U.S. patent application number 16/109138 was filed with the patent office on 2018-12-20 for soft creped tissue.
The applicant listed for this patent is Kimberly-Clark Worldwide, Inc.. Invention is credited to John Paul David, Thomas Joseph Dyer, Mike Thomas Goulet, Frederick John Lang, Michael John Rekoske, Christopher Lee Satori, Kenneth John Zwick.
Application Number | 20180363246 16/109138 |
Document ID | / |
Family ID | 57198741 |
Filed Date | 2018-12-20 |
United States Patent
Application |
20180363246 |
Kind Code |
A1 |
Lang; Frederick John ; et
al. |
December 20, 2018 |
SOFT CREPED TISSUE
Abstract
The invention provides a creped tissue web having satisfactory
softness without the excess use of water insoluble creping
compositions. The satisfactory softness levels, which may be
measured as TS7, are generally less than about 10.0 and may be
achieved by creping the tissue web with less than about 100
mg/m.sup.2 (milligrams of creping composition per square meter of
creping cylinder surface area) such as from about 25 to about 100
mg/m.sup.2 and more preferably from about 50 to about 75
mg/m.sup.2. It was previously believed that water insoluble creping
compositions need to be added at high add-on levels, such as 100
mg/m.sup.2 or greater to achieve a desirable softness at a given
tensile strength. It has now been surprisingly discovered that the
add-on of water insoluble creping composition may be reduced
significantly by adding a water soluble adhesive to the creping
composition.
Inventors: |
Lang; Frederick John;
(Neenah, WI) ; Satori; Christopher Lee;
(Hortonville, WI) ; David; John Paul; (Appleton,
WI) ; Dyer; Thomas Joseph; (Neenah, WI) ;
Goulet; Mike Thomas; (Neenah, WI) ; Rekoske; Michael
John; (Appleton, WI) ; Zwick; Kenneth John;
(Neenah, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kimberly-Clark Worldwide, Inc. |
Neenah |
WI |
US |
|
|
Family ID: |
57198741 |
Appl. No.: |
16/109138 |
Filed: |
August 22, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15565921 |
Oct 12, 2017 |
10081914 |
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PCT/US16/27114 |
Apr 12, 2016 |
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16109138 |
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62154915 |
Apr 30, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21H 19/74 20130101;
D21H 17/33 20130101; D21H 27/002 20130101; D21H 21/146
20130101 |
International
Class: |
D21H 17/33 20060101
D21H017/33; D21H 21/14 20060101 D21H021/14; D21H 19/74 20060101
D21H019/74; D21H 27/00 20060101 D21H027/00 |
Claims
1. A process for manufacturing a creped tissue product comprising
the steps of: a. dispersing a furnish to form a fiber slurry; b.
forming a wet tissue web; c. partially dewatering the wet tissue
web; d. applying a non-fibrous olefin polymer and a water soluble
adhesive polymer to a creping cylinder, wherein the mass ratio of
the non-fibrous olefin polymer to the water soluble adhesive
polymer is from about 5:1 to about 75:1; e. pressing the partially
dewatered tissue web to the creping cylinder; f. drying the tissue
web; g. creping the dried tissue web from the creping cylinder to
produce a creped tissue web; and h. plying two or more creped
tissue webs together to form a tissue product having a basis weight
greater than about 25 gsm, a GMT from about 700 to about 1,500
g/3'' and a TS7 value less than about 10.0.
2. The process of claim 1 wherein the non-fibrous olefin polymer
comprises an alpha olefin interpolymer of ethylene or propylene and
at least one comonomer, each comonomer being selected from the
group consisting of octene, heptene, hexene, decene, and dodecene
and the water soluble adhesive polymer is selected from the group
consisting of a water soluble adhesive selected from the group
consisting of polyoxazolines, polyamidoamine-epichlorohydrin resin,
polyamine epichlorohydrin resin, polyvinyl alcohol, polyvinylamine,
polyethylenimine, acrylamide polymers, polymethacrylamide,
poly(acrylic acid), poly(methacrylic acid), poly(hydroxyethyl
methacrylate), poly(n-vinyl pyrrolidinone), poly(ethylene oxide),
saccharides, polysaccharides and modified polysaccharides.
3. The process of claim 1 wherein the tissue product has a TS7
value from about 8.0 to about 9.5 and the GMT is from about 750 to
about 1,000 g/3''.
4. The process of claim 1 wherein the non-fibrous olefin polymer is
applied to the creping cylinder at add-on levels less than about
100 mg/m.sup.2.
5. The process of claim 1 wherein the non-fibrous olefin polymer is
applied to the creping cylinder at add-on levels from about 50 to
about 75 mg/m.sup.2 and the water soluble adhesive polymer is
applied to the creping cylinder at add-on levels from about 1.0 to
about 20 mg/m.sup.2.
Description
RELATED APPLICATIONS
[0001] The present application is a divisional application and
claims priority to U.S. patent application Ser. No. 15/565,921,
filed on Oct. 12, 2017, which is a national-phase entry, under 35
U.S.C. .sctn. 371, of PCT Patent Application No. PCT/US16/27114,
filed on Apr. 12, 2016, which claims priority to U.S. Provisional
Application No. 62/154,915, filed on Apr. 30, 2015, all of which
are incorporated herein by reference.
BACKGROUND OF THE DISCLOSURE
[0002] Tissue products such as paper towels, facial tissues, bath
tissues, are often designed to have a soft feel. Softness is
typically increased by decreasing or reducing bonding between
fibers within the tissue product. While potentially improving
softness, inhibiting or reducing inter-fiber bonding may adversely
affect other important properties, such as the strength of the
tissue product.
[0003] In other instances, softness may be enhanced by the topical
addition of a softening agent to the tissue product. The softening
agent may comprise, for instance, a silicone chemistry and may be
topically applied to the tissue product by printing, coating or
spraying. Although softening agents, such as silicone chemistries,
make the tissue product feel softer, the agents can be relatively
expensive, reduce absorbent rate and capacity, and may adversely
affect the strength of the product.
[0004] In other instances softness may be enhanced by creping the
tissue web. For example, U.S. Pat. No. 7,785,443 discloses creping
a tissue web using a non-fibrous alpha-olefin polymer. The
non-fibrous alpha-olefin polymer forms a thin film onto the tissue
web, a portion of which remains on the surface of the web after it
is creped from the dryer surface. While creping the tissue web in
this manner improves softness, the water insoluble nature of the
non-fibrous alpha-olefin polymer presents challenges to tissue
machine operation. Further, to achieve the desired softness levels
the non-fibrous alpha-olefin polymer is generally applied to the
dryer at significantly high add-on levels compared to conventional
creping compositions. For example, the non-fibrous alpha-olefin
polymer may be applied in excess of 100 mg of creping composition
per square meter of Yankee dryer surface area compared to about 5
to about 15 mg/m.sup.2 (milligrams per square meter of dryer
surface area) for conventional creping compositions. The high
add-on levels exacerbate the processing difficulties and increase
costs.
[0005] Thus, there remains a need for treatments which improve
softness without negatively affecting other important tissue
product properties, such as strength, and which are compatible with
current tissue machine operation. There also remains a need for
treatments which produce the desirable tissue product improvements
without excessive chemical usage or increased processing complexity
and costs.
SUMMARY OF THE DISCLOSURE
[0006] It has now been discovered that the softness (measured as
TS7) of a tissue web, and more particularly a creped tissue web,
may be met or exceeded without the excess use of creping chemistry,
more specifically without the excess use of water insoluble creping
compositions such as a non-fibrous olefin polymer. For example, by
creping a tissue web with a creping composition comprising a
non-fibrous olefin polymer and a water soluble adhesive, a tissue
web that is both sufficiently strong to withstand use, such as a
tissue product having a geometric mean tensile (GMT) from about 700
to about 1,500 g/3'' and more preferably from about 800 to about
1,000 g/3'', and soft, such as a tissue having a TS7 value less
than about 10.0, and more preferably less than about 9.5 and still
more preferably less than about 8.5, may be produced. Moreover,
these product properties may be achieved despite applying less than
100 mg/m.sup.2 (milligrams per square meter of dryer surface area),
and in certain embodiments less than about 80 mg/m.sup.2, of water
insoluble creping composition to the Yankee dryer. This discovery
provides the flexibility to produce a tissue product with
satisfactory softness at a given tensile strength while reducing
the add-on of water insoluble creping compositions.
