999 and DB1009, both
available from Cellulose Solutions. Other surfactants may be including, but
not limited to BerolTM 388 an ethoxylated nonylphenol ether from Akzo Nobel,
and TQ-2021 and TQ-2028, both debonders from Ashland, Inc.
[0135] Biodegradable softeners can be utilized. Representative
biodegradable cationic softeners/debonders are disclosed in U.S. Pat. Nos.
5,312,522; 5,415,737; 5,262,007; 5,264,082; and 5,223,096. The compounds
are biodegradable diesters of quaternary ammonia compounds, quaternized
amine-esters, and biodegradable vegetable oil based esters functional with
quaternary ammonium chloride and diester dierucyldimethyl ammonium
chloride and are representative biodegradable softeners.
[0136] The surfactant is added in an amount of up to 8 lbs/ton, such as
from 2 lbs/ton to 7 lbs/ton, such as from 4 lbs/ton to 7 lbs/ton such as from
6
lbs/ton to 7 lbs/ton.
[0137] The surface active agent may be added at any point prior to
forming rolls, bales, or sheets of pulp. According to one embodiment, the
surface active agent is added just prior to the headbox of the pulp machine,
specifically at the inlet of the primary cleaner feed pump.
[0138] According to one embodiment, the fiber of the present invention
has an improved filterability over the same fiber without the addition of
surfactant when utilized in a viscose process. For example, the filterability
of
a viscose solution comprising fiber of the invention has a filterability that
is at
least 10% lower than a viscose solution made in the same way with the
identical fiber without surfactant, such as at least 15% lower, such as at
least
30% lower, such as at least 40% lower. Filterability of the viscose solution
is
measured by the following method. A solution is placed in a nitrogen
pressurized (27 psi) vessel with a 1 and 3/16ths inch filtered orifice on the
bottom- the filter media is as follows from outside to inside the vessel: a
perforated metal disk, a 20 mesh stainless steel screen, muslin cloth, a
Whatman 54 filter paper and a 2 layer knap flannel with the fuzzy side up
toward the contents of the vessel. For 40 minutes the solution is allowed to
Date Recue/Date Received 2020-06-04
39
filter through the media, then at 40 minutes for an additional 140 minutes the
(so t=0 at 40 minutes) the volume of filtered solution is measured (weight)
with
the elapsed time as the X coordinate and the weight of filtered viscose as the
Y coordinate- the slope of this plot is your filtration number. Recordings to
be
made at 10 minute intervals. The reference standard for comparison with the
surfactant treated fiber is the identical fiber without the addition of
surfactant.
[0139] According to one embodiment of the invention, the surfactant
treated fiber of the invention exhibits a limited increase in specific
absorption
rate, e.g., less than 30% with a concurrent decrease in filterability, e.g.,
at
least 10%. According to one embodiment, the surfactant treated fiber has an
increased specific absorption rate of less than 30% and a decreased
filterability of at least 20%, such as at least 30%, such as at least
40%. According to another embodiment, the surfactant treated fiber has an
increased specific absorption rate of less than 25% and a decreased
filterability of at least 10%, such as at least about 20%, such as at least
30%,
such as at least 40%. According to yet another embodiment, the surfactant
treated fiber has an increased specific absorption rate of less than 20% and a
decreased filterability of at least 10%, such as at least about 20%, such as
at
least 30%, such as at least 40%. According to another embodiment, the
surfactant treated fiber has an increased specific absorption rate of less
than
15% and a decreased filterability of at least 10%, such as at least about 20%,
such as at least 30%, such as at least 40%. According to still another
embodiment, the surfactant treated fiber has an increased specific absorption
rate of less than 10% and an decreased filterability of at least 10%, such as
at
least about 20%, such as at least 30%, such as at least 40%.
IV. Products Made from Kraft Fibers
[0140] The present disclosure provides products made from the
modified kraft fiber described herein. In some embodiments, the products are
those typically made from standard kraft fiber. In other embodiments, the
products are those typically made from cotton linter or sulfite pulp. More
specifically, modified fiber of the present invention can be used, without
further modification, in the production of absorbent products and as a
starting
Date Recue/Date Received 2020-06-04
40
material in the preparation of chemical derivatives, such as ethers and
esters.
Heretofore, fiber has not been available which has been useful to replace both
high alpha content cellulose, such as cotton and sulfite pulp, as well as
traditional kraft fiber.
[0141] Phrases such as "which can be substituted for cotton linter (or
sulfite pulp). . ." and "interchangeable with cotton linter (or sulfite pulp).
. ." and
"which can be used in place of cotton linter (or sulfite pulp). . ." and the
like
mean only that the fiber has properties suitable for use in the end
application
normally made using cotton linter (or sulfite pulp). The phrase is not
intended
to mean that the fiber necessarily has all the same characteristics as cotton
linter (or sulfite pulp).
[0142] In some embodiments, the products are absorbent products,
including, but not limited to, medical devices, including wound care (e.g.
bandage), baby diapers nursing pads, adult incontinence products, feminine
hygiene products, including, for example, sanitary napkins and tampons, air-
laid non-woven products, air-laid composites, "table-top" wipers, napkin,
tissue, towel and the like. Absorbent products according to the present
disclosure may be disposable. In those embodiments, modified fiber
according to the invention can be used as a whole or partial substitute for
the
bleached hardwood or softwood fiber that is typically used in the production
of
these products.
[0143] In some embodiments, modified cellulose fiber is in the form of
fluff pulp and has one or more properties that make the modified cellulose
fiber more effective than conventional fluff pulps in absorbent products. More
specifically, modified fiber of the present invention may have improved
compressibility and improved odor control, both of which make it desirable as
a substitute for currently available fluff pulp fiber. Because of the improved
compressibility of the fiber of the present disclosure, it is useful in
embodiments which seek to produce thinner, more compact absorbent
structures. One skilled in the art, upon understanding the compressible
nature of the fiber of the present disclosure, could readily envision
absorbent
products in which this fiber could be used. By way of example, in some
Date Recue/Date Received 2020-06-04
41
embodiments, the disclosure provides an ultrathin hygiene product comprising
the modified kraft fibers of the disclosure. Ultra-thin fluff cores are
typically
used in, for example, feminine hygiene products or baby diapers. Other
products which could be produced with the fiber of the present disclosure
could be anything requiring an absorbent core or a compressed absorbent
layer. When compressed, fiber of the present invention exhibits no or no
substantial loss of absorbency, but shows an improvement in flexibility.
[0144] According to one embodiment, the absorbent product may be a
product, such as a diaper or incontinence device that will absorb and hold
urine. Such devices generally contain an absorbent fluff core. The fibers of
the present disclosure may be used to produce absorbent devices that can
improve both urine wicking and retention thereby resulting in a more
comfortable garment or device for the user.
[0145] Fibers of the present disclosure can improve vertical wicking,
horizontal wicking, and/or 45 degree wicking. According to one embodiment,
absorbent products made with fibers of the present disclosure improve vertical
wicking over products made from fiber not subjected to an oxidation step by
10%. According to another embodiment, absorbent products made with fibers
of the present disclosure improve vertical wicking over products made from
fiber not subjected to an oxidation step by 15%. According to yet another
embodiment, absorbent products made with fibers of the present disclosure
improve vertical wicking over products made from fiber not subjected to an
oxidation step by at least 20%. Similar improvements can be seen in
horizontal and 45 degree wicking.
[0146] Fibers of the present disclosure can improve absorption rate and
retention. According to one embodiment, absorbent products made with
fibers of the present disclosure improve absorption rate over products made
from fiber not subjected to an oxidation step by 10%. According to another
embodiment, absorbent products made with fibers of the present disclosure
improve absorption rate over products made from fiber not subjected to an
oxidation step by 15%. According to yet another embodiment, absorbent
products made with fibers of the present disclosure improve absorption rate
Date Recue/Date Received 2020-06-04
42
over products made from fiber not subjected to an oxidation step by 20%.
Similar improvements can be seen in horizontal and 45 degree wicking.
Similarly, according to one embodiment, absorbent products made with fibers
of the present disclosure improve total absorption over products made from
fiber not subjected to an oxidation step by 5%. According to another
embodiment, absorbent products made with fibers of the present disclosure
improve total absorption over products made from fiber not subjected to an
oxidation step by 10%. According to yet another embodiment, absorbent
products made with fibers of the present disclosure improve total absorption
over products made from fiber not subjected to an oxidation step by 15%.
[0147] The products as described when compared to products made
with fibers not subjected to an oxidation step can exhibit improved
flexibility
(especially when used in the bending side of a multilayer core), improved
dimensional stability after insult, and improved wet and dry strength
(especially when placing the disclosed fiber in the top layer of a multilayer
core) and elongation.
[0148] According to one embodiment, the absorbent core for use in an
absorbent device can include one or more layers of fiber that have been
treated differently to improve the overall uptake and retention of the device.
As used herein, treated refers to any chemical or physical process that
changes the absorbency, wicking or retention of the fiber. One common
treatment is the addition of a surface active agent. According to one
embodiment, the core can have a multitude of layers, for example, 2, 3 ,4 or
5. According to one embodiment, fibers of the present invention can be used
in any layer of a multi-layer absorbent core and be treated or untreated.
[0149] According to another embodiment, the fibers of the present
invention are used in the top layer of the absorbent core. As used herein
"top"
refers to the place on the core that is first insulted with urine and closest
to the
skin. Likewise "bottom" refers to the layer farthest away from the user. Other
layers may be referred to as "intermediate." The fibers of the present
disclosure may be used either "untreated," which refers to fiber which has not
been post-treated, for example, with a surfactant. The fibers may also be
Date Recue/Date Received 2020-06-04
43
used in a "treated" state, which refers to fibers that have been modified by
the
inclusion of a surfactant. Treated or untreated fibers may be used in any
layer
and any combination.
[0150] According to one embodiment, fibers of the present invention
are used in the top layer of an absorbent core. According to another
embodiment, the fibers of the present invention are used in the bottom layer
of an absorbent core. According to yet another embodiment, the fibers of the
invention are used in the intermediate layer of the absorbent core.
[0151] In still another embodiment, fiber of the present disclosure is
used in more than one layer of the absorbent core. The fiber of the present
disclosure may be used in both the top and bottom layers of the absorbent
core. Still further, the fiber of the present disclosure may be used in the
top,
bottom and intermediate layers of an absorbent core. According to one
embodiment, the fibers in the top layer are treated fibers. According to
another embodiment, the fibers in the bottom layer are treated fibers.
According to yet another embodiment, the fibers in the intermediate layer are
treated fibers.
[0152] The treated and untreated fibers of the present disclosure may
be combined in a single layer or may be used in separate layers of the
absorbent core. According to one embodiment, the top layer of the absorbent
core comprises fiber of the disclosure that has not been treated and the
bottom layer of the absorbent core comprises fiber of the disclosure that has
been treated. According to another embodiment, the absorbent core is made
with treated fibers of the disclosure in the top layer, untreated fibers of
the
disclosure in one or more intermediate layers and treated fibers of the
disclosure in the bottom layer.
[0153] The density of the absorbent core may vary and will typically
range from 0.10 g/cm3to 0.45 g/cm3. According to one embodiment, the
absorbent core may have a density of about 0.15 g/cm3. According to another
embodiment, the absorbent core may have a density of about 0.20 g/cm3.
According to yet another embodiment, the absorbent core may have a density
of about 0.25 g/cm3.
Date Recue/Date Received 2020-06-04
44
[0154] Modified fiber of the present invention may, without further
modification, also be used in the production of absorbent products including,
but not limited to, tissue, towel, napkin and other paper products which are
formed on a traditional papermaking machine. Traditional papermaking
processes involve the preparation of an aqueous fiber slurry which is
typically
deposited on a forming wire where the water is thereafter removed. The
increased functionality of the modified cellulose fibers of the present
disclosure may provide improved product characteristics in products including
these modified fibers. For the reasons discussed above, the modified fiber of
the present invention may cause the products made therewith to exhibit
improvements in strength, likely associated with the increased functionality
of
the fibers. The modified fiber of the invention may also result in products
having improved softness.
[0155] In some embodiments, the modified fiber of the present
disclosure, without further modification, can be used in the manufacture of
cellulose ethers (for example carboxymethylcellulose) and esters as a
substitute for fiber with very high DP from about 2950 to about 3980 (i.e.,
fiber having a viscosity, as measured by 0.5% Capillary CED, ranging from
about 30 mPa.s to about 60 mPa.$) and a very high percentage of cellulose
(for example 95% or greater) such as those derived from cotton linters and
from bleached softwood fibers produced by the acid sulfite pulping process.
