Note: Descriptions are shown in the official language in which they were submitted.
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PAPERS COMPRISING A BORON-CONTAINING COMPOUND AND A METHOD OF MAKING SAME
FIELD OF THE INVENTION
The invention relates to the field of paper and paperboard products and, in
particu-
lar, to paper and paperboard products having improved dimensional stability
properties. Another
aspect of this invention relates a process of making the paper and paperboard
products of this
invention.
BACKGROUND OF THE INVENTION
A continuing problem in the papermaking arts is the tendency of papers to
expand
or contract in size based on ambient moisture conditions. In a high moisture
environment, paper
fibers will generally absorb moisture and expand. As the fibers expand, the
dimensions of the
overall paper also expand, a phenomena referred to as hygroexpansion. On the
other hand, when
papers are exposed to particularly dry ambient conditions, the paper fibers
may give off previ-
ously retained moisture leading to fiber and paper shrinkage. Additionally,
variations in humid-
ity conditions may lead to other variations and instabilities in the
dimensions of the paper includ-
ing curling and cockling.
Moreover, exposure to high humidity levels may lead to reductions in the
strength
and stiffness properties of papers. This is particularly problematic in
heavier paperboards that
are used for packaging wherein maintenance of high strength and stiffness is
essential.
Accordingly, there is a need for papers which are less sensitive to ambient
condi-
tions and which do not tend to expand or shrink due to local moisture
conditions.
SUMMARY OF THE INVENTION
With regard to the foregoing and other objects and advantages, the present
inven-
tion provides a method for forming a paper or paperboard. The method includes
provid-
ing a papermaking furnish comprising cellulosic fibers, starch and a boron-
containing compound.
The amount of starch compound may vary widely as for example equal to or less
than about 200
lbs per ton of fiber and is preferably equal to or less than about 170 lbs per
ton of fiber, more
preferably from about 2 lbs to about 150 lbs per ton of fiber and most
preferably from about 2 lbs
to about 100 lbs per ton of fiber with amount of more preferably from about 3
lbs to about 50 lbs
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of starch per ton of fiber in the embodiments of choice. The amount of boron
containing com-
pound may also vary widely. In the preferred embodiments the amount of boron
containing com-
pound will depend on the amount of starch. In these preferred embodiments, the
compound is
present in an amount equal to or less than about 7 % of the weight of starch
added to the furnish,
preferably equal to or less than about 5 % of the weight of starch added to
the furnish, more pref-
erably equal to or less than about 3 % of the weight of starch added to the
furnish and most, pref-
erably from about 0.2 % to about 2% of the weight of starch added to the
furnish. In the em-
bodiments of choice, the amount of starch is from about 0.7 % to about 0.8 %
of the weight of
starch added to the furnish. The method further includes forming a fibrous web
from the paper-
making furnish and drying the web. In the preferred embodiments of the
invention, the dried web
is calendered to provide a finished paper or paperboard.
In another aspect, the invention relates to a paper or paperboard formed by
the
method of this invention. The paper or paperboard comprises a paper web formed
from a pulp
furnish comprising cellulosic fibers, starch and a boron-containing compound.
In one embodi-
ment, the major portion (e.g. greater than 50%, preferably greater than 75%
and more preferably
greater than about 80% to about 90%) of the starch and a boron-containing
compound is at or
about the surfaces of the web. In another embodiment, the major portion (e.g.
greater than 50%,
preferably greater than 75% and more preferably greater than about 80% to
about 90%) of the
starch and a boron-containing compound is dispersed through out the web the
web.
In forming the paper or paperboard, it is preferred that cooked starch and at
least a
portion of the boron-containing compound are premixed with one another to
provide a slurry and
the resultant slurry is then added to the pulp furnish. In certain
embodiments, it is further pre-
ferred to mix the unconverted starch and at least a portion of the boron-
containing compound are
premixed with one another to provide a slurry and the resultant slurry is then
cooked to convert
the starch prior to adding the slurry to the pulp furnish. However, in certain
other embodiments
of the invention, it may be preferred that the boron-containing compound is
added directly to the
pulp furnish.