[0007] Hence, in one aspect, the present invention provides a
creped tissue product produced by dispersing a furnish to form a
fiber slurry; forming a wet tissue web; partially dewatering the
wet tissue web; applying a non-fibrous olefin polymer at add on
levels less than about 100 mg/m.sup.2 and a water soluble adhesive
to a creping cylinder; pressing the partially dewatered tissue web
to the creping cylinder; drying the tissue web; creping the dried
tissue web from the creping cylinder to produce a creped tissue
web; calendering the creped tissue web and plying two or more
creped tissue webs together to form a tissue product having a basis
weight greater than about 25 grams per square meter (gsm), GMT
greater than about 700 g/3'' and a TS7 value less than about 10.0
and more preferably less than about 9.5 and still more preferably
less than about 9.0, such as from about 8.0 to about 9.0.
[0008] In other aspects the invention provides a creped tissue
product characterized in that the tissue product comprises at least
one tissue web that has been creped using a creping composition
comprising non-fibrous olefin polymer and a water soluble adhesive
wherein the add on level of the non-fibrous olefin polymer is less
than about 100 mg/m.sup.2, the tissue product having a GMT greater
than about 700 g/3'' and a TS7 value from about 8.0 to about
9.5.
[0009] In still other aspects the invention provides a creped
tissue product characterized in that the tissue product comprises
at least one tissue web that has been creped using a creping
composition comprising non-fibrous olefin polymer and a water
soluble adhesive selected from the group consisting of
polyoxazolines, polyamidoamine-epichlorohydrin resin, polyamine
epichlorohydrin resin, polyvinyl alcohol, polyvinylamine,
polyethylenimine, acrylamide polymers, polymethacrylamide,
poly(acrylic acid), poly(methacrylic acid), poly(hydroxyethyl
methacrylate), poly(n-vinyl pyrrolidinone), poly(ethylene oxide),
saccharides, polysaccharides and modified polysaccharides, wherein
the add on levels of the non-fibrous olefin polymer are from about
50 to about 100 mg/m.sup.2 and the add-on levels of the water
soluble adhesive are from about 1.0 to about 25 mg/m.sup.2, the
tissue product having a GMT greater than about 700 g/3'' and a TS7
value from about 8.0 to about 9.5.
[0010] In yet other aspects the present invention provides a creped
tissue product comprising two or more creped tissue plies, each
tissue ply prepared by adding less than about 100 mg/m.sup.2 of a
creping composition consisting essentially of a non-fibrous olefin
polymer and a water soluble adhesive, the tissue product having a
GMT greater than about 700 g/3'' and a TS7 value from about 8.0 to
about 10.0.
Definitions
[0011] As used herein, the term "adhesive" generally refers to
chemical additive(s) present on the dryer surface to adhere the wet
tissue web to the dryer and control the adhesion level during the
drying process such that energy can be imparted into the dry web
during the creping step, resulting in a high quality creped tissue
sheet.
[0012] As used herein the term "water soluble" generally refers to
the ability of a material, such as a creping component according to
the present disclosure, to be substantially dissolved into a
solution when mixed with water at the concentrations required by
the application of the process described herein. Preferably water
soluble creping compositions of the present invention are soluble
in water to at least one percent. Water solubility is determined
prior to the product being used in the manufacture of the tissue
product.
[0013] As used herein, the term "basis weight" generally refers to
the bone dry weight per unit area of a tissue and is generally
expressed as grams per square meter (gsm). Basis weight is measured
using TAPPI test method T-220.
[0014] As used herein, the term "caliper" is the representative
thickness of a single sheet (caliper of tissue products comprising
two or more plies is the thickness of a single sheet of tissue
product comprising all plies) measured in accordance with TAPPI
test method T402 using a ProGage 500 Thickness Tester
(Thwing-Albert Instrument Company, West Berlin, N.J.). The
micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an
anvil pressure of 132 grams per square inch (per 6.45 square
centimeters) (2.0 kPa).
[0015] As used herein, the term "layer" refers to a plurality of
strata of fibers, chemical treatments, or the like within a
ply.
[0016] As used herein, the terms "layered tissue web,"
"multi-layered tissue web," "multi-layered web," and "multi-layered
paper sheet," generally refer to sheets of paper prepared from two
or more layers of aqueous papermaking furnish which are preferably
comprised of different fiber types. The layers are preferably
formed from the deposition of separate streams of dilute fiber
slurries, upon one or more endless foraminous screens. If the
individual layers are initially formed on separate foraminous
screens, the layers are subsequently combined (while wet) to form a
layered composite web.
[0017] The term "ply" refers to a discrete product element.
Individual plies may be arranged in juxtaposition to each other.
The term may refer to a plurality of web-like components such as in
a multi-ply facial tissue, bath tissue, paper towel, wipe, or
napkin.
[0018] As used herein, the term "slope" refers to slope of the line
resulting from plotting tensile versus stretch and is an output of
the MTS TestWorks.TM. in the course of determining the tensile
strength as described in the Test Methods section herein. Slope is
reported in the units of mass per unit of sample width and is
measured as the slope of the least-squares line fitted to the
load-corrected strain points falling between a specimen-generated
force of 70 to 157 grams (0.687 to 1.540 N) divided by the specimen
width. Slopes are generally reported herein as having units of
grams force (gf) or kilograms force (kgf).
[0019] As used herein, the term "geometric mean slope" (GM Slope)
generally refers to the square root of the product of machine
direction slope and cross-machine direction slope. GM Slope
generally is expressed in units of kilograms (kg).
[0020] As used herein, the term "geometric mean tensile" (GMT)
refers to the square root of the product of the machine direction
tensile strength and the cross-machine direction tensile strength
of the web. While the GMT may vary, tissue products prepared
according to the present disclosure generally have a GMT greater
than about 700 g/3'', such as from about 700 to about 1,500 g/3''
and more preferably from about 750 to about 1,000 g/3''.
[0021] As used herein, the term "Stiffness Index" refers to the
quotient of the geometric mean tensile slope, defined as the square
root of the product of the MD and CD slopes (typically having units
of kgf), divided by the geometric mean tensile strength (typically
having units of gf).
Stiffness Index = MD Tensile Slope ( kgf ) .times. CD Tensile Slope
( kgf ) GMT ( g / 3 '' ) .times. 1 , 000 ##EQU00001##
While the Stiffness Index may vary tissue products prepared
according to the present disclosure generally have a Stiffness
Index less than about 18.0, more preferably less than about 16.0,
still more preferably less than about 14.0 and still more
preferably less than about 12.0.
[0022] As used herein, the term "T57" refers to the output of the
EMTEC Tissue Softness Analyzer (commercially available from Emtec
Electronic GmbH, Leipzig, Germany) as described in the Test Methods
section. TS7 has units of dB V2 rms; however, TS7 may be referred
to herein without reference to units. While the TS7 value may vary,
tissue products prepared according to the present disclosure
generally have a TS7 value less than about 10.0, such as from about
8.0 to about 10.0.
[0023] As used herein, the term "fine crepe structure" refers to
the structure of crepe folds on the surface of a creped tissue web.
Fine crepe structure is measured using the crepe structure test
method described below. Fine crepe structure is reported as the
percent coefficient-of-variation (% COV) at 200-390 .mu.m.
Generally a lower % COV value indicates a finer crepe structure,
which generally translates to a softer, improved tissue web or
product.