The modified fiber of the present invention which has not been subjected to
acid hydrolysis will generally receive such an acid hydrolysis treatment in
the
production process for creating cellulose ethers or esters.
[0156] As described, the second and third types of fiber are produced
through processes that derivatize or hydrolyze the fiber. These fibers can
also be useful in the production of absorbent articles, absorbent paper
products and cellulose derivatives including ethers and esters.
V. Acid/Alkaline Hydrolyzed Products
[0157] In some embodiments, this disclosure provides a modified kraft
fiber that can be used as a substitute for cotton linter or sulfite pulp. In
some
Date Recue/Date Received 2020-06-04
45
embodiments, this disclosure provides a modified kraft fiber that can be used
as a substitute for cotton linter or sulfite pulp, for example in the
manufacture
of cellulose ethers, cellulose acetates and microcrystalline cellulose.
[0158] Without being bound by theory, it is believed that the increase in
aldehyde content relative to conventional kraft pulp provides additional
active
sites for etherification to end-products such as carboxymethylcellulose,
methylcellulose, hydroxypropylcellulose, and the like, enabling production of
a
fiber that can be used for both papermaking and cellulose derivatives.
[0159] In some embodiments, the modified kraft fiber has chemical
properties that make it suitable for the manufacture of cellulose ethers.
Thus,
the disclosure provides a cellulose ether derived from a modified kraft fiber
as
described. In some embodiments, the cellulose ether is chosen from
ethylcellulose, methylcellulose, hydroxypropyl cellulose, carboxymethyl
cellulose, hydroxypropyl methylcellulose, and hydroxyethyl methyl cellulose.
It is believed that the cellulose ethers of the disclosure may be used in any
application where cellulose ethers are traditionally used. For example, and
not by way of limitation, the cellulose ethers of the disclosure may be used
in
coatings, inks, binders, controlled release drug tablets, and films.
[0160] In some embodiments, the modified kraft fiber has chemical
properties that make it suitable for the manufacture of cellulose esters.
Thus,
the disclosure provides a cellulose ester, such as a cellulose acetate,
derived
from modified kraft fibers of the disclosure. In some embodiments, the
disclosure provides a product comprising a cellulose acetate derived from the
modified kraft fiber of the disclosure. For example, and not by way of
limitation, the cellulose esters of the disclosure may be used in, home
furnishings, cigarettes, inks, absorbent products, medical devices, and
plastics including, for example, LCD and plasma screens and windshields.
[0161] In some embodiments, the modified kraft fiber has chemical
properties that make it suitable for the manufacture of microcrystalline
cellulose. Microcrystalline cellulose production requires relatively clean,
highly purified starting cellulosic material. As such, traditionally,
expensive
sulfite pulps have been predominantly used for its production. The present
Date Recue/Date Received 2020-06-04
46
disclosure provides microcrystalline cellulose derived from modified kraft
fiber
of the disclosure. Thus, the disclosure provides a cost-effective cellulose
source for microcrystalline cellulose production. In some embodiments, the
microcrystalline cellulose is derived from modified kraft fiber having a DP
which is less than about 100, for example, less than about 75 or less than
about 50. In some embodiments, the microcrystalline cellulose is derived
from modified kraft fiber having an R10 value ranging from about 65% to
about 85%, for instance from about 70% to about 85%, or from about 75% to
about 85% and an R18 value ranging from about 75% to about 90%, for
instance from about 80% to about 90%, for example from about 80% to about
87%.
[0162] The modified cellulose of the disclosure may be used in any
application that microcrystalline cellulose has traditionally been used. For
example, and not by way of limitation, the modified cellulose of the
disclosure
may be used in pharmaceutical or nutraceutical applications, food
applications, cosmetic applications, paper applications, or as a structural
composite. For instance, the modified cellulose of the disclosure may be a
binder, diluent, disintegrant, lubricant, tabletting aid, stabilizer,
texturizing
agent, fat replacer, bulking agent, anticaking agent, foaming agent,
emulsifier,
thickener, separating agent, gelling agent, carrier material, opacifier, or
viscosity modifier. In some embodiments, the microcrystalline cellulose is a
colloid
VI. Products Comprising Acid Hydrolyzed Products
[0163] In some embodiments, the disclosure provides a pharmaceutical
product comprising a microcrystalline cellulose that has been produced from a
modified kraft fiber of the disclosure that has been hydrolyzed. The
pharmaceutical product may be any pharmaceutical product in which
microcrystalline cellulose has traditionally been used. For example, and not
by way of limitation, the pharmaceutical product may be chosen from tablets
and capsules. For instance, the microcrystalline cellulose of the present
disclosure may be a diluent, a disintegrant, a binder, a compression aid,
coating and/or a lubricant. In other embodiments, the disclosure provides a
Date Recue/Date Received 2020-06-04
47
pharmaceutical product comprising at least one modified derivatized kraft
fiber
of the disclosure, such as a hydrolyzed modified kraft fiber.
[0164] In some embodiments, the disclosure provides a food product
comprising a bleached kraft fiber of the disclosure that has been hydrolyzed.
In some embodiments, the disclosure provides a food product comprising at
least one product derived from bleached kraft fiber of the disclosure. In
further embodiments, the disclosure provides a food product comprising
microcrystalline cellulose derived from kraft fibers of the disclosure. In
some
embodiments, the food product comprises colloidal microcrystalline cellulose
derived from kraft fibers of the disclosure. The food product may be any food
product in which microcrystalline cellulose has traditionally been used.
Exemplary food categories in which microcrystalline cellulose may be used
are well known to those of ordinary skill in the art, and can be found, for
example, in the Codex Alimentarius, for instance at Table 3. For instance,
microcrystalline cellulose derived from chemically modified kraft fibers of
the
disclosure may be an anticaking agent, bulking agent, emulsifier, foaming
agent, stabilizer, thickener, gelling agent, and/or suspension agent.
[0165] Other products comprising cellulose derivatives and
microcrystalline cellulose derived from chemically modified kraft fibers
according to the disclosure may also be envisaged by persons of ordinary skill
in the art. Such products may be found, for example, in cosmetic and
industrial applications.
[0166] As used herein, "about" is meant to account for variations due to
experimental error. All measurements are understood to be modified by the
word "about", whether or not "about" is explicitly recited, unless
specifically
stated otherwise. Thus, for example, the statement "a fiber having a length of
2 mm" is understood to mean "a fiber having a length of about 2 mm."
[0167] The details of one or more non-limiting embodiments of the
invention are set forth in the examples below. Other embodiments of the
invention should be apparent to those of ordinary skill in the art after
consideration of the present disclosure.
Date Recue/Date Received 2020-06-04
48
Examples
A. Test Protocols
1. Caustic solubility (R10, S10, R18, S18) is
measured according to TAPPI T235-cm00.
2. Carboxyl content is measured according to
TAPPI T237-cm98.
3. Aldehyde content is measured according to
Econotech Services LTD, proprietary procedure
ESM 055B.
4. Copper Number is measured according to TAPPI
T430-cm99.
5. Carbonyl content is calculated from Copper
Number according to the formula: carbonyl =
(Cu. No. ¨ 0.07)/0.6, from Biomacromolecules
2002, 3, 969-975.
6. 0.5% Capillary CED Viscosity is measured
according to TAPPI T230-0m99.
7. Intrinsic Viscosity is measured according to
ASTM D1795 (2007).
8. DP is calculated from 0.5% Capillary CED
Viscosity according to the formula: DPw = -
449.6 + 598.4In(0.5% Capillary CED) +
118.02In2(0.5% Capillary CED), from the 1994
Cellucon Conference published in The Chemistry
and
Processing Of Wood And Plant Fibrous Materials,
p. 155, woodhead Publishing Ltd, Abington Hall,
Abington, Cambridge CBI 6AH, England, J.F.
Kennedy, et a/. editors.
Date Recue/Date Received 2020-06-04
49
9. Carbohydrates are measured according to
TAPPI T249-cm00 with analysis by DionexTM ion
chromatography.
10. Cellulose content is calculated from carbohydrate
composition according to the formula:
Cellulose=Glucan-(Mannan/3), from TAPPI
Journal 65(12):78-80 1982.
11. Hemicellulose content is calculated from the sum
of sugars minus the cellulose content.
12. Fiber length and coarseness is determined on a
Fiber Quality AnalyzerTM from OPTEST,
Hawkesbury, Ontario, according to the
manufacturer's standard procedures.
13. Wet Zero Span Tensile is determined according
to TAPPI T273-pm99.
14. Freeness is determined according to TAPPI
T227-om99.
15. Water Retention Value is determined according
to TAPPI UM 256.
16. DCM (dichloromethane) extractives are
determined according to TAPPI T204-cm97.
17. Iron content is determined by acid digestion and
analysis by ICP.
18. Ash content is determined according to TAPPI
T211-0m02.
19. Peroxide residual is determined according to
lnterox procedure.
20. Brightness is determined according to TAPPI
T525-0m02.
21. Porosity is determined according to TAPPI 460-
om02.
Date Recue/Date Received 2020-06-04
50
22. Burst factor is determined according to TAPPI
T403-om02.
23. Tear factor is determined according to TAPPI
T414-om98.
24. Breaking length and stretch are determined
according to TAPPI T494-om01.
25. Opacity is determined according to TAPPI T425-
om01.
26. Frazier porosity is determined on a Frazier Low
Air Permeability Instrument from Frazier
Instruments, Hagerstown, MD, according to the
manufacturer's procedures.
27. Fiber Length and shape factor are determined on
an L&W Fiber Tester from Lorentzen & Wettre,
Kista, Sweden, according to the manufacturer's
standard procedures.
28. Dirt and shives are determined according to
TAPPI T213-om01
B. Exemplary Method for Makinci Modified Cellulose Fiber
[0168] A semi-bleached or mostly bleached kraft pulp may be treated
with an acid, iron and hydrogen peroxide for the purposes of reducing the
fiber's viscosity or DP. The fiber may be adjusted to a pH of from about 2 to
about 5 (if not already in this range) with sulfuric, hydrochloric, acetic
acid, or
filtrate from the washer of an acidic bleach stage, such as a chlorine dioxide
stage. Iron may be added in the form of Fe+2, for example iron may be added
as ferrous sulfate heptahydrate (FeSO4.7H20). The ferrous sulfate may be
dissolved in water at a concentration ranging from about 0.1 to about 48.5
g/L.
The ferrous sulfate solution may be added at an application rate ranging from
about 25 to about 200 ppm as Fe+2 based on the dry weight of pulp. The
ferrous sulfate solution may then be mixed thoroughly with the pH-adjusted
Date Recue/Date Received 2020-06-04
51
pulp at a consistency of from about 1% to about 15% measured as dry pulp
content of the total wet pulp mass. Hydrogen peroxide (H202) may then be
added as a solution with a concentration of from about 1% to about 50% by
weight of H202 in water, at an amount of from about 0.1% to about 3% based
on the dry weight of the pulp. The pulp at a pH of from about 2 to about 5
mixed with the ferrous sulfate and peroxide may be allowed to react for a time
ranging from about 40 to about 80 minutes at a temperature of from about 60
to about 80 degrees C. The degree of viscosity (or DP) reduction is
dependent on the amount of peroxide consumed in the reaction, which is a
function of the concentration and amount of peroxide and iron applied and the
retention time and temperature.
[0169] The treatment may be accomplished in a typical five-stage
bleach plant with the standard sequence of Do El DI E2 D2. With that
scheme, no additional tanks, pumps, mixers, towers, or washers are required.
The fourth or E2 stage may be preferably used for the treatment. The fiber on
the DI stage washer may be adjusted to a pH of from about 2 to about 5, as
needed by addition of acid or of filtrate from the D2 stage. A ferrous sulfate
solution may be added to the pulp either (1) by spraying it on the D1 stage
washer mat through the existing shower headers or a new header, (2) added
through a spray mechanism at the repulper, or (3) added through an addition
point before a mixer or pump for the fourth stage. The peroxide as a solution
may be added following the ferrous sulfate at an addition point in a mixer or
pump before the fourth stage tower. Steam may also be added as needed
before the tower in a steam mixer. The pulp may then be reacted in the tower
for an appropriate retention time. The chemically modified pulp may then be
washed on the fourth stage washer in a normal fashion. Additional bleaching
may be optionally accomplished following the treatment by the fifth or D2
stage operated in a normal fashion.