In still another aspect, the invention provides a method for forming a paper
or pa-
perboard including the steps of providing a papermaking furnish comprising
cellulosic fibers,
forming a fibrous web from the papermaking furnish, drying the web and sizing
the web by ap-
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plying a slurry to the web, the slurry comprises starch solids and a boron-
containing compound.
The amount of boron containing compound may also vary widely. In the preferred
embodiments
the amount of boron containing compound will depend on the amount of starch.
In these pre-
ferred embodiments, the compound is present in an amount equal to or less than
about 7 % of the
weight of starch added to the furnish, preferably equal to or less than about
5 % of the weight of
starch added to the furnish, more preferably equal to or less than about 3 %
of the weight of
starch added to the furnish and most, preferably from about 0.2 % to about 2%
of the weight of
starch added to the furnish. In the embodiments of choice, the amount of
starch is from about 0.7
% to about 0.8 % of the weight of starch added to the furnish. In the
preferred embodiments of
the invention, the dried web is calendered to provide a finished paper or
paperboard.
In yet another aspect, the invention relates to a paper or paperboard formed
by the
method of this invention The paper or paperboard comprises comprising a paper
web formed
from a pulp furnish including cellulosic fibers and having a sizing applied to
the paper web, the
sizing including starch solids and a boron-containing compound present in the
amounts described
above.
Illustrative of useful boron containing compounds are boric acid and metal
borate
salts. Preferred boron-containing compounds for the practice of the invention
may be selected
from the group consisting of boric acid, borax, and zinc borate.
The starch employed in the invention maybe either an anionic starch, a
cationic
starch, or an amphipathic depending on the particular embodiment being
practiced. Preferred
starch sources may be selected from the group consisting of cornstarch, wheat
starch, potato
starch, rice starch, tapioca starch, and sago starch.
DETAILED DESCRIPTION OF THE INVENTION
The invention involves papers having either an internal starch or a size press
ap-
plied starch and a boron-containing compound which is added in proportion to
the starch and
which is believed to interact with the starch to provide improved physical and
mechanical proper-
ties in the paper. (As used herein, paper refers to and includes both paper
and paperboard un-
less otherwise noted.)
The paper is provided as a web containing cellulosic pulp fibers such as fiber
de-
rived from hardwood trees, softwood trees, or a combination of hardwood and
softwood trees
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prepared for use in a papermaking furnish by any known suitable digestion,
refining, and bleach-
ing operations. In a preferred embodiment, the cellulosic fibers in the paper
include from about
0 % to about 40 % by weight dry basis softwood fibers and from about 100 % to
about 60 % by
weight dry basis hardwood fibers. In certain embodiments, at least a portion
of the fibers may
be provided from non-woody herbaceous plants including, but not limited to,
kenaf, hemp, jute,
flax, sisal, or abaca although legal restrictions and other considerations may
make the utilization
of hemp and other fiber sources impractical or impossible. The paper may also
include other
conventional additives such as, for example, starch, mineral fillers, sizing
agents, retention aids,
and strengthening polymers. Among the fillers that may be used are organic and
inorganic pig-
ments such as, by way of example, polymeric particles such as polystyrene
latexes and poly-
methylmethacrylate, and minerals such as calcium carbonate, kaolin, and talc.
In some instance,
the papers may also include hollow microspheres.
A variety of papers and paperboards may be provided by the invention having a
wide variety of basis weights and formed from a wide variety of cellulosic
fibers. These include
but are not limited to, including office papers, forms papers, envelope
papers, label stock, bris-
tols, and printing and publication papers as well as bleached boards and
linerboards.
Office papers formed according to the present invention preferably have a
final
caliper, after calendering of the paper, and any nipping or pressing such as
may be associated
with subsequent coating of from about 3.5 to about 10 mils. Office papers of
the invention also
preferably exhibit basis weights of from about 18 lb/1300ft 2 to about 32
lb/1300ft 2. Bleached
boards formed according to the present invention preferably have a final
caliper, after calender-
ing of the board, and any nipping or pressing such as may be associated with
subsequent coating
of up to about 45 mils. Bleached boards of the invention also typically
exhibit basis weights of
from about 40 lb/1000 ft 2 to about 90 lb/1000 ft 2.
