U.S. patent application number 12/557969 was filed with the patent office on 2010-06-24 for water-soluble creping materials.
Invention is credited to Frank G. Druecke, Jian Qin, Christopher L. Satori, Dave A. Soerens, Cathleen M. Uttecht, James H. Wang, John A. Werner.
Application Number | 20100155004 12/557969 |
Document ID | / |
Family ID | 42264357 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100155004 |
Kind Code |
A1 |
Soerens; Dave A. ; et
al. |
June 24, 2010 |
Water-Soluble Creping Materials
Abstract
Fibrous articles are disclosed containing an additive
composition. The additive composition, for instance, may include a
water-soluble film forming component and water-soluble modifying
components that is deposited at least at the surface of a fibrous
web. In some aspects, the additive composition includes polymers
that demonstrate a certain LCST and melting temperature. In another
aspect, the additive composition is applied to the fibrous web
during the heated drying phase, such as with a Yankee dryer. The
fibrous web with additive composition is then creped. The additive
composition may improve the perceived softness of the web without
substantially affecting the absorbency of the web in an adverse
manner.
Inventors: |
Soerens; Dave A.; (Neenah,
WI) ; Qin; Jian; (Appleton, WI) ; Werner; John
A.; (Hortonville, WI) ; Druecke; Frank G.;
(Oshkosh, WI) ; Uttecht; Cathleen M.; (Menasha,
WI) ; Satori; Christopher L.; (Hortonville, WI)
; Wang; James H.; (Appleton, WI) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.;Tara Pohlkotte
2300 Winchester Rd.
NEENAH
WI
54956
US
|
Family ID: |
42264357 |
Appl. No.: |
12/557969 |
Filed: |
September 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12317137 |
Dec 19, 2008 |
|
|
|
12557969 |
|
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Current U.S.
Class: |
162/111 |
Current CPC
Class: |
D21H 17/36 20130101;
D21H 17/28 20130101; D21H 17/25 20130101; D21H 19/74 20130101; D21H
19/22 20130101; D21H 25/005 20130101; D21H 17/35 20130101; D21H
19/20 20130101 |
Class at
Publication: |
162/111 |
International
Class: |
D21H 19/74 20060101
D21H019/74 |
Claims
1. A fibrous article comprising: a creped fibrous web having a
first side and an opposite second side, wherein the fibrous web
comprises pulp fibers; an additive composition disposed on the pulp
fibers, the additive composition comprising a first polymer and a
second polymer, wherein the first and second polymers are each
water-soluble and non-crosslinked; and wherein the first polymer
has a LCST of equal to or greater than 40.degree. C., and the
second polymer has a melting point of equal to or less than
90.degree. C.
2. The fibrous article of claim 1 further comprising a third
polymer having a LCST of equal to or greater than 40.degree. C.
and/or a melting point of equal to or less than 90.degree. C.
3. The fibrous article of claim 1 wherein the first polymer is
selected from poly(2-ethyloxazoline), vinyl caprolactone-vinyl
pyrrolidone copolymers, polyethylene glycol methacrylates, and/or
hydroxyalkylated carbohydrate polymers comprising hydroxypropyl
cellulose, hydroxyethyl cellulose, methyl cellulose, and/or
hydroxypropyl starch.
4. The fibrous article of claim 1 comprising a lubricious hand feel
of greater than a 53% reduction with respect to untreated collagen
as determined by a Lubricious Hand Feel test described herein.
5. The fibrous article of claim 1 comprising a fuzz on edge value
of greater than 1.2 as determined by a Fuzz On Edge test described
herein.
6. The fibrous article of claim 1 comprising a water extractable
value of greater than 0.35% as determined by a Water Extractable
test described herein.
7. The fibrous article of claim 1 comprising a fine crepe structure
of less than or equal to 25% as determined by a Fine Crepe
Structure test described herein.
8. The fibrous article of claim 1 wherein the first and second
polymers are non-ionic.
9. The fibrous article of claim 1 wherein the wet out time is less
than 14.8 seconds as determined by an Absorbent Rate test described
herein.
10. The fibrous article of claim 1 wherein the fibrous web contains
pulp fibers in an amount of at least 30% by weight.
11. (canceled)
12. (canceled)
13. The fibrous article of claim 1 wherein the second polymer is
selected from polyethylene glycol polymers and/or polyalkylene
oxides.
14. The fibrous article of claim 13 wherein the polyalkylene oxides
are selected from polyethylene glycols with crystalline melting
points of 30.degree. C. or greater; polyethylene oxide; and/or
polyethylene oxide-polypropylene oxide block copolymers.
15. The fibrous article of claim 1 wherein an outer ply of the
fibrous article has a water extractable value of greater than 0.051
g/m.sup.2 as determined by the product of each outer ply's Water
Extractable test described herein and its corresponding conditioned
basis weight.
16. The fibrous article of claim 1 wherein an outer ply of the
fibrous article has a water extractable value of greater than 0.044
g/m.sup.2 as determined by the product of each outer ply's Water
Extractable test described herein and its corresponding conditioned
basis weight, and a wet-out time of less than 14.8 seconds.
17. A method of applying an additive composition to a fibrous
material comprising the steps of: (a) preparing the additive
composition comprising a first polymer and a second polymer,
wherein the first and second polymers are each water-soluble and
non-crosslinked; and wherein the first polymer has a LCST of equal
to or greater than 40.degree. C., and the second polymer has a
melting point of equal to or less than 90.degree. C.; (b) mixing
the first polymer and the second polymer into an aqueous solution
to have a solute concentration of equal to or less than 30%; (c)
applying the aqueous solution to a heated dryer surface; (d)
applying the fibrous material to the solute; and (e) removing the
fibrous material attached to the solute from the heated dryer
surface.
18. The method of claim 17 further comprising the step supplying
the fibrous material having pulp fibers at least 30% by weight.
19. The method of claim 17 wherein the additive composition is
applied to the heated dryer surface at 50 to 1000 mg/square
meter.
20. A fibrous article comprising: a creped fibrous web comprising
pulp fibers; an additive composition disposed on the pulp fibers,
wherein the additive composition comprises two components; and
wherein the fibrous article has a fuzz on edge value greater than
1.2 as determined by a Fuzz on Edge test described herein.
21. The fibrous article of claim 20 wherein the components of the
additive composition comprise a first polymer and a second polymer,
wherein the first polymer and the second polymer are each water
soluble and non-crosslinked.
22. The fibrous article of claim 1 further comprising a third
polymer.
Description
[0001] This application is a continuation-in-part of application
Ser. No. 12/317,137 filed on Dec. 19, 2008.
BACKGROUND
[0002] Absorbent fibrous articles such as paper towels, facial
tissues, bath tissues and other similar products, for example, are
designed to include several characteristics. One such
characteristic is a soft feel. Softness is typically increased by
decreasing or reducing cellulosic fiber bonding within the fibrous
product. Inhibiting or reducing fiber bonding, however, can
adversely affect properties, such as the strength of the fibrous
web.
[0003] In other instances, softness can be enhanced by the topical
addition of a softening agent to the outer surfaces of the fibrous
web. The softening agent may comprise, for instance, a silicone
chemistry. The silicone chemistry may be applied to the web by
printing, coating or spraying. Although silicone chemistries make
the fibrous webs feel softer, silicone chemistries can be
relatively expensive, reduce absorbent rate and capacity, and may
lower sheet durability as measured by other strength
properties.
[0004] Recent technology has enabled a significant improvement in
the tactile perception of tissue products as a result of the unique
surface modification brought about by creping with a water
insoluble surface modifying material. The surface modification
consists of the deposition of a thin but discontinuous film onto
the surface of the pulp fiber matrix. This film deposition results
from a unique mode of cohesive failure at a creping blade such that
a portion of the creping composition remains bonded to the tissue
surface.
[0005] While the recent surface modifying technology has generated
a significant improvement in tissue tactile properties (e.g. it is
softer than conventionally-creped tissues), the water insoluble
nature of these materials introduces changes in tissue machine
operations which can reduce manufacturing efficiency. Specifically,
the surface modification material dispersion is not stable in mill
water resulting in deposition of the material on parts of the
tissue machine which require removal and disposal. This material
further has to be removed out of the mill waste water system due to
its insolubility and instability in hard water.
[0006] Previous research efforts on developing water soluble
alternatives indicated that while they did not have the same
technical challenges in terms of ease of processing, they also
seemed not effective in terms of improving soft hand feel.
Therefore, there is a need to develop alternative chemistries to
replace the current water-insoluble chemistry. Desirably, the new
chemistry would be affordable, absorbent, and water soluble, while
exhibiting a good hand feel as determined by one or more tests,
e.g. an In-Hand Ranking Test ("IHR," see below), absorbent rate and
capacity, etc.
SUMMARY
[0007] In one aspect is a fibrous article composed of a creped
fibrous web having a first side and an opposite second side. The
fibrous web includes pulp fibers with an additive composition
disposed on the pulp fibers. The additive composition includes a
first polymer and a second polymer, wherein the first and second
polymers are each water-soluble and non-crosslinked. The first
polymer has a LCST of >40 C, and the second polymer has a
melting point of <90 C.
[0008] In a second aspect is a fibrous article composed of a creped
fibrous web having a first side and an opposite second side. The
fibrous web includes pulp fibers with an additive composition
disposed on the pulp fibers. The additive composition includes a
first polymer and a second polymer, wherein the first and second
polymers are each water-soluble and non-crosslinked. The fibrous
article has a water soluble extractable of at least 0.35% as
determined by the Water Extractable test described herein.
[0009] In another aspect is a fibrous article composed of a creped
fibrous web having a first side and an opposite second side,
wherein the fibrous web includes pulp fibers. An additive
composition is disposed on the pulp fibers. The additive
composition includes a first polymer and a second polymer, wherein
the first and second polymers are each water-soluble and
non-crosslinked. The fibrous article has a fuzz on edge greater
than 1.25 as determined by the Fuzz on Edge test described
herein.