Date Recue/Date Received 2020-06-04
52
EXAMPLE 1
Methods of Preparing Fibers of the Disclosure
A. Mill Method A
[0170] Southern pine cellulose was digested and oxygen delignified in
a conventional two-stage oxygen delignification step to a kappa number of
from about 9 to about 10. The delignified pulp was bleached in a five-stage
bleach plant, with a sequence of Do(E0)D1E2D2. Before the fourth or E2
stage, the pH of the pulp was adjusted to a range of from about 2 to about 5
with filtrate from a D stage of the sequence. After the pH was adjusted, 0.2%
hydrogen peroxide based on the dry weight of the pulp and 25 ppm Fe+2 in
the form of FeSO4.7H20 based on the dry weight of the pulp were added to
the kraft fibers in the E2 stage tower and reacted for about 90 minutes at a
temperature of from about 78 to about 82 degrees C. The reacted fibers were
then washed on the fourth stage washer, and then bleached with chlorine
dioxide in the fifth (D2) stage.
B. Mill Method B
[0171] Fibers were prepared as described in Mill Method A, except that
the pulp was treated with 0.6% peroxide and 75 ppm Fe+2.
C. Mill Method C
[0172] Fibers were prepared as described in Mill Method A, except that
the pulp was treated with 1.4% peroxide and 100 ppm Fe+2.
Properties of Exemplary Fibers
[0173] Samples of fibers prepared according to Mill Methods A (sample
2), B (sample 3), and C (sample 4) were collected following the five-stage
bleaching sequence described above. Several properties of these samples
along with a standard fluff grade fiber (GP Leaf River Cellulose, New Augusta,
MS; Sample 1), and a commercially available sample (PEACH TM, sold by
Weyerhaeuser Co.; Sample 5), were measured according to the protocols
described above. The results of these measurements are reported in Table 1
below.
Date Recue/Date Received 2020-06-04
53
Table 1
Sample Sample Sample Sample Sample
1 2 3 4 5
GP Leaf Mill Mill Mill
Weyerhaeuser
River Method Method Method Co.
Cellulose, A B C PEACH
Fiber Measurement fluff
grade
fiber
R10 % 86.8 85.2 82.4 72.5 78.4
S10 % 13.2 14.8 17.6 27.5 2t6
R18 % 87.0 87.2 85.4 78.7 84.4
S18 % 13.0 12.8 14.6 2t3 15.6
AR 0.2 2.0 3.0 6.2 6.0
Carboxyl meq/100 g 3.13 3.53 3/0 3.94 3/4
Aldehydes meq/100 g 0.97 1.24 2.15 4.21 0.87
Copper No. 0.51 1.2 t3 4.25 t9
Calculated Carbonyl mmole/100 g 0/3 1.88 2.05 6.97 3.05
Calculated 0/5 1.52 0.95 t66 3.5
carbonyl/Aldehyde
ratio
0.5% Capillary CED mPa.s 15.0 8.9 6.5 3.50 4.16
Viscosity
Intrinsic Viscosity HE dUg 7.14 544 4.33 249
3.00
Calculated DP DP w 2036 1423 1084 485 643
Glucan % 83.0 85.9 84.6 85.4 82
Xylan % 9.0 8.8 94 8.2 84
Galactan % 0.2 0.2 0.2 0.2 0.2
Mannan % 5.9 54 5.3 5.5 6.2
Arabinan % OA 0.3 0.3 OA 0.3
Calculated Cellulose % 81.0 84.1 82.8 83.6 79.9
Calculated % 17.5 16.5 17.0 16.1 17.2
Hemicelllulose
Lwl Fiber Length MITI 2.34 2.57 2.53 2.30 2.19
Lww Fiber Length mm 3.39 3.34 3.34 3.01
Coarseness 0.222 0.234 0.19 0.254
Wet Zero Span km 9.38 6.83 5.01 2.3
Breaking Length
DCM extractives 0.006 0.006
Iron ppm 5.5 44
WRV 0.98 0.99 0.85
Brightness %ISO 89.6 89.0 88.2 88.5 88.5
[0174] As reported in Table 1, iron content of the control fiber, Sample
1, was not measured. However, the iron content of four mill-made pulp
samples treated under the same conditions as those reported for Sample 1
Date Recue/Date Received 2020-06-04
54
were taken. The iron content of those samples averaged 2.6
ppm. Accordingly, for Sample 1, one would expect the iron content to be on
the order of about 2.5 ppm.
[0175] As can be seen from Table 1, modified fiber according to the
present invention is unexpectedly different from both the control fiber,
Sample
1, and an alternative commercially available oxidized fiber, Sample 5, in the
total carbonyl content as well as the carboxyl content and aldehyde
content. To the extent there is a difference between the total carbonyl groups
and aldehyde groups, additional carbonyl functionality may be in the form of
other ketones. The data shows that we achieve relatively high levels of
aldehydes while retaining carboxylic acid groups and while retaining a near
unity ratio of aldehydes to total carbonyl groups (as seen in Table 1, about
1.0
(0.95) to 1.6). This is more surprising in a fiber that exhibits high
brightness
and that is also relatively strong and absorbent.
[0176] As can be seen in Table 1, the standard fluff grade fiber
(Sample 1) had a carboxyl content of 3.13 meq/100 g, and an aldehyde
content of 0.97 meq/100 g. After a low-dose treatment with 0.2% H202 and
25 ppm Fe+2 (Sample 2) or a higher-dose treatment with 0.6% H202 and 75
ppm Fe+2 (Sample 3), or a higher-dose treatment with 1.4% H202 and 100
ppm Fe+2 (Sample 4), the fiber length and calculated cellulose content were
relatively unchanged, and fiber strength as measured by the wet zero span
method was diminished somewhat, yet the carboxyl, carbonyl, and aldehyde
contents were all elevated, indicating extensive oxidation of the cellulose.
[0177] In comparison, a commercially available sample of oxidized kraft
softwood southern pine fiber manufactured by an alternative method (Sample
5), shows significant reduction in fiber length and about a 70 percent loss in
fiber strength as measured by the wet zero span method as compared to the
fluff grade fiber reported as Sample 1. The aldehyde content of Sample 5
was virtually unchanged compared to the standard fluff grade fibers, while the
inventive fibers prepared by mill methods A-C (Samples 2-4) had highly
elevated aldehyde levels representing from about 70 to about 100 percent of
the total calculated carbonyl content of the cellulose. In contrast, the
Date Recue/Date Received 2020-06-04
55
PEACH aldehyde level was less than 30 percent of the total calculated
carbonyl content of the cellulose. The ratio of total carbonyl to aldehyde
would
appear to be a good indicator of a fiber that has the broad applicability of
the
modified fibers within the scope of this disclosure, particularly if the ratio
is in
the range of about 1 to about 2, as are Samples 2-4. Low viscosity fibers,
such as Samples 3 and 4, and with carbonyl/aldehyde ratios of about 1.5 to
less than 2.0, maintained fiber length, while those of the comparative Sample
did not.
[0178] The freeness, density, and strength of the standard fiber
described above (Sample 1) were compared with Sample 3 described above.
The results of this analysis are depicted in Table 2.
Table 2 Pulp, Paper & Fiber Properties of Standard & Modified Kraft
Fiber
PFI Freeness Density Breaking Wet Zero Span
refining (CSF) g/cm3 Length Breaking Length
revs km km
Standard Leaf 0 737 0.538 2.16 938
River Fluff
having 0.5%
Capillary CED 300 721 0.589 3.57
viscosity of about
mPa.s
(Sample 1)
Modified cellulose 0 742 0.544 2.19 6.83
fiber as in
(ULDP) having 300 702 0.595 3.75
0.5% Capillary
CED viscosity 6.5
mPa.s
(Sample 3)
[0179] As can be seen in the above Table 2, the modified cellulose
fibers according to this disclosure may have a freeness comparable to
standard fluff fibers that have not undergone an oxidation treatment in the
bleaching sequence.
Date Recue/Date Received 2020-06-04
56
EXAMPLE 2
[0180] A sample of Southern pine pulp from the D1 stage of a
OD(EOP)D(EP)D bleach plant with a 0.5% Capillary CED viscosity of about
14.6 mPa.s was treated at about 10% consistency with hydrogen peroxide
applications of from 0.25% to 1.5% and either 50 or 100 ppm of Fe+2 added
as FeSO4.7H20. The Fe+2 was added as a solution in water and mixed
thoroughly with the pulp. The hydrogen peroxide as a 3% solution in water
was then mixed with the pulp. The mixed pulp was held in a water bath for 1
hour at 78 C. After the reaction time, the pulp was filtered and the filtrate
measured for pH and residual peroxide. The pulp was washed and the 0.5%
Capillary CED viscosity determined according to TAPPI T230. The results are
shown in Table 3.
Table 3
H202 H202 Fe+2 pH 0.5% AViscosity DPw
added consumed Capillary
CED
Viscosity
% on % on pulp ppm on final mPa.s
pulp pulp
Control 14.6 2003
0.25 0.25 100 4.8 8.6 6.0 1384
0.50 0.34 50 4/ 8.9 5/ 1423
0.50 0.50 100 4.8 6.8 7.8 1131
0.75 0.19 50 4.6 10.6 4.0 1621
0/5 0/5 100 4/ 5.8 8.8 967
1.0 0.20 50 4.6 9.0 5.6 1435
1.0 040 100 4/ 7.8 6.8 1278
t5 0.30 50 4.6 10.0 4.6 1554
1.5 040 100 4.6 7.5 7.1 1235
EXAMPLE 3
[0181] A sample of D1 pulp from the bleach plant described in Example
2, with a 0.5% Capillary CED viscosity of 15.8 mPa.s (DPw 2101) was
treated with 0.75% hydrogen peroxide applied and Fe+2 was added from 50 to
200 ppm in the same manner as Example 2, except the retention times were
Date Recue/Date Received 2020-06-04
57
also varied from 45 to 80 minutes. The results are shown in Table 4.
Table 4
Treatment H202 H202 Fe+2 pH 0.5%
AViscosity DPw
time added consumed Capillary
CED
Viscosity
minutes % on % on pulp ppm on final mPa.s 2101
pulp pulp
Control 15.8 1291
45 0.75 0/2 100 44 7.9 7.9 1035
60 0/5 0/5 200 4.1 6.2 9.6 1384
80 0/5 0.27 50 8.6 7.2 1018
80 0/5 0/5 100 4.6 6.1 9/ 2101
EXAMPLE 4
[0182] A sample of D1 pulp from the bleach plant described in Example
2, with a 0.5% Capillary CED viscosity of 14.8 mPa.s (DPw 2020) was
treated with 0.75% hydrogen peroxide and 150 ppm of Fe+2 in the same
manner as described in Example 2, except that the treatment time was 80
minutes. The results are shown in Table 5.
Table 5
Treatment H202 H202 Fe+2 pH 0.5% AViscosity DPw
time added consumed Capillary
CED
Viscosity
minutes % on % on pulp ppm on final mPa.s
pulp pulp
Control 14.8 2020
80 0/5 0/5 150 3.9 5.2 9.6 858
EXAMPLE 5
[0183] A Southern pine pulp from the D1 stage of a ODo(E0)D1(EP)D2
sequence with a 0.5% Capillary CED viscosity of 15.6 mPa.s (DPw 2085) was
treated at 10% consistency with hydrogen peroxide applications of either
0.25% or 0.5% by weight on pulp and 25, 50, or 100 ppm of Fe+2 added as
FeSO4.7H20. The Fe+2 was added as a solution in water and mixed
Date Recue/Date Received 2020-06-04
58
thoroughly with the pulp. The hydrogen peroxide was a 3% solution in water
that was then mixed with the pulp, and the mixed pulp was held in a water
bath for 1 hour at 78 C. After the reaction time, the pulp was filtered and
the
filtrate measured for pH and residual peroxide. The pulp was washed and the
0.5% Capillary CED viscosity determined according to TAPPI T230. The
results are shown in Table 6.
Table 6
H202 H202 Fe+2 pH 0.5% AViscosity DPw
added consumed Capillary
CED
Viscosity
% on % on pulp ppm on final mPa.s
pulp pulp
Control 15.6 2085
0.25 0.25 25 3.5 64 9.2 1068
0.50 0.50 50 2.9 4.5 11.1 717
0.50 0.50 100 2.7 4.5 11.1 717
EXAMPLE 6
[0184] Another sample of D1 pulp, with a 0.5% Capillary CED viscosity
of 15.2 mPa.s (DPw 2053) was treated with 0.10, 0.25, 0.50, or 0.65%
hydrogen peroxide and 25, 50, or 75 ppm of Fe+2 in the same manner as
Example 5. The results are shown in Table 7.