Linerboards formed according to the present invention preferably have a final
ca-
liper, after calendering of the board, and any nipping or pressing such as may
be associated with
subsequent coating of up to about 45 mils. Linerboards of the invention also
preferably exhibit
basis weights of from about 251b/1000 ft 2 to about 100lb/1000 ft 2.
Importantly, the papers of the present invention include a boron-containing
com-
pound in combination with starch. The boron-containing compound is preferably
selected from
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the group consisting of boric acid and anhydrous and hydrated metal borate
salts. Particularly
preferred boron-containing compounds include anhydrous and hydrated sodium
borate (Borax),
potassium borate, boric oxide, boric acid, and zinc borate. The boron-
containing compound is
added in proportion to the amount of starch being added and the amount may
also vary widely. In
the preferred embodiments the amount of boron containing compound will depend
on the amount
of starch. In these preferred embodiments, the compound is present in an
amount equal to or less
than about 7 % of the weight of starch added to the furnish, preferably equal
to or less than about
% of the weight of starch added to the furnish, more preferably equal to or
less than about 3 %
of the weight of starch added to the furnish and most, preferably from about
0.2 % to about 2%
of the weight of starch added to the furnish. In the embodiments of choice,
the amount of starch
is from about 0.7 % to about 0.8 % of the weight of starch added to the
furnish. .
A starch solution is added to the paper in combination with the boron-
containing
compound. The starch solution may include a cationic starch, an anionic
starch, an amphipathic
starch, or a combination of more of more of these starches. Suitable starch
sources include corn-
starch, wheat starch, potato starch, rice starch, tapioca starch, and sago
starch. The type and
amount of starch added to the paper may vary depending on the particular
embodiment of the
invention as described in more detail herein below.
The addition of the starch and boron-containing compound to the paper may vary
depending on the particular embodiment of the invention. In one embodiment of
the invention,
the starch and boron-containing compound are added to the furnish prior to the
forming of the
web on the papermaking machine. In another embodiment, the combination of
starch and boron-
containing compound are added at the size press after the web has been formed
and at least par-
tially dried. Papers according to the invention have been observed to have
improved resistance to
moisture expansion and shrinkage. That is the papers exhibit less fiber
expansion when in a
moist or humid environment than conventional papers and also exhibit less
fiber shrinkage when
in a particularly and environment In some embodiments of the invention, the
papers exhibit im-
provements in strength and stiffness properties including Gurley stiffness,
modulus of elasticity,
tensile energy absorption, and/or tensile strength.
The method of forming the paper materials of the present invention includes
pro-
viding an initial paper furnish. The cellulosic fibrous component of the
furnish is suitably of the
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CA 02513488 2010-04-30
chemically pulped variety, such as a bleached kraft pulp, although the
invention is not believed to
be limited to kraft pulps, and may also be used with good effect with other
chemical pulps such
as sulfite pulps, mechanical pulps such as ground wood pulps, and other pulp
varieties and mix-
tures thereof such as chemical-mechanical and thermo-mechanical pulps.
While not essential to the invention, the pulp is preferably bleached to
remove lig-
nins and to achieve a desired pulp brightness according to one or more
bleaching treatments
known in the art including, for example, elemental chlorine-based bleaching
sequences, chlorine
dioxide-based bleaching sequences, chlorine-free bleaching sequences,
elemental chlorine-free
bleaching sequences, and combinations or variations of stages of any of the
foregoing and other
bleaching related sequences and stages.
After`bleaching is completed and the pulp is washed and screened, it is
generally
subjected to one or more refining steps. Thereafter, the refined pulp is
passed to a blend chest
where it is mixed with various additives and fillers typically incorporated
into a papermaking
furnish as well as other pulps such as unbleached pulps and/or recycled or
post-consumer pulps.