[0010] In a further aspect is a method of applying an additive
composition for a fibrous material including the following steps
(not necessarily in order):
(a) preparing the additive composition including a first polymer
and a second polymer, wherein the first and second polymers are
each water-soluble and non-crosslinkable, and wherein the first
polymer has a LCST of <40 C, and the second polymer has a
melting point of >90 C; (b) mixing the first polymer and the
second polymer in a water solution to create a solute having a
concentration of >30%; (c) applying the solute to a heated dryer
surface; (d) allowing the solute to phase separate; (e) applying
the fibrous material to the phase separated solute; and (f)
removing the fibrous material from the heated dryer surface.
FIGURES
[0011] The foregoing and other features, aspects and advantages of
the present invention will become better understood with regard to
the following description, appended claims and accompanying
drawings where:
[0012] FIG. 1 is a schematic diagram of one aspect of a Yankee
dryer used to dry the fibrous web of the present invention;
[0013] FIG. 2 is a is a schematic diagram of one aspect of a
process for forming wet creped fibrous webs for use in the present
disclosure;
[0014] FIG. 3 is a schematic diagram of one portion of a fibrous
web forming machine, illustrating one aspect of the formation of a
stratified fibrous web having multiple layers;
[0015] FIG. 4 is a schematic diagram of a fibrous web forming
machine having a throughdryer, illustrating the formation of a
fibrous web;
[0016] FIG. 5 is a micrograph of a facial tissue with an additive
composition of the present invention;
[0017] FIG. 6 is a plan view of one aspect of a pattern that may be
used to apply additive compositions to fibrous webs in accordance
with the present disclosure;
[0018] FIG. 7 is a plan view of another aspect a pattern that may
be used to apply additive compositions to fibrous webs in
accordance with the present disclosure;
[0019] FIG. 8 is a photograph of an LCST material of the present
invention, demonstrating how the composition precipitates when a
critical temperature is reached;
[0020] FIG. 9 is a setup used in the method for image
generation;
[0021] FIG. 10 shows the analysis areas that are used as part of
the method for image generation as it relates to FIG. 9;
[0022] FIG. 11 is a depiction of fuzz on edge of one sample
according to the present invention;
[0023] FIG. 12 is a front perspective view of samples used to
obtain the fuzz on edge results;
[0024] FIG. 13 is a perspective view of the samples of FIG. 13,
showing how a camera is oriented to obtain the fuzz on edge data;
and
[0025] FIG. 14 is a side elevation of a beveled glass used in
fuzz-on-edge analysis.
[0026] Repeated use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present invention. The
drawings are representational and are not necessarily drawn to
scale. Certain proportions thereof may be exaggerated, while others
may be minimized.
Test Methods
(1) In-Hand Ranking Test for Tactile Properties (IHR Test):
[0027] The In-Hand Ranking Test (IHR) is a basic assessment of
in-hand feel of fibrous webs and assesses attributes such as
softness and stiffness. It can provide a measure of
generalizability to the consumer population.
[0028] The softness test involves evaluating the velvety, silky or
fuzzy feel of a tissue sample when rubbed between the thumb and
fingers. The stiffness test involves gathering a flat sample into
one's hand and moving the sample around in the palm of the hand by
drawing the fingers toward the palm and evaluating the amount of
pointed, rigid or cracked edges or peaks felt.
[0029] Rank data generated for each sample code by the panel are
analyzed using a proportional hazards regression model. This model
assumes computationally that the panelist proceeds through the
ranking procedure from most of the attribute being assessed to the
least of the assessed attribute. The softness and stiffness test
results are presented as log odds values. The log odds are the
natural logarithm of the risk ratios that are estimated for each
code from the proportional hazards regression model. Larger log
odds indicate the attribute of interest is perceived with greater
intensity.
[0030] The IHR is employed to obtain a holistic assessment of
softness and stiffness, or to determine if product differences are
humanly perceivable. This panel is trained to provide assessments
more accurately than an average untrained consumer might provide.
The IHR is useful in obtaining a quick read as to whether a process
change is humanly detectable and/or affects the softness or
stiffness perception, as compared to a control.
[0031] The data from the IHR can also be presented in rank format.
The data can generally be used to make relative comparisons within
tests as a product's ranking is dependent upon the products it is
ranked with. Across-test comparisons can be made when at least one
product is tested in both tests.
(2) Crepe Structure Analysis/Fine Crepe Structure Test
[0032] The STFI mottling program has been written to run with
Matlab computer software for computation and programming. A
grayscale image is uploaded to the program where an image of the
tissue in question had been generated under controlled, low-angle
lighting conditions with a video camera, frame grabber and an image
acquisition algorithm. Images are generated according to the method
described below. The resulting image has a pixel resolution of
1024.times.1024 and represents a 12.5 mm.times.12.5 mm field of
view.
[0033] The STFI mottling software analyzes the grayscale variation
of the image in both the MD and CD directions by using FFT (Fast
Fourier Transform). The FFT is used to develop gray-scale images at
different wavelength ranges based on the frequency information
present within the FFT. The gray-scale coefficient-of-variation (%
COV) is then calculated from each of the images (e.g. inverse
FFT's) corresponding to the wavelengths which were pre-determined
by the STFI software. Since these images are generated with
low-angle lighting, the tissue surface structure is shown as areas
of light and dark, due to shadowing, and consequently the grayscale
variation can be related to the tissue surface structure. For each
code, 3 tissues are analyzed with 5 images from each tissue,
resulting in a total of 15 images analyzed per code.
Detailed Method for Image Generation and STFI Mottling Analysis
[0034] The test method involves retaining tissues, from which
samples will be cut, at room temperature of between 68.degree. F.
to 72.degree. F., and a relative humidity between 45 to 55%, for a
time period of 24 hours. After the tissues have been acclimated,
samples are prepared for imaging. Three randomly sampled,
wrinkle-free tissues specimens are mounted on a 10.times.12-inch
glass plate by adhering with an adhesive tape at their corners and
along their sides. The tissues are drawn snug under mild tension
during this tape adhering step. The specimens are cut and mounted
so that the machine direction runs parallel with the longer
dimension of the 2.times.3 inch piece. The basesheet samples are
one-ply, and finished product samples are two-ply. For basesheet
and finished product samples, each sample specimen is mounted with
the creped side of the tissue in an upward position. Each sample
specimen is "painted" with a 50:50 mixture of PENTEL.RTM.
Correction Pen.TM. fluid and n-butanol, using a top quality camel's
hair brush, applying in one direction parallel to the machine
direction. This preparation will reduce light reflection and
refraction. A 20 minute drying time is sufficient.
[0035] Referring to the schematic representation of the image
acquisition apparatus shown in FIG. 9, a specimen is illuminated in
a darkened room with a collimated light source produced by a slide
projector. The slide projector used may be a Kodak Ektagraphic
slide projector (Model B-2) 228 having a lens 230. The slide
projector 228 may be connected to a POWERSTAT Variable
Auto-transformer, type 3PN117C (or equivalent, which can be
purchased from Superior Electric, Co. having an office in Bristol,
Conn. The auto-transformer is used to adjust the illumination level
of the slide projector. The slide projector 228, with its attached
lens 230, is mounted on a support 232. In turn, the support is
attached to a base 234. The collimated light source is adjusted to
hit the top surface of the tissue specimen 222 at an angle of 20
degrees. The prepared tissue sample 222 is positioned flat on top
of the auto-stage 246 with the crepe pattern orthogonally aligned
with respect to the light source, resulting in shadows cast by the
crepe folds. The reflected light is viewed and an image acquired by
a camera such as a Dage 81 monochrome camera (available from
Dage-MTI, Michigan City, Ind.) 236 having a 40-mm El-Nikkor lens
(f-stop=4) 238 with a 30-mm extension tube 240 to generate a
1024.times.1024 pixel gray-scale image.
[0036] The Dage 81 video camera 236 is mounted on a Polaroid MP-4
Land Camera (Polaroid Resource Center, Cambridge, Mass.) standard
support 242. The support is attached to a KREONITE macro-viewer 244
available from Kreonite, Inc., having an office in Wichita, Kans.
An auto-stage Model HM-1212, 246 is placed on the upper surface of
the KREONITE macro-viewer. The auto-stage 246 is a motorized
apparatus known to those skilled in the analytical arts which can
be purchased from Design Components Incorporated (DCI), having an
office in Franklin, Mass. The auto stage 246 is used to move the
sample 222 in order to obtain five separate and distinct,
non-overlapping images from the approximately 3.times.2 inch size
specimen. The glass plates 224 with painted tissue are placed on
the auto macro-stage (DCI 12.times.12 inch) of a Leica Microsystems
Quantimet 600 Image Analysis system, under the optical axis of a 40
mm El-Nikkor lens 238 with a 30-mm extension tube 240. The sample
is illuminated at 20 degrees with a slide projector to form
shadows.
[0037] Referring again to FIG. 9, the distance D.sub.1 represents
the distance between the upper surface of the sample and the bottom
of the lens. The distance D.sub.1 is set to be approximately 6
centimeters (cm). The distance D.sub.2 represents the vertical
distance between the lens attached to the slide projector and the
upper surface of the sample. The distance D.sub.2 is set at 26 cm.
The sample is illuminated by the slide projector. The distance
D.sub.3 represents 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. The
distance D.sub.3 is set at 58 cm. These dimensions, combined with
the video camera set-up, will result in a field-of-view size of the
sample surface to be approximately 12.5 millimeters (mm) by 12.5
mm.
[0038] The image analysis system used to acquire images may be a
Quantimet 600 Image Analysis System available from Leica
Microsystems, having an office in Heerbrugg, Switzerland. The
system is controlled and run by QWIN Version 1.06A software. The
image analysis algorithm `OSC6C` is used to acquire and process
gray-scale monochrome images using Quantimet User Interactive
Programming System (QUIPS) language. Alternatively, the OSC6C
program could be used with a Quantimet 550 IW Image Analysis System
or newer QWIN Pro platforms which run newer versions of the
software (e.g. QWIN Pro Version 3.2.1). The custom image
acquisition program is shown below.