Table 7
Treatment H202 H202 Fe2 pH 0.5% AViscosity DPw
time added consumed Capillary
CED
Viscosity
minutes % on % on pulp ppm on final mPa.s
pulp pulp
Control 15.2 2053
60 0.10 0.10 25 4.1 9.6 5.6 1508
60 0.25 0.19 25 4.0 7.9 73 1291
60 0.50 040 50 3.5 6.7 8.5 1116
80 0.65 0.65 75 3.3 44 10.8 696
Date Recue/Date Received 2020-06-04
59
EXAMPLE 7
[0185] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D bleaching sequence, after the extent of delignification in the
kraft and oxygen stages was increased to produce a pulp with a lower DPw or
0.5% Capillary CED viscosity. The starting 0.5% Capillary CED viscosity was
12.7 mPa.s (DPw 1834). Either 0.50 or 1.0% hydrogen peroxide was added
with 100 ppm of Fe+2. Other treatment conditions were 10% consistency, 78
C, and 1 hour treatment time. The results are shown in Table 8.
Table 8
H202 H202 Fe+2 pH 0.5% AViscosity DPw
added consumed Capillary
CED
Viscosity
% on % on pulp ppm on final mPa.s
pulp pulp
Control 12/ 1834
0.50 0.50 100 2.1 5.6 7.1 932
1.0 037 100 2.6 4.2 8.5 652
EXAMPLE 8
[0186] A low viscosity sample of D1 pulp from the D1 stage of a
OD(E0)D(EP)D sequence, with a 0.5% Capillary CED viscosity of 11.5 mPa.s
(DPw 1716), was treated with either 0.75 or 1.0% hydrogen peroxide and 75
or 150 ppm of Fe+2 in a manner similar to Example 7, except the treatment
time was 80 minutes. The results are shown in Table 9.
Table 9
H202 H202 Fe+2 pH 0.5% AViscosity DPw
added consumed Capillary
CED
Viscosity
% on % on pulp ppm on final mPa.s
pulp pulp
Control 11.5 1716
0.75 0.75 75 3.2 3.6 7.9 511
0.75 0.75 150 3.0 3.8 7/ 560
1 1 75 2.6 3.4 8.1 459
1 1 150 2.6 3.4 8.1 459
Date Recue/Date Received 2020-06-04
60
EXAMPLE 9
[0187] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D sequence. The starting 0.5% Capillary CED viscosity was
11.6 mPa.s (DPw 1726). Either 1.0%, 1.5%, 0r2% hydrogen peroxide was
added with 75, 150, or 200 ppm of Fe+2. Other treatment conditions were
10% consistency, 78 C, and 1.5 hour treatment time. The results are shown
in Table 10.
Table 10
H202 H202 Fe.2 pH 0.5%
AViscosity DPw Carboxyl Aldehyde Copper
added consumed Capillary no.
CED
Viscosity
% on % on pulp ppm on final mPa-s meq/100 meq/100
pulp pulp
Control 11.6 1726
3.67 0.35 0.52
1.0 0.98 75 3.4 3.5 8.1 485 3.73 4.06
3.05
1.5 1.49 150 2.7 3.2 8.4 406 3.78 5.06
2.57
2.0 2.0 200 2.9 3.0 8.6 350 3.67 5.23
2.06
EXAMPLE 10
[0188] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D sequence. The starting 0.5% Capillary CED viscosity was
14.4 mPa.s (DPw 1986). Either 1.0%, 1.5%, 0r2% hydrogen peroxide was
added with 75, 150, or 200 ppm of Fe+2. Other treatment conditions were 10%
consistency, 78 C, and 1.5 hour reaction time. The results are shown in Table
11.
Table 11
H202 H202 Fe*2 pH 0.5%
AViscosity DPw Carboxyl Aldehyde Copper
added consumed Capillary no.
CED
Viscosity
% on % on pulp ppm final mPa.s meq/100 meq/100
pulp on
pulp
Control 14.4 1986
3.52 0.23 0.67
1.0 0.95 75 3.3 3.8 10.6 560 3.65 3.48
2.47
1.5 1.5 150 2.4 3.7 10.7 535 4.13 4.70
2.32
2.0 2.0 200 2.8 3.2 11.2 406 3.93 5.91
1.88
Date Recue/Date Received 2020-06-04
61
EXAMPLE 11
[0189] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D sequence. The starting 0.5% Capillary CED viscosity was
15.3 mPa.s (DPw 2061). Hydrogen peroxide was added at 3% on pulp with
200 ppm of Fe+2. Other treatment conditions were 10% consistency, 80 C,
and 1.5 hour reaction time. The results are shown in Table 12.
Table 12
H202 H202 Fe*2 pH 0.5%
AViscosity DPw Carboxyl Aldehyde Copper
added consumed Capillary no.
CED
Viscosity
% on % on pulp ppm on final mPa.s
meq/100 meq/100
pulp pulp
Control 15.3 2061
3.0 2.9 200 2.8 2.94 12.4 333 4.66
6.74 5.14
[0190] The above Examples 2-11 show that a significant decrease in
0.5% Capillary CED viscosity and/or degree of polymerization can be
achieved with the acidic, catalyzed, peroxide treatment of the present
disclosure. The final viscosity or DPw appears to be dependent on the
amount of peroxide that is consumed by the reaction, as shown in Figure 1,
which reports the viscosity of pulp from two different mills ("Brunswick" and
Leaf River ("LR")) as a function of the percent peroxide consumed. The
peroxide consumption is a function of the amounts and concentrations of
peroxide and iron applied, the reaction time, and the reaction temperature.
EXAMPLE 12
[0191] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D sequence. The starting 0.5% Capillary CED viscosity was
14.8 mPa.s (DPw 2020). Hydrogen peroxide was added at 1% on pulp with
either 100, 150, or 200 pm of Cu+2 added as CuSO4-5H20. Other treatment
conditions were 10% consistency, 80 C, and 3.5 hours reaction time. The
results are shown in Table 13.
Date Recue/Date Received 2020-06-04
62
Table 13
H202 H202 cu*2 pH 0.5%
AViscosity Dpw Carboxyl Aldehyde Copper
added consumed Capillary no.
CED
Viscosity
% on % on pulp ppm final mPa.s
meq/100 meq/100
pulp on
pulp
Control 14.8 2020
3.36 0.37 0.51
1.0 0.82 100 2.4 6.1 8.7 1018
1.0 0.94 150 2.3 5.9 8.9 984
1.0 0.94 200 2.4 6.0 8.8 1001 3.37 2.71 1.8
[0192] The use of copper instead of iron resulted in a slower reaction
and a lower reduction in viscosity, but still a significant change in
viscosity,
carboxyl content, and aldehyde content over the control, untreated pulp.
EXAMPLE 13
[0193] The E2 (EP) stage of an OD(EOP)D(EP)D sequence was
altered to produce the ultra low degree of polymerization pulp. A solution of
FeSO4-7H20 was sprayed on the pulp at the washer repulper of the D1 stage
at an application rate of 150 ppm as Fe+2. No caustic (NaOH) was added to
the E2 stage and the peroxide application was increased to 0.75%. The
retention time was approximately 1 hour and the temperature was 79 C. The
pH was 2.9. The treated pulp was washed on a vacuum drum washer and
subsequently treated in the final D2 stage with 0.7% C102 for approximately 2
hours at 91 C. The 0.5% Capillary CED viscosity of the final bleached pulp
was 6.5 mPa.s (DPw 1084) and the ISO brightness was 87.
EXAMPLE 14
[0194] The pulp produced in Example 13 was made into a pulp board
on a Fourdrinier type pulp dryer with standard dryer cans. Samples of a
control pulp and the pulp of the present invention (ULDP) were collected and
analyzed for chemical composition and fiber properties. The results are
Date Recue/Date Received 2020-06-04
63
shown in Table 14.
Table 14
Property Standard ULDP
R10 % 85.2 8t5
S10 % 14.8 18.5
R18 % 86.4 84A
S18 % 13.6 15.6
AR 1.2 2.9
Carboxyl meq/100 g 4.06 4.27
Aldehydes meq/100 g 043 1.34
Copper No. 032 1.57
Calculated Carbonyl mmole/100 g 042 2.50
0.5% Capillary CED Viscosity mPa.s 14.2 73
Intrinsic Viscosity dUg 6.76 4.37
Calculated DP DP w 1969 1206
Glucan % 83.6 83.6
Xylan % 9.2 9.0
Galactan % 0.2 0.2
Mannan % 6.3 64
Arabinan % 04 OA
Calculated Cellulose % 81.5 81.5
Calculated Hemicelllulose % 18.2 18.1
Lwl Fiber Length mm 2.51 2.53
Lww Fiber Length mm 3.28 3.26
Coarseness mg/m 0.218 0.213
Wet Zero Span Tensile km 9.86 6.99
Freeness (CSF) mls 720 742
Water Retention Value g H20/g pulp 0.96 0.84
DCM extractives 0.008 0.007
Iron ppm 3.5 10.7
Ash % 0.20 0.22
Brightness % ISO 90.4 86.5
Date Recue/Date Received 2020-06-04
64
[0195] The treated pulp (ULDP) had a higher alkali solubility in 10%
and 18% NaOH and a higher aldehyde and total carbonyl content. The ULDP
was significantly lower in DP as measured by 0.5% Capillary CED viscosity.
The decrease in fiber integrity was also determined by a reduction in wet zero
span tensile strength. Despite the significant reduction in DPw, the fiber
length and freeness were essentially unchanged. There were no deleterious
effects on drainage or board making on the machine.
EXAMPLE 15
[0196] The E2 (EP) stage of a OD(E0)D(EP)D sequence was altered
to produce the ultra low degree of polymerization pulp in a similar manner as
Example 13. In this example, the FeSO4-7H20 was added at 75 ppm as Fe+2
and the hydrogen peroxide applied in the E2 stage was 0.6%. The pH of the
treatment stage was 3.0, the temperature was 82 C, and the retention time
was approximately 80 minutes. The pulp was washed and then treated in a
D2 stage with 0.2% C102 at 92 C for approximately 150 minutes. The 0.5%
Capillary CED viscosity of the fully bleached pulp was 5.5 mPa.s (DPw 914)
and the ISO brightness was 88.2.
EXAMPLE 16
[0197] The pulp produced in Example 15 was made into a pulp board
on a Fourdrinier type pulp dryer with an airborne FlaktTM dryer section.
Samples of a standard pulp and the pulp of the present invention (ULDP)
were collected and analyzed for chemical composition and fiber properties.
The results are shown in Table 15.
Date Recue/Date Received 2020-06-04
65
Table 15
Property Standard ULDP
R10 % 86.8 82.4
S10 % 13.2 17.6
R18 % 87.0 85.4
S18 % 13.0 14.6
AR 0.2 3.0
Carboxyl meq/100 g 3.13 3/0
Aldehydes meq/100 g 0.97 2.15
Copper No. 0.51 1.3
Calculated Carbonyl mmole/100 g 0/3 2.05
0.5% Capillary CED mPa.s 15.0 6.5
Viscosity
Intrinsic Viscosity dUg 7.14 4.33
Calculated DP DRA, 2036 1084
Glucan % 83.0 84.6
Xylan % 9.0 94
Galactan % 0.2 0.2
Mannan % 5.9 53
Arabinan % 04 03
Calculated Cellulose % 81.0 82.8
Calculated Hemicelllulose % 17.5 17.0
Lwl Fiber Length mm 2.55 2.53
Lww Fiber Length mm 3.29 334
Coarseness mg/m 0.218 0.234
Wet Zero Span Tensile km 938 6.83
Freeness (CSF) mls 738 737
Iron PPm 1.6 44
Brightness % ISO 89.6 88.2
[0198] The treated pulp (ULDP) had a higher alkali solubility in 10%
and 18% NaOH and a higher aldehyde and total carbonyl content. The ULDP
was significantly lower in DP as measured by 0.5% Capillary CED viscosity
and lower wet zero span breaking length. The brightness was still an
acceptable value of 88.2. The treatment preserved the fiber length and
Date Recue/Date Received 2020-06-04
66
freeness and there were no operational issues forming and drying the board.
EXAMPLE 17
[0199] The E2 (EP) stage of a OD(E0)D(EP)D sequence was altered
to produce a low degree of polymerization pulp in a similar manner as
Example 13. In this case the FeSO4-7H20 was added at 25 ppm as Fe+2 and
the hydrogen peroxide applied in the E2 stage was 0.2%. The pH of the
treatment stage was 3.0, the temperature was 82 C and the retention time
was approximately 80 minutes. The pulp was washed then treated in a D2
stage with 0.2% C102 at 92 C for approximately 150 minutes. The 0.5%
Capillary CED viscosity of the fully bleached pulp was 8.9 mPa-s (DPw 1423)
and the ISO brightness was 89.