The additives may include so-called internal sizing agents used primarily to
increase the con-
tact angle of polar liquids contacting the surface of the paper such as
alkenyl succinic anhydride
(ASA), alkyl ketene dimer (AKD), and rosin sizes. Retention aids may also be
added at this sta-
ge, including both cationic and anionic retention aids.
An amount of internal starch is typically added to the paper furnish at this
point as
well. In one embodiment of the invention, the boron-containing compound is
added in to the
furnish in combination with this starch. In this embodiment, starch is
typically added to the fur-
nish in an amount as described above as for example an amount of about 3 lb of
starch / ton of
paper to about 30 lbs of starch / ton of paper. Also, boron-containing
compound is typically
added to the furnish in an amount based on the weight of the starch added to
the furnish in an
amount as described above.
In this embodiment, it is preferred that the boron-containing compound has a
rela-
tively high water solubility. It is preferred to pre-mix the converted
(cooked) starch solution and
the boron-containing compound with one another, thereby providing a slurry of
starch and boron-
containing compound and then add this slurry mixture to the furnish as a later
step.
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In this embodiment, the preferred boron-containing compound is boric acid. It
is
also preferred that the starch being added to the furnish is a cationic
starch. The invention may
employ a preconverted starch, that is, a starch which has been previously
reacted with additives
such as ammonium persulfate and / or conversion enzymes in order to partially
convert the high-
ly branched molecular structure of the raw starch into a structure which is
somewhat more linear
and less branched. However, if the starch has not been preconverted, then it
may be cooked and
converted in the slurry with the boron-containing compound at a temperature of
about 95-100 C
and then cooled to about 40-60 C prior to addition to the furnish.
In another embodiment of the invention, the boron-containing compound may be
directly added to the furnish mixture, and separately, the starch solution may
be directly added to
the furnish. This is typically preferred if the boron-containing compound is
one of relatively low
aqueous solubility such as zinc borate for example.
Once prepared, the furnish is formed into a single or multi-ply web on a paper-
making machine such as a Fourdrinier machine or any other suitable papermaking
machine
known in the art, as well as those which may become known in the future. The
basic methodolo-
gies involved in making paper on various papermaking machine configurations
are well known
to those of ordinary skill in the art and accordingly will not be described in
detail herein. In gen-
eral, a furnish consisting of a relatively low consistency aqueous slurry of
the pulp fibers (typi-
cally about 0.1 to about 1.0%) along with the microspheres and various
additives and fillers dis-
persed therein is ejected from a headbox onto a porous endless moving forming
sheet or wire
where the liquid is gradually drained through small openings in the wire until
a mat of pulp fibers
and the other materials is formed on the wire. The still-wet mat or web is
transferred from the
wire to a wet press where more fiber-to-fiber consolidation occurs and the
moisture is further
decreased. The web is then passed to an initial dryer section to remove most
of the retained
moisture and further consolidate the fibers in the web. After initial drying,
the web may be fur-
ther treated using a size press wherein additional starch, pigments, and other
additives may be
applied to the web and incorporated therein by the action of the press.
In another embodiment of the invention, the boron-containing compound may also
be added to the paper along with this starch addition in addition to, or in
place of, addition of the
boron-containing compound with the wet end internal starch. In this
embodiment, starch is typi-
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cally added at the size press in the desired amount as for example at a starch
pickup rate of from
about 40 to about 150 lbs starch / ton of paper and the boron-containing
compound is typically
added with the starch at the size press, in the desired amount and based on
the weight of starch
solids added as for example from about 0.2% to about 1.0% (preferably 0.7% to
about 0.8%) by
weight of the starch.
In this embodiment as well, it may be preferred that the starch and the boron-
containing compound be pre-mixed into a slurry. In addition, if the starch is
a raw, unconverted
starch, such as a pearl starch, then it may be preferred to mix the raw starch
and the boron-
containing compound, and then cook the resultant slurry to convert the starch
prior to application
at the size press. The conversion may be aided by the use of additives such as
ammonium per-
sulfate and conversion enzymes. The conversion may be carried at a temperature
of from about
100-105 C. After conversion, the starch is then maintained at about 60-70 C
until it is applied at
the size press. For application at the size press, a preferred boron-
containing compound is borax
(sodium borate).