TABLE-US-00001 NAME: OSC6C CONDITIONS: Dage 81 w/ 40 mm EI-Nikkor
lens (f/4) and 30 mm ext. tube; Projected, collimated light @ 20
deg. angle; 50/50 PENTEL/n-Butanol coating on samples; mounted on
1/4'' glass plate; Front of fixture is 46 cm from front of camera;
fixture base is raised to 4th hole from bottom. INITIALIZE
VARIABLES FRAMEHEIGHT = 400 FRAMEWIDTH = 800 LFRAMECNT = 0 CALVALUE
= 12.2 IMAGE = 0 ACQOUTPUT = 1 SET-UP AND CALIBRATION Clear Accepts
Image frame (x 0, y 0, Width 1024, Height 1024) Measure frame (x
92, y 325, Width 800, Height 400) PauseText ("Position Sample and
use Polaroid 803 reference to adjust white level to 1.0. After
clicking `OK`, adjust Variac so readout is in 190-194 range. ")
Image Setup [PAUSE] (Camera 0, White 71.65, Black 99.76, Lamp
49.99) Calibrate (CALVALUE CALUNITS$ per pixel) Display (Image0
(on), frames (on,on), planes (off,off,off,off,off,off), lut 0, x 0,
y 49, z 1, Reduction off) For (SAMPLE = 1 to 3, step 1) ROUTINE TO
STABILIZE LIGHT LEVEL Y = 0 Z = 0 SP = 0 SIB = 0 P = 0 MGREYIMAGE =
0 FIELDS = 1000 TWICE = 0 Correlation GL Value for top 1% px
Method, and SONY DXC930 = 187 For (LIGHT = 1 to 100, step 1) Image
Setup (Camera 0, White 68.06, Black 99.76, Lamp 49.99) Live Image
(into Image0) Measure Grey (plane MGREYIMAGE, 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 Next (LIGHT)
END LIGHT STABILIZER ROUTINE CONTINUE STAGE SCAN PARAMETERS Stage
(Define Origin) Stage (Scan Pattern, 1 .times. 5 fields, size
13400.156250 .times. 9200.039063) IMAGE ACQUISITION AND DETECTION
For ( FIELD = 1 to 5, step 1 ) IMAGE = IMAGE+1 Image Setup (Camera
0, White 68.06, Black 99.76, Lamp 49.99) Acquire (into Image0) Grey
Transform (WSmooth from Image0 to Image1, cycles 2, operator Horiz)
ACQFILE$ = "C:\images\17516\test_"+STR$(IMAGE)+".TIF" (Note: This
line indicates the image file save location and will vary with
application) Write image (from ACQOUTPUT into file ACQFILE$, type
TIF) Image frame (x 0, y 0, Width 1024, Height 1024) Measure frame
(x 92, y 325, Width 800, Height 400 ) Stage (Step, Wait until
stopped + 10 .times. 55 msecs) Next (FIELD) PauseText ("Position
Plate to Analyze Next Tissue and click `Continue.`") Image Setup
[PAUSE] (Camera 0, White 71.67, Black 99.76, Lamp 49.99) Next
(SAMPLE) END
[0039] Prior to acquiring the first sample images, shading
correction is performed using 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 shading correction is performed
using a `live` mode. The system and images are accurately
calibrated using QWIN software and a standard ruler with metric
markings. The calibration is performed in the horizontal dimension
of the video camera image.
[0040] After calibrating, the QUIPS algorithm OSC6C is 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 POWERSTAT variable auto transformer)
to register between Gray-Level readings of 190-194. During this
process of light adjustment, a QUIPS algorithm OSC6C will
automatically display the current Gray-Level value on the video
screen.
[0041] After the light has been properly adjusted, the QUIPS
algorithm OSC6C will then automatically acquire the five images for
a single tissue specimen. The analyst will then be prompted to
reposition the plate, so that the next specimen can be imaged
accordingly. This repositioning step will re-occur again for the
third tissue specimen as well. The Gray-Level scale used on the
Quantimet 600 system, or equivalent, is 8-bit and ranges from 0-255
(0 represents `black` and 255 represents `white`).
[0042] Using the set-up described above, an image representing a
12.5 mm.times.12.5 mm field of view is generated and saved as *.tif
image file. Typically, 3 tissue specimens are selected per sample
code and 5 images generated per tissue specimen resulting in 15
images generated per sample or code.
[0043] The STFI Mottling software used for this analysis is
STFI-Mottling v2.61 created by INNVENTIA (BOX 5604, SE-114 86,
Stockholm, Sweden +46 8 676 7000--formerly STFI-Packforsk),
designed for use with Matlab v7.x for Windows 95/98/2000/XP. The
following inputs are entered in the STFI Mottling user
interface.
Report: Table
Statistics: COV
Read TIFF-files: Single
Calibration Set: None
[0044] No. of measuring areas: 4
Size: 180.6 mm
[0045] Wavelength, mm--min: 2 Wavelength, mm--max: 64
[0046] Images are uploaded to the software by clicking the Select
TIFF-file button and then choosing the appropriate file. The image
then appears in the image window and the "Mark two corners" button
is chosen. Diagonally opposite corners of the image are selected
resulting in 4 regions on the tissue image boxed to denote the 4
measuring areas 250, 252, 253, and 254. The image analysis areas
are illustrated in FIG. 10. It should be noted that there is slight
overlap 255 of the four analysis regions.
[0047] The "Add to batch" button is then clicked to ready the
measuring areas for analysis. All images for a sample are "added to
batch" prior to clicking the "Start evaluation" button. Once the
evaluation is complete, data files are then saved automatically for
summary and analysis. A data file is saved for each image analyzed.
A FFT calculation is completed for each analysis area and the
average of the four FFTs is used for the image. Since there is a
magnification difference of 29.times. between the actual images
used and what the STFI mottling software normally uses from an
image provided by a flatbed scanner, the wavelength ranges provided
by the STFI software has to be recalculated to reflect this
difference.
[0048] The data file for each image contains % COV for 2-4 mm, 4-8
mm, 8-16 mm, 16-32 mm, and 32-64 mm wavelengths for each of the
four image areas 250-256 and the mean of those areas. The total
variation and gray level is also included in each data file. The
mean of the 4 image analysis areas for the 8-16 mm wavelength % COV
is used for each image for data analysis. Since there are 15 images
total per code, 15% COV is used to calculate a mean for the code or
sample. Since images are acquired at a magnification of 29.times.,
the 8-16 mm wavelength reported by the STFI software is actually
0.28-0.55 mm on the tissue specimens. 0.28-0.55 mm is generally
considered by those skilled in the art to reflect good crepe. In
the case of this analysis technique, lower % COV numbers in this
wavelength area suggest less variation in the surface or a smoother
surface.
(4) PEG Transfer Test
[0049] This test is used to determine the amount of water-soluble
creping blend component transferred from a facial tissue to a
collagen film which serves as a model for skin. Collagen film may
be obtained from Viscofan Group (located in Pomplona, Spain). An
Ink Rub Tester Model #10-18-01, manufactured by Testing Machines
Inc. (located in Ronkonkoma, N.Y.) is used in this test method. A
block 5 cm by 10 cm and 2 cm thick, with a weight of 908 grams, is
covered with the collagen film which is secured with magnets. The
prepared block, covered by the collagen film is rubbed against the
stable base of the instrument, which is covered by the tissue
sample which is secured to the base with tape on the edges.
[0050] One set of films are equilibrated at 50% Relative Humidity
(RH), and another set at an equilibration of 100% RH. Conditioning
to 100% RH can be achieved by placing the collagen in a closed
container containing water, without immersing the collagen in the
water, and equilibrating the collagen in the closed container for
24 hours. Each sample is rubbed 8 cycles at a speed of 85 cycles
per minute.
[0051] Prior to sample analysis, collagen is extracted and analyzed
to ensure that no possible components could interfere with the
quantification of PEG. Also, addition/recovery experiments are
conducted to determine the extraction efficiency of the PEG from
collagen. A stock ethanol solution of PEG is generated and a known
amount (20 .mu.L) is applied to collagen. The ethanol is allowed to
evaporate and the samples are analyzed as per the methodology
specified below. The addition/recovery results indicate that the
methodology is sufficient for the accurate determination of PEG
transferred to collagen.
[0052] Following the transfer procedure, each collagen sample is
placed into a 20-mL vial. To each vial, 5-mL water is added and the
contents sonicated for 10 minutes and shaken for 10 minutes. The
ultrasonic action may be performed using a BRANSON Ultrasonic
Cleaner, Model BRANSONIC 52, from the Branson Company in Danbury,
Conn. The resulting solutions are filtered through a filter such as
a PALL ACRODISC Syringe filter, 25 mm with 5 micron VERSAPOR
membrane. These solutions are used for quantification. A PEG 8,000
calibration curve is generated for quantification purposes.
HPLC Conditions
Column: Alltech Alltima C4 WP
Column Temperature: Ambient
[0053] Mobile Phase: 85:15 (IPA: 0.1% acetic acid) Flow rate: 0.7
mL/min. Injection volume: 100 microliters ELS detection: 70C
nebulizer, 90C evaporator, 1 Liter N.sub.2
(5) Lubricious Hand Feel
[0054] Lubricious or lubricated hand feel can be demonstrated by a
significant reduction in coefficient of friction on a skin simulant
of collagen film. Collagen film can be obtained from various
sources such as Viscofan Group (located in Pomplona, Spain). The
films are conditioned to 100% RH. Each collagen sample is rubbed
against a tissue sample as follows:
[0055] An Ink Rub Tester Model #10-18-01, manufactured by Testing
Machines Inc. (located in Ronkonkoma, N.Y.) functions by rubbing a
block 5 cm by 10 cm and 2 cm thick, with a weight of 908 grams,
covered with the collagen film (secured with magnets), against the
stable base of the instrument, covered by a tissue sample (secured
with tape on the edges). Conditioning the collagen films to 100% RH
is achieved by placing the collagen in a closed container
containing water, without immersing the collagen in the water, and
equilibrating the collagen in the closed container for 24 hours.
Each sample is rubbed 8 cycles at a speed of 85 cycles per
minute.
