Note: Descriptions are shown in the official language in which they were submitted.
PAPER SHEET MULCHES AND METHODS OF MAKING THE SAME
[001] This application claims priority to PCT/1620/54254, filed May 5,
2020.
Technical Field
[002] The present disclosure relates to sheet mulches made from paper
substrates having benefits over prior sheet mulches, including an improved
combination
of environmental impact, cost, and performance, as well as methods for
manufacturing
such paper sheet mulches.
Background
[003] Mulch is a layer of material applied to the surface of soil for the
purpose of
improving soil productivity and resultant crop yield. Mulch may be applied
either in the
form of loose material, such as grass clippings, leaves, bark, wood chips and
the like,
or in the form of a more structured material, such as a sheet. Benefits of
mulches may
include one or more of increased soil temperature (which can allow earlier
planting and
earlier maturation of crops), deterred weed growth (which can reduce
mechanical
weeding that can disrupt the roots of crop plants), decreased soil compaction
(which
results in better soil oxygenation for beneficial microbial activity),
conserved moisture
(by inhibiting evaporation or allowing vaporized and condensed water to fall
back onto
the soil), reduction in the number of harmful insects (by keeping insects from
locating
the crop plants), increased efficiency of soil nutrients (by preventing
nutrients and
fertilizers from leaching below the root zone), and/or reduced fruit/vegetable
contact with
the soil (which results in cleaner product with less chance of contamination).
The extent
to which a particular mulch may produce one or more of these benefits depends
on the
physical properties and material makeup of the mulch.
[004] Recently, synthetic plastic sheet mulches have dominated the market,
for
example, polyethylene-based sheet mulches. While synthetic sheet mulches have
proven effective for improving crop yield, their use also has a number of
negative
attributes and costs. Synthetic sheet mulches require not only installation of
the sheet,
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but removal of the sheet, which is time consuming and typically involves
manual labor,
resulting in significant cost to the farmer. The removed synthetic sheet mulch
must also
be disposed of, which has presented a large environmental problem. The
synthetic
sheets cannot simply be tilled into the soil, as they will cause contamination
and year-
to-year accumulation. Synthetic sheet mulches also cannot be burned, as
burning
releases harmful pollutants. Recycling is typically also not feasible with the
high levels
of contaminants (e.g., soil, fertilizer, vegetation) and the photodegraded
nature of the
sheet. Landfilling has thus become the primary accepted practice for disposing
of
synthetic sheet mulches, but this practice also has significant environmental
and
economic costs. It has thus been desirable to develop a biodegradable mulch
that can
replace prior non-degradable synthetic sheet mulches.
[005] To address these concerns, biodegradable and photodegradable plastics
have been and are being developed. Introduced in the 1980's, many are not
suited to
organic farming because they are not entirely composed of constituents derived
from
natural sources. There is also concern that these materials do not break down
completely, leading to accumulation of plastic fragments in the soil and,
ultimately, in
the oceans. These films are also costly, often 2-3 times the cost of
polyethylene-based
sheet mulches. It is thus desirable to develop a biodegradable sheet mulch
derived from
organic, non-plastic materials.
[006] Paper based sheet mulches have been proposed as a possible option.
Because they are biodegradable, paper mulches may be tilled into the soil
after they
have served their purpose, thus greatly reducing disposal costs. To be
effective,
however, paper mulches must have adequate strength and stretch to withstand
the
physical abuses throughout their lifecycle, such as during laying and
embedding by
mechanical equipment, puncturing for planting, and tearing by the action of
workers.
Paper sheet mulches must also possess an appropriate biodegradation lifespan.
If the
paper degrades too quickly, it can render the sheet useless.
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[007] To date, existing paper sheet mulches have been found to have an
unacceptable combination of physical properties, for example the combination
of basis
weight, strength, and stretch needed to ensure a cost effective product that
can
withstand the required physical abuse. Prior paper sheet mulches have also
been found
to have inferior soil temperature, moisture retention, weed control, whether
resistance,
and/or crop yield properties, particularly compared to synthetic
nonbiodegradable sheet
mulches. Prior paper mulches have also been found to be costly compared to
even
biodegradable plastic mulch alternatives.
[008] There is thus a long-felt, but unmet need in the industry to develop
a
biodegradable paper sheet mulch exhibiting performance attributes comparable
to
synthetic sheet mulches, but with improved environmental impact, and at a
reasonable
cost.
[009] The present inventors have developed a novel solution to this
problem,
having developed a paper sheet mulch product made from a single-ply nonwoven
creped paper sheet comprising additives to achieve water resistance and
substantially
100% opacity.
Summary of the Disclosure
[010] The present inventors have developed novel paper sheet mulch products
having benefits over prior sheet mulches, including a combination of improved
stretch,
strength, opacity, and water-resistance characteristics. In some embodiments,
the paper
sheet mulch products may comprise brown or recycled fibers. In some
embodiments,
the paper sheet mulch products may contain one or more opacity modifiers. In
some
embodiments, the paper sheet mulch products may contain one or more water-
resistance additives. In some embodiments, the paper sheet mulch products may
contain one or more wet or dry strength additives. In some embodiments,
stretch may
further be increased in order to withstand the physical stress of use.
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Date Recue/Date Received 2021-08-18
Detailed Description
[011] The base sheet for use in the paper sheet mulch products of the
present
disclosure may be made from any art recognized cellulosic papermaking fibers.
The
papermaking fibers may be either bleached, brown, recycled, or a mixture
thereof. In
some embodiments, the paper sheet mulch product comprises at least about 75%
cellulosic papermaking fibers based on the dry weight of the sheet, for
example, at least
85%, at least about 90%, or at least about 95%.
[012] In some embodiments, the cellulosic papermaking fibers include at
least
some fibers having an ISO brightness of less than about 80 in order to reduce
cost and
increase opacity of the final product. In some embodiments, the papermaking
fibers may
include those having an ISO brightness of less than about 70 or less than
about 60. ISO
brightness may be determined according to TAPPI T525. In some embodiments, the
paper sheet mulch product may comprise at least about 50% cellulosic
papermaking
fibers having an ISO brightness less than about 80 based on the dry weight of
the sheet,
for example at least about 75%, at least about 90%, at least about 95%, or
from about
75% to about 100% fibers having an ISO brightness less than about 80 based on
the
dry weight of the sheet.