After treatment in the size press and subsequent drying, the paper is
preferably ca-
lendered to achieve the desired final caliper as discussed above to improve
the smoothness and
other properties of the web. The calendering may be accomplished by steel-
steel calendaring at
nip pressures sufficient to provide a desired caliper. It will be appreciated
that the ultimate cali-
per of the paper will be largely determined by the selection of the nip
pressure.
As noted the resultant papers are observed to have improved resistance to
hygro-
expansion and to other detrimental effects of high humidity environments such
as curling and
cockling. Without being bound by theory, it is believed that the inclusion of
the boron-
containing compound achieves this affect by promoting formation of a complex
between the
starch molecules and the boron-containing compound. The complexing is believed
to limit the
penetration of the starch into the cellulosic fibers.
Penetration of the starch solids into the cellulosic fibers is believed to
provide a
route for moisture to penetrate into the fibers as well. Thus, starch addition
typically makes the
paper more susceptible to hygroexpansion and other dimensional instability
when in a high hu-
midity environment. However, by promoting complexing of starch molecules one
with another,
the amount of starch available to penetrate the cellulosic fibers is reduced.
Accordingly the fibers
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are less susceptible to moisture penetration and exhibit less dimensional
variation with changing
environmental conditions.
Surprisingly, it has also been observed that in some embodiments the use of
the
boron-containing compounds leads to improvements in the strength and stiffness
properties of the
paper formed according to the invention. The papers may also exhibit
improvements in Gurley
stiffness, modulus of elasticity, tensile energy absorption, and/or tensile
strength.
The following no limiting examples illustrate various additional aspects of
the in-
vention. Unless otherwise indicated, temperatures are in degrees Celsius,
percentages are by
weight and the percent of any pulp additive or moisture is based on the oven-
dry weight of the
pulp.
Example I
A series of hand sheet samples of a linerboard were produced to determine the
ef-
fect of addition of a boron-containing compound, together with starch, in a
pulp furnish. The
board was formed from a pulp mixture of about 80% hardwoods and about 20%
softwoods.
The first (control) sample was formed without any internal starch or boron-
containing compound.
Sample 2 was formed from the same furnish, except that starch was added to the
furnish mixture at a ratio of about 20 lb starch / ton of pulp fibers prior to
the furnish being for-
med into the hand sheets. Again, no boron-containing compound was included in
the furnish.
In Sample 3, the pulp mixture was used and in this sample, the furnish was com-
bined with about 20 lb starch/ ton of pulp fibers and about 1% of boric acid,
based on the weight
of starch added. The starch and boric acid were initially combined with one
another to form
slurry. This slurry was cooked and then added to the furnish prior to hand
sheet formation.
In Sample 4, zinc borate was added to the pulp mixture at a ratio of about 20
lb
zinc borate / ton of pulp fibers. No internal starch was added to the pulp
mixture.
In Sample 5, about 20 lb of starch / ton of pulp fibers and about 20 lb of
zinc bo-
rate / ton of pulp fibers were added to the furnish. No boric acid was
included with the starch.
Finally, in Sample 6, about 20 lb of starch / ton of pulp fibers (with about 1
% boric acid based on
the weight of starch added) and about 20 lb of zinc borate / ton of pulp
fibers were added to the
furnish.
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The physical and mechanical properties of each hand sheet sample were then mea-
sured. The results are listed in Table I.