EXAMPLE 18
[0200] The pulp produced in Example 15 was made into a pulp board
on a Fourdrinier type pulp dryer with an airborne FlaktTM dryer section.
Samples of a standard pulp and the low degree of polymerization pulp of the
present invention (LDP) were collected and analyzed for chemical
composition and fiber properties. The results are shown in Table 16.
Date Recue/Date Received 2020-06-04
67
Table 16
Property Standard LDP
R10 % 86.8 85.2
S10 % 13.2 14.8
R18 % 87.0 87.2
S18 % 13.0 12.8
AR 0.2 2.0
Carboxyl meq/100 g 3.13 3.53
Aldehydes meq/100 g 0.97 1.24
Copper No. 0.51 1.2
Calculated Carbonyl mmole/100 g 0/3 1.88
0_5% Capillary CED mPa.s 15_0 8_9
Viscosity
Intrinsic Viscosity dUg 7.14 544
Calculated DP DRA, 2036 1423
Glucan % 83.0 85.9
Xylan % 9.0 8.8
Galactan % 0.2 0.2
Mannan % 5.9 54
Arabinan % 04 03
Calculated Cellulose % 81.0 84.1
Calculated Hemicelllulose % 17.5 16.5
Lwl Fiber Length mm 2.55 2.57
Lww Fiber Length mm 3.29 334
Coarseness mg/m 0.218 0.222
Iron PPm 1.6 5.5
Brightness % ISO 89.6 89.0
[0201] The treated pulp (LDP) had a higher alkali solubility in 10% and
18% NaOH and a higher aldehyde and total carbonyl content. The LDP was
lower in DP as measured by 0.5% Capillary CED viscosity. There was a
minimal loss in brightness. The treatment preserved the fiber length and there
were no operational issues forming and drying the board.
Date Recue/Date Received 2020-06-04
68
EXAMPLE 19
[0202] The pulp boards described in Example 14 were fiberized and
airformed into 4"x7" pads using a Kamas Laboratory Hammermill (Kamas
Industries, Sweden). The airformed pads were then compressed at various
gauge pressures using a laboratory press. After pressing, the pad caliper was
measured using an Emveco microgage caliper gage model 200-A with a foot
pressure of 0.089 psi. Pad density was calculated from the pad weight and
caliper. The results are depicted in Table 17.
Table 17
Gauge 5 psi 10 psi 20 psi
Pressure
Caliper Pad Density Caliper Pad Density Caliper Pad Density
Wt Wt Wt
mm g g/cc mm g g/cc mm g g/cc
Standard
Kraft 2.62 5.14 0.108 2.29 5.27 0.127 1.49
5.29 0.196
Southern
Pine Fiber 2.81 5.14 0.101 2.26 5.19 0.127 1.42
5.23 0.203
Modified
Kraft 2.51 5.16 0.114 2.13 5.33 0.138 1.23
5.39 0.242
Southern
Pine Fiber 2.56 5.26 0.114 1.93 5.37 0.154 1.32
5.26 0.220
Percent 8.43 14.94 15.67
Increase in
Density
[0203] The data in Table 17 show that the modified fibers produced
within the scope of this disclosure were more compressible, resulting in
thinner and higher density structures more suitable for today's disposable
absorbent product designs.
[0204] Without being bound by theory, it is believed that the oxidation
of the cellulose disrupts the crystalline structure of the polymer, rendering
it
less stiff and more conformable. The fibers composed of the modified
cellulose structure then become more compressible, allowing for the
production of higher density absorbent structures.
EXAMPLE 20
[0205] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D(EP)D sequence. The starting 0.5% Capillary CED viscosity was
Date Recue/Date Received 2020-06-04
69
14.9 mPa.s (DPw 2028). Either 1.0% or 2% hydrogen peroxide was added
with 100 or 200 ppm of Fe+2 respectively. Other treatment conditions were
10% consistency, 80 C, and 1 hour retention time. These fluff pulps were
then slurried with deionized water, wetlaid on a screen to form a fiber mat,
dewatered via roller press, and dried at 250 F. The dry sheets were
defibrated and airformed into 4" x 7" airlaid pads weighing 8.5 grams (air
dried) using a Kamas Laboratory Hammermill (Kamas Industries, Sweden). A
single, complete coverage sheet of nonwoven coverstock was applied to one
face of each pad and the samples were densified using a Carver hydraulic
platen press applying a load of 145 psig.
[0206] These pads were placed in individual 1.6 L airtight plastic
containers having a removable lid fitted with a check valve and sampling port
of 1/4" ID Tygon0 tubing. Before securing the lid of the container, an insult
of
60 grams deionized water and 0.12 gram 50% NH4OH at room temperature
was poured into a centered 1" ID vertical tube on a delivery device capable of
applying a 0.1 psi load across the entirety of the sample. Upon full
absorption
of the insult, the delivery device was removed from the sample, the lid, with
sealed sampling port, was fitted to the container, and a countdown timer
started. At the conclusion of 45 minutes, a headspace sample was taken
from the sampling port with an ammonia-selective short-term gas detection
tube and ACCUROO bellows pump, both available from Draeger Safety Inc.,
Pittsburgh, PA. The data in Table 18 show that the modified fibers produced
within the scope of this disclosure were able to reduce the amount of
ammonia gas in the headspace, resulting in a structure that provides
suppression of a volatile malodorous compound often cited as unpleasant in
wetted incontinence products.
Date Recue/Date Received 2020-06-04
70
Table 18
Insult- 60g H20 / 0.5% CED Aldehyde Air Laid
Pad Ammonia (ppm)
0.12g 50% NH4OH Viscosity Content Weight (g)
45mins
(mPas) meq/100g
Standard Kraft 14.9 0.23 9.16 210
Southern Pine Fiber
Modified Kraft 4.7 3.26 9.11 133
Southern Pine Fiber-
1.0% H202/100ppm
Fe
Modified Kraft 3.8 4.32 9.23 107
Southern Pine Fiber-
2.0% H202/200ppm
Fe
EXAMPLE 21
[0207] The E2 stage of a OD(E0)D(EP)D sequence of a commercial
kraft pulping facility was altered to produce the low degree of polymerization
pulp in a similar manner as Example 14. In this example, the FeSO4-7H20
was added at 100 ppm as Fe+2 and the hydrogen peroxide applied in the E2
stage was 1.4%. The pulp properties are shown in Table 19.
Table 19
Property ULDP
R10 % 72.5
S10 % 27.5
R18 % 78.7
S18 % 21.3
AR 6.2
Carboxyl meq/100 g 3.94
Aldehydes meq/100 g 4.21
Copper No. 4.25
Calculated Carbonyl mmole/100 g 6.97
0.5% Capillary CED mPa.s 3.50
Viscosity
Intrinsic Viscosity dUg 249
Calculated DP DRA, 485
Lwl Fiber Length mm 231
Coarseness mg/m 0.19
Brightness % ISO 88.5
Date Recue/Date Received 2020-06-04
71
[0208] The modified chemical cellulose produced was made into a pulp
board on a Fourdrinier type pulp dryer with an airborne FlaktTM dryer section.
Samples of this product and control kraft pulp board were defibrated using the
Kamas laboratory hammermill. Optical analysis of fiber properties were
performed on both pre and post Kamas mill samples via HiRes Fiber Quality
Analyzer available from Optest Equipment, Inc., Hawkesbury, ON, Canada,
according to the manufacturer's protocols. The results are depicted in the
table below.
Table 20
Property Control ULDP Control ULDP
post-hammermill post-
hammerm ill
Kink index 1.79 2.29 t51 232
Kink angle 59.15 79.56 48.52 80.26
Kinks per mm 0.81 1.07 0.68 1.06
Curl Index 0.171 0.211 0.149 0.225
(length
weighted)
[0209] As can be seen in Table 20, the ULDP fibers prepared in
accordance with the disclosure have higher kink and curl than control fibers
not treated with iron and peroxide.
[0210] The defibrated fibers above were airformed into 4" x 7" pads
weighing 4.25 grams (air-dried). Sodium polyacrylate superabsorbent (SAP)
granules sourced from BASF were applied evenly between two 4.25 gram
pads. A full coverage nonwoven coverstock was applied to the top face of the
fiber/SAP matrix and the pad was densified by a load of 145 psig applied via
Carver platen press.
[0211] Synthetic urine was prepared by dissolving 2% Urea, 0.9%
Sodium Chloride, and 0.24% nutrient broth (Criterion TM brand available
through Hardy Diagnostics, Santa Maria, CA) in deionized water, and adding
an aliquot of Proteus Vulgaris resulting in a starting bacterial concentration
of
1.4 x 107CFU/ml. The pad described above was then placed in a headspace
Date Recue/Date Received 2020-06-04
72
chamber as described in Example 20 and insulted with 80 ml of the synthetic
urine solution. Immediately after insult, the chamber was sealed and placed
in an environment with a temperature of 30 C. Drager sampling was
performed in series at time intervals of four hours and seven hours. The
experiment was repeated three times, and the average results are reported in
Table 21.
Table 21
% Ammonia %reduction Ammonia %reduction
SAP (ppm) @ over (PPm)@ over
add 4hrs control 7hrs control
on
Modified Kraft Southern Pine 23 2.5 29
Fiber
Control Kraft Southern Pine 23 21.5 88 175 83
Fiber
Modified Kraft Southern Pine 16.5 6.5 123
Fiber
Control Kraft Southern Pine 16.5 36.5 82 550 78
Fiber
Modified Kraft Southern Pine 0 70 317
Fiber
Control Kraft Southern Pine 0 1975. 65 575 45
Fiber
[0212] As can be seen from the data, atmospheric ammonia resulting
from bacterial hydrolysis of urea is lower in composite structures (similar in
construction to retail urinary incontinence products) incorporating modified
cellulose fibers produced within the scope of this disclosure versus composite
structures produced with standard kraft southern pine fibers. Thus, structures
comprising modified cellulose fibers according to the disclosure had better
odor control properties than standard kraft southern pine fibers.
EXAMPLE 22 -COMPARISON OF 4TH STAGE TO POST-BLEACH
TREATMENT
[0213] A Southern pine pulp was collected from the D1 stage of a
OD(E0)D1(EP)D2 sequence. The starting 0.5% Capillary CED viscosity was
14.1 mPa.s. Hydrogen peroxide was added as 1.5% based on the dry weight
Date Recue/Date Received 2020-06-04
73
of the pulp with 150 ppm of Fe+2. As used herein, "P*" is used to indicate an
iron and hydrogen peroxide treatment stage The treatment was conducted at
10% consistency at a temperature of 78 C for 1 hour in the fourth stage of
the
sequence. This treated pulp was then washed and bleached in D2 stage with
0.25% C102 for 2 hours at 78 C. The results are shown in Table 22.
Table 22
StageChemical added pH 0.5% AViscosity DPw Bright- Length
Capillary ness weighted
CED Fiber
Viscosity Length
% on pulp final mPa.s % ISO mm
D1 14A 1960 83.5
P* 1.5% H202 150 ppm 3.1 8Z0
Fe-'2
D2 0.25% C102 2/ 3/ 10.4 540 89.5 2.20
[0214] The D2 sample above was also tested for brightness reversion
by placing it in an oven at 105 C for 1 hour. The brightness as well as L*
(whiteness), a* (red to green), and b* (blue to yellow) values were measured
by a Hunterlab MiniScan, according to the manufacturer's protocols, before
and after the reversion treatment. The results are shown in Table 23 below.
More positive b values indicate a more yellow color. Thus, higher b values
are undesirable in most paper and pulp applications. Post color number,
reported below, represents the difference in the ratio k/s before and after
aging, where k = absorption coefficient and s = scattering coefficient. i.e.,
post
color no. = 100{ (k/s) after aging ¨ (k/5)before aging/. See, e.g., H.W.
Giertz, Svensk
Papperstid., 48(13), 317 (1945).
Table 23 Brightness Reversion
Stage L* a* b* Brightness ABrightness Post Color
No.
D1 96.89 -0.28 5.13 85.8
DP*D initial 97.89 -047 2.96 90.8
DP*D reverted 96.08 -0.55 8.01 80.4 10.4 1.92
[0215] A Southern pine pulp was collected from the D2 stage of the
same bleach plant as above with the same starting Capillary CED viscosity
Date Recue/Date Received 2020-06-04
74
and was treated with hydrogen peroxide and Fe+2 as described above.