[0056] The coefficient of friction for the tissue-rubbed collagen
film samples is determined with a Lab Master Friction and Slip
tester, Model 32-90, available from Testing Machines Inc.,
Ronkonkoma, N.Y. The films are tested under TAPPI conditions (50%
relative humidity and 23.degree. C.) at a test speed of 122
cm/minute, with a sled weight of 250 grams and a contact area of
38.4 cm.sup.2. A first film is placed, treated side up, on the base
platform and secured with tape. A second identically treated film
is secured on the sled with the treated side facing the first film.
Identical collagen films, which are not rubbed with the tissue, are
tested in the same manner.
(6) Sheet Bulk Test
[0057] Sheet bulk is calculated as the quotient of the sheet
caliper of a conditioned fibrous sheet, expressed in microns,
divided by the conditioned basis weight, and expressed in grams per
square meter. The resulting sheet bulk is expressed in cubic
centimeters per gram. More specifically, the sheet caliper is the
representative thickness of a single sheet measured in accordance
with TAPPI test methods T402 "Standard Conditioning and Testing
Atmosphere For Paper, Board, Pulp Handsheets and Related Products"
and T411 om-89 "Thickness (caliper) of Paper, Paperboard, and
Combined Board" with Note 3 for stacked sheets. The micrometer used
for carrying out T411 om-89 is an Emveco 200-A Tissue Caliper
Tester available from Emveco, Inc., Newberg, Oreg. The micrometer
has a load of 2 kilo-Pascals, a pressure foot area of 2500 square
millimeters, a pressure foot diameter of 56.42 millimeters, a dwell
time of 3 seconds and a lowering rate of 0.8 millimeters per
second.
(7) Geometric Mean Tensile (GMT) Strength
[0058] As used herein, the "geometric mean tensile (GMT) strength"
is the square root of the product of the machine direction tensile
strength multiplied by the cross-machine direction tensile
strength. The "machine direction (MD) tensile strength" is the peak
load per 3 inches (76.2 mm) of sample width when a sample is pulled
to rupture in the machine direction. Similarly, the "cross-machine
direction (CD) tensile strength" is the peak load per 3 inches
(76.2 mm) of sample width when a sample is pulled to rupture in the
cross-machine direction. The "stretch" is the percent elongation of
the sample at the point of rupture during tensile testing. The
procedure for measuring tensile strength is as follows.
[0059] Samples for tensile strength testing are prepared by cutting
a 3 inch (76.2 mm) wide by a 5 inch (127 mm) long strip in 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, Serial No. 37333).
Samples must be conditioned to 50% relative humidity at a
temperature of 23.degree. C. and handled with rubber gloves. The
instrument used for measuring tensile strengths is an MTS Systems
Insight 1 Material Testing Work Station. The data acquisition
software is MTS TestWorks.RTM. 4 (MTS Systems Corp., 14000
Technology Driver, Eden Prairie, Minn. 55344). The load cell is
selected from either a 50 Newton or 100 Newton maximum (S-Beam TEDS
ID Load Cell), depending on the strength of the sample being
tested, such that the majority of peak load values fall between
10-90% of the load cell's full scale value.
[0060] The gauge length between jaws is 4.+-.0.04 inches
(101.6.+-.1 mm). 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).
[0061] The crosshead speed is 10.+-.0.4 inches/min (254.+-.1
mm/min), and the break sensitivity is set at 65%. The data is
recorded at 100 hz. 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 the "MD tensile strength" or the "CD tensile strength"
of the specimen. At least six (6) representative specimens are
tested for each product or sheet, taken "as is", and the arithmetic
average of all individual specimen tests is the MD or CD tensile
strength for the product or sheet.
(8) Basis Weight Test
[0062] The "Basis Weight" test is used to determine the mass of
tissue fibers per unit area of the tissue sheet for napkins,
towels, facial and bath tissue product. The basis weight can be
measured in As-Is (no conditioning), Conditioned (equilibrated to
laboratory conditions of 23+/-3.0.degree. C. and 50+/-5% relative
humidity) or Bone Dry (oven dried at 105+/-2.0.degree. C. for 25
minutes for a sample weight less than 10.0 grams and a minimum of 8
hours for a sample weighing more than 10 grams). To carry out the
test, 16 sheets are stacked and cut to a dimension of
76.2.times.76.2+/-1 mm using a die cutter capable of cutting the
specimen to the specified dimensions such as a Hudson Machinery
part number SE-25 or equivalent with an appropriately designed die.
Weigh the cut specimen in grams for as-is, conditioned or bone dry
basis weight after appropriate conditions of previously mentioned
preparations are completed. If bone dry basis weight is required,
the oven dried sample will be placed into an air-tight can after
drying to prevent moisture from penetrating the sample--the weight
of the can is then removed from the calculation of the sample
weight. This weight in grams is then multiplied by 6.3492 to report
the finished product basis weight in pounds per ream or multiply
the sample weight in grams by 10.764 to report the finished product
basis weight in grams per square meter (gsm).
(9) Absorbent Rate Test
[0063] The "Absorbency Rate (Wet-Out Time) Test" is used to
determine the absorbency wet out time of napkins, towels, facial
and bath tissue product. To carry out the test, the test product is
first equilibrated to ambient conditions for at least four hours at
23+/-3.0.degree. C. and 50+/-5% relative humidity. 20 sheets are
stacked and cut to a sixty three millimeter by sixty three
millimeter (+/-three millimeters) square using a device capable of
cutting to the specified dimensions such as a Hudson Machinery part
number se-25 or equivalent. The square is then fixed in each corner
by staples delivered by a standard, commercially available manual
office stapler. The staples are placed diagonally across each
corner far enough into the sheet so that the staples are completely
contacting the tissue sheets, staples should not wrap the corner of
the sample. The sample is then held horizontally and approximately
25 mm (1 inch) over a container containing distilled or de-ionized
water at 23.0.degree. C..+-.3.0.degree. C. The container should be
of sufficient size and depth to ensure that the saturated specimen
does not contact the sides, bottom of the container, and the top
surface of the water at the same time. The container should contain
a minimum depth of 51 mm of water to ensure complete saturation of
the test specimen and this depth should be maintained throughout
the testing. The specimen is then dropped flat onto the water
surface and a timing device is started when the specimen contacts
the water surface. As soon as the specimen is completely saturated,
stop the timing device and record the absorbency wet out time in
seconds.
(10) % Water Soluble Extractables
[0064] A 1-2 gram sample of the tissue to be tested is weighed and
placed in a 100 mL specimen cup. Fifty milliliters of room
temperature deionized water is added to each specimen cup. The
specimen cup is capped and extracted on a flat-bed shaker at 150
rpm for one hour.
[0065] After extraction the sample is filtered through a Buchner
funnel containing a Whatman 934-AH glass microfiber filter (Whatman
Catalog Number 1827-055, Whatman Inc., GE Healthcare,
www.whatman.com) using vacuum. The specimen cup is rinsed twice
with deionized water and poured into the funnel. The tissue is then
rinsed an additional two times with deionized water. The extract is
transferred to a tared 100 mL beaker and the filter flask is rinsed
twice with deionized water and combined with the extract in the
beaker. The total volume in the beaker is nearly 100 mL. The beaker
is dried in an oven at 105.degree. C., cooled, and weighed. The %
water soluble extractables are calculated from the tissue weight
and the tare and final weights of the beaker.
% Water Soluble Extractables = ( final weight of beaker - tare
weight of beaker ) tissue weight .times. 100 ##EQU00001##
[0066] Three tests are completed per sample. The average, % water
soluble extractables is reported for each sample.
(11) Fuzz on Edge Test
[0067] The fuzz-on-edge methodology measures the amount of fibers
that protrude from the surface of a fibrous material. The
measurement is performed using image analysis to detect and then
measure the total perimeter of protruding surface fibers observed
when the material in question is wrapped over an `edge` to that
allow the fibers to be viewed from the side using transmitted
light. An image analysis algorithm was developed to detect and
measure the perimeter length of the fibers per edge length of
material, where the perimeter length is defined as the total length
of the boundaries of all of the protruding fibers (i.e.
Perimeter/Edge Length or PR/EL for short). For example, an edge
along the majority of the length of a fibrous material (e.g. facial
tissue) can be measured by acquiring and analyzing multiple,
adjacent fields-of-view to arrive at a single PR/EL value.
Typically, several such material specimens are analyzed for a
sample to arrive at a mean PR/EL value. FIG. 11 shows an example of
a transmitted light image along the edge of a fibrous nonwoven
material and highlights the in-focus protruding fibers 408 (as
opposed to out-of-focus fibers 407) that can be measured for their
PR/EL value. Thus, the PR/EL is the accumulated perimeter of the
detected fiber areas divided by the edge length 409 (which is
depicted in FIG. 11 and is the frame or image width of that
figure).
Detailed Method for Fuzz-on-Edge Analysis
[0068] A tissue sample is allowed to equilibrate at laboratory
temperature conditions ranging from 68-72 degrees Fahrenheit, and a
relative humidity between 45 to 55% for at least 24 hours. A sample
specimen 400 of the tissue is first prepared by cutting it into a
strip that is approximately 20 cm in length. The width is cut to
approximately 4-5 cm. A folded edge is imparted along the
machine-direction (MD) length of the tissue strip by taping down
one end onto a piece of beveled glass plate 402 using a common,
transparent tape (e.g., SCOTCH.RTM. tape) so that approximately
half the width of the material hangs over the beveled glass edge
404.
[0069] See FIG. 14 for specific dimensions of the beveled glass
plate 402. The beveled edge height 450 is 2.4 mm thick. The
non-beveled edge 452 thickness is 6.0 mm. The overall width 454 of
the plate is 76 mm, while the non-beveled width 456 is 54 mm. The
sample is lightly stretched on the opposite end and then fastened
down to the beveled glass plate with another small piece of tape
458. See FIG. 12. The light stretching is done to remove any
macro-wrinkles and puckers inherently present in the material.