[013] In some embodiments, the cellulosic papermaking fibers include at
least
some recycled fibers, for example mixed recycled fibers (MRF), old newsprint
(ONP)
fibers, old corrugated container (OCC) fibers, and the like. In some
embodiments, the
paper sheet mulch product may comprise at least about 50% recycled cellulosic
papermaking fibers based on the dry weight of the sheet, for example at least
about
75%, at least about 90%, at least about 95%, or from about 75% to about 100%
recycled
fibers based on the dry weight of the sheet. Without wishing to be bound by
theory, it is
believed that incorporation of high lignin recycled fibers such as, for
example, ONP fibers
and/or OCC fibers, may beneficially decrease the rate of biodegradation of the
paper
sheet. On the other hand, too much lignin can reduce inter-fiber bonding,
resulting in a
weaker sheet.
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Date Recue/Date Received 2021-08-18
[014] In some embodiments, the paper sheet may have a kappa number of at
least about 45, at least about 70, at least about 130, or at least about 150,
for example
from about 45 to about 200, from about 70 to about 180, or from about 130 to
about 160
(where kappa number is used as a valuation of lignin content). Kappa number
may be
determined by Tappi T236.
[015] In some embodiments, the paper sheet mulch product may comprise at
least about 30% ONP fibers based on the dry weight of the sheet, for example
at least
about 50%, or at least about 75%. In addition to slowing biodegradation
through
increased lignin content, it is also believed that incorporation of ONP fibers
may
beneficially increase the opacity of the paper sheet mulch product due to the
inks and/or
pigments used in the newsprint process. In some embodiments, the paper sheet
mulch
product may comprise at least about 30% OCC fibers based on the dry weight of
the
sheet, for example at least about 50%, or at least about 75%. In some
embodiments,
the paper sheet mulch product may comprise at least about 30% MRF fibers based
on
the dry weight of the sheet, for example at least about 50%, or at least about
75%. In
some embodiments, the paper sheet mulch product may comprise a combination of
ONP and OCC fibers in an amount of at least about 75% based on the dry weight
of the
sheet, for example, at least 85%, at least about 90%, or at least about 95%
based on
the dry weight of the sheet. In some embodiments, the paper sheet mulch
product may
comprise a combination of MRF and OCC fibers in an amount of at least about
75%
based on the dry weight of the sheet, for example, at least 85%, at least
about 90%, or
at least about 95% based on the dry weight of the sheet. In some embodiments,
the
paper sheet mulch product may comprise a combination of from about 55% to
about
65% OCC fibers and from about 35% to about 45% MFR fibers based on the dry
weight
of the sheet.
[016] The paper sheet mulch products of the present invention may be
manufactured on a non-woven tissue paper-making machine. In a typical process,
the
fiber is fed into a headbox where it will be admixed with water and chemical
additives,
Date Recue/Date Received 2021-08-18
as appropriate, before being deposited on a forming wire. The chemical
additives for
use in the formation of the base sheets can be any known combination of
papermaking
chemicals. Papermaking chemicals include, for example, one or more of strength
agents, softeners, debonders, creping modifiers, sizing agents, optical
brightening
agents, retention agents, and the like. As used herein "sheet," "web,"
"tissue," "nascent
web," "tissue product," "base sheet" or "tissue sheet," can be used
interchangeably to
refer to the paper web during various stages of its development. Nascent web,
for
example, refers to the embryonic web that is deposited on the forming wire.
Once the
web achieves about 30% solids content, it is referred to as a tissue, or a
sheet, or a web.
Post-production, the single-ply of tissue is typically called a paper sheet or
base sheet.
[017] In some embodiments, the paper sheet mulch products of the present
invention may be manufactured using through-air-drying ("TAD") methods. In TAD
methods the nascent web is partially dewatered using vacuum suction.
Thereafter, the
partially dewatered web is dried without compression by passing hot air
through the web
while it is supported by a through-drying fabric. In some embodiments, the TAD
processes use special fabrics or belts to impart a structure to the sheet
during drying.
While one through-air-drying operation is described above, the system is only
exemplary
and variations on the described system will be readily apparent to the skilled
artisan.
[018] In some embodiments, the paper sheet mulch products of the present
invention may be manufactured using conventional wet pressing ("CWP") methods.
In
conventional wet pressing, the nascent web is transferred to a papermaking
felt and is
dewatered by passing it between the felt and a press roll under pressure. The
web is
then pressed by a suction press roll against the surface of a rotating Yankee
dryer
cylinder that is heated to cause the paper to substantially dry on the
cylinder surface.
The moisture within the web as it is laid on the Yankee surface causes the web
to
transfer to the surface. Liquid adhesive may be applied to the surface of the
dryer, as
necessary, to provide substantial adherence of the web to the surface. The web
is then
removed from the Yankee surface with a creping blade. The creped web is then
passed
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Date Recue/Date Received 2021-08-18
between calender rollers and rolled up to be used in the downstream production
of a
paper product. This method of making tissue sheets is commonly referred to as
"wet-
pressed" because of the compactive method used to dewater the wet web. While
one
conventional wet pressing operation is described above, the system is only
exemplary
and variations on the described system will be readily apparent to the skilled
artisan.
[019] In some embodiments, the paper sheet may be creped to enhance stretch
and bulk, for example creped from a Yankee dryer in a conventional wet
pressing
process. Creping may be performed by any known type of creping blade. In some
embodiments, a non-Taurus (e.g., blue steel) blade is used. In some
embodiments, a
Taurus crepe blade is used. Without wishing to be bound by theory, it is
believed that
use of a Taurus blade may increase the stretch of the sheet (for example the
cross-
direction (CD) stretch), which is believed to improve the handling of the
sheet during the
mulch laying operation. In some embodiments, the paper-making machine may be
run
with a speed differential between the Yankee dryer and a rolling reel in order
to increase
MD stretch. In some embodiments, the sheet may be creped from the Yankee dryer
in
a wet creping process, wherein the sheet is creped at a moisture level of from
about 8%
to about 12% of the dry weight of the sheet. In some embodiments, the sheet
may be
creped from the Yankee dryer in a dry creping process, wherein the sheet is
creped at
a moisture level of from about 3% to about 5% of the dry weight of the sheet.
[020] In a typical process, after drying, the base sheet is rolled and
awaits
converting. Converting refers to the process that changes or "converts" base
sheets into
final products. In some embodiments, wrinkles may be imparted to the sheet
during
converting, for example with a bowed roll or a roll with annular rings.