Hydrogen peroxide was added as 1.5% based on the dry weight of the pulp
with 150 ppm of Fe+2. The properties of this treated pulp are depicted in
Table
24.
Table 24
Stage Chemical added pH 0.5% AViscosity DPw Brightness Length
Capillary
weighted
CED Fiber
Viscosity Length
% on pulp final mPa.s % ISO mm
D2 14A 1960 90.2
P* 1.5% 150 ppm Fe+2 2.8 3.5 10.6 485 86.8 2.17
H202
[0216] The P* pulp was tested for brightness reversion as described
above. The results are depicted in Table 25 below.
Table 25 Brightness Reversion
Stage L* a* b*
Brightness ABrightness Post
Color
No.
D2 Initial 98.34 -0.61 2.54 92.54
D2 Reverted 97.87 -0.57 3.67 89.92 2.62 0.26
D(EP)DP* initial 97.39 -047 449 87.68
D(EP)DP* reverted 95.25 -0.34 9.78 76.45 11.2 2.76
[0217] As can be seen from the above data, acidic catalyzed peroxide
treatment in the fourth stage of a five-stage bleach plant compared to
treatment following the final stage of a five-stage bleach plant results in
beneficial brightness properties. In the fourth stage treatment, any
brightness
loss from the treatment stage can be compensated for with the final D2
bleaching stage so that a high brightness pulp is still obtained. In the case
of
post-bleach treatment, there is a significant brightness loss of 3.4 points
that
cannot be compensated for. After an accelerated brightness reversion
treatment, the latter case still has a significantly lower brightness.
Date Recue/Date Received 2020-06-04
75
EXAMPLE 23 STRENGTH DATA
[0218] The strength of fluff pulp produced from modified cellulose with
a viscosity of 5.1 mPa.s according to the disclosure was compared with
conventional fluff pulp having a viscosity of 15.4 mPa.s. The results are
depicted in Table 26 below.
Table 26
Control Modified
Fluff Cellulose
Basis Wt., gm/m2 AD 65.12 68.15
Basis Wt., gm/m2 OD 60.56 63.38
Freeness CSF, mls 732 717
Caliper, in/1000 4.88 5.09
Bulk, cm3/gm 1.90 1.90
Apparent Density, gm/cm3 0.53 0.53
Porosity, sec/100 mls air 0.59 0.67
Burst Factor, (gm/cm2)/(gm/m2) 16.6 14.0
Tear Factor, grrn2/gm 242 198
Breaking Length, km 2.52 249
Stretch, % 2/6 248
Opacity, % 72.1 73.5
Dirt and Shives, mm2/m2 0_3 1_5
Viscosity, cP 15.4 5.1
ISO Brightness 88.9 88.9
Frazier Porosity, cfm 45.4 55.1
Fiber Length, mm 2.636 2.661
Shape Factor, % 85.8 85.8
EXAMPLE 24 DERIVATIZATION OF MODIFIED CELLULOSE
[0219] A sample of ULDP from Example 21 was acid hydrolyzed with
0.05 M HCI at 5% consistency for 3 hours at 122 C. The initial pulp from the
D1 stage, the ULDP, and the acid hydrolyzed ULDP were tested for average
molecular weight or degree of polymerization by the method below.
Date Recue/Date Received 2020-06-04
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[0220] Three pulp samples were grounded to pass a 20 mesh screen.
Cellulose samples (15 mg) were placed in separate test tubes equipped with
micro stir bars and dried overnight under vacuum at 40 C. The test tubes
were then capped with rubber septa. Anhydrous pyridine (4.00 mL) and
phenyl isocyanate (0.50 mL) were added sequentially via syringe. The test
tubes were placed in an oil bath at 70 C and allowed to stir for 48 h.
Methanol (1.00 mL) was added to quench any remaining phenyl isocyanate.
The contents of each test tube were then added dropwise to a 7:3
methanol/water mixture (100 mL) to promote precipitation of the derivatized
cellulose. The solids were collected by filtration and then washed with
methanol/water (1 x 50 mL) followed by water (2 x 50 mL). The derivatized
cellulose was then dried overnight under vacuum at 40 C. Prior to GPC
analysis the derivatized cellulose was dissolved in THF (1 mg/mL), filtered
through a 0.45 pm filter, and placed in a 2 mL auto-sampler vial. The
resulting DPw and DPn (number average degree of polymerization) are
reported in Table 27 below.
Table 27 DPn and DPw test results
Sample Mn (g/mol) Mw (g/mol) DPn DPw
D1 14601e5 2.2702e6 281 4374
ULDP 4.0775e4 7.4566e5 78 1436
Acid Hydrolyzed 2.52.5e4 1.8966e5 48 365
ULDP
[0221] As can be seen in the above table, modified cellulose after acid
hydrolysis according to the disclosure can have a DPn of 48.
EXAMPLE 25
[0222] Leaf River ULDP fibers and standard softwood fibers were made
into handsheets by slurrying the fiber, adjusting the pH to about 5.5, and
then
adding, as a temporary wet strength agent, a glyoxylated polyacrylamide from
Kemira Chemicals. The fibers were then formed, pressed into sheets and
dried. The characteristics of the sheets were measured by known methods.
Date Recue/Date Received 2020-06-04
77
The results are reported in Table 28 below.
Table 28 Hands heet properties
LR SW (Control) ULDP
TVVS #T 0 10 20 40 0 10 20 40
mL/10
Titratable
mL 10- -
0.166 +0.204 +0389 +2.899 -0.143 -0.134 +047 +t91
Charge 4 9
3N
Basis #/R 15.11 16.19 15.59 14.64 15/5 14.83 13.08 15.3
Weight g/m2 24_59 26_35 25_37 23_83 25_63 24_14 21_29 24_9
1-ply
Caliper, 3.68 3.78 3.80 4.04 3.80 3/2 4.12
4.08
Bulk mils
Bulk,
3.80 3.64 3.80 4.31 3/7 3.91 4.92
4.16
cm3/g
Tensile' 747 1335 1187 1118 716 825 866
864
Breaking
Length, 1.196 1995. t842
t847 t100 t346 t602 1366
Dry km
Tensile Stretch, % 2.6 3.2 2.9 3.0 2.2 2/ 3.3
2.9
T.E.A.,
mm- 0.10 0.28 0.21 0.21 0.06 0.11
0.17 0.12
gm/mm2
Tensile,
4 209 218 256 23 148 200 168
Wet g/1"
Breaking
Tensile 0 035 0.241
0.369 0.265
Length, 0.0064 0.3123 0.3383 0423 3
km. 4 9 6
Capacity, 2059. 194/ 187.0 1909. 185.0 173.0 182.0 2020.
gim2
SAT 0
Rate,
.06 0.08 0.07 0.05 0.08 0.07 0.07
0.10
g/s 3
Time,
89.6 59.1 59.2 83.8 55.5 50.0 57.7
49.9
Wet/Dry
1% 16% 18% 23% 3% 18% 23% 19%
ratio
[0223] As can be seen in the above Table 28, ULDP according to the
disclosure may be used in production of wet pressed paper. As is shown in
Figure 2, the wet/dry ratio of the handsheets formed from ULDP is higher than
the wet/dry ratio of comparative sheets made from only standard southern
softwood.
EXAMPLE 26 WICKING, REWET, AND STRENGTH DATA
[0224] The synthetic urine wicking capability of sheets of various
densities (0.15, 0.25, and 0.35 g/cm3) and basis weights (60, 150, 300 gsm)
made from pulp produced from modified cellulose according to the disclosure
and 10% bicomponent fiber was compared with sheets made from
Date Recue/Date Received 2020-06-04
78
conventional kraft pulp. Tests were conducted by Materials Testing Service of
Kalamazoo, MI, using their own test equipment and procedures. The
synthetic urine wicking capability of the products was tested using 6.0 cm x
16.0 cm samples and a 600 second pin read time. The results are depicted in
Table 29 below.
Table 29 Synthetic Urine 45 Wicking Data
Densit Bottom Pin Wicking Top Pin Wicking Time
Total Wicking Time
y 0.15 Time (sec) (sec) (sec)
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 36.86 3t24 365.4 306.63 394/1 -- 337.87
150 30_13 30_80 270_43 292_56 296_53 --
319_57
gsm
300 25.98 25.05 105.86 88.03 131.84 113.08
gsm
Densit Bottom Pin Wicking Top Pin Wicking Time
Total Wicking Time
y 0.25 Time (sec) (sec) (sec)
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 40.25 45.65 2207. 226.59 260.95
272.24
150 3t13 2T14 119/0 156_15 150_83 18319
gsm
300 39.18 37.58 118A4 123A1 157.62 160.68
gsm
Densit Bottom Pin Wicking Top Pin Wicking Time
Total Wicking Time
y 0.35 Time (sec) (sec) (sec)
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
Date Recue/Date Received 2020-06-04
79
60 gsm 42.24 40A4 206.08 186.27 248.32 226/1
150 43.32 35.55 148.91 127.45 192.23 163.00
gsm
300 50.84 55.65 176/4 183.59 227.57 239.24
gsm
[0225] The amount retained, change in thickness, and wicking height
were also determined. The results are depicted in Table 30 below:
Table 30
Wet Dry Amount Beginning End Wicking
Wt. Wt. Retained Thickness Thickness % Height
(g) (g) (g) (mm) (mm) Change (g)
Conventional
60GSM -
0.15
DENSITY 5.26 0.62 4.63 040 0.66 66.0 15.2
60GSM -
0.25
DENSITY 4.62 0.61 4.01 0.24 0.54 122.9 15/
60GSM -
0.35
DENSITY 4.32 0.62 3.70 0.17 0.53 213.5 16.0
150GSM -
0.15
DENSITY 15.63 1.73 13.91 1.00 t67 67.2
16.0
150GSM -
0.25
DENSITY 1207. 1.72 10.35 0.60 t30 116.0
16.0
150GSM -
0.35
DENSITY 942 1.78 7.64 043 0.92 114.9 16.0
300GSM -
0.15
DENSITY 29.64 3.51 26.14 1.95 3.12 59.8
16.0
300GSM -
0.25
DENSITY 21.36 3.51 17.85 1.20 2.09 74.2
16.0
300GSM -
0.35
DENSITY 13/0 349 10.22 0.87 1.73 99.3
16.0
Modified
60GSM -
0.15
DENSITY 517 0_60 4_57 040 0/9 98_3 15_5
60GSM -
0.25
DENSITY 4.07 0.61 346 0.24 0.54 125A 15.9
60GSM -
0.35
DENSITY 3.96 0.60 336 0.17 0A8 180.6 16.0
150GSM -
0.15
DENSITY 15.08 1.77 1331 1.00 1/6 75.5
16.0
Date Recue/Date Received 2020-06-04
80
150GSM -
0.25
DENSITY 13.02 1.72 1t29 0.60 t47 145.3
16.0
150GSM -
0.35
DENSITY 10.53 1.76 8/7 043 1.21 180/
16.0
300GSM -
0.15
DENSITY 32.73 3.59 29A4 t95 2.58 32.2
16.0
300GSM -
0.25
DENSITY 22.98 3.55 1943. 1.20 2.14 78.0
16.0
300GSM -
0.35
DENSITY 12.41 3.50 8.91 0.87 1.73 98.4 16.0
[0226] The same sheets were also subjected to rewet testing. The
rewet of the products was tested with 9.0 cm x20.3 cm sample cutouts using
the dosing tube method and one dose of 10 ml of 0.9% saline solution. 120
seconds after the dose the dosing tube was removed and a recorded
preweighed 6" x 6" sheet of Verigood blotter paper was placed on top and a
3kpa load was applied for 60 seconds. The results are depicted in Table 31
below.
Table 31 Rewet Data
Density Rewet (GMS)
0.15 g/cm3
Basis Wt. Conventional Modified
60 gsm 5.89 6.13
150 gsm 5.19 5.52
300 gsm 3.98 349
Density Rewet (GMS)
0.25 g/cm3
Basis Wt. Conventional Modified
60 gsm 6.01 6.20
150 gsm 446 5.00
300 gsm 3.59 4.14
Date Recue/Date Received 2020-06-04
81
Density Rewet (GMS)
0.35 g/cm3
Basis Wt. Conventional Modified
60 gsm 6.06 6.50
150 gsm 3.66 4.11
300 gsm 2.64 2.59
[0227] The same sheets were also subjected to dry and wet tensile
strength and percent elongation testing. Tensile strength and percent
elongation were determined for each product in the machine direction using a
gauge length of 5.00 cms, a sample width of 1.3 cms., a crosshead speed of
2.5 cm/min and a load cell of 30 kg. The results are depicted in Tables 32
and 33 below.