Table I
Property and Units Sample Sample Sample Sample Sample Sample
1 3 4 5 6
Air Resistance Gurley 3.1 2.8 3.8 4.5 3.1 3.5
S/100 cc
Apparent Density g/cm3 0.468 0.492 0.526 0.492 0.506 0.527
Basis weight g/m2 307 328 326 326 346 325
Basis weight lb/1000 ft 62.9 67.1 66.7 66.7 70.6 66.5
Bulk cm3/g 2.14 2.03 1.90 2.03 1.99 1.90
Burst factor gf/cm2/g/m2 20.2 23.8 25.7 23.6 24.5 24.9
Burst lbf/in2 88.1 111 119 109 120 115
Caliper mil 25.86 26.11 24.31 26.18 26.48 24.35
Instron Breaking Length m 2940 3410 3290 3430 3180 3250
Instron Stretch at Peak % 2.18 2.65 2.84 2.76 2.74 2.74
Instron TEA at peak 0.825 1.21 1.26 1.20 1.16 1.16
in*lbf/in2
Instron tensile strength 50.5 62.7 60.1 62.6 61.5 59.2
lbf/in
Instron Young's Modulus 159 186 176 188 179 190
of Elasticity. I E+3 lbf/in2
Internal Bond 1E-3 56 65 100 80 109 93
ft*lb/in2
Compressive strength, 26.32 31.46 32.06 31.79 35.15 30.38
lbf/in
Stiffness Gurley mgf 8010 9930 8840 10000 12600 9500
Tear Factor 100 gf/g/m2 171 181 198 176 193 169
Tear gf 524 592 646 572 668 550
Z-direction direction ten- 26 30 35 33 37 42
sile strength lbf/in2
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Example II
A series of hand sheet samples of an offset printing paper were produced to de-
termine the effect of addition of a boron-containing compound, together with
starch, in the sizing
of a paper at the size press. The board was formed from a pulp mixture of
about 80% hard-
woods and about 20% softwoods. The first (control) sample was formed as a
control. This sheet
was not treated with either starch or boron-containing compound at the size
press. In Sample 2, a
base sheet formed in accordance with Sample 1 was sized by applying a 16%
starch solids mix-
ture with a rod-metering device and sizing the sheet using a Beloit size
press. No boron-
containing compound was included with the sizing starch. The starch was a
Staley Pearl AP
starch that was converted using ammonium persulfate. The starch was applied at
a pickup rate
of about 100lb/ ton of base sheet.
In Sample 3, the sheet was formed and sized as in Sample 2, except that the
starch
solids were applied at 10 % solids rather than 16% solids. Again, no boron-
containing com-
pound was included with the sizing starch.
In Sample 4, a base sheet formed in accordance with Sample 1 was sized by ap-
plying a mixture comprising 16% starch solids and borax (sodium borate
pentahydrate). The
ratio (by weight) of the borax in the mixture to the starch solids was about
0.25 %. Prior to being
applied to the sheet, the mixture of starch and borax was cooked with of
ammonium persulphate
in order to convert the starch. The mixture was applied with a rod-metering
device, and the sheet
was sized using a Beloit size press.
In Sample 5, the sizing was carried out in accordance with Sample 4, except
that
the weight ratio of borax to starch solids was 0.50 % rather than 0.25%.
In Sample 6, the starch was applied at a 10% starch solids concentration in
the
mixture. Borax was added in a ration of 0.50% borax to starch solids by
weight. Finally, the
pickup rate of the rod-metering device was lowered from 100 lb/ ton to 60
lb/ton.
The physical and mechanical properties of each hand sheet sample were then mea-
sured. The results are listed in Table II.