[0024] As used herein, a "tissue product" generally refers to
various paper products, such as facial tissue, bath tissue, paper
towels, napkins, and the like. Tissue products may comprise one,
two, three or more plies. The tissue product may be a web of tissue
spirally wound onto a core or may comprise individual folded sheets
that may be stacked together. Normally, the basis weight of a
tissue product of the present invention is less than about 80 grams
per square meter (gsm), in some embodiments less than about 60 gsm,
and in some embodiments from about 10 to about 60 gsm and more
preferably from about 20 to about 50 gsm.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0025] Generally, the present invention provides a creped tissue
web having a softness that meets or exceeds satisfactory levels
without the excess use of water insoluble creping compositions. The
satisfactory level of softness, which may be measured as TS7, is
generally less than about 10.0, and more preferably less than about
9.5, such as from about 8.0 to about 10.0. The satisfactory level
of softness is surprisingly achieved by creping the tissue web with
less than about 100 mg/m.sup.2 (milligrams of creping composition
per square meter of creping cylinder surface area) water insoluble
creping composition, and more preferably about 90 mg/m.sup.2 or
less, such as from about 25 to about 80 mg/m.sup.2, and more
preferably from about 50 to about 75 mg/m.sup.2. It was previously
believed that water insoluble creping compositions, such as a
non-fibrous olefin polymer, need to be added at high add-on levels,
such as 100 mg/m.sup.2 or greater to achieve a desirable softness
at a given tensile strength. It has now been surprisingly
discovered that the add-on of water insoluble creping composition
may be reduced significantly by adding a water soluble adhesive to
the creping composition.
[0026] Accordingly, tissue webs and products prepared according to
the present disclosure are manufactured using a creping composition
comprising a water insoluble component and water soluble component,
and more specifically a non-fibrous olefin polymer and a water
soluble adhesive. There exists a surprising synergistic effect
between the non-fibrous olefin polymer composition and the water
soluble adhesive, which allows the add-on of non-fibrous olefin
polymer to be reduced to less than 100 mg/m.sup.2 without
negatively affecting softness. In fact, creping the web with lower
amounts of non-fibrous olefin polymer in combination with a water
soluble adhesive, maintains or improves softness while improving
other product properties such as absorption rate.
[0027] In certain embodiments the non-fibrous olefin polymer may
comprise an alpha olefin interpolymer of ethylene or propylene and
at least one comonomer, each comonomer being selected from the
group consisting of octene, heptene, hexene, decene, and dodecene.
Suitable olefin polymers are disclosed, for example, in U.S. Pat.
No. 7,883,604, the contents of which are incorporated by reference
herein in a manner consistent with the present disclosure. In
certain preferred embodiments the olefin polymer may comprise the
alpha-olefin interpolymer of ethylene and the comonomer comprises
1-heptene, 1-hexene, 1-octene, 1-decene, or 1-dodecene. The olefin
polymer is generally considered a thermoplastic resin and is not
water soluble. Rather, the olefin polymer is typically formed as a
dispersion when mixed with water. For instance, the olefin polymer
may be present in the aqueous dispersion in an amount from about 10
to about 70 percent by weight, such as from about 20 to about 50
percent by weight. In addition to an olefin polymer, the aqueous
dispersion may also contain a dispersing agent. A dispersing agent
is an agent that aids in the formation and/or the stabilization of
the dispersion. Thus, in certain embodiments the creping
composition may comprise one or more dispersing agents incorporated
into the composition.
[0028] In addition to the non-fibrous olefin polymer the creping
composition comprises a water soluble adhesive. Suitable water
soluble adhesives may be selected from the group consisting of
polyoxazolines, such as poly(2-ethyl-2-oxazoline), polyamidoamines,
including silylated polyamidoamines and highly branched
polyamidoamines and their reaction product with epichlorohydrin,
such as polyamidoamine-epichlorohydrin and
polyamine-epichlorohydrin resins, polyvinyl alcohol,
polyvinylamine, polyethylenimine, acrylamide polymers,
polymethacrylamide, poly(acrylic acid), poly(methacrylic acid),
poly(hydroxyethyl methacrylate), poly(n-vinyl pyrrolidinone),
polyethylene oxide), saccharides, polysaccharides, and modified
polysaccharides, including for example starches, gums, chitosans,
and modified celluloses such as hydroxyethyl cellulose,
hydroxypropyl cellulose and carboxymethyl cellulose. In a still
more preferred embodiment the water soluble adhesive component is
selected from the group consisting of polyvinyl alcohol,
poly(ethylene oxide), hydroxyethyl cellulose, hydroxypropyl
cellulose, starch and carboxymethyl cellulose.
[0029] Additional components of the creping package may include a
creping release agent, such as the release agents disclosed in U.S.
Pat. No. 5,660,687, the contents of which are incorporated herein
in a manner consistent with the present disclosure. Suitable
release agents include, for example, aliphatic polyols or oligomers
thereof having a number average molecular weight of less than 600,
polyalkanolamines, aromatic sulfonamides, pyrrolidone, and mixtures
thereof. Specific examples of release agents include, for example,
ethylene glycol, propylene glycol, diethylene glycol, glycerol,
pyrrolidone, triethanolamine, diethanolamine, polyethylene glycol
and dipropylene glycol.
[0030] In a particularly preferred embodiment the water soluble
adhesive component of the creping package is a polyvinyl alcohol.
Suitable polyvinyl alcohols can be of any water soluble molecular
weight sufficient to form an adhesive film. Generally, an average
molecular weight of from about 13,000 to about 140,000 is
preferred, such as from about 30,000 to about 100,000 and more
preferably from about 40,000 to about 80,000. Suitable polyvinyl
alcohols are commercially available under several trademarks such
as Selvol.TM. (Sekisui Specialty Chemicals LLC, Dallas, Tex.),
Elvanol.RTM. (DuPont Company, Wilmington, Del.) and Royal.RTM.
(Kuraray Americas, Inc., Houston, Tex.). Useful commercially
available polyvinyl alcohols may have a viscosity from about 3 to
about 50 centipoise for a 4 percent aqueous solution at 20.degree.
C. and a degree of hydrolysis from about 85 to about 99 percent.
Those skilled in the art will appreciate that lowering the degree
of hydrolysis and the molecular weight will improve water
solubility but may reduce adhesion.
[0031] The water soluble adhesive is generally added at lower
add-on levels, such as from about 1.0 to about 30 mg/m.sup.2, more
preferably from about 1.0 to about 25 mg/m.sup.2 and still more
preferably from about 1.0 to about 10 mg/m.sup.2, such as from
about 2.0 to about 8.0 mg/m.sup.2. Thus the ratio of non-fibrous
olefin polymer to the water soluble adhesive added to the dryer
surface, on a mass basis, may range from about 100:1 to about 5:1.
Further, the total add-on of creping composition is generally less
than about 150 mg/m.sup.2 and more preferably less than about 125
mg/m.sup.2 and still more preferably less than about 100
mg/m.sup.2.
[0032] Surprisingly, despite adding less than about 100 mg/m.sup.2
of the water insoluble component a tissue product may be produced
having relatively low TS7 at a given strength, while also having
generally low stiffness and favorable absorbent properties. Thus,
in one embodiment the present invention provides a creped tissue
product creped using a creping composition comprising a non-fibrous
olefin polymer and a water soluble adhesive wherein the tissue
product has a GMT greater than about 700 g/3'', a TS7 value less
than about 9.0 and a Stiffness Index less than about 18.0.
[0033] Generally the instant tissue products are less stiff than
tissue products produced solely with a non-fibrous olefin polymer.
As such, the present invention provides a creped tissue web having
a Stiffness index less than about 18.0, more preferably less than
about 16.0, still more preferably less than about 14.0 and still
more preferably less than about 12.0. In one embodiment the
inventive tissue products have a GMT from about 700 to about 900
g/3'' and a Stiffness Index from about 10.0 to about 15.0.
[0034] In other embodiments the tissue products also have well
balanced absorbent properties and a Hercules Size Test (HST) less
than about 3.0 seconds, such as from about 1.5 to about 3.0 seconds
and more preferably from about 1:75 to about 2.5 seconds.