Table 32 Dry Tensile Strength and Percent Elongation Summary
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.15
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.21 0.24 30A1 24.66 23/3 29.80
150 0.54 045 34/8 30.62 7t23 57.85
gsm
300 1.03 t46 3t35 21/0 132A2 157.90
gsm
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.25
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.23 0.24 30.59 22.90 27.02 29A3
150 1.04 0.52 27.66 37A3 135.89 74A4
gsm
Date Recue/Date Received 2020-06-04
82
300 1.61 t38 23.81 22.63 177.01 16t93
gsm
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.35
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.18 0.16 30.25 20/5 2050. 17.78
150 0/8 0.88 26A4 27.60 10t51 11t05
gsm
300 436 3.82 1t22 8.25 20t33 182.50
gsm
Table 33 Wet Tensile Strength and Percent Elongation Summary
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.15
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.07 0.09 2091. 23A3 6/5 10.28
150 0.21 0.16 46.85 25A2 25.89 20/0
gsm
300 040 0.60 45.23 2020. 48.94 66.69
gsm
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.25
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.08 0.09 22.57 21.10 8.19 9.18
150 0.36 0.21 39.03 24.96 48.09 27.25
gsm
Date Recue/Date Received 2020-06-04
83
300 0/3 0.60 26.82 19A4 83.21 68.20
gsm
Densit Peak (KGS) Elongation (%) TEA (JLS/M2)
y 0.35
g/cm3
Basis Conventiona Modifie Conventiona Modifie Conventiona Modifie
Wt. I d I d I d
60 gsm 0.07 0.06 2t67 22.55 7.56 7.11
150 033 031 2088. 22.69 39.20 39A1
gsm
300 1.85 t97 22.58 15.84 206.55 186.85
gsm
EXAMPLE 27 WETTABILITY, VERTICAL WICKING AND HORIZONTAL
WICKING DATA
[0228] The wettability, vertical wicking, and horizontal wicking of sheets
of various densities (0.15, 0.30, and 0.45 g/cm3) made from pulp produced
from modified cellulose according to the disclosure was compared with sheets
made from conventional pulp. Tests were conducted by Materials Testing
Service of Kalamazoo, MI, using their own test equipment and procedures.
[0229] The demand wettability characteristics were determined using
50 cm2 samples. The results are depicted in Tables 34-36 below.
Table 34 Demand Wettability Test Final Absorption Rate
Absorption Rate
(ML/G*sec^.5)
Density Conventional Modified
g/cm3
0.15 0.80 0.92
0.30 0.55 0.62
0.45 042 046
Date Recue/Date Received 2020-06-04
84
Table 35 Demand Wettability Test Total Absorption Amount
Absorption (MLS)
Density Conventional Modified
g/cm3
0.15 18.99 21.53
0.30 1433 15A1
0.45 11.91 1204.
Table 36 Demand Wettability Test Absorption Capacity Index
Absorption Capacity
(MUG)
Density Conventional Modified
g/cm3
0.15 633 7.18
0.30 4/8 5.04
0.45 3.97 4.01
[0230] The vertical wicking characteristics were determined using 10
samples and a 600 second probe read time. The results are depicted in
Tables 37-38 below.
Table 37 Vertical Wicking Test Total Wicking Time
Average Total Wicking
Time (seconds)
Density Conventional Modified
g/cm3
0.15 29.68 29.14
0.30 29.36 2434
0.45 51.40 39/2
Date Recue/Date Received 2020-06-04
85
Table 38 Vertical Wicking Test Total Amount Retained
Amount Retained (ML)
Density Conventional Modified
g/cm 3
0.15 13.49 13.43
0.30 1t36 11.48
0.45 7.79 8/0
[0231] The horizontal wicking characteristics were determined using 10
samples, a 600 second probe read time, and one 30 ml dose at 7 ml/sec. The
results are depicted in Table 39 below.
Table 39 Horizontal Wicking Time
Density Average Wicking Time
0.15 g/cm3 (seconds)
Level Conventional Modified
1 1.07 0.97
2 247 230
3 4.80 447
4 23.80 15.46
131.70 154.96
Density Average Wicking Time
0.30 g/cm 3 (seconds)
Level Conventional Modified
1 1.02 1.14
2 244 248
3 4.77 4.57
4 25.18 18.21
5 163.45 81.93
Date Recue/Date Received 2020-06-04
86
Density Average Wicking Time
0.45 g/cm3 (seconds)
Level Conventional Modified
1 1.05 0.99
2 2.61 2.33
3 5.08 436
4 3t08 9/5
165.95 75.90
EXAMPLE 28 Multilayer Absorbent Sheets
[0232] Five different airlaid multilayer sheets were prepared and cut
into 200 4 X 8 inch rectangles. The differing sets were labeled as shown in
Table 40. Where noted, conventional sheets were treated with TQ-2021 and
modified sheets were treated with TQ-2028, both surface active agents
supplied by Ashland, Inc.
Table 40
Sheet Top Layer Middle Layer Bottom Layer
Standard MR4 Conventional with Non GP Conventional
TQ-2021 untreated with TQ-
2021
Trial MR5 Conventional with Non GP
Modified with
TQ-2021 untreated TQ-2028*
Trial MR6 Conventional with Modified
Modified with
TQ-2021 TQ-2028*
Trial MR7 Modified with Modified
Conventional
TQ-2028* with TQ-
2021
Trial MR8 Modified with Non GP
Conventional
TQ-2028* untreated with 10-
2021
[0233] The products were tested for fluid acquisition, profile, and
capacity. The fluid acquisition was done by applying 5 ml of 0.9% saline
solution to the sample then letting the fluid wick for 5 minutes. After 5
minutes,
the rewet was taken for 2 minutes using standard laboratory filter paper. The
Date Recue/Date Received 2020-06-04
87
products had the characteristics shown in Tables 41 and 42.
Table 41
Product Profile Front Front Middle Back
Middle Back
Standard MR4
Basis Wt. (g/m2) 173 171 174 168
Density (g/cc) 0.20 0.19 0.20 0.19
Caliper (cm) 0.09 0.09 0.09 0.09
Trial MR5
Basis Wt. (g/m2) 175 171 172 174
Density (g/cc) 0.20 0.19 0.19 0.20
Caliper (cm) 0.09 0.09 0.09 0.09
Trial MR6 Basis Wt. (g/m2) 168 171 170 172
Density (g/cc) 0.20 0.19 0.19 0.20
Caliper (cm) 0.09 0.09 0.09 0.09
Trial MR7 Basis Wt. (g/m2) 174 173 173 167
Density (g/cc) 0.20 0.20 0.20 0.19
Caliper (cm) 0.09 0.09 0.09 0.09
Trial MR8
Basis Wt. (g/m2) 181 182 177 177
Density (g/cc) 0.20 0.20 0.20 0.20
Caliper (cm) 0.09 0.09 0.09 0.09
Date Recue/Date Received 2020-06-04
88
Table 42
Product Properties
Standard Trial MR5 Trial MR6 Trial MR7
Trial MR8
MR4
Product Wt.
3.51 3.53 3.51 3.55 3.56
(g)
Core Weight
3.52 346 347 3.52 3.54
(g)
Pulp Wt. (g) 3.05 3.05 3.10 3.21 3.20
SAP Wt. (g) 048 046 0.39 0.34 0.34
SAP/Core
13.5 13.1 11.2 9.5 9.5
Ratio (%)
Basis Wt. 172.8 173 179.6 172
1742 .
(g/m2) Std. Dev. Std. Dev. Std. Dev.
Std. Dev.
Std. Dev. 5.8
4.0 3.9 44 2.5
Density .203 Std. .195 Std. .193 Std. .210 Std.
.204 Std.
(g/cm3) Dev. 009 Dev. 006 Dev. 007 Dev. 004 Dev. 003
Product Performance
Absorbent
40.9 41.4 37.2 35.0 34.4
Capacity
Absorbent
Capacity 11.6 12.0 10/ 9.9 9/
Index (g/g)
Retention
29.4 27.6 26.1 24.7 25.2
Capacity
Retention
Capacity 84 8.0 7.5 7.0 7.1
Index (g/g)
Rewet and Strike Thru
Primary
Strike Thru 16.4 21.2 18.4 16.4 16.7
(sec)
Primary
0.1 0.1 0.1 0.1 0.1
Rewet (g)
Secondary
Strike Thru 24.4 23.1 24.5 22.6 29.1
(sec)
Secondary
0.5 0.5 0.5 0.5 OA
Rewet (g)
Tertiary
Strike Thru 14.0 14.2 15.4 13.2 14.8
(sec)
Tertiary
14 1.5 1.6 14 1.3
Rewet (g)
Date Recue/Date Received 2020-06-04
89
[0234] The synthetic urine wicking capability of the products was tested
using ten 6.0 cm x 16.0 cm samples and a 600 second pin read time. Tests
were conducted by Materials Testing Service of Kalamazoo, MI, using their
own test equipment and procedures. The results are depicted in Tables 43
and 44 below.
Table 43
Average 45 Wicking Time In Seconds
Product Bottom Pin Top Pin Wicking Total Wicking Time
Wicking Time Time
Standard MR4 199.90 600.00* 600.00*
Trial MR5 141.53 600.00* 600.00*
Trial MR6 144.64 600.00* 600.00*
Trial MR7 169.48 600.00* 600.00*
Trial MR8 163.71 600.00* 600.00*
*600 seconds was entered if the wicking did not reach the pin level
Table 44
Retention Thickness
Product Wet Dry Amount Beginning End Percent Wicking
Wt. Wt. Retained Thickness Thickness Change Height
(g) (g) (g) (mm) (mm) (cm)
Standard MR4 11.59 1.66 9.93 0.70 2.36 .. 236.9 .. 10.3
Trial MRS 11.76 1.65 10.10 0.74 1.99 169.2
10.8
Trial MR6 10.74 1.59 9.14 0.70 1.94 176.7
.. 10.6
Trial MR7 10.06 1.68 8.38 0.81 2.04 154.7
.. 10.0
Trial MR8 10.46 1.61 8.85 0.83 2.11 153.9
10.2
[0235] Materials Testing Service tested the rewet of the products using
ten 9.0 cm x 20.3 cm sample cutouts, the dosing tube method, and one dose
of 10 ml of 0.9% saline solution. The results are shown in Table 45.
Date Recue/Date Received 2020-06-04
90
Table 45
Product Dry Blotter (g) Wet Blotter (g) Rewet (g)
Standard MR4 7.67 8.29 0.61
Trial MR5 7.87 8.60 0.72
Trial MR6 7.35 8.13 0.78
Trial MR7 7.84 8.79 0.95
Trial MR8 7.68 8.48 0.80
[0236] Materials Testing Service tested the wet tensile strength for
each product in the machine direction using ten samples, a gauge length of
5.00 cms, a sample width of 1.3 cms., a crosshead speed of 2.5 cm/min and a
load cell of 30 kg. The results are shown in Table 46.
Table 46
Product Peak (kg) Elongation (%) TEA (JLS/M2)
Standard MR4 0.243 15.78 16.268
Trial MR5 0.266 16.67 19.247
Trial MR6 0.259 18.20 19.900
Trial MR7 0336 2062. 28.268
Trial MR8 0.342 2078. 28.799
[0237] Materials Testing Service tested the dry tensile strength and
percent elongation for each product in the machine direction using ten
samples, a gauge length of 5.00 cms, a sample width of 1.3 cms., a
crosshead speed of 2.5 cm/min and a load cell of 30 kg. The results are
shown in Table 47.
Date Recue/Date Received 2020-06-04
91
Table 47
Product Peak (kg) Elongation (%) TEA (JLS/M2)
Standard MR4 1.009 7.56 34.807
Trial MR5 1.009 7.89 34.585
Trial MR6 0.898 8.59 33/00
Trial MR7 1.144 9.60 48A28
Trial MR8 1.091 9.56 46.308
OTHER INVENTIVE EMBODIMENTS
[0238] Although the Applicants' presently desired inventions are
defined in the attached claims, it is to be understood that the invention may
also be defined in accordance with the following embodiments, which are not
necessarily exclusive or limiting of those claimed:
A. A fiber derived from a bleached softwood or hardwood kraft
pulp, in which the fiber has a 0.5% capillary CED viscosity of
about 13 mPa.s or less, preferably less than about 10
mPa.s, more preferably less than 8 mPa.s, still more
preferably less than about 5 mPa.s, or further still more
preferably less than about 4 mPa.s.