[0070] After taping down the entire long edge stretching between
the two ends, the beveled glass plate 402 and holding apparatus 424
is inverted. The loose specimen portion sticking out past the
beveled edge 404 is then gently pulled over the edge 404 and taped
onto the opposite side of the glass relative to the first specimen
edge. When taping down the second edge on the opposite glass
surface, the material is again lightly stretched in an effort to
remove any macro wrinkles. FIG. 12 shows the specimen apparatus 424
possessing two beveled glass plates 402 after two tissue specimens
are mounted via the taping instructions described above. Along the
edge of the fold, fifteen discrete fields of view along the tissue
edge showing any fibers 408 that protrude from the surface of the
material are counted and their cumulative perimeter measured. The
PR/EL value is the sum of the perimeters of the detected and then
measured fibers divided by the length of the edge over which they
were measured.
[0071] A Dage 81 video camera (Dage-MTI, Michigan City, Ind.) 420
is mounted on a Polaroid MP-4 Land Camera (Polaroid Resource
Center, Cambridge, Mass.) standard support 422. The support is
attached to a KREONITE macro-viewer available from Kreonite, Inc.,
having an office in Wichita, Kans. An auto-stage, DCI Model
HM-1212, is placed on the upper surface of the KREONITE
macro-viewer and the sample mounting apparatus was placed atop the
auto-stage. The auto-stage is a motorized apparatus known to those
skilled in the analytical arts which was purchased from Design
Components Incorporated (DCI), having an office in Franklin, Mass.
The auto stage is used to move the sample in order to obtain 15
separate and distinct, non-overlapping images from the specimen.
The sample mounting apparatus 424 is placed on the auto macro-stage
(DCI 12.times.12 inch) of a Leica Microsystems Quantimet 600 Image
Analysis system, under the optical axis of a 60-mm AF Micro Nikkor
lens (Nikon Corp., Japan) fitted with a 30-mm extension tube. The
lens focus is adjusted to provide the maximum magnification and the
camera position on the Polaroid MP-4 support is adjusted to provide
optimum focus of the tissue edge. The sample is illuminated from
beneath the auto-stage using a Chroma Pro 45 (Circle 2, Inc.,
Tempe, Ariz.). The Chroma Pro settings are such that the light is
`white` and not filtered in any way to bias the light's spectral
output. The Chroma Pro may be connected to a POWERSTAT Variable
Auto-transformer, type 3PN117C, which may be purchased from
Superior Electric, Co. having an office in Bristol, Conn. The
auto-transformer is used to adjust the Chroma Pro's illumination
level. FIG. 13 shows the tissue sample mounting device sitting atop
the auto macro-stage with the Dage 81 camera overhead.
[0072] The image analysis system used to acquire images and perform
the PR/EL measurements may be a Quantimet 600 Image Analysis System
available from Leica Microsystems, having an office in Heerbrugg,
Switzerland. The system is controlled and run by QWIN Version 1.06A
software. The image analysis algorithm `FOE2` is used to acquire
and process gray-scale monochrome images using Quantimet User
Interactive Programming System (QUIPS) language. Alternatively, the
FOE2 program could be used with a Quantimet 550 IW Image Analysis
System or newer QWIN Pro platforms which run newer versions of the
software (e.g. QWIN Pro Version 3.2.1). The custom image analysis
program is shown below.
TABLE-US-00002 NAME = FOE2 PURPOSE = Measures Fuzz-on-edge and
fiber orientation properties of fibrous materials CONDITIONS = Dage
81 vid.; 60-mm Micro-Nikkor (f/4) w/ 30 mm ext. tube (max. mag. for
focus); Transmitted light through 4''.times.5'' mask; DCI stage;
beveled glass sample holders. DATE = July 29, 2009 AUTHOR = D. G.
Biggs OPEN FILES AND INITIAL VARIABLES Open File (
C:\EXCEL\DATA\18277\FOE.XLS, channel #1 ) PERIM = 0 PREL = 0
TOTPREL = 0 TOTFIELDS = 0 MFLDIMAGE = 0 FRAGMENTS = 0 TOTFRAGMENTS
= 0 -- Calvalue = 7.69 um/px CALVALUE = 7.69 IMAGE AND FRAMES
SET-UP Image frame ( x 0, y 0, Width 1024, Height 1024 ) Measure
frame ( x 32, y 61, Width 964, Height 962 ) Calibrate ( CALVALUE
CALUNITS$ per pixel ) PauseText ( "Set up sample and adjust white
level to 1.00" ) Enter Results Header File Results Header ( channel
#1 ) For ( REPLICATE = 1 to 4, step 1 ) Clear Field Histogram #1
Clear Field Histogram #2 Image Setup [PAUSE] ( Camera 0, Gain
71.65, Offset 99.76, Lamp 49.99 ) File Line ( channel #1 ) File
Line ( channel #1 ) File ( "PR/EL", channel #1, field width: 5,
left justified ) File ( "Anisotropy", channel #1, field width: 10,
left justified ) File ( "Count", channel #1, field width: 5, left
justified ) File Line ( channel #1 ) ENTER SAMPLE LOOP Stage (
Define Origin ) Stage ( Scan Pattern, 15 .times. 1 fields, size
11299.843750 .times. 132400.937500 ) For ( FIELD = 1 to FIELDS,
step 1 ) IMAGE ACQUIRE AND DETECT Image Setup ( Camera 0, Gain
71.65, Offset 99.76, Lamp 49.99 ) Acquire ( into Image0 ) Detect (
blacker than 127, from Image0 into Binary0 delineated ) IMAGE
PROCESSING Binary Amend ( Open from Binary0 to Binary1, cycles 9,
operator Disc, edge erode on ) Binary Logical ( C = A XOR B : C
Binary2, A Binary0, B Binary1 ) Binary Amend ( Close from Binary2
to Binary3, cycles 1, operator Disc, edge erode on ) Binary Amend (
Open from Binary3 to Binary4, cycles 1, operator Disc, edge erode
on ) FIELD MEASUREMENTS MFLDIMAGE = 4 Measure field ( plane
MFLDIMAGE, into FLDRESULTS(4), statistics into not found ) Selected
parameters: Area, Perimeter, Count, Anisotropy PERIM =
FLDRESULTS(2) ANISOT = FLDRESULTS(4) PREL = (PERIM)/(964*CALVALUE)
TOTPREL = TOTPREL+PREL TOTFIELDS = TOTFIELDS+1 File ( PREL, channel
#1, 3 digits after `.` ) File ( ANISOT, channel #1, 3 digits after
`.` ) Field Histogram #1 ( Y Param Number, X Param PREL, from 0. to
20., linear, 20 bins ) Field Histogram #2 ( Y Param Number, X Param
Anisotropy, from 0.40 to 1.20, linear, 20 bins ) Display Field
Histogram Results ( #1, horizontal, differential, bins + graph (Y
axis linear), statistics ) Data Window ( 741, 553, 529, 467 )
FEATURE MEASUREMENTS Measure feature ( plane Binary4, 32 ferets,
minimum area: 10, grey image: Image0 ) Selected parameters: Area, X
FCP, Y FCP, Perimeter FRAGMENTS = Field Sum of ( PACCEPTED(FTR) )
File ( FRAGMENTS, channel #1, 0 digits after `.` ) TOTFRAGMENTS =
TOTFRAGMENTS+FRAGMENTS File Line ( channel #1 ) Stage ( Step, Wait
until stopped + 550 msecs ) Next ( FIELD ) OUTPUT File Line (
channel #1 ) File Line ( channel #1 ) File Line ( channel #1 ) File
Line ( channel #1 ) File ( "Matrix Anisotropy Histogram", channel
#1 ) File Line ( channel #1 ) File Field Histogram Results ( #2,
differential, statistics, bin details, channel #1 ) File Line (
channel #1 ) File ( "PR/EL Histogram", channel #1 ) File Line (
channel #1 ) File Field Histogram Results ( #1, differential,
statistics, bin details, channel #1 )
+++++++++++++++++++++++++++++++= Set Print Position ( 8 mm, 8 mm )
Print Results Header Print Line Print ( "Mean PR/EL = ", no tab
follows ) Print ( TOTPREL/TOTFIELDS, 3 digits after `.`, no tab
follows ) Print Line Print ( "Total Fields = ", no tab follows )
Print ( TOTFIELDS, 0 digits after `.`, no tab follows ) Print Line
Print ( "Mean Fragments per Field = ", no tab follows ) Print (
TOTFRAGMENTS/TOTFIELDS, 2 digits after `.`, no tab follows ) Print
Line Print Line Print ( "Count vs. PR/EL (mm/mm)", no tab follows )
Print Line Print Field Histogram Results (#1, horizontal,
differential, bins + graph (Y axis linear), statistics ) Set Image
Position ( left 98 mm, top 128 mm, right 183 mm, bottom 195 mm,
Aspect = Image Window, Caption:Bottom Centre,"Example Image" ) Grey
Util ( Print Image0 ) Print Page Next ( REPLICATE ) Close File (
channel #1 ) END
[0073] Prior to acquiring the first sample images, shading
correction is performed using the QWIN software and blank
field-of-view illuminated only by the Chromo Pro 45. The shading
correction is performed using the `live` mode. The system and
images are also accurately calibrated using the QWIN software and a
standard ruler with metric markings. The calibration is performed
in the horizontal dimension of the video camera image.
[0074] After calibrating, the QUIPS algorithm FOE2 is executed via
the QWIN software and this initially prompts the analyst to place
the sample specimen 400 within the field-of-view of the video
camera. After positioning the specimen so the machine direction
runs horizontally in the image the specimen is properly aligned for
auto-stage motion, the analyst will then be prompted to adjust the
light level setting (via the POWERSTAT variable auto transformer)
to register a white level reading of 1.0. During this process of
light adjustment, the QUIPS algorithm FOE2 will automatically
display the current white level value within a small window on the
video screen.
[0075] After the light has been properly adjusted, the QUIPS
algorithm FOE 2 will then automatically acquire the 15 images and
make corresponding PR/EL measurements for a single tissue specimen.
The analyst will then be prompted to reposition the tissue mounting
apparatus, so that the next specimen can be imaged accordingly.