[0035] Further, the foregoing levels of softness and absorbent
properties may generally be achieved without the addition of oils,
waxes, silicones, latexes, fatty alcohols, or lotions comprising
one or more emollients during manufacture of the tissue web or by
post-treatment. For example, in certain embodiments, tissue webs
and products prepared therefrom, may be prepared without
post-treating (i.e., the addition of components by printing,
spraying, coating, or the like after the web has been formed and
dried to greater than about 95 percent consistency) the tissue web
with oils, waxes, silicones, latexes, fatty alcohols, or lotions
comprising one or more emollients.
[0036] Generally the non-fibrous olefin polymer and water soluble
adhesive are applied to the creping cylinder during manufacture of
the tissue web and transferred to at least one surface of the web.
Preferably the creping compositions of the present disclosure are
typically transferred to the web at high levels, such that at least
about 30 percent of the creping composition applied to the surface
of the creping cylinder is transferred to the web, more preferably
at least about 45 percent is transferred and still more preferably
at least about 60 percent is transferred. Generally from about 45
to about 65 percent of the creping composition applied to the
surface of the creping cylinder is transferred to the web. Thus,
the amount of creping additive transferred to the sheet is a
function of the amount of creping additive applied to the dryer
surface.
[0037] At the foregoing levels of add-on and transfer the amount of
creping composition applied to each side of the web can be in the
range of from about 0.1 to about 1.5 percent by weight, based upon
the total weight of the web, such as from about 0.1 to about 1.0
percent by weight. Further, the creping composition is applied to
the paper web so as to cover from about 15 to about 99 percent of
the surface area of the web. More particularly, in most
applications, the creping composition will cover from about 20 to
about 60 percent of the surface area of the web.
[0038] Although such low levels of add-on of non-fibrous olefin
polymer had not been previously believed to be suitable for
producing soft tissue, it has now been discovered that combining
lower levels of non-fibrous olefin polymer with a water soluble
adhesive yields tissue webs having a TS7 value less than about
10.0, such as from about 8.0 to about 10.0 and more preferably from
about 8.5 to about 9.5, at a GMT greater than about 700 g/3''. The
ability to produce a soft tissue at a given tensile strength using
less non-fibrous olefin polymer is surprising as generally reducing
the amount of non-fibrous olefin polymer reduces TS7 values (as
illustrated in Table 1, below). It has now been demonstrated that
by adding a water soluble adhesive the amount of non-fibrous olefin
polymer may be reduced significantly, while actually improving
product properties such as improved softness, reduced stiffness and
better balance of absorbent properties. Not only does the present
invention provide an improved product, reducing non-fibrous olefin
polymer reduces operational costs and improves manufacture.
TABLE-US-00001 TABLE 1 Non-fibrous Water Soluble olefin polymer
Adhesive GMT GM Slope Stiffness Softness (mg/m.sup.2) (mg/m.sup.2)
(g/3'') (kgf) Index TS7 100 0 932 14.00 15.0 9.58 75 10 811 11.07
13.6 8.66 50 10 807 11.29 14.0 8.89
[0039] Thus, it has now been demonstrated that the add-on of the
water insoluble component may be reduced to less than about 100
mg/m.sup.2 without negatively effecting important tissue product
properties. As such, in certain embodiments, tissue products
prepared according to the present invention generally have a TS7
value less than about 10.0 and more preferably less than about 9.5
and still more preferably less than about 9.0, such as from about
8.0 to about 9.5, a GMT from about 700 to about 1,500 g/3'' and
more preferably from about 750 to about 1,000 g/3'', and a HST from
less than about 3.0 seconds.
[0040] In other embodiments tissue webs and products prepared
according to the present invention have a fine crepe structure. In
certain embodiments the present invention provides a tissue web
having a fine crepe structure less than 25% COV, measured at a
wavelength from 200-390 .mu.m, such as from about 15 to about 25%
COV and more preferably from about 15 to about 20% COV. Thus, in
one embodiment the present invention provides a creped tissue web
comprising less than 100 mg creping composition per square meter of
tissue web, the tissue web having a fine crepe structure from about
15 to about 20% COV, measured at a wavelength from 200-390
.mu.m.
[0041] Not only are the instant tissue products soft (measured as
TS7 value) and produced with a fine crepe structure, they may also
have desirable absorption properties. For example, in certain
embodiments the tissue products may have a HST less than about 3.0
seconds, such as from about 1.0 to about 3.0 seconds and more
preferably from about 1.75 to about 2.5 seconds. Accordingly, in
certain embodiments the present invention provides a soft and
strong tissue having favorably balanced absorption properties such
as a tissue product having a GMT from about 700 to 1,500 g/3'', a
TS7 value less than about 10.0 and more preferably less than about
9.5 and still more preferably less than about 9.0, such as from
about 7.5 to about 9.5, and a HST less than about 3.0 seconds, such
as from about 0.5 to about 3.0 seconds and more preferably from
about 1.0 to about 2.5 seconds.
[0042] The tissue products of the present invention are preferably
formed from cellulosic fibers and more preferably from wood fibers
and still more preferably wood pulp fibers such as, but not limited
to, northern softwood, southern softwood, redwood, red cedar,
hemlock, pine (e.g., southern pines), spruce (e.g., black spruce),
combinations thereof, and the like. Additionally, if desired,
secondary fibers obtained from recycled materials may be used, such
as fiber pulp from sources such as, for example, newsprint,
reclaimed paperboard, and office waste.
[0043] Tissue webs useful in forming tissue products of the present
invention can generally be formed by any of a variety of
papermaking processes known in the art. For example, a papermaking
process of the present disclosure can utilize adhesive creping, wet
creping, double creping, embossing, wet-pressing, air pressing,
through-aft drying, creped through-air drying, as well as other
steps in forming the paper web. Examples of papermaking processes
and techniques useful in forming tissue webs according to the
present invention include, for example, those disclosed in U.S.
Pat. Nos. 5,048,589, 5,399,412, 5,129,988 and 5,494,554 all of
which are incorporated herein in a manner consistent with the
present disclosure. In one embodiment the tissue web is formed by
creped through-air drying. When forming mufti-ply tissue products,
the separate plies can be made from the same process or from
different processes as desired.
[0044] In one embodiment the tissue product may be formed from
creped, wet-pressed tissue webs. In the process, a head box
delivers a furnish onto a forming fabric wrapped around a vacuum
breast roll. The furnish may be at a fiber consistency of from
about 0.08 to about 0.6 percent and, more desirably, at a fiber
consistency of from about 0.1 to about 0.5 percent. Immediately
after the vacuum breast roll, the forming fabric passes over the
vacuum box to further vacuum dewater the embryonic web.
[0045] It should be noted that the type of headbox used is not
critical to the practice of the method of the present invention.
Any headbox which delivers a well-formed web may be employed.
Further, although the embodiments discussed herein utilize a vacuum
breast roll, this too is not critical to the practice of the method
of the present invention. The method may be used with crescent
formers, breast roll formers, twin wire formers and fourdriniers,
as well as variations thereof.
[0046] The forming fabric may then pass through a transfer zone
wherein the web is transferred onto a carrier felt. The transfer is
made with the help of a vacuum pickup roll or transfer shoe. The
transfer of the web from forming fabric to the carrier felt should
be made when the web consistency is in the range of from about 18
to about 35 percent and is desirably in the range of from about 22
to about 32 percent.
[0047] The web is then transferred from the carrier felt to a
Yankee dryer using a vacuum press roll. It is contemplated that
other transfer mechanisms such as, for example, a transfer shoe,
may be employed. The consistency of the web when transferred to the
Yankee dryer may from about 35 to about 50 percent or more
desirably, to a dryness ranging from about 40 to about 45
percent.
[0048] At the Yankee dryer, the creping chemicals are continuously
applied by any convenient means, such as using a spray boom that
evenly sprays the surface of the dryer with the creping solution.