Without wishing to
be bound by theory, it is believed that adding wrinkles to the sheet further
increases the
stretch or "give" of the sheet. In some embodiments, wrinkles may be added in
an
orientation fully or partially aligned in the machine direction (the direction
the sheet
travels in the papermaking machine during formation and processing). Without
wishing
to be bound by theory, it is believed that adding wrinkles to the sheet that
are fully or
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Date Recue/Date Received 2021-08-18
partially aligned in the machine direction provides particular increase to the
cross-
direction stretch of the sheet. In some embodiments, the paper sheet has
wrinkles in a
direction between about 300 and about 90 from the cross-machine direction,
for
example, between about 60 and about 90 .
[021] In some embodiments, pleated folds may be imparted to the sheet
during
converting. In some embodiments, folds may be created during a rewinding
operation
by running the sheet over folding boards or plows to impart one or more folds
in the
sheet, for example in the form of back-and-forth folds. The sheet may then be
directed
through one or more pressing nips, for example between calender rolls, to fix
the pleated
folds into place. Without wishing to be bound by theory, it is believed that
creating
pleated folds in the sheets provides stress relief points that allow the sheet
to relax,
rather than tear, particularly during the mulch laying process. In some
embodiments,
pleated folds may be added in an orientation fully or partially aligned in the
machine
direction. Without wishing to be bound by theory, it is believed that adding
pleated folds
to the sheet that are fully or partially aligned in the machine direction
provides particular
increase to the cross-direction stretch of the sheet. In some embodiments, the
paper
sheet has pleated folds running in a direction between about 30 and about 90
from the
cross-machine direction, for example, between about 60 and about 90 .
[022] In some embodiments, the paper sheet mulch product may be single-ply,
comprising only one paper base sheet. In some embodiments, the paper sheet
mulch
product may be a multi-ply product formed by combining two or more paper base
sheets.
[023] In some embodiments, the paper sheet may be treated with an opacity
modifier to increase opacity. The opacity modifier may be any additive
sufficient to obtain
substantially 100% opacity (at least 95% opacity). Opacity may be determined
according
to TAPPI T425. In some embodiments, the opacity modifier may comprise one or
more
of carbon black (for example a bio-based carbon black), biochar, pigments or
dyes (for
example organic and/or inorganic pigments or dyes), fillers (for example clay,
kaolin,
and titanium oxide), and the like. In some embodiments, the opacity modifier
may
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Date Recue/Date Received 2021-08-18
comprise a black pigment, for example an organic black pigment. In some
embodiments,
the opacity modifier may comprise a blue pigment, for example an organic blue
pigment,
or for example blue pigment comprising a phthalocyanine derivative. In some
embodiments, the opacity modifier may comprise a blue pigment comprising
copper, for
example, a blue pigment comprising a phthalocyanine copper complex. Without
wishing
to be bound by theory, it is believed that the presence of copper may
contribute to
antimicrobial properties of the sheet, which could improve (slow) the
biodegradation rate
of the sheet.
[024] In some embodiments, an opacity modifier may be an opacity surface
coating. The opacity surface coating may be applied after sheet formation by
any known
technique, for example, by printing, coating, or spraying. In some
embodiments, the
opacity modifier may be applied as a coating on both sides of the sheet. In
some
embodiments, when applied as an opacity surface coating, the opacity modifier
may be
applied in an amount of from about 0.2 to about 20 lbs/ream based on the dry
weight of
the sheet, for example, from about 2 to about 10 lbs/ream. In some
embodiments,
carbon black may be applied as an opacity surface coating in an amount of from
about
1 to about 10 lbs/ream based on the dry weight of the sheet, for example, from
about
from about 2 to about 5 lbs/ream. In some embodiments, biochar may be applied
as an
opacity surface coating in an amount of from about 2 to about 10 lbs/ream, for
example
from about 7 to about 10 lbs/ream or from about 8 to about 9 lbs/ream based on
the dry
weight of the sheet.
[025] In some embodiments, an opacity modifier may be added in the wet-end
of the papermaking machine prior to sheet formation. Such addition of the
opacity
modifier in the wet-end results in a paper sheet mulch wherein the opacity
modifier is
distributed substantially uniformly throughout the paper sheet mulch product,
which
does not occur when application is only in the dry-end after sheet formation
by, for
example, printing, coating, or spraying. In some embodiments, the opacity
modifier may
be added in the headbox. In some embodiments, the opacity modifier may be
added
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before the headbox, for example at the stuff box, fan pump, or machine chest
pump. In
some embodiments, an opacity modifier may be added at the suction side of a
machine
chest pump. In some embodiments, the opacity modifier may be at least one
organic
and/or inorganic pigment, such as a blue or black pigment, added in the wet-
end of the
papermaking machine prior to sheet formation in an amount of from about 0.2 to
about
30 pounds per ton of dry weight of the fiber, for example from about 2 to
about 20, about
to about 15, or about 8 to about 12 pounds per ton of dry weight of the fiber.
Without
wishing to be bound by theory, it is believed that addition of the opacity
modifier in the
dry-end, after sheet formation, may result in undesirable re-wet and loss of
some of the
stretch imparted during sheet formation and creping. In contrast, application
of the
opacity modifier in the wet-end, before the end of sheet formation and
creping, preserves
that stretch by obviating the need for application in the dry-end.
[026] In some embodiments, where an opacity modifier is added in the wet-
end
of the papermaking machine prior to sheet formation, a fixative may also be
added in an
amount of from about 0.2 to about 10 pounds per ton of dry weight of the
fiber, for
example from about 1 to about 7 or from about 2 to about 5 pounds per ton of
dry weight
of the fiber. The fixative may be any known fixative known to increase the
retention of
the opacity modifier in the paper sheet. In some embodiments, the fixative may
be a
cationic fixative, for example a low to medium molecular weight cationic
polymer.
[027] In some embodiments, an opacity modifier may be added in the wet-end
of the papermaking machine prior to sheet formation and an opacity modifier
may be
added as an opacity surface coating following sheet formation.
[028] In some embodiments, the paper sheet may be treated with a water-
resistant modifier. The water-resistant modifier can be any substance that
will bond to
cellulose and also repel a liquid such as water, for example an oleophobe or a
hydrophobe. In some embodiments, the water-resistant modifier may comprise one
or
more of acrylics, waxes, alkenyl ketene dimers (ALKD), alkyl ketene dimers
(AKD),
alkenyl succinic anhydrides (ASA), fluorochemicals, silicones, hydrophobically
modified
Date Recue/Date Received 2021-08-18
anionic polymers (HMAP), hydrophobically modified cationic polymers (HMCP),
ethylene-acrylic acids (EAA), neutral rosin emulsions, conventional paper
sizing agents,
and the like. In some embodiments, the water-resistance additive may be
acrylic. In
some embodiments, the water-resistance additive may be AKD.