B. A fiber derived from a bleached softwood kraft pulp, in which
the fiber has an average fiber length of at least about 2 mm,
preferably at least about 2.2 mm, for instance at least about
2.3 mm, or for example at least about 2.4 mm, or for
example about 2.5 mm, more preferably from about 2 mm to
about 3.7 mm, still more preferably from about 2.2 mm to
about 3.7 mm.
C. A fiber derived from a bleached hardwood kraft pulp, in
which the fiber has an average fiber length of at least about
0.75 mm, preferably at least about 0.85 mm, or at least about
0.95 mm, or more preferably at least about 1.15, or ranging
from about 0.75 mm to about 1.25 mm.
D. A fiber derived from a bleached softwood kraft pulp, in which
the fiber has a 0.5% capillary CED viscosity of about 13
Date Recue/Date Received 2020-06-04
92
mPa.s or less, an average fiber length of at least about 2
mm, and an ISO brightness ranging from about 85 to about
95.
E. A fiber according any of the embodiments A-D, in which the
viscosity ranges from about 3.0 mPa.s to about 13 mPa.s,
for example from about 4.5 mPa.s to about 13 mPa.s,
preferably from about 7 mPa.s to about 13 mPa.s, or for
example from about 3.0 mPa.s to about 7 mPa.s, preferably
from about 3.0 mPa.s to about 5.5 mPa.s.
F. A fiber according to embodiments A-D, in which the viscosity
is less than about 7 mPa.s.
G. A fiber according to embodiments A-D, in which the viscosity
is at least about 3.5 mPa.s.
H. A fiber according to embodiments A-D, in which the viscosity
is less than about 4.5 mPa.s.
I. A fiber according to embodiments A-D, in which the viscosity
is at least about 5.5 mPa.s
J. A fiber according to embodiment E, in which the viscosity is
no more than about 6 mPa.s.
K. A fiber according to one of the embodiments above, in which
the viscosity is less than about 13 mPa.s.
L. A fiber according to one of embodiments A-B and D-K, in
which the average fiber length is at least about 2.2 mm.
M. A fiber according to one of embodiments A-B and D-L, in
which the average fiber length is no more than about 3.7
mm.
N. A fiber according to one of embodiments A-M, in which the
fiber has an S10 caustic solubility ranging from about 16% to
about 30%, preferably from about 16% to about 20%.
0. A fiber according to one of embodiments A-M, in which the
fiber has an S10 caustic solubility ranging from about 14% to
about 16%.
Date Recue/Date Received 2020-06-04
93
P. A fiber according to one of embodiments A-0, in which the
fiber has an S18 caustic solubility ranging from about 14% to
about 22%, preferably from about 14% to about 18%, more
preferably from about 14% to about 16%.
Q. A fiber according to one of embodiments A-P, in which the
fiber has an S18 caustic solubility ranging from about 14% to
about 16%.
R. A fiber according to one of embodiments A-Q, in which the
fiber has a AR of about 2.9 or greater.
S. A fiber according to one of embodiments A-Q, in which the
fiber has a AR or about 3.0 or greater, preferably about 6.0
or greater.
T. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content ranging from about 2 meq/100 g
to about 8 meq/100 g, preferably from about 2 meq/100 g to
about 6 meq/100 g, more preferably from about 3 meq/100 g
to about 6 meq/100 g.
U. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 2 meq/100g.
V. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 2.5 meq/100g.
W. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 3 meq/100g.
X. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 3.5 meq/100g.
Y. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 4 meq/100g.
Z. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 4.5 meq/100g.
AA. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of at least about 5 meq/100g.
Date Recue/Date Received 2020-06-04
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BB. A fiber according to one of embodiments A-S, in which the
fiber has a carboxyl content of about 4 meq/100g.
CC. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content ranging from about 1 meq/100
g to about 9 meq/100 g, preferably from about 1 meq/100g to
about 3 meq/100 g.
DD. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 1.5
meq/100g.
EE.
FF. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 2.0
meq/100g.
GG. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 2.5
meq/100g.
HH. A fiber according to one of embodiments A-BB, in which
the fiber has an aldehyde content of at least about 3.0
meq/100g.
II. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 3.5
meq/100g.
JJ. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 4.0
meq/100g.
KK. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 5.5
meq/100g.
LL. A fiber according to one of embodiments A-BB, in which the
fiber has an aldehyde content of at least about 5.0
meq/100g.
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MM. A fiber according to one of embodiments A-MM, in which the
fiber has a carbonyl content as determined by copper
number of greater than about 2, preferably greater than
about 2.5, more preferably greater than about 3, or a
carbonyl content as determined by copper number of from
about 2.5 to about 5.5, preferably from about 3 to about 5.5,
more preferably from about 3 to about 5.5, or the fiber has a
carbonyl content as determined by copper number of from
about 1 to about 4.
NN. A fiber according to one of embodiments A-NN, in which the
carbonyl content ranges from about 2 to about 3.
00. A fiber according to one of embodiments A-NN, in which the
fiber has a carbonyl content as determined by copper
number of about 3 or greater.
PP. A fiber according to one of embodiments A-NN, in which the
fiber has a ratio of total carbonyl to aldehyde content ranging
from about 0.9 to about 1.6.
QQ. A fiber according to one of embodiments A-NN, in which the
ratio of total carbonyl to aldehyde content ranges from about
0.8 to about 1Ø
RR. A fiber according to one of the embodiments above, in which
the fiber has a Canadian Standard Freeness ("freeness") of
at least about 690 mls, preferably at least about 700 mls,
more preferably at least about 710 mls, or for example at
least about 720 mls or about 730 mls.
SS. A fiber according to one of the embodiments above, in which
the fiber has a freeness of at least about 710 mls.
TT. A fiber according to one of the embodiments above, in which
the fiber has a freeness of at least about 720 mls.
UU. A fiber according to any one of embodiments above, in which
the fiber has a freeness of at least about 730 mls.
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96
VV. A fiber according to one
of the embodiments above, in which
the fiber has a freeness of no more than about 760 mls.
WW. A fiber according to one
of embodiments A-WW, in which the
fiber has a fiber strength, as measured by wet zero span
breaking length, ranging from about 4 km to about 10 km.
XX. A fiber according to one
of embodiments A-WW, in which the
fiber has a fiber strength ranging from about 5 km to about
8km.
YY. A fiber according to one
of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, of at least about 4 km.
ZZ. A fiber according to one
of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, of at least about 5 km.
AAA. A fiber according to one of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, of at least about 6 km.
BBB. A fiber according to one
of embodiments A-WW, in which
the fiber has a fiber strength, measured by wet zero span
breaking length, of at least about 7 km.
CCC. A fiber according to one of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, of at least about 8 km.
DDD. A fiber according to one of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, ranging from about 5 km to about 7 km.
EEL. A fiber according to one of embodiments A-WW, in which the
fiber has a fiber strength, measured by wet zero span
breaking length, ranging from about 6 km to about 7 km.
FFF. A fiber according to one of the embodiments above, in which
the ISO brightness ranges from about 85 to about 92,
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97
preferably from about 86 to about 90, more preferably from
about 87 to about 90 or from about 88 to about 90 ISO.
GGG. A fiber according to one of the embodiments above, in which
the ISO brightness is at least about 85, preferably at least
about 86, more preferably at least about 87, particularly at
least about 88, more particularly at least about 89 or about
90 ISO.
HHH. A fiber according to one of embodiments A-FFF, in which the
ISO brightness is at least about 87.
III. A fiber according to one of embodiments A-FFF, in which the
ISO brightness is at least about 88.
JJJ. A fiber according to one of embodiments A-FFF, in which the
ISO brightness is at least about 89.
KKK. A fiber according to one of embodiments A-FFF, in which the
ISO brightness is at least about 90.
LLL. A fiber according to any of the embodiments above, wherein
the fiber has about the same length as standard kraft fiber.
MMM. A fiber according to one of embodiments A-S and SS-MMM,
having higher carboxyl content than standard kraft fiber.
NNN. A fiber according to one of embodiments A-S and SS-NNN,
having higher aldehyde content than standard kraft fiber.
000. A fiber according to embodiments A-S and SS-MMM, having
a ratio of total aldehyde to carboxyl content of greater than
about 0.3, preferably greater than about 0.5, more preferably
greater than about 1.4, or for example ranging from about
0.3 to about 0.5, or ranging from about 0.5 to about 1, or
ranging from about 1 to about 1.5.
PPP. A fiber according to any of the embodiments above, having a
higher kink index than standard kraft fiber, for example
having a kink index ranging from about 1.3 to about 2.3,
preferably from about 1.7 to about 2.3, more preferably from
about 1.8 to about 2.3 or ranging from about 2.0 to about 2.3.
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QQQ. A fiber according to any of the embodiments above, having a
length weighted curl index ranging from about 0.11 to about
0.2, preferably from about 0.15 to about 0.2.
RRR. A fiber according to any of the embodiments above, having a
lower crystallinity index than standard kraft fiber, for example
a crystallinity index reduced from about 5% to about 20%
relative to standard kraft fiber, preferably from about 10% to
about 20%, more preferably reduced from 15% to 20%
relative to standard kraft fiber.
SSS. A fiber according to any of the embodiments above, in which
the R10 value ranges from about 65% to about 85%,
preferably from about 70% to about 85%, more preferably
from about 75% to about 85%.
TTT. A fiber according to any of the embodiments above, in which
the R18 value ranges from about 75% to about 90%,
preferably from about 80% to about 90%, more preferably
from about 80% to about 87%.
UUU. A fiber according to any of the embodiments above, in which
the fiber has odor control properties.
VW. A fiber according to any of the embodiments above, in which
the fiber reduces atmospheric ammonia concentration at
least 40% more than standard kraft fiber, preferably at least
about 50% more, more preferably at least about 60% more,
in particular at least about 70% more, or at least about 75%
more, more particularly at least about 80% more or about
90% more.
WVVW. A fiber according to any of the embodiments above, in which
the fiber absorbs from about 5 to about 10 ppm ammonia per
gram of fiber, preferably from about 7 to about 10 ppm, more
preferably from about 8 to about 10 ppm ammonia per gram
of fiber.
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XXX. A fiber according to any of the embodiments above, in which
the fiber has an MEM Elution Cytotoxicity Test value of less
than 2, preferably less than about 1.5, more preferably less
than about 1.
YYY. A fiber according to any of the embodiments above, in which
the copper number is less than 2, preferably less than 1.9,
more preferably less than 1.8, still more preferably less than
1.7.
ZZZ. A fiber according to any of embodiments A-YYY having a
kappa number ranging from about 0.1 to about 1, preferably
from about 0.1 to about 0.9, more preferably from about 0.1
to about 0.8, for instance from about 0.1 to about 0.7 or from
about 0.1 to about 0.6 or from about 0.1 to about 0.5, more
preferably from about 0.2 to about 0.5.
AAAA. A fiber according to any of the embodiments above, having a
hemicellulose content substantially the same as standard
kraft fiber, for instance, ranging from about 16% to about
18% when the fiber is a softwood fiber or ranging from about
18% to about 25% when the fiber is a hardwood fiber.
BBBB. A fiber according to any of the embodiments above, in which
the fiber exhibits antimicrobial and/or antiviral activity.
CCCC. A fiber according to any of embodiments B-C or L-CCCC, in
which the DP ranges from about 350 to about 1860, for
example from about 710 to about 1860, preferably from
about 350 to about 910, or for example from about 1160 to
about 1860.
DDDD. A fiber according to any of embodiments B-C or L-CCCC, in
which the DP is less than about 1860, preferably less than
about 1550, more preferably less than about 1300, still more
preferably less than about 820, or less than about 600.
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EEEE. A fiber according to any of the embodiments above, in which
the fiber is more compressible and/or embossible than
standard kraft fiber.
FFFF. A fiber according to embodiments A-000, in which the fiber
may be compressed to a density of at least about 0.210 g/cc,
preferably at least about 0.220 g/cc, more preferably at least
about 0.230 g/cc, particularly at least about 0.240 g/cc.
GGGG. A fiber according to embodiments A-000, in which the fiber
can be compressed to a density of at least about 8% higher
than the density of standard kraft fiber, particularly ranging
from about 8% to about 16% higher than the density of
standard kraft fiber, preferably from about 8% to about 10%,
or from about 12% to about 16% higher, more preferably
from about 13% to about 16% higher, more preferably from
about 14% to about 16% higher, in particular from about 15%
to about 16% higher.
[0239] A number of embodiments have been described. Nevertheless,
it will be understood that various modifications may be made without
departing from the spirit and scope of the disclosure. Accordingly, other
embodiments are within the scope of the following claims.
Date Recue/Date Received 2020-06-04