Generally, the point of application on the surface of the dryer is
immediately following the creping doctor blade or cleaning doctor
blade, permitting time for the spreading and drying of the creping
solution.
[0049] The creping solution facilitates adhesive of the web to the
Yankee dryer surface as it is transferred from the carrier felt.
Once adhered to the Yankee surface the web is dried and then
removed from the Yankee surface using a creping blade. The creping
blade crepes the tissue from the Yankee surface yielding a
substantially dry, creped, tissue web.
[0050] The substantially dry, creped, tissue web may be subjected
to converting, such as calendering or embossing. In certain
preferred embodiments the tissue webs are converted to tissue
products by calendering alone, without embossing. Further, multiple
tissue webs, such as two, three or four webs may be plied together
to form a multi-ply tissue product. Generally, multi-ply tissue
products of the present invention comprise two, three or four
plies. The exact manufacture of individual plies may vary, but
generally the basis weight of the tissue web will be from about 5
to about 50 gsm, such as from about 10 to about 40 gsm. The basis
weights of the resulting tissue products may range from about 10 to
about 80 gsm and more preferably from about 20 to about 60 gsm.
[0051] At the foregoing basis weights, the tissue webs and products
of the present invention are generally strong enough to withstand
use. As such the tissue products of the present invention generally
have a GMT greater than about 700 g/3'', such as from about 700 to
about 1,500 g/3'' and more preferably from about 750 to about 1,000
g/3''. At these tensile strengths the products generally have a GM
Slope less than about 15.0 kg and more preferably less than about
13.5 kg, such as from about 10.0 to about 15.0 kg. At the foregoing
tensile strengths and modulus the tissue products generally have a
Stiffness index less than about 18.0, more preferably less than
about 16.0, still more preferably less than about 14.0 and still
more preferably less than about 12.0.
Test Methods
Basis Weight
[0052] The basis weight was measured as bone dry basis weight.
Basis weight of the tissue sheet specimens may be determined using
the TAPPI T410 procedure or a modified equivalent such as: Tissue
samples are conditioned at 23.+-.1.degree. C. and 50.+-.2 percent
relative humidity for a minimum of 4 hours. After conditioning, a
stack of 16 3-inch by 3-inch samples are cut using a die press and
associated die. This represents a tissue sheet sample area of 144
in.sup.2 or 929 cm.sup.2. Examples of suitable die presses are TMI
DGD die press manufactured by Testing Machines, Inc., Islandia,
N.Y., or a Swing Beam testing machine manufactured by USM
Corporation, Wilmington, Mass. Die size tolerances are .+-.0.008
inches in both directions. The specimen stack is then weighed to
the nearest 0.001 gram using an analytical balance. The basis
weight in grams per square meter (gsm) is calculated using the
following equation: Basis weight=stack weight in grams/0.0929.
Tensile
[0053] Samples for tensile strength testing are prepared by cutting
a 3 inches (76.2 mm) by 5 inches (127 mm) long strip in either the
machine direction (MD) or cross-machine direction (CD) orientation
using a JDC Precision Sample Cutter (Thwing-Albert Instrument
Company, Philadelphia, Pa., Model No. JDC 3-10, Ser. No. 37333).
The instrument used for measuring tensile strengths is an MTS
Systems Sintech 11S, Serial No. 6233. The data acquisition software
is MTS TestWorks.TM. for Windows Ver. 4 (MTS Systems Corp.,
Research Triangle Park, N.C.). The load cell is selected from
either a 50 Newton or 100 Newton maximum, depending on the strength
of the sample being tested, such that the majority of peak load
values fall between 10 and 90 percent of the load cell's full scale
value. The gauge length between jaws is 4.+-.0.04 inches. The jaws
are operated using pneumatic-action and are rubber coated. The
minimum grip face width is 3 inches (76.2 mm), and the approximate
height of a jaw is 0.5 inches (12.7 mm). The crosshead speed is
10.+-.0.4 inches/min (254.+-.1 mm/min), and the break sensitivity
is set at 65 percent. The sample is placed in the jaws of the
instrument, centered both vertically and horizontally. The test is
then started and ends when the specimen breaks. The peak load is
recorded as either the "MD tensile strength" or the "CD tensile
strength" of the specimen depending on the sample being tested. At
least six (6) representative specimens are tested for each product,
taken "as is," and the arithmetic average of all individual
specimen tests is either the MD or CD tensile strength for the
product.
"Hercules Size Test" (HST)
[0054] The "Hercules Size Test" (HST) is a test that generally
measures how long it takes for a liquid to travel through a tissue
sheet. Hercules size testing was done in general accordance with
TAPPI method T 530 PM-89, Size Test for Paper with Ink Resistance.
Hercules Size Test data was collected on a Model HST tester using
white and green calibration tiles and the black disk provided by
the manufacturer. A 2 percent Napthol Green N dye diluted with
distilled water to 1 percent was used as the dye. All materials are
available from Ashland, Inc., Covington, Ky.
[0055] Six (6) tissue sheets (18 plies for a 3-ply tissue product,
12 plies for a two-ply product, 6 plies for a single ply product,
etc.) form the specimen for testing. All specimens were conditioned
for at least 4 hours at 23.+-.1.degree. C. and 50.+-.2 percent
relative humidity prior to testing. Specimens are cut to an
approximate dimension of 2.5.times.2.5 inches. The specimen (12
plies for a 2-ply tissue product) is placed in the sample holder
with the outer surface of the plies facing outward. The specimen is
then clamped into the specimen holder. The specimen holder is then
positioned in the retaining ring on top of the optical housing.
Using the black disk, the instrument zero is calibrated. The black
disk is removed and 10.+-.0.5 mm of dye solution is dispensed into
the retaining ring and the timer started while placing the black
disk back over the specimen. The test time in seconds (sec.) is
recorded from the instrument.
Tissue Softness
[0056] Tissue softness was analyzed using an EMTEC Tissue Softness
Analyzer ("TSA") (Emtec Electronic GmbH, Leipzig, Germany). The TSA
comprises a rotor with vertical blades which rotate on the test
piece applying a defined contact pressure. Contact between the
vertical blades and the test piece creates vibrations, which are
sensed by a vibration sensor. The sensor then transmits a signal to
a PC for processing and display. The signal is displayed as a
frequency spectrum. The frequency analysis in the range of
approximately 200 to 1000 Hz represents the surface smoothness or
texture of the test piece. A high amplitude peak correlates to a
rougher surface. A further peak in the frequency range between 6
and 7 kHZ represents the softness of the test piece. The peak in
the frequency range between 6 and 7 kHZ is herein referred to as
the TS7 Softness Value and is expressed as dB V2 rms. The lower the
amplitude of the peak occurring between 6 and 7 kHZ, the softer the
test piece.
[0057] Test samples were prepared by cutting a circular sample
having a diameter of 112.8 mm. All samples were allowed to
equilibrate at TAPPI standard temperature and humidity conditions
for at least 24-hours prior to completing the TSA testing. Only one
ply of tissue is tested. Multi-ply samples are separated into
individual plies for testing. The sample is placed in the TSA with
the softer (dryer or Yankee) side of the sample facing upward. The
sample is secured and the TS7 Softness Values measurements are
started via the PC. The PC records, processes and stores all of the
data according to standard TSA protocol. The reported TS7 Softness
Value is the average of 5 replicates, each one with a new
sample.
Fine Crepe Structure
[0058] Wrinkle-free tissues specimens are cut to 2.times.3 inches,
such that the machine direction runs parallel with the longer
dimension. Samples are used as-is, that is one-ply samples are
sampled as a single ply, while two-ply samples are sampled as two
plies. Cut samples are mounted on a 10.times.12-inch glass plate by
adhering with SCOTCH.RTM. tape, or equivalent, at their corners and
along their sides. Each sample is "painted" with a 50:50 mixture of
PENTEL.RTM. Correction Pen fluid and n-butanol, using a top quality
camel's hair brush and applying in one direction parallel to the
machine direction. This preparation will reduce light reflection
and refraction.