[029] In some embodiments, the water-resistant modifier may be applied as a
surface coating. The water-resistant surface coating may be applied after
sheet
formation by any known technique, for example printing, coating, or spraying.
In some
embodiments, the water-resistant modifier may be applied as a coating on both
sides of
the sheet. In some embodiments, a water-resistant modifier may be applied as a
surface
coating in an amount of from about 0.2 to about 20 lbs/ream based on the dry
weight of
the sheet. In some embodiments, an acrylic containing water-resistant coating
may be
applied as a surface coating in an amount of from about 1 to about 15 lbs/ream
based
on the dry weight of the sheet, for example, from about 8 to about 12
lbs/ream.
[030] In some embodiments, the water-resistant modifier may be added in the
wet-end of the papermaking machine prior to sheet formation. Such addition of
the
water-resistant modifier in the wet-end results in a paper sheet mulch wherein
the water-
resistant modifier is distributed substantially uniformly throughout the paper
sheet mulch
product, which does not occur when application is only in the dry-end after
sheet
formation by, for example, printing, coating, or spraying. In some
embodiments, the
water-resistant modifier may be added in the headbox. In some embodiments, the
water-resistant modifier may be added before the headbox, for example at the
stuff box,
fan pump, or machine chest pump. In some embodiments, a water-resistant
modifier
may be added at the machine fan pump. In some embodiments, when applied in the
wet-end of the papermaking machine, the water-resistant modifier may be
applied in an
amount of from about 0.2 to about 30 pounds per ton of dry weight of the
fiber, for
example, from about 2 to about 20 pounds per ton. In some embodiments, alkyl
ketene
dimer may be added in the wet-end of the papermaking machine prior to sheet
formation
as a water-resistant modifier in an amount of from about 1 to about 10 pounds
per ton
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of dry weight of the fiber, for example from about 4 to about 6 pounds per ton
of dry
weight of the fiber.
[031] In some embodiments, a water-resistant modifier may be added in the
wet-
end of the papermaking machine prior to sheet formation and a water-resistant
modifier
may be added as a surface coating following sheet formation.
[032] In some embodiments, one or more wet strength additives may be added
to the paper sheet mulch. In some embodiments, the one or more wet strength
additives
may be added in the wet-end of the papermaking machine prior to sheet
formation.
Such addition of the wet strength additive in the wet-end results in a paper
sheet mulch
wherein the wet strength additive is distributed substantially uniformly
throughout the
paper sheet mulch product, which does not occur when application is only in
the dry-
end after sheet formation by, for example, printing, coating, or spraying. In
some
embodiments, the one or more wet strength additives may be added in an amount
of
from about 0.2 to about 30 pounds per ton of dry weight of the fiber, for
example, from
about 2 to about 20, or from about 5 to about 10 pounds per ton of dry weight
of the
fiber. Wet strength additives suitable for use include, but are not limited
to, one or more
of aliphatic and aromatic aldehydes, urea-formaldehyde resins, melamine
formaldehyde
resins, polyamide-epichlorohydrin resins, and the like. In one embodiment, the
at least
one wet strength additive may be a polyamide-epichlorohydrin (PAE) resin, and
the like.
[033] In some embodiments, one or more dry strength additives may be added
to the paper sheet mulch. In some embodiments, the one or more dry strength
additives
may be added in the wet-end of the papermaking machine prior to sheet
formation. Such
addition of the dry strength additive in the wet-end results in a paper sheet
mulch
wherein the dry strength additive is distributed substantially uniformly
throughout the
paper sheet mulch product, which does not occur when application is only in
the dry-
end after sheet formation by, for example, printing, coating, or spraying. In
some
embodiments, the one or more dry strength additives may be added in an amount
of
from about 0.2 to about 10 pounds per ton of dry weight of the fiber, for
example, from
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Date Recue/Date Received 2021-08-18
about 0.5 to about 7, or from about 1 to about 4 pounds per ton of dry weight
of the fiber.
Dry strength additives suitable for use include, but are not limited to,
anionic
polyacrylam ide, carboxymethylcellulose, ethylene-maleam ic acid copolymer,
acrylamide-maleic acid copolymer, starch, guar gum, cationic guar gum,
cationic starch,
cationic polyacrylamide, poly-DADMAC, cationic polyacrylates, anionic starch,
cationic
latex, glyoxylated polyacrylamide, polyamine, cationic PVA, amphoteric dry
strength
resins, and the like.
[034] In some embodiments, the paper sheet mulch products of the present
disclosure may have a basis weight of from about 20 lb/3000ft2 to about 50
lb/3000ft2,
for example, from about 25 lb/3000ft2 to about 45 lb/3000ft2, or from about 30
lb/3000ft2
to about 40 lb/3000ft2. Basis weight may be measured according to Tappi T410.
[035] In some embodiments, the paper sheet mulch products of the present
disclosure may have a caliper of from about 3 mils/1sht to about 10 mils/1sht,
for
example, from about 4 mils/1sht to about 8 mils/1sht. Caliper may be
determined by
Tappi T411.
[036] In some embodiments, the paper sheet mulch products of the present
disclosure may have a machine-direction tensile strength (Tensile MD) of at
least about
lb/1in, for example, at least about 10 lb/1in, or from about 5 lb/1in to about
20 lb/1in,
or from about 6 lb/1in to about 13 lb/1in. In some embodiments, the paper
sheet mulch
products of the present disclosure may have a cross machine-direction tensile
strength
(Tensile CD) of at least about 2 lb/1in, for example, at least about 5 lb/1in,
or from about
2 lb/1in to about 10 lb/1in, or from about 3 lb/1in to about 8 lb/1in. Tensile
MD and
Tensile CD may be determined according to Tappi TM-494.