This repositioning step will occur two more times so that a third
and forth tissue specimen will be measured as well. The Gray-Level
scale used on the Quantimet 600 system, or equivalent, is 8-bit and
ranges from 0-255 (0 represents `black` and 255 represents
`white`).
[0076] The PR/EL data are exported directly to an EXCEL.RTM.
spreadsheet. The data are then processed so that the mean PR/EL
value obtained from each of the four tissue specimens are then
combined together resulting in a final mean PR/EL value. This final
sample mean PR/EL value is based on an N=4 analysis from the four
tissue specimens. A comparison between different tissue samples is
performed using a Student's T analysis at the 90% confidence
level.
Sheet Split PEG Analysis Test Method
[0077] This test method is directed to a single-ply creped tissue
sample. The dryer-side and felt-side of the sample must be
identified. Machine direction (MD) and Cross-machine direction (CD)
must also be known.
[0078] SCOTCH.RTM. Box Sealing Tape 373, available from 3M, St.
Paul, Minn., is used to split the tissue sheet samples. The tape is
supplied at 48 mm wide. Five samples of the tape alone, each 102 mm
long, are weighed and averaged to determine an average weight per
length. This is used as the tare weight of the tape.
[0079] A 48 mm by 102 mm piece of the SCOTCH.RTM. 373 tape is
applied to the felt-side of the tissue sample, with the longer
dimension aligned with the MD of the tissue sample. The actual tape
length is longer than 102 mm in order to create a tab at one end by
folding over the tape end. However, the actual effective applied
length to the tissue is 102 mm. A 2.0 kg roller, which is
approximately the same width as the tape, is rolled once over the
taped portion at a speed of 305 mm per minute, down and back.
[0080] In the same manner, another 48 mm by 102 mm piece of
SCOTCH.RTM. 373 tape is applied to the dryer-side of the tissue
sample, over the same exact area, but on the opposite side of the
tissue sample. After the 2.0 kg roller is rolled over the taped
portion, on the dryer-side, as described above, the sample is
equilibrated at TAPPI conditions (23 degrees C. and 50% relative
humidity) for 12 hours.
[0081] After conditioning, the tissue sample is pulled apart by
grasping the two tape tabs and pulling them apart at a speed of
about 102 mm per minute. The result is a split tissue sheet sample,
with a portion attached to each piece of tape.
[0082] Each of the two 48 mm by 102 mm tape/tissue samples is
weighed. The tare weight of the tape is subtracted from the
tape/tissue sample weight to obtain the weight of tissue and
additive composition that is attached to each piece of tape.
[0083] Each of the two tape/tissue samples is placed in a 100-mL
specimen cup and 15 ml of a 90:10 (isopropyl alcohol:water) mixture
is added by pipette. The specimen cup was capped and then placed on
a flatbed shaker at 150 rpm for 2 hours.
[0084] The amount of PEG extracted is determined by the HPLC
procedure as described as follows:
[0085] The resulting extraction solutions are filtered through a
PALL ACRODISC Syringe filters 25 mm with a 5 micron VERSAPOR
membrane and used for quantification. A PEG 8,000 calibration curve
was generated for quantification purposes.
HPLC Conditions
TABLE-US-00003 [0086] Column: Phenomenex Luna NH.sub.2; 5 micron
particle size; 25 cm .times. 4.6 mm; n 100 .ANG.; part number
00G-4378-E0 Column Ambient Temperature: Mobile Phase: 90:10
(isopropyl alcohol: 0.1% aqueous Acetic acid) Flow rate: 0.5
mL/min. Injection volume: 100 microliters Run time: 6 minutes ELS
detection: 70 C nebulizer, 90 C evaporator, 1 Liter Nitrogen
[0087] The amounts of PEG isolated are normalized by the
tissue/additive composition weight for that split and recorded as
weight percent of PEG in the tissue split:
% PEG = 100 PEG weight from HPLC analysis ( Tape & Tissue
weight ) - ( Tape Tare weight ) ##EQU00002##
DEFINITIONS
[0088] It should be noted that, when employed in the present
disclosure, the terms "comprises," "comprising" and other
derivatives from the root term "comprise" are intended to be
open-ended terms that specify the presence of any stated features,
elements, integers, steps, or components, and are not intended to
preclude the presence or addition of one or more other features,
elements, integers, steps, components, or groups thereof.
[0089] The term "Lower Critical Solution Temperature" (hereinafter
"LCST") refers to a water soluble composition that is water soluble
until it reaches a threshold temperature. Once the threshold
temperature has been met, the composition's polymer chains shrivel
into an insoluble mass as the hydrophobic components interact with
each other and the polymer chains become dehydrated.
[0090] "Conventional" creping chemistries for tissue manufacturing
have typically included an adhesive which comprises an aqueous
admixture of polyvinyl alcohol (PVOH) and a water-soluble,
thermosetting, cationic polyamide-epihalohydrin resin, as described
in Soerens U.S. Pat. No. 4,501,640. The polyvinyl alcohol can be,
for instance, Celvol 523, available from Celanese Corporation
(Dallas, Tex.). The polyamide-epihalohydrin resin can be Kymene
557-H, available from Ashland Corporation (Covington, Ky.).
Additional variations of conventional creping chemistries also
include Rezosol 1095, available from Ashland Corporation
(Covington, Ky.). The ratio of chemicals included in the
conventional creping mixtures has varied over a large range.
However, a typical mixture can be 40% PVOH, 40% Kymene 557-H, and
20% Rezosol 1095.
[0091] Other water soluble creping chemistries can include an
additive composition having a water insoluble polyolefin dispersion
as described in U.S. Pat. Pub. No. 2007/0144697, incorporated
herein to the extent that it is consistent with the present
invention.
[0092] Unless otherwise specified, all comparisons made with
respect to webs are compared to webs of the same base substrates,
but with a conventional treatment or other treatments. In other
words, with the exception of the treatment, all other aspects of
the web are the same.
[0093] These terms may be defined with additional language in the
remaining portions of the specification.
DETAILED DESCRIPTION
[0094] It is to be understood by one of ordinary skill in the art
that the present discussion is a description of exemplary aspects
only, and is not intended as limiting the broader aspects of the
present disclosure.
[0095] In general, the present disclosure is directed to the
incorporation of an additive composition onto at least the surface
of a fibrous article in order to maintain or improve certain
physical characteristics such softness and absorbency, while
improving the related manufacturing efficiency. The additive
composition is made from a water-soluble film-forming component and
a water-soluble modifier component. In some aspects, the additive
may also contain additional water-soluble modifier components.
[0096] Polymers which have the property of a Lower Critical
Solution Temperature (LCST) are particularly beneficial as a
non-uniform coating of the present invention because they are
soluble in water at an ambient temperature of about 22.degree. C.
The composition quickly precipitates at the relatively high
temperature of the dryer surface, which is greater than 50.degree.
C. This property allows discrete deposition onto the tissue fibers
while increasing efficiency of processing. The polymers having the
desired LCST property generally have both hydrophobic and
hydrophilic segments in their macromolecular structure which
results in the solubility change at a LCST.
[0097] Below the LCST, the polymer chains hydrophilic segments
interact with water and are elongated. At the critical solution
temperature, the polymer chains shrivel into an insoluble mass as
the hydrophobic segments interact each other and the polymer chains
become dehydrated. The composition examples from this group
include, but are not limited to, hydroxypropyl cellulose (HPC),
hydroxypropyl starch (HPS), hydroxyethyl cellulose (HEC),
poly-N-isopropylacrylamide (poly-NIPAAm), polyethylene
oxide-polypropylene oxide block copolymers (such as Pluronic F127),
poly(2 ethyl oxazoline).
[0098] When a LCST polymer solution hits the hot surface of the
Yankee dryer (temperature above 50.degree. C.), the LCST polymer
will precipitate and the transparent solution will become milky. In
order to demonstrate this phenomenon, a metal plate was heated in
an oven at 150.degree. C. for 2 hours and then taken out of the
oven. A 5 wt % of KLUCEL solution, available from Ashland, Inc.
(Covington, Ky.), was sprayed onto its hot surface immediately. As
a control, the solution was also sprayed onto a similar metal plate
at room temperature. When a LCST polymer solution hits the hot
surface of the Yankee dryer (temperature above 50.degree. C.) the
LCST polymer will be precipitated. See FIG. 8 where a 5% KLUCEL
solution 112, available from Ashland, Inc. (Covington, Ky.) was
applied to a plate 110 at ambient temperature. After heating the
plate to the threshold temperature, the KLUCEL solution became an
opaque mass 114.
[0099] Blends of the present invention consist of water soluble,
polymers with melting points in the range of 35.degree. C. to
95.degree. C., which are utilized to crepe a fibrous web. These
polymers are in the molten state at temperatures 20.degree. C. to
80.degree. C. above their melting point of the components. The
molten state refers to a polymer or blend of polymers that is above
the melting point of all components and has a water content of less
than 5% by weight and a melt viscosity of 400-600,000 centipoise at
120.degree. C., as measured by the Melt Viscosity test method, ASTM
D 3236, 2004 version.
[0100] Blends of the present invention at the creping blade
function like a hot melt adhesive with a high affinity for the
metal surface and the cellulosic fiber web along with a low
cohesive strength which facilitates failure, at least partially
within the creping blend layer on the Yankee dryer, resulting in
significant transfer of the creping blend to cellulosic fiber web.
Since the blends of the present invention have relatively low
melting points and have no functionality to promote crosslinking
they are relatively stable and provide consistent creped tissue
properties because there is less tendency for chemical
transformation during the process by crosslinking or decomposition.
Furthermore, if the polymer blends are nonionic (without charge)
they are less sensitive to the ionic content of the process water.
These properties enhance stability which provides for a robust
process window.
[0101] In some aspects, the additive composition is non-ionic.
However, cationic and anionic polymers may be used if they produce
a similar effect as the non-ionic polymers.