[0059] A specimen is illuminated in a darkened room with a
collimated light source produced by a slide projector or similar
device. The projector used was a Kodak Ektagraphic slide projector
(Model B-2) having a lens. The projector was connected to a
Variable Auto-transformer, type 3PN1010, which was purchased from
Staco Energy Products, Co. having an office in Dayton, Ohio. The
auto-transformer is used to adjust the projector's illumination
level. The projector with its attached lens was mounted on a
support. In turn, the support was attached to a base. The
collimated light source was adjusted to hit the top surface of the
tissue specimen at an angle of 20 degrees. The prepared tissue
sample is positioned flat on top of the auto-stage with the crepe
pattern aligned orthogonal with respect to the light source,
resulting in shadows cast by any crepe folds. The reflected light
is viewed and an image acquired by a Leica Microsystems DFC-310
camera operated in monochrome mode having a 40-mm El-Nikkor lens
(f-stop=4) with a 20-mm extension tube to generate a
1024.times.1024 pixel gray-scale image.
[0060] The DFC-310 video camera was mounted on a Polaroid MP-4 Land
Camera (Polaroid Resource Center, Cambridge, Miss.) standard
support. The support was attached to a KREONITE macro-viewer
available from Kreonite, Inc., having an office in Wichita, Kans.
An auto-stage, Prior Model H112/25T, was placed on the upper
surface of the KREONITE macro-viewer. The auto-stage 146 is a
motorized apparatus known to those skilled in the analytical arts
which was purchased from Prior Scientific, Inc., having an office
in Rockland, Mass. The auto stage was used to move the sample in
order to obtain six separate and distinct, non-overlapping images
from the approximately 3.times.2-inch size specimen. The glass
plates with painted tissue are placed on the auto macro-stage of a
Leica Microsystems QWIN Pro Image Analysis system, under the
optical axis of a 40 mm El-Nikkor lens with a 20-mm extension tube.
The sample is illuminated with a slide projector to form
shadows.
[0061] The distance between the upper surface of the sample and the
bottom of the lens was set to be approximately 7 cm. The vertical
distance between the lens attached to the slide projector and the
upper surface of the sample was set at 23 cm. The sample was
illuminated by the slide projector. The horizontal distance between
a vertical line extending to the center of the video camera lens
and a vertical line extending to the center of the slide projector
lens was set at 65 cm. These dimensions, combined with the video
camera set-up, resulted in a field-of-view size of the sample
surface to be approximately 8.8 by 8.8 mm.
[0062] The image analysis system used to acquire images was a QWIN
Pro (v. 3.5.1) available from Leica Microsystems (Heerbrugg,
Switzerland). A custom image acquisition program used to acquire
and process gray-scale monochrome images using Quantimet User
Interactive Programming System
[0063] (Quips) Language:
[0064] CONDITIONS: DFC 310 FX; 40 mm El-Nikkor lens (f/4) and 20 mm
ext. tube; Projected, collimated light@20 deg. angle; 50/50
PENTEL/n-Butanol coating on samples; mounted on 1/4'' glass
plate.
TABLE-US-00002 INITIALIZE VARIABLES CALVALUE = 8.57 IMAGE = 0
ACQOUTPUT = 1 SET-UP AND CALIBRATION Configure (Image Store 1024
.times. 1024, Grey Images 45, Binaries 24) Clear Accepts Image
frame ( x 0, y 0, Width 1024, Height 1024 ) Measure frame ( x 30, y
150, Width 934, Height 700 ) PauseText ("Enter image file prefix
name.") Input (TITLE$) PauseText ("Position Sample and use Polaroid
803 reference to adjust white level to 0.5.") Image Setup DC Twain
[PAUSE] (Camera 1, AutoExposure Off, Gain 0.00, ExposureTime 78.43
msec, Brightness 0, Lamp 49.99) Calibrate (CALVALUE CALUNITS$ per
pixel) For (SAMPLE = 1 to 3, step 1) ROUTINE TO STABILIZE LIGHT
LEVEL Y = 0 Z = 0 SP = 0 SIB = 0 P = 0 MGREYIMAGE = 0 MGREYMASK = 0
FIELDS = 1000 TWICE = 0 Correlation GL Value for top 1% px Method,
and DFC 310 FX = 187 For (LIGHT = 1 to 30, step 1) Image Setup DC
Twain [PAUSE] (Camera 1, AutoExposure Off, Gain 0.00, ExposureTime
78.43 msec, Brightness 0, Lamp 49.99) Acquire (into Image0)
Graphics (Inverted Grid, 1 .times. 1 Lines, Grid Size 930 .times.
693, Origin 30 .times. 151, Thickness 5, Orientation 0.000000, to
Binary0) Image frame ( x 0, y 0, Width 1024, Height 1024 ) Measure
frame ( x 30, y 150, Width 934, Height 700 ) Measure Grey ( plane
MGREYIMAGE, mask MGREYMASK, histogram into GREYHIST(256), stats
into GREYSTATS(3) ) Selected parameters: Pixels, MeanGrey, Std Dev
A = GREYSTATS(2) B = GREYSTATS(3) D = A+B For ( X = 129 to 256,
step 1 ) Y = Y+(X*GREYHIST(X)) Z = Z+GREYHIST(X) Next ( X ) R = Y/Z
TP = GREYSTATS(1) ONEPCTPX = .01 * TP For ( X = 256 to 1, step -1 )
If ( ONEPCTPX > SP ) P = GREYHIST(X) SP = SP + P SIB = SIB + (X
* P) If ( ONEPCTPX < SP ) X = 1 Endif Endif Next ( X ) AVEGL =
SIB / SP E = AVEGL Display ( E, field width: 8, left justified, 1
digit after `.`, no tab follows ) If ( E<194 ) If ( E>190 )
TWICE = TWICE+1 If ( TWICE=2 ) Goto CONTINUE Endif Endif Endif Y =
0 Z = 0 SP = 0 SIB = 0 Display ( Image0 (on), frames (on,on),
planes (off,off,off,off,off,off), lut 0, x 0, y 49, z 1, Reduction
off ) Next ( LIGHT ) END LIGHT STABILIZER ROUTINE CONTINUE: STAGE
SCAN PARAMETERS Stage ( Define Origin ) Stage ( Scan Pattern, 1
.times. 6 fields, size 13400.150391 .times. 6100.000000 ) IMAGE
ACQUISITION AND DETECTION For ( FIELD = 1 to 6, step 1 ) IMAGE =
IMAGE+1 Image Setup DC Twain ( Camera 1, AutoExposure Off, Gain
0.00, ExposureTime Acquire ( into Image0 ) Grey Transform ( WSmooth
from Image0 to Image1, cycles 2, operator Horiz ) The following
line is the computer location where the acquired images are saved
ACQFILE$ = "C:\Images\65104 - Busch\"+TITLE$+"_"+STR$(IMAGE)+".TIF"
Write image ( from ACQOUTPUT into file ACQFILE$ ) Image frame ( x
0, y 0, Width 1024, Height 1024 ) Stage ( Step, Wait until stopped
+ 550 msecs ) Next ( FIELD ) PauseText ( "Position Plate to Analyze
Next Tissue and click `Continue.`" ) Image Setup DC Twain [PAUSE] (
Camera 1, AutoExposure Off, Gain 0.00, ExposureTime 78.43 msec,
Brightness 0, Lamp 49.99 ) Next ( SAMPLE ) END
[0065] Prior to acquiring the first sample images, shading
correction was performed using the QWIN software and a white 803
Polaroid film positive (or equivalent white material) covered with
an opaque, translucent film. Alternatively, other non-glossy white
films or sheets could be used. The system and images were also
accurately calibrated using the QWIN software and a standard ruler
with metric markings. The calibration was performed in the
horizontal dimension of the video camera image.