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Table II
Property and Units Sample Sample Sample Sample Sample Sample
1 2 3 4 5 6
Hygroexpansion from 0.87% 1.05% 1.08% 0.85% 1.10%
15% to 85% rel. humidity
Air Resistance Gurley 9.5 11.8 11.6 12.5 10.6 11.3
s/100 cc
Apparent Density g/cm3 0.620 0.623 0.618 0.620 0.626 0.623
Basis Weight g/m2 69.7 70.4 70.0 71.0 71.1 70.7
Basis Weight lb/1300 ft2 18.5 18.7 18.6 18.9 18.9 18.8
Basis Weight lb/3300 ft2 47.1 47.6 47.3 48.0 48.0 47.8
Brightness Directional 84.2 83.4 83.5 83.0 83.3 83.6
(GE), % FS
Brightness Directional 84.2 83.8 83.8 83.6 83.7 83.7
(GE), % WS
Bulk ASV cm3/g 1.61 1.61 1.62 1.61 1.60 1.61
Caliper? mil 4.43 4.46 4.46 4.52 4.47 4.48
COF Kinetic 0.353 0.306 0.304 0.312 0.258 0.266
COF Static 0.456 0.440 0.415 0.471 0.396 0.444
Dry Pick IGT, VVP FS 27.0 53.2 47.8 60.8 51.6 47.7
Dry Pick IGT, VVP WS 36.3 35.7 40.2 40.1 35.8 37.4
Instron stretch at peak, % 1.56 1.76 1.68 1.65 1.65 1.58
(MD)
Instron stretch at peak, % 3.28 4.14 3.77 3.83 3.26 3.90
(CD)
Instron TEA at peak 0.161 0.216 0.210 0.194 0.205 0.197
in*lbf/in2 (MD)
Instron TEA at peak 0.219 0.290 0.259 0.302 0.227 0.259
in*lbf/in2 (CD)
Instron Tensile Strength 2.01 2.21 2.35 1.92 2.19 2.35
MD/CD Ratio
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Property and Units Sample Sample Sample Sample Sample Sample
1 2 3 4 5 6
Instron tensile strength 18.0 19.9 19.8 19.8 20.4 20.5
lbf/in (MD)
Instron tensile strength 8.94 9.01 8.44 10.3 9.32 8.74
lbf/in (CD)
Instron Young's Modulus. 469 506 524 515 533 547
of Elasticity
1E+3 lbf/in2 (MD)
Instron Young's Modulus 209 200 190 228 209 185
of Elasticity
1E+3 lbf/in2 (CD)
Instron Internal Bond, 1E- 118 127 126 126 116 118
3 ft*lb/in2 (MD)
Instron Internal Bond, 1E- 114 127 124 131 113 116
3 ft*lb/in2 (CD)
Opacity Tappi, % (89% 89.1 98.8 88.9 89.0 89.2 89.0
backing)
Pick Velocity m/s FS 3.00 3.00 3.00 3.00 3.00 3.00
Pick Velocity m/s WS 3.00 3.00 3.00 3.00 3.00 3.00
Roughness Parker, um 10 7.49 7.96 7.75 8.40 7.96 7.93
kgf/cm2 softback FS
Roughness Parker, um 10 9.73 10.07 10.00 9.72 9.68 9.96
kgf/cm2 softback WS
Roughness Sheffield FS 258 263 270 270 266 281
Roughness Sheffield WS 302 323 320 320 313 329
Size Hercules, sec (1% 1 33 26 40 49 33
ink, 80% endpt) FS
Size Hercules, sec (1% 1 14 18 21 21 19
ink, 80% endpoint) WS
Stiffness Gurley, mgf 123 130 149 154 148 146
(MD)
Stiffness Gurley, mgf 48.4 62.5 67.9 81.7 70.6 65.3
(CD)
13
CA 02513488 2005-07-15
WO 2004/027149 PCT/IB2003/003983
Property and Units Sample Sample Sample Sample Sample Sample
1 2 3 4 5 6
Tear factor 100 gf/g/m 15.8 15.6 15.7 14.1 15.5 15.6
(MD)
Tear factor 100 gf/g/m2 17.2 17.0 15.7 16.9 18.3 17.0
(CD)
Tear gf (MD) 55.7 53.8 53.8 51.8 53.8 55.4
Tear gf (CD) 57.6 58.2 56.6 61.4 60.2 57.0
Wax pick, critical wax 7 11 10 14 11 11
strength no. FS
Wax pick, critical wax 11 10 10 10 10 10
strength no. WS
Z-direction tensile 97 106 107 112 105 110
strength lbf/in2
Having now described various aspects of the invention and preferred embodi-
ments thereof, it will be recognized by those of ordinary skill that numerous
modifications, varia-
tions and substitutions may exist within the spirit and scope of the appended
claims.
14