[0102] Referring now to FIG. 1, the additive composition of the
present invention is applied directly onto the dryer surface 20
(e.g., a Yankee dryer) using a spray boom 22. Once the LCST has
been reached, it will precipitate to form insoluble masses that can
be transferred to the web surface during a creping process. (The
creping process is disclosed in U.S. Pat. Pub. No. US2008/0073046
to Dyer et al., which is incorporated herein by reference in a
manner that is consistent herewith.) The fibrous web 13 is adhered
to the surface of the Yankee dryer when it is pressed into contact
with the composition. The fibrous web and the composition are
subsequently scraped off of the dryer surface by a creping blade
24.
[0103] Due to the water soluble nature of the present invention,
the process may provide among other advantages, the advantage of
not having to remove the polymer from the process waste water.
Other process advantages include but are not limited to: (1)
solubility at ambient temperature prevents unwanted deposition on
tissue machine felts or fabrics; (2) insolubility at high
temperature enables surface deposition onto the tissue surface; and
(3) hydrophobic segment interaction at high temperature encourages
the hydrophobic segment to stay on the surface of deposited
material. This morphological conformation may be related to
improved tissue tactile properties.
[0104] The moisture sensitivity of the creping composition can also
be used to modify the frictional properties of the tissue as well
as control coating transfer to the skin. At least a portion of the
creping composition will dissolve in the presence of water. Creping
compositions of the present invention when applied at levels
greater than 100 mg/m.sup.2 have water soluble extractives greater
than 0.35% at a conditioned basis weight of about 28 gsm.
[0105] Four biodegradable and water soluble modified
polysaccharides were selected to demonstrate this invention. They
are hydroxypropyl cellulose, hydroxyethyl cellulose, methyl
cellulose, all available from Ashland, Inc. (Covington, Ky.) with
commercial names of KLUCEL, NATROSOL, BENECEL respectively, and
hydroxypropyl starch which is available from Chemstar (Minneapolis,
Minn.) with a trade name of GLUCOSOL 800 (hereinafter referred to
as GLUCOSOL). Of course, there may be other LCST materials, and
this invention is not to be limited to these four compositions.
Other LCST materials are listed herein. The examples from this
group include, but are not limited to, hydroxypropyl cellulose
(HPC), hydroxypropyl starch (HPS), hydroxypropyl methylcellulose
(HPMC), hydroxyethyl cellulose (HEC), polyethylene oxide,
polyethylene oxide-polypropylene oxide block polymers (such as
PLUCONIC F127) poly(2 ethyl oxazoline, vinyl caprolactone-vinyl
pyrrolidone copolymers, and polyethylene glycol methacrylates.
[0106] The additive composition of the present invention includes
at least one water-soluble film forming component capable of
forming a coating on the surface of a dryer. When applied to a hot
dryer surface the composition goes from a liquid solution to a
suspension containing a precipitate. When transferred to a fibrous
web, the additive composition in the form of a precipitate forms a
deposit that not only stays on top of the tissue, but penetrates
beyond the tissue surface as well.
[0107] Thus, of particular advantage, the deposit allows liquids to
be absorbed therethrough and into the interior of the fibrous web.
Furthermore, the polymer network is wettable due to the water
soluble nature of the additive composition. As such, the additive
composition does not significantly interfere with the liquid
absorption properties of the web while increasing the softness of
the web.
[0108] The water-soluble film forming components contained within
the additive composition may vary depending upon the particular
application and the desired result. In one particular aspect, for
instance, the water-soluble film forming component is GLUCOSOL 800.
The water-soluble film forming component can be present in the
additive composition in any operative amount and will vary based on
the chemical component selected, as well as on the end properties
that are desired. For example, in the exemplary case of GLUCOSOL
800, the water-soluble film forming component can be present in the
additive composition in an amount of about 10-90 wt %, such as
20-80 wt % or 30-70 wt % based on the total weight of the additive
composition, to provide improved benefits.
[0109] An additional water-soluble film forming component is
poly(ethylene oxide) such as POLYOX N3000, available from Dow
Chemical, having a place of business located in Midland, Mich. For
example, in the exemplary case of POLYOX N3000, the second
water-soluble film forming component can be present in the additive
composition in an amount of about 1-30 wt %, such as 5-20% or
10-15% based on the total weight of the additive composition, to
provide improved benefits.
[0110] Suitable water-soluble film forming components also include,
cellulose ethers and esters, poly(acrylic acid) and salts thereof,
poly(acrylate esters), and poly(acrylic acid) copolymers. Other
suitable water-soluble film forming components include
polysaccharides of sufficient chain length to form films such as,
but not limited to, pullulan and pectin. The water soluble
film-forming polymer can also contain additional monoethylenically
unsaturated monomers that do not bear a pendant acid group, but are
copolymerizable with monomers bearing acid groups. Such compounds
include, for example the monoacrylic esters and monomethacrylic
esters of polyethylene glycol or polypropylene glycol, the molar
masses (Mn) of the polyalkylene glycols being up to about 2,000,
for example.
[0111] In some aspects, the water-soluble film forming component is
dissolved into a 1 wt % aqueous solution, and diluted further as
required to provide the desired dosage in mg/m2 of tissue surface.
The dosage is estimated based on the volume of film forming
solution multiplied by the film forming concentration and divided
by the square meters of tissue treated per unit time. In one
particular aspect, the water-soluble film forming component is
hydroxypropyl cellulose (HPC) sold by Ashland, Inc. under the brand
name of KLUCEL. The water-soluble film forming component can be
present in the additive composition in any operative amount and
will vary based on the chemical component selected, as well as on
the end properties that are desired. For example, in the exemplary
case of KLUCEL, the biodegradable, water-soluble modifier component
can be present in the additive composition in an amount of about
1-70 wt %, or at least about 1 wt %, such as at least about 5 wt %,
or least about 10 wt %, or up to about 30 wt %, such as up to about
50 wt % or up to about 75 wt % or more, based on the total weight
of the additive composition, to provide improved benefits. Other
examples of suitable first water-soluble biodegradable film forming
components include methyl cellulose (MC) sold by Ashland, Inc.
under the brand name of BENECEL; hydroxyethyl cellulose sold by
Ashland, Inc. under the brand name of NATROSOL; and hydroxypropyl
starch sold by Chemstar (Minneapolis, Minn.) under the brand name
of GLUCOSOL 800. Any of these chemistries, once diluted in water,
are disposed onto a Yankee dryer surface with a spray boom 22 to
ultimately transfer to the web surface.
[0112] In addition to a water-soluble film forming component, the
additive composition can include a first water-soluble modifier
component. The first water-soluble modifier component is used,
among other things, to adjust adhesion of the web to a paper drying
surface. The water-soluble modifier component can also improve
paper machine cleanliness (e.g., the paper machine dryer surface
and paper machine felts or fabrics). In some aspects, the
water-soluble modifier component is a first water-soluble modifier
component. In one particular aspect, the water-soluble modifier
component is Carbowax PEG 8000, available from Dow Chemical, having
a place of business located in Midland, Mich. The water-soluble
modifier component can be present in the additive composition in
any operative amount and will vary based on the chemical component
selected, as well as on the end properties that are desired. For
example, in the exemplary case of Carbowax PEG 8000, the
water-soluble modifier component can be present in the additive
composition in an amount of about 1-90 wt %, or at least about 1 wt
%, such as at least about 5 wt %, or least about 10 wt %, or up to
about 30 wt %, such as up to about 50 wt % or up to about 75 wt %,
or more, based on the total weight of the additive composition, to
provide improved benefits. Examples of suitable first water-soluble
modifier components include ethylene oxide-propylene oxide block
copolymers.
[0113] The additive composition of the present invention can also
include an additional water-soluble modifier component. The
additional water-soluble modifier component can be utilized, among
other things, as a plasticizer for the water-soluble film forming
component thereby reducing the stiffness and cohesive strength of
the water-soluble film forming component. The additional
water-soluble modifier component can also contribute to improved
end-properties of the web, including but not limited to, increased
void volume of the sheet and/or improved perceived softness.
Desirably, the additional water-soluble modifier component is
different than the first water-soluble modifier component. In one
particular aspect, the additional water-soluble modifier component
is. The additional water-soluble modifier component can be present
in the additive composition in any operative amount and will vary
based on the chemical component selected, as well as on the end
properties of the web that are desired. For example, in the
exemplary case of glycerol, the additional water-soluble modifier
component can be present in the additive composition in an amount
of up to about 10 wt %, such as up to about 20 wt % or up to about
40 wt % or more, based on the total weight of the additive
composition, to provide improved benefits. Examples of suitable
additional water-soluble modifier components include sorbitol,
sucrose, glycerol, glycerol esters, and propylene glycol.
[0114] In some aspects, the additive composition can be diluted
prior to application. The pH of the aqueous solution is generally
less than about 12, such as from about 5 to about 9, and preferably
about 6 to about 8. In this aspect, the additive composition can be
diluted to between 0.20 wt % to 10 wt %, desirably to between 4 to
7 wt %.
[0115] In one aspect, the additive composition may be applied
topically to the web during a creping process. For instance, the
additive composition may be sprayed onto a heated dryer drum in
order to adhere the web to the dryer drum. The web can then be
creped from the dryer drum.
[0116] Referring to FIG. 5, it is worthy to note that it is typical
that individual fibers are coated with a thin film of the additive
composition rather than having a film that covers more than one
fiber.
[0117] The range of operation is a much wider window of chemistry
addition than conventional creping chemistry packages. A
conventionally creped sheet uses a multi-component creping
chemistry package including one component which is a polymer that
forms a relatively hard solid after drying and water removal, such
as a cross-linking or non-crosslinking resin, and a material such
as low molecular weight organic compound which does not form a
solid after drying and water removal, such as an emulsified oil.
This total chemistry package addition range is generally below a
level of 30 milligrams per square meter of the Yankee surface. This
operating range for traditional coating chemistry is desired
because the Yankee dryer coating typically becomes compromised at
higher addition rates. This compromised condition can include
excessively thick coating, discontinuous coating and high coating
variability in both the machine and cross direction of the Yankee
dryer which may result in reduced blade life, sheet quality issues,
increased drying load and low machine efficiency due to breaks and
poor winding. The desirable combinations of the alternative
chemistries of the present invention have been successfully applied
to the Yankee dryer at levels from about 50 to about 1000
milligrams per square meter of Yankee surface. The sheet and
process have been acceptable at these addition ranges. The coating
build up has not been excessive, sheet quality has remained
acceptable at high addition rate and the machine efficiency has not
been affected.