[0066] After calibrating, a custom image acquisition program was
executed via the QWIN software and this initially prompts the
analyst to place the sample specimen within the field-of-view of
the video camera. After positioning the specimen so the machine
direction is parallel to the light source and the specimen is
properly aligned for auto-stage motion, the analyst will then be
prompted to adjust the light level setting (via the variable
auto-transformer) to register between Gray-Level readings of
190-194. During this process of light adjustment, the algorithm OSC
Tissue--1 will automatically display the current Gray-Level value
on the video screen. After the light has been properly adjusted,
the custom image acquisition acquires six images for a single
tissue specimen.
[0067] Using the set-up described above, an image representing an
8.8 mm.times.8.8 mm field of view was generated and saved as a
*.tif image file. Typically, 3 tissue specimens were selected per
sample code and 6 images generated per tissue specimen resulting in
18 images generated per sample or code.
[0068] A custom Matlab software algorithm is used for this
analysis. The algorithm is shown below.
TABLE-US-00003 % OSC Matlab FFT Filter_1 % Condtions: Uses
gray-scale images generated from % DGB, 11/6/2013 % EXCEL Output
header hdr={`Image`,`50-100um`,`100-200um`,`200-390um`,
`390-790um`,`790-1580um`}; data(1,:)=[hdr]; % get the images
[fn,pn]=uigetfile(`C:\Matlab\Images\Zhe - OSC Matlab
Method\*.*`,`Pick your images`,`MultiSelect`,`on`); for
j=1:length(fn), %% Read in image fnimg=([pn fn{j}]);
a=imread(fnimg); figure(1);clf;imshow(a);title(`Original Image`);
%% Create distance map for filtering
sz=size(a);bw=zeros(sz);half=floor(sz/2)+1;bw(half(1),half(2))=1;
D=bwdist(bw); figure(1);clf;imagesc(D);axis equal
off;colorbar;title(`Distance Map`); %% Fourier Transform % fourier
fa=fftshift(fft2(a)); % shift to put DC component at center
pa=fa.*conj(fa); % power spectum % hard to see anything in raw
power, so log transform it figure(1);clf;imagesc(log(1+pa));axis
equal off; %% Sweep Frequency Range freqRng=[87 172; 46 87; 23 46;
12 23; 7 12]; clear mn sd covar; for i=1:size(freqRng,1), % filter
% -- note: unless you have DC signal back in, all the % values are
centered around zero. This is done by % keeping the very center of
the image (bw). fa1=fa.*(D>=freqRng(i,1) & D<freqRng(i,2)
| bw); % convert back to real space ra1=ifft2(ifftshift(fa1)); % in
this example the values were real, but | suspect in % general there
will be a small complex component ra1=real(ra1);
mn(i)=mean(ra1(:)); sd(i)=std(ra1(:)); covar(i)=sd/mn;
figure(1);clf;set(gcf,`color`,`w`);
subplot(1,3,1:2),imagesc(ra1);axis equal off;
subplot(1,3,3),hist(ra1(:)); xlabel(`Value`);ylabel(`Frequency
[#]`); ttl=sprintf(`Mean: %.2f, Stdv: %.2f, COV:
%.2f`,mn,sd,covar); title(ttl); snapnow; end; %% Output
data(j+1,:)=[{fnimg} num2cell([covar(:)`*100])]; %data=[{fnimg}
num2cell([covar(:)`*100])]; end;
xlswrite(`C:\Matlab\data\fft_output.xls`,data);
[0069] Images were analyzed by running the algorithm in Matlab
algorithm. The analyst is initially prompted to select the images
located in the designated directory folder on the computer. After
images are selected, the algorithm then processes each image and
places the resulting data into an EXCEL spreadsheet located in a
designated directory folder on the computer. The 200-390 .mu.m
range data set has been used to compare and contrast the surface of
the crepe structure of different tissues.
Examples
[0070] Samples were made using a conventional wet pressed
tissue-making process on a pilot scale tissue machine. Initially,
northern softwood kraft (NSWK) pulp was dispersed in a pulper for
30 minutes at about 4 percent consistency at about 100.degree. F.
The NSWK pulp was then transferred to a dump chest and subsequently
diluted with water to approximately 2 percent consistency. Softwood
fibers were then pumped to a machine chest. Generally the softwood
fibers were added to the middle layer in the 3-layer tissue
structure. The NSWK content contributed approximately 25 to 35
percent of the final sheet weight. The specific layer splits (dryer
layer/middle layer/felt layer) are as set forth in the table
below.
[0071] Eucalyptus hardwood kraft (EHWK) pulp was dispersed in a
pulper for 30 minutes at about 4 percent consistency at about
100.degree. F. The EHWK pulp was then transferred to a dump chest
and diluted to about 2 percent consistency. Generally the EHWK
fibers were added to the dryer and felt layers of the 3-layer sheet
structure and contributed approximately 65 to 75 percent of the
final sheet weight. The specific layer splits (dryer layer/middle
layer/felt layer) are as set forth in the table below.
[0072] Wet strength resin (Kymene.TM. 920A, Solenis LLC,
Wilmington, Del.) was added to the NSWK and EHWK pulp as it was
metered from the machine chest to the tissue machine. The amount of
wet strength added to the furnish was 2 kg/MT and was incorporated
into each layer of the three layered tissue sheet.
[0073] The pulp fibers from the machine chests were pumped to the
headbox at a consistency of about 0.1 percent. Pulp fibers from
each machine chest were sent through separate manifolds in the
headbox to create a 3-layered tissue structure. The fibers were
deposited onto a felt using a Crescent Former. The wet sheet, about
10 to about 20 percent consistency, was further dewatered via a
pressure roll nip to a post-pressure roll consistency (PPRC) of
about 40 percent. The partially dewatered sheet was adhered to the
Yankee dryer due to the additive composition that is applied to the
dryer surface. A spray boom situated underneath the Yankee dryer
sprayed the creping composition, described in the present
disclosure, onto the dryer surface at addition levels set forth in
the table below.
[0074] The water insoluble creping composition comprised a
non-fibrous olefin dispersion, sold under the trade name HYPOD 8510
(Dow Chemical Co., Midland, Mich.). The HYPOD 8510 was prepared at
10 percent solids and delivered at a total addition level as set
forth in Table 2.
[0075] Water soluble creping components were prepared by
dissolution of the solid polymers into water followed by stirring
until the solution was homogeneous. Solutions of water soluble
creping components were diluted depending on the desired spray
coverage on the Yankee dryer.
[0076] Rezosol.TM. 8207N (Solenis LLC, Wilmington, Del.) was
prepared by diluting with deionized water to 3 percent solids.
Selvol.RTM. 523 or 15-103 (Sekisui Specialty Chemicals America,
LLC, Dallas, Tex.) was prepared by slowly adding 55 lbs of
Selvol.RTM. to an agitated tank containing 75 gallons of cold
deionized water. An additional 25 gallons of cold deionized water
were added. The agitated tank was then heated to 85-90.degree. C.
to dissolve the polymer. The solution was cooled (approximately 6
percent solids) and subsequently diluted with deionized water to
about 0.5 percent solids before use. A carboxymethylcellulose
solution was prepared by slowly adding 0.9 kg Aqualon.TM. Sodium
Carboxymethylcellulose (Ashland, Inc., Covington, Ky.) to an
agitated tank containing 48 gallons of deionized water. The tank
was agitated for about one hour to dissolve the polymer; solution
solids was about 0.5 percent solids.
[0077] The water insoluble and water soluble creping compositions
were metered and further diluted with water to a final
concentration depending on the desired add-on levels. The water
soluble and water insoluble creping components were blended
together immediately prior to spraying onto the Yankee dryer
surface.
TABLE-US-00004 TABLE 2 Layer Split Dryer/Middle/Felt HYPOD .TM.