[037] In some embodiments, the paper sheet mulch products may have a
machine-direction stretch (Stretch MD) of at least about 1%, for example, at
least about
5%, at least about 8%, or at least about 10%, or from about 1% to about 30%,
for
example, from about 5% to about 20%, or from about 10% to about 20%. In some
embodiments, the paper sheet mulch products of the present disclosure may have
a
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cross machine-direction stretch (Stretch CD) of at least about 1%, for
example, at least
about 3%, at least about 5%, or at least about 10%, or from about 1% to about
30%, for
example, from about 3% to about 20%. In some embodiments where wrinkles or
pleated
folds have been imparted to the paper sheet mulch products, the cross-machine
direction stretch may be from about 10% to about 20%, for example, from about
13% to
about 17%. Stretch MD and Stretch CD may be determined according to Tappi TM-
576
[038] In some embodiments, the paper sheet mulch products may have a
machine-direction tensile energy absorption (MD TEA) of at least about 2 mm-
g/mm2,
for example, at least about 3 mm-g/mm2, at least about 5 mm-g/mm2, or at least
about
7 mm-g/mm2, or from about 3 mm-g/mm2 to about 10 mm-g/mm2, or from about 5 mm-
g/mm2 to about 8 mm-g/mm2. MD TEA may be determined according to Tappi T 576.
[039] In some embodiments, the paper sheet mulch products of the present
disclosure may have a machine-direction wet tensile strength (Wet Tensile MD)
of at
least about 1 lb/1n, for example, at least about 3 lb/1in, at least about 5
lb/1in, or from
about 1 lb/1n to about 7 lb/1in, or from about 1.5 lb/1n to about 3 lb/1n. In
some
embodiments, the paper sheet mulch products of the present disclosure may have
a
cross machine-direction wet tensile strength (Wet Tensile CD) of from about
0.5 lb/1in
to about 6 lb/1in, for example, from about 0.7 lb/1in to about 2 lb/1in. Wet
Tensile MD
and Wet Tensile CD may be determined according to Tappi TM-494.
[040] In some embodiments, the paper sheet mulch products of the present
disclosure may have an opacity of at least about 95%, for example, at least
about 98%,
or about 100%. Opacity may be determined according to TAPPI T425.
[041] In some embodiments, the paper sheet mulch products of the present
disclosure may have a 0.1 ml water absorption rate (WAR) of at least about 90
seconds,
for example, at least about 200 seconds, at least about 500 seconds, or at
least about
1000 seconds. WAR may be determined by Tappi T432.
[042] Contact angle is often used to evaluate the wettability or water
resistance
of cellulose-based surfaces. In some embodiments, the paper sheet mulch
products of
14
Date Recue/Date Received 2021-08-18
the present disclosure may have a contact angle of from about 00 to about 150
. The
contact angle may depend on the method by which water resistance is imparted
to the
sheet. In some embodiments where water resistance is imparted by addition of a
water-
resistant modifier in the wet-end of a papermaking machine, the contact angle
may be
less than about 50 , for example, from about 0 to about 20 . In some
embodiments
where water resistance is imparted by addition of a water-resistant modifier
to the
surface of the sheet, the contact angle may be greater than about 750, for
example great
than about 90 , greater than about 110 , or from about 750 to about 160 , or
from about
110 to about 150 . Contact angle may be determined by Tappi T558.
[043] The biodegradation rate of the paper sheet mulches described herein
may
be evaluated by measuring gaseous carbon generation over time. The
biodegradation
rate may be measured using a slightly modified version of ASTM method D5988.
Paper
sheet mulch samples are mixed with defined amounts of soil as in the original
ASTM
D5988 method to create test samples, which are placed in sealed jars and
incubated at
a controlled temperature of 40C for 45 days. Unlike ASTM method D5988, the
soil is not
adjusted with nitrogen to achieve a designated Carbon to nitrogen ratio.
Reference
samples consisting of only the defined amount of soil are similarly prepared
and
incubated for 45 days. After 45 days, the CO2 generated by each of the test
samples
and the reference samples are measured. The biodegradation rate may be
inferred from
the amount of CO2 generated by a test sample minus the amount of CO2 generated
by
its corresponding reference sample. In some embodiments, the paper sheet mulch
products described herein may have a biodegradation rate according to this
test method
of from about 50mg to about 800mg of CO2 in 45 days, from about 100mg to about
700mg of CO2 in 45 days, for example, or from about 200mg to about 600mg of
CO2 in
45 days.
[044] In some embodiments, the paper sheet mulch products of the present
disclosure may have a Gurley Porosity of from about 1 s/100cm3to about 100
s/100cm3.
Gurley Porosity may be determined by Tappi T460.
Date Recue/Date Received 2021-08-18
[045] It will be understood that various modifications may be made without
departing from the spirit and scope of the disclosure.
Example 1
[046] Single-ply paper basesheets were produced at different basis weights
using conventional wet press drying methods with wet creping using non-Taurus
crepe
blades. The basesheets were produced using a furnish of 60% old corrugated
container
(OCC) fibers and 40% mixed recycled paper fibers (MRF). Process parameters for
manufacturing the basesheets are reported in Table 1.
Table 1
Target Basis Weight 27.5# 34.0#
Yankee Speed fpm 2575 2450
AD Speed fpm 2382 2265
Reel Speed fpm 2422 2306
Refiner - North amps 28 28
Refiner - South amps 25 34
Hood Temp WE F 740 800
Hoof Temp DE F 740 800
Yankee Steam psi 75 82
AD Steam psi 4 30
Wet Strength Flow ml/min 1250 1350
Dry Strength Flow ml/min 1600 1600
PVOH ml/mmn 455 455
Modifier ml/min 31 31
Coating ml/min 46 46
Stock Flow gpm 915 1070
[047] Chemicals added to the basesheets in the wet-end of the papermaking
process during production are reported in Table 2 as a percentage based on the
dry
weight of the fiber. Less than 100% of the chemicals added in the wet-end are
retained
in the final basesheet. For example, it is estimated that only 5% of the
Yankee coating
package ends up in the final basesheet.
16
Date Recue/Date Received 2021-08-18
Table 2
Additive Type Additive 27.5# 34.0#
Wet Strength polyamide-epichlorohydrin (PAE) resin 0.35% 0.34%
Dry Strength glyoxylated polyacrylamide (GPAM) 0.13% 0.12%
Creping Adhesive Poly(vinyl alcohol) (PVOH) 0.02% 0.02%
Creping Modifier polyolefin and mineral oil 0.01% 0.01%
Creping Adhesive polyamide-epichlorohydrin (PAE) resin 0.01% 0.01%
[048] The bases heets were tested for physical properties and then split
into two
50.25 inch parent rolls and tested for opacity, WAR (water absorption), and
contact
angle (water resistance). The results of these tests are reported in Table 3.
Table 3
Sample A B C D
Target Basis Weight 27.5# 27.5# 34.0# 34.0#
Before After Before After
Property Units Splitting Splitting Splitting Splitting
Basis Weight lb/3000ft2 27.8 33.6
Caliper mils/8 sht 56.7 52.5 55 50.9
Stretch MD % 10.8 9.6 10.8 9.1
Stretch CD % 3.2 4.1
Tensile CD g/3 in 5815 6943
Tensile MD g/3 in 9656 9669 11001 11974
Wet Tensile CD g/3 in 2015 2158
Wet Tensile MD g/3 in 3326 3247
WAR 0.1 mL sec 180+ 139
Contact Angle degree 0 0
Opacity MacBeth opacity units 91.2 95.6
17
Date Recue/Date Received 2021-08-18
[049] The trial produced reels at approximately 27.5 lbs/ream and 34
lbs/ream
basis weights. Reducing the caliper and increased smoothness were target
properties
to improve the final coated sheet. The 34 lbs/ream sheet had lower caliper
than the 27.5
lbs/ream sheet. This was attributed to higher sheet moisture at the Yankee and
steam
in the after dryers. Reel moisture increased from 1.6% on the 27.5 lbs/ream to
2.5% for
the 34 lbs/ream.
[050] Paper sheets made with target basis weights of 27.5 and 34 lbs/ream
were
further coated with a carbon black ink opacity coating and/or an acrylic water-
resistance
coating. The sheets were tested for certain properties reported in Table 4.
Table 4
Sample E F G H
Target Basis Weight 27.5# 27.5# 34# 34#
Basis Weight lb/3000ft2 28.6 30.2 36.5
37.1
Carbon black ink coating lb/3000ft2 2.0 2 2.4 2.4
Acrylic coating lb/3000ft2 0 1.2 0 1.1
Caliper m ils/1sht 5.3 5.4 6.4 6.4
Tensile MD lb/1in 6.3 6.0 7.7 7.4
Tensile CD lb/1in 3.8 4.0 5.0 4.8
Stretch MD % 5.4 6.0 7.3 7.7
Stretch CD % 2.6 2.6 2.8 2.7
TEA MD in-lb/in2 0.19 0.20 0.32
0.31
TEA CD in-lb/in2 0.06 0.06 0.09
0.08
Tensile Modulus MD psi/1000 20 23 22 23
Tensile Modulus CD psi/1000 53 59 55 55
Wet Tensile MD lbf/1in 1.9 1.9 2.3 2.3
Wet Tensile CD lbf/1in 1.1 1.2 1.4 1.5
Tear MD g 31 32 40 39
Tear CD g 37 40 51 56
Gurley Stiffness MD 6 6 10 10
Gurley Stiffness CD 12 12 21 26
Trapezoidal MD Tensile gf 906 911 1844
2313
Trapezoidal MD Elongation % 7.6 6.5 9.2
10.1
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Date Recue/Date Received 2021-08-18
Trapezoidal MD Energy gf-mm 1702 1735 4764
6344
Opacity MacBeth Opacity units 96.3 96.3 97.7
98.3
WAR (0.1 ml) s 176 180+ 135 157
Contact Angle degrees 0 0 0 0
Gurley Porosity s/100cm3 1.1 1.4 1.6 1.7
Example 2
[051] A second trial was conducted, with the goal of improving certain
properties
of the paper sheet mulch products, including sheet toughness (the combination
of
strength and stretch) and biodegradation rate. Single-ply paper basesheets
were
produced on a pilot scale paper making machine to target basis weights of 30
lb/3000ft2
and 40 lb/3000ft2 using conventional wet press drying methods. The basesheets
were
produced using a furnish of 100% mixed recycled paper fibers (MRF).
[052] Chemicals added to the basesheets in the wet-end of the papermaking
process during production are reported in Tables 5 and 6 as pounds per ton
based on
the dry weight of the fiber. The type of creping blade used is also reported.
Table 5
Additive Type Additive
Wet Strength polyamide-epichlorohydrin (PAE) resin
Pigment (Blue) phthalocyanine copper complex
Pigment (Black) carbon black
Fixative cationic polymer
Size alkyl ketene dimer (AKD)
Table 6
Target Wet
Pigment Fixative Size Crepe
Sample Basis Strength Weight lbs/ton
Type @ lbs/ton lbs/ton lbs/ton Blade
I 40 7 Blue @ 10 3 0 Non-Taurus 10 bevel
J 30 7 Blue @ 10 3 0 Non-Taurus 10 bevel
19
Date Recue/Date Received 2021-08-18
K 40 7 Black @ 10 3 5
Non-Taurus 100 bevel
L 40 7 Black @ 10 3 0
Non-Taurus 10 bevel
M 30 7 Black @ 10 3 0
Non-Taurus 10 bevel
[053] The Yankee dryer was run at a speed of 75 fpm and the reel at a speed
of
69 fpm. A polyolefin and mineral oil creping modifier was added at 4 mg/m2 and
a PAE
creping adhesive was added at 50 mg/m2.
[054] Basesheet Samples I-M were tested for physical properties and
compared
with Sample C from Example 1, as reported in Table 7.
Table 7
Sample I J K L M C
Target Basis Weight 40# 30# 40# 40# 30# 34#
Pigment Type Blue Blue Black Black Black None
Size Added No No Yes No No No
Basis Weight (1b/3000ft^2) 38.9 30.9 40.7 39.3 30.1
33.6
Caliper (mils/1sht) 11.3 10.1 14.0 11.5 12.6 6.9
Tensile MD (lb/1 in) 3.3 2.8 4.9 4.5 2.6 7.2
Tensile CD (lb/1 in) 1.5 1.2 1.9 2.0 1.7 4.6
Stretch MD (%) 13.4 10.8 10.8 11.8 14.0
10.8
Stretch CD (%) 3.4 3.8 2.9 3.5 2.7 4.1
TEA MD (mm-g/mmA2) 2.89 2.00 3.34 3.89 2.31
7.16
TEA CD (mm-g/mmA2) 0.58 0.50 0.60 0.74 0.39
1.92
Wet Tensile MD (lbf/1 in) 0.5 0.3 1.2 1.1 0.9 1.7
Wet Tensile CD (lbf/1 in) 0.2 0.2 0.5 0.5 0.5 1.0
Tear MD (g) 24.1 20.1 28.9 34.8 30.6 na
Tear CD (g) 22.9 21.6 40.6 37.5 29.5 na
Trapezoidal Tensile (g) 973 685 1087 1330 877
2311
Trapezoidal Stretch (%) 17.9 13.5 15.7 17.4 18.2
19.8
Date Recue/Date Received 2021-08-18
Trapezoidal Energy (g-mm) 3583 1897 3055 4711 2626 7426
Opacity MacBeth (%) 99.9 98.5 100.0 100.5 99.9
95.6
WAR (sec) 9 14 180+ 12 28 93
Contact Angle (deg) 0 0 119 0 0 0
[055] The addition of both pigments (blue, black) was found to impart an
opacity
of 98+% at both the target basis weights of 30 lb/3000ft2 and 40 lb/3000ft2.