8510 Rezosol .TM. 8207N Selvol .RTM. 523 Selvol .RTM. 15-103
Aqualon .TM. CMC Sample (wt %) (mg/m.sup.2) (mg/m.sup.2)
(mg/m.sup.2) (mg/m.sup.2) (mg/m.sup.2) Control 1 44/28/28 100 -- --
-- Inventive 1 44/32/24 75 10 -- -- Inventive 2 44/32/24 50 10 --
-- Inventive 3 44/32/24 100 10 -- -- Inventive 4 44/32/24 75 2.5 --
-- Inventive 5 44/32/24 75 1.0 Inventive 6 44/28/28 50 -- 10
Inventive 7 44/28/28 75 -- 10 Inventive 8 44/28/28 75 -- -- 2.5 --
Inventive 9 44/28/28 75 -- -- 10 Inventive 10 44/28/28 75 -- --
2.5
[0078] The sheet was dried to about 98 to 99 percent consistency as
it traveled on the Yankee dryer and to the creping blade. The
Yankee dryer was heated with 105 psi of steam pressure and the
Yankee hood was set to a supply temperature of 650 to 750.degree.
F. to dry the sheet to a target sheet temperature of 250 to
260.degree. F. before the creping blade. The creping blade, a
75-Proto-HY03 Durablade.RTM. (BTG, Eclepens, Switzerland) with a 15
degree grind angle, was loaded at a pressure of 60 psi. The crepe
ratio was 1.27. The creping blade subsequently scraped the tissue
sheet off of the Yankee dryer. The creped tissue basesheet was then
wound onto a core into soft rolls for converting.
[0079] To produce the 2-ply facial tissue products two soft rolls
of the creped tissue were then rewound, calendered between two
steel rolls to a 2-ply caliper of approximately 230 microns, and
plied together so that both creped sides were on the outside of the
2-ply structure. Mechanical crimping on the edges of the structure
held the plies together. The plied sheet was then slit on the edges
to a standard width of approximately 8.5 inches and folded, and cut
to facial tissue length. Tissue samples were conditioned and
tested. The results of the testing are summarized in Table 3,
below.
TABLE-US-00005 TABLE 3 Basis Weight Sheet Bulk GMT GM Slope
Stiffness HST Fine Crepe Structure Sample (gsm) (cc/g) (g/3'')
(kgf) Index (sec) (% COV at 200-390 .mu.m) TS7 Control 1 31.5 6.6
932 14.00 15.0 2 18.57 9.58 Inventive 1 31.2 7.3 811 11.07 13.6 1.8
18.79 8.66 Inventive 2 30.7 6.7 807 11.29 14.0 1.6 17.95 8.89
Inventive 3 31.8 6.7 876 12.63 14.4 1.7 17.76 9.33 Inventive 4 29.8
7.0 861 14.22 16.5 2.7 16.46 9.20 Inventive 5 29.8 6.7 863 14.58
16.9 2.0 17.18 9.19 Inventive 6 31.2 7.1 941 14.20 15.1 2 18.18
9.25 Inventive 7 31.4 7.4 878 13.09 14.9 2.1 18.2 8.91 Inventive 8
31.1 8.0 822 11.81 14.4 2.3 20.00 8.83 Inventive 9 30.8 7.1 810
12.81 15.8 2.1 16.43 9.10 Inventive 10 31.0 7.2 811 12.17 15.0 2.6
16.84 8.57
[0080] In view of the foregoing description and examples, the
present invention provides, in a first embodiment, a tissue product
comprising at least one creped tissue web having a first side and
an opposite second side, a creping composition disposed on the
first side, the creping composition comprising a non-fibrous olefin
polymer and a water soluble adhesive polymer, the tissue product
having a GMT from about 700 to about 1,500 g/3'' and a TS7 value
less than about 10.0.
[0081] In a second embodiment the invention provides the tissue
product of the first embodiment characterized in that at least one
creped tissue web has been creped using a creping composition
comprising non-fibrous olefin polymer and a water soluble adhesive
wherein the add on level of the non-fibrous olefin polymer is less
than about 100 mg/m.sup.2.
[0082] In a third embodiment the invention provides the tissue
product of the first or second embodiments characterized in that at
least one creped tissue web has been creped using a creping
composition comprising non-fibrous olefin polymer and a water
soluble adhesive wherein the total add-on of creping composition is
less than about 100 mg/m.sup.2.
[0083] In a fourth embodiment the invention provides the tissue of
any one of the first through third embodiments wherein the tissue
product comprises two creped wet pressed tissue webs plied
together.
[0084] In a fifth embodiment the invention provides the tissue
product of any one of the first through fourth embodiments wherein
the non-fibrous olefin polymer comprises an alpha olefin
interpolymer of ethylene or propylene and at least one comonomer,
each comonomer being selected from the group consisting of octene,
heptene, hexene, decene, and dodecene and the water soluble
adhesive polymer is selected from the group consisting of a water
soluble adhesive selected from the group consisting of
polyoxazolines, polyamidoamine-epichlorohydrin resin, polyamine
epichlorohydrin resin, polyvinyl alcohol, polyvinylamine,
polyethylenimine, acrylamide polymers, polymethacrylamide,
poly(acrylic acid), poly(methacrylic acid), poly(hydroxyethyl
methacrylate), poly(n-vinyl pyrrolidinone), polyethylene oxide),
saccharides, polysaccharides and modified polysaccharides.
[0085] In a sixth embodiment the invention provides the tissue
product of any one of the first through fifth embodiments wherein
the ratio of the non-fibrous olefin polymer to the water soluble
adhesive polymer is from about 75:1 to about 5:1.
[0086] In a seventh embodiment the invention provides the tissue
product of any one of the first through sixth embodiments wherein
the product has a Stiffness Index less than about 18.0, more
preferably less than about 16.0, still more preferably less than
about 14.0 and still more preferably less than about 12.0.
[0087] In an eight embodiment the invention provides the tissue
product of any one of the first through seventh embodiments wherein
the product has a HST less than about 3.0.
[0088] In a ninth embodiment the invention provides the tissue
product of any one of the first through eighth embodiments wherein
the product has a fine crepe structure from about 15.0 to about
20.0% COV at 200-390 .mu.m.
[0089] In a tenth embodiment the invention provides a creped tissue
product characterized in that the tissue product comprises at least
one tissue web that has been creped using a creping composition
comprising non-fibrous olefin polymer and a water soluble adhesive
wherein the add-on level of the non-fibrous olefin polymer is less
than about 100 mg/m.sup.2, the tissue product having a GMT greater
than about 700 g/3'' and a TS7 value from about 8.0 to about
10.0.
[0090] In an eleventh embodiment the invention provides the creped
tissue product of the tenth embodiment wherein the add-on level of
the non-fibrous olefin polymer is from about 50 to about 90
mg/m.sup.2 and the ratio of the non-fibrous olefin polymer to the
water soluble adhesive polymer is from about 10:1 to about 5:1.
[0091] In a twelfth embodiment the invention provides the tissue
product of the tenth or eleventh embodiments wherein the product
has a HST less than about 3.
[0092] In a thirteenth embodiment the invention provides a tissue
product manufacturing process comprising the steps of dispersing a
furnish to form a fiber slurry; forming a wet tissue web; partially
dewatering the wet tissue web; applying a non-fibrous olefin
polymer at add on levels less than about 100 mg/m.sup.2 and a water
soluble adhesive to a creping cylinder; pressing the partially
dewatered tissue web to the creping cylinder; drying the tissue
web; creping the dried tissue web from the creping cylinder to
produce a creped tissue web; and plying two or more creped tissue
webs together to form a tissue product having a Basis Weight
greater than about 25.0 gsm, a GMT from about 700 to about 1,500
g/3'' and a TS7 value less than about 10.0.
[0093] In a fourteenth embodiment the invention provides the creped
tissue product of the thirteenth embodiment wherein the add-on
level of the non-fibrous olefin polymer is from about 50 to about
90 mg/m.sup.2 and the ratio of the non-fibrous olefin polymer to
the water soluble adhesive polymer is from about 10:1 to about
5:1.
* * * * *