[056] The addition of an opacity modifier pigment in the wet-end of the
paper
machine in Example 2 resulted in increased stretch (important for sheet
toughness), as
compared to the samples where an opacity modifier ink was added in the dry end
during
converting as in in Example 1 (Sample E-H). Without wishing to be bound by
theory, it
is believed that addition of the opacity modifier ink in the dry end during
converting
results in the introduction of moisture to the sheet that causes the crepe to
relax stretch
to undesirably decrease.
[057] Compared to the basesheets produced in Example 1, the basesheets of
Example 2 had wet and dry strengths reduced by about one half. This is likely
due to
the combined effects of a variety of factors, including the change in furnish
(the use of
OCC as in Example 1 is believed to result in increased strength) and the fact
that the
basesheets of Example 2 were made on a pilot dry crepe machine instead of a
full-scale
wet crepe machine.
[058] The addition of a size additive (AKD) in Sample K was also found to
have
the desired effect of increasing contact angle and therefore inhibiting
penetration of
water into the sheet.
[059] Basesheet Samples I-M were further tested for biodegradation rate by
analyzing CO2 generation and compared with Samples F and H from Example 1, as
reported in Tables 8 and 9. A lower biodegradation rate indicates a lower
amount of
CO2 reacted after 45 days, which indicates a slower (beneficial)
biodegradation rate.
21
Date Recue/Date Received 2021-08-18
Table 8
Biodegradation
Sample Rate STD
-- Soil Only 0 56
I 40# Blue Pigment 412 247
J 30# Blue Pigment 624 195
K 40# Black Pigment, Sized 545 390
L 40# Black Pigment 607 93
M 30# Black Pigment 663 160
F 27.5# Black Ink + Acrylic Coating 678 38
H 34# Black Ink + Acrylic Coating 715 85
Table 9
No
Treatment Treatment Difference
Effect of Blue Pidment vs. Black Pidment
Blue (Sample I) vs. Black (Sample L) 412 607 -195
Blue (Sample J) vs. Black (Sample M) 624 663 -39
Effect of Size vs. No Size
Sized (Sample K) vs. Unsized (Sample L) 545 607 -62
Effect of Hidh vs. Low Basis Weidht
22
Date Recue/Date Received 2021-08-18
40# (Sample I) vs. 30# (Sample J) 412 624 -212
40# (Sample L) vs. 30# (Sample M) 607 663 -56
[060] The blue pigment, which was based on a phthalocyanine copper complex,
yielded somewhat lower levels of CO2 than did the black (carbon black)
pigment. Both
pigments are alkaline. Without wishing to be bound by theory, it is believed
that this
may be due, in part, to the presence of copper in the blue pigment, which may
act to
inhibit the growth of microbes that accelerate degradation. Regardless of
which pigment
is used, it is believed that addition in the wet-end, which distributes the
pigment
throughout the thickness of the sheet, results in slower biodegradation when
compared
with the application of the opacity modifier in the dry end following sheet
formation.
Though the effect is relatively small, it appears that addition of internal
size may also
contribute to slower biodegradation by hindering the movement of water into
the mulch
structure, which is needed for some microbial growth. The results of the
present
experiment appear to also confirm that basesheets with the higher basis weight
have
beneficially slower biodegradation rates.
OTHER INVENTIVE EMBODIMENTS
[061] Descriptions of the disclosed embodiments are not exhaustive and are
not
limited to the precise forms or exemplary embodiments disclosed. Modifications
and
adaptations of the exemplary embodiments will be apparent from consideration
of the
specification and practice of the disclosed embodiments. 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 paper sheet mulch product having a machine-direction tensile
strength (Tensile MD) of at least about 5 lb/1in, for example, at least
23
Date Recue/Date Received 2021-08-18
about 10 lb/1in, or from about 5 lb/1in to about 20 lb/1in, or from about
6 lb/1in to about 13 lb/1in.
B. A paper sheet mulch product according to embodiment A, further
having a machine-direction stretch (Stretch MD) of at least about 1%,
for example, at least about 5%, at least about 8%, or at least about
10%, or from about 1% to about 30%, for example, from about 5% to
about 20%, or from about 10% to about 20%.
C. A paper sheet mulch product according to embodiments A-B, further
having an opacity of at least about 95%, for example, at least about
98%, or about 100%.
D. A paper sheet mulch product according to embodiments A-C, further
having a basis weight of from about 20 lb/3000ft2 to about 50 lb/3000ft2,
for example, from about 25 lb/3000ft2 to about 45 lb/3000ft2, or from
about 30 lb/3000ft2 to about 40 lb/3000ft2.
E. A paper sheet mulch product according to embodiments A-D, further
having a caliper of from about 3 mils/1sht to about 10 mils/1sht, for
example, from about 4 mils/1sht to about 8 mils/1sht.
F. A paper sheet mulch product according to embodiments A-E, further
having a biodegradation rate according to this test method of from
about 50mg to about 800mg of CO2 in 45 days, from about 100mg to
about 700mg of CO2 in 45 days, for example, or from about 200mg to
about 600mg of CO2 in 45 days.
G. A paper sheet mulch product according to embodiments A-F, further
having a machine-direction tensile energy absorption (MD TEA) of at
least about 2 mm-g/mm2, for example, at least about 3 mm-g/mm2, at
least about 5 mm-g/mm2, or at least about 7 mm-g/mm2, or from about
3 mm-g/mm2 to about 10 mm-g/mm2, or from about 5 mm-g/mm2 to
about 8 mm-g/mm2.
24
Date Recue/Date Received 2021-08-18
H. A paper sheet mulch product according to embodiments A-G, further
having a cross machine-direction stretch (Stretch CD) of at least about
1%, for example, at least about 5%, at least about 8%, or at least about
10%, or from about 1% to about 30%, for example, from about 3% to
about 20%. In some embodiments where wrinkles or pleated folds
have been imparted to the paper sheet mulch products, the cross-
machine direction stretch may be from about 10% to about 20%, for
example, from about 13% to about 17%.
I. A paper sheet mulch product according to embodiments A-H, further
having a cross machine-direction tensile strength (Tensile CD) of at
least about 2 lb/1in, for example, at least about 5 lb/1in, or from about
2 lb/1in to about 10 lb/1in, or from about 3 lb/1in to about 8 lb/1in.
J. A paper sheet mulch product according to embodiments A-I, further
having a 0.1 ml water absorption rate (WAR) of at least about 90
seconds, for example, at least about 200 seconds, at least about 500
seconds, or at least about 1000 seconds.
K. A paper sheet mulch product according to embodiments A-J, further
having a contact angle greater than about 75 , for example great than
about 90 , greater than about 1100, or from about 1100 to about 1500
.
L. A paper sheet mulch product according to embodiments A-J, further
having cellulosic fibers comprising an ISO brightness of less than about
80, less than about 70, or less than about 60.
M. A paper sheet mulch product according to embodiments A-J, further
having cellulosic fibers comprising a kappa number of at least about
45, at least about 70, at least about 130, or at least about 150, for
example from about 45 to about 200, from about 70 to about 180, or
from about 130 to about 160.
Date Recue/Date Received 2021-08-18
N. A method of making a paper sheet mulch comprising adding an
opacity
modifier to obtain at least 95% opacity.
0. A method of making a paper sheet mulch according to embodiment
N,
wherein the opacity modifier comprises at least one of carbon black
and biochar, and is applied as a surface coating after sheet formation
in an amount of from about 0.2 to about 20 lbs/ream based on the dry
weight of the sheet, for example, from about 1 to about 10 lbs/ream.
P. A method of making a paper sheet mulch according to embodiment N,
wherein the opacity modifier comprises at least one organic and/or
inorganic pigment, such as a blue or black pigment, and is added in
the wet-end of a papermaking machine prior to sheet formation in an
amount of from about 0.2 to about 30 pounds per ton of dry weight of
the fiber, for example from about 2 to about 20, about 5 to about 15, or
about 8 to about 12 pounds per ton of dry weight of the fiber.
Q. A method of making a paper sheet mulch according to embodiments
N-P, wherein a water-resistant modifier, for example one or more of
acrylics, waxes, alkenyl ketene dimers (ALKD), alkyl ketene dimers
(AKD), alkenyl succinic anhydrides (ASA), fluorochemicals, silicones,
hydrophobically modified anionic polymers (HMAP), hydrophobically
modified cationic polymers (HMCP), ethylene-acrylic acids (EAA), and
neutral rosin emulsions, is applied as a surface coating after sheet
formation in an amount of from about 0.2 to about 20 lbs/ream based
on the dry weight of the sheet, for example, from about 1 to about 15
lbs/ream or from about 8 to about 12 lbs/ream.
R. A method of making a paper sheet mulch according to embodiments
N-P, wherein a water-resistant modifier, for example one or more of
acrylics, waxes, alkenyl ketene dimers (ALKD), alkyl ketene dimers
(AKD), alkenyl succinic anhydrides (ASA), fluorochemicals, silicones,
26
Date Recue/Date Received 2021-08-18
hydrophobically modified anionic polymers (HMAP), hydrophobically
modified cationic polymers (HMCP), ethylene-acrylic acids (EAA), and
neutral rosin emulsions, is added in the wet-end of a papermaking
machine prior to sheet formation in an amount of from about 0.2 to
about 30 pounds per ton of dry weight of the fiber, for example, from
about 2 to about 20 pounds per ton, from about 1 to about 10 pounds
per ton of dry weight of the fiber, or from about 4 to about 6 pounds per
ton of dry weight of the fiber.
S. A method of making a paper sheet mulch according to embodiments
N-R, wherein a wet strength additive, for example one or more of
aliphatic and aromatic aldehydes, urea-formaldehyde resins,
melamine formaldehyde resins, and polyamide-epichlorohydrin resins,
is added in the wet-end of the papermaking machine prior to sheet
formation in an amount of from about 0.2 to about 30 pounds per ton
of dry weight of the fiber, for example, from about 2 to about 20, or from
about 5 to about 10 pounds per ton of dry weight of the fiber.
T. A method of making a paper sheet mulch according to embodiments
N-S, wherein a dry strength additive, for example one or more of
anionic polyacrylam ide, carboxymethylcellu lose, ethylene-maleam ic
acid copolymer, acrylamide-maleic acid copolymer, starch, guar gum,
cationic guar gum, cationic starch, cationic polyacrylamide, poly-
DADMAC, cationic polyacrylates, anionic starch, cationic latex,
glyoxylated polyacrylamide, polyamine, cationic PVA, and am photeric
dry strength resins, is added in the wet-end of the papermaking
machine prior to sheet formation in an amount of from about 0.2 to
about 10 pounds per ton of dry weight of the fiber, for example, from
about 0.5 to about 7, or from about 1 to about 4 pounds per ton of dry
weight of the fiber.
27
Date Recue/Date Received 2021-08-18
U. A method of making a paper sheet mulch according to embodiments
N-T, wherein the paper sheet mulch is manufactured using a through-
air-drying ("TAD") method.
V. A method of making a paper sheet mulch according to embodiments
N-T, wherein the paper sheet mulch is manufactured using
conventional a wet pressing ("CWP") method including drying the sheet
on the surface of a Yankee cylinder.
W. A method of making a paper sheet mulch according to embodiments
N-T and V, wherein the paper sheet is creped from the Yankee dryer
in a wet creping process, wherein the sheet is creped at a moisture
level of from about 8% to about 12% of the dry weight of the sheet.
X. A method of making a paper sheet mulch according to embodiments
N-T and V, wherein the paper sheet is creped from the Yankee dryer
in a dry creping process, wherein the sheet is creped at a moisture
level of from about 3% to about 5% of the dry weight of the sheet.
Y. A method of making a paper sheet mulch according to embodiments
N-X, wherein wrinkles are imparted to the sheet during converting in a
direction between about 300 and about 90 from the cross-machine
direction, for example, between about 60 and about 90 , for example
with a bowed roll or a roll with annular rings.
A method of making a paper sheet mulch according to embodiments
N-Y, wherein pleated folds are imparted to the sheet during converting
in a direction between about 30 and about 90 from the cross-machine
direction, for example, between about 60 and about 90 , for example
during a rewinding operation by running the sheet over folding boards
or plows to impart one or more folds in the sheet, and then directing
the sheet through one or more pressing nips to fix the pleated folds into
place.
28
Date Recue/Date Received 2021-08-18