[0118] In general, any suitable fibrous web may be treated in
accordance with the present disclosure. For example, in one aspect,
the base sheet can be a tissue product, such as a bath tissue, a
facial tissue, a paper towel, a napkin, dry and moist wipes, and
the like. In some aspects, the fibrous products may have a bulk
density of at least 3 cc/g. Fibrous products can be made from any
suitable types of fiber. Fibrous products made according to the
present disclosure may include single-ply fibrous products or
multiple-ply fibrous products. For instance, in some aspects, the
product may include two plies, three plies, or more.
[0119] Fibers suitable for making fibrous webs comprise any natural
or synthetic fibers including, but not limited to nonwoody fibers,
such as cotton, abaca, kenaf, sabai grass, flax, esparto grass,
straw, jute hemp, bagasse, milkweed floss fibers, and pineapple
leaf fibers; and woody or pulp fibers such as those obtained from
deciduous and coniferous trees, including softwood fibers, such as
northern and southern softwood kraft fibers; hardwood fibers, such
as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared
in high-yield or low-yield forms and can be pulped in any known
method, including kraft, sulfite, high-yield pulping methods and
other known pulping methods. Fibers prepared from organosolv
pulping methods can also be used, including the fibers and methods
disclosed in U.S. Pat. No. 4,793,898, issued Dec. 27, 1988 to
Laamanen et al.; U.S. Pat. No. 4,594,130, issued Jun. 10, 1986 to
Chang et al.; and U.S. Pat. No. 3,585,104. Useful fibers can also
be produced by anthraquinone pulping, exemplified by U.S. Pat. No.
5,595,628 issued Jan. 21, 1997, to Gordon et al.
[0120] The fibrous webs of the present invention can also include
synthetic fibers. For instance, the fibrous webs can include up to
about 10%, such as up to about 30% or up to about 50% or up to
about 70% or more by dry weight, to provide improved benefits.
Suitable synthetic fibers include rayon, polyolefin fibers,
polyester fibers, bicomponent sheath-core fibers, multi-component
binder fibers, and the like. Synthetic cellulose fiber types
include rayon in all its varieties and other fibers derived from
viscose or chemically-modified cellulose.
[0121] Chemically treated natural cellulosic fibers can be used,
for example, mercerized pulps, chemically stiffened or crosslinked
fibers, or sulfonated fibers. For good mechanical properties in
using web forming fibers, it can be desirable that the fibers be
relatively undamaged and largely unrefined or only lightly refined.
While recycled fibers can be used, virgin fibers are generally
useful for their mechanical properties and lack of contaminants.
Mercerized fibers, regenerated cellulosic fibers, cellulose
produced by microbes, rayon, and other cellulosic material or
cellulosic derivatives can be used. Suitable web forming fibers can
also include recycled fibers, virgin fibers, or mixes thereof.
[0122] In general, any process capable of forming a web can also be
utilized in the present disclosure. For example, a web forming
process of the present disclosure can utilize creping, wet creping,
double creping, recreping, double recreping, embossing, wet
pressing, air pressing, through-air drying, hydroentangling, creped
through-air drying, co-forming, air laying, as well as other
processes known in the art. For hydroentangled material, the
percentage of pulp is about 70-85%.
[0123] Also suitable for articles of the present disclosure are
fibrous sheets that are pattern densified or imprinted, such as the
fibrous sheets disclosed in any of the following U.S. Pat. No.
4,514,345 issued on Apr. 30, 1985, to Johnson et al.; U.S. Pat. No.
4,528,239 issued on Jul. 9, 1985, to Trokhan; U.S. Pat. No.
5,098,522 issued on Mar. 24, 1992; U.S. Pat. No. 5,260,171 issued
on Nov. 9, 1993, to Smurkoski et al.; U.S. Pat. No. 5,275,700
issued on Jan. 4, 1994, to Trokhan; U.S. Pat. No. 5,328,565 issued
on Jul. 12, 1994, to Rasch et al.; U.S. Pat. No. 5,334,289 issued
on Aug. 2, 1994, to Trokhan et al.; U.S. Pat. No. 5,431,786 issued
on Jul. 11, 1995, to Rasch et al.; U.S. Pat. No. 5,496,624 issued
on Mar. 5, 1996, to Steltjes, Jr. et al.; U.S. Pat. No. 5,500,277
issued on Mar. 19, 1996, to Trokhan et al.; U.S. Pat. No. 5,514,523
issued on May 7, 1996, to Trokhan et al.; U.S. Pat. No. 5,554,467
issued on Sep. 10, 1996, to Trokhan et al.; U.S. Pat. No. 5,566,724
issued on Oct. 22, 1996, to Trokhan et al.; U.S. Pat. No. 5,624,790
issued on Apr. 29, 1997, to Trokhan et al.; and, U.S. Pat. No.
5,628,876 issued on May 13, 1997, to Ayers et al., the disclosures
of which are incorporated herein by reference to the extent that
they are non-contradictory herewith. Such imprinted fibrous sheets
may have a network of densified regions that have been imprinted
against a drum dryer by an imprinting fabric, and regions that are
relatively less densified (e.g., "domes" in the fibrous sheet)
corresponding to deflection conduits in the imprinting fabric,
wherein the fibrous sheet superposed over the deflection conduits
was deflected by an air pressure differential across the deflection
conduit to form a lower-density pillow-like region or dome in the
fibrous sheet.
[0124] The fibrous web can also be formed without a substantial
amount of inner fiber-to-fiber bond strength. In this regard, the
fiber furnish used to form the base web can be treated with a
chemical debonding agent. The debonding agent can be added to the
fiber slurry during the pulping process or can be added directly to
the headbox. Suitable debonding agents that may be used in the
present disclosure include cationic debonding agents such as fatty
dialkyl quaternary amine salts, mono fatty alkyl tertiary amine
salts, primary amine salts, imidazoline quaternary salts, silicone,
quaternary salt and unsaturated fatty alkyl amine salts. Other
suitable debonding agents are disclosed in U.S. Pat. No. 5,529,665
to Kaun which is incorporated herein by reference. In particular,
Kaun discloses the use of cationic silicone compositions as
debonding agents.
[0125] Optional chemical additives may also be added to the aqueous
web forming furnish or to the formed embryonic web to impart
additional benefits to the product and process and are not
antagonistic to the intended benefits of the invention. The
following chemicals are included as examples and are not intended
to limit the scope of the invention.
[0126] The types of chemicals that may be added to the paper web
include, but are not limited to, absorbency aids usually in the
form of cationic, anionic, or non-ionic surfactants, humectants and
plasticizers such as low molecular weight polyethylene glycols and
polyhydroxy compounds such as glycerin and propylene glycol.
Materials that supply skin health benefits such as mineral oil,
aloe extract, vitamin-E, silicone, lotions in general and the like
may also be incorporated into the finished products. Such chemicals
may be added at any point in the web forming process.
[0127] In general, the products of the present invention can be
used in conjunction with any known materials and chemicals that are
not antagonistic to its intended use. Examples of such materials
include but are not limited to odor control agents, such as odor
absorbents, activated carbon fibers and particles, baby powder,
baking soda, chelating agents, zeolites, perfumes or other
odor-masking agents, cyclodextrin compounds, oxidizers, and the
like. Superabsorbent particles, synthetic fibers, or films may also
be employed. Additional options include cationic dyes, optical
brighteners, humectants, emollients, and the like.
[0128] Fibrous webs that may be treated in accordance with the
present disclosure may include a single homogenous layer of fibers
or may include a stratified or layered construction. For instance,
the fibrous web ply may include two or three layers of fibers. Each
layer may have a different fiber composition. For example,
referring to FIG. 3, one aspect of a device for forming a
multi-layered stratified pulp furnish is illustrated. As shown, a
three-layered headbox 10 generally includes an upper head box wall
12 and a lower head box wall 14. Headbox 10 further includes a
first divider 16 and a second divider 19, which separate three
fiber stock layers.
[0129] Each of the fiber layers comprise a dilute aqueous
suspension of papermaking fibers. The particular fibers contained
in each layer generally depend upon the product being formed and
the desired results. For instance, the fiber composition of each
layer may vary depending upon whether a bath tissue product, facial
tissue product or paper towel is being produced. In one aspect, for
instance, middle layer 21 contains southern softwood kraft fibers
either alone or in combination with other fibers such as high yield
fibers. Outer layers 23 and 25, on the other hand, contain softwood
fibers, such as northern softwood kraft.
[0130] In an alternative aspect, the middle layer may contain
softwood fibers for strength, while the outer layers may comprise
hardwood fibers, such as eucalyptus fibers, for a perceived
softness.
[0131] An endless traveling forming fabric 26, suitably supported
and driven by rolls 28 and 30, receives the layered papermaking
stock issuing from headbox 10. Once retained on fabric 26, the
layered fiber suspension passes water through the fabric as shown
by the arrows 32. Water removal is achieved by combinations of
gravity, centrifugal force and vacuum suction depending on the
forming configuration.
[0132] Forming multi-layered paper webs is also described and
disclosed in U.S. Pat. No. 5,129,988 to Farrington, Jr., which is
incorporated herein by reference in a manner that is consistent
herewith.
[0133] The basis weight of fibrous webs made in accordance with the
present disclosure can vary depending upon the final product. For
example, the process may be used to produce bath tissues, facial
tissues, paper towels, and the like. In general, the basis weight
of such fibrous products may vary from about 5 gsm to about 110
gsm, such as from about 10 gsm to about 90 gsm. For bath tissue and
facial tissues, for instance, the basis weight may range from about
10 gsm to about 40 gsm. For paper towels, on the other hand, the
basis weight may range from about 25 gsm to about 80 gsm or
more.
[0134] Fibrous products made according to the above processes can
have relatively good bulk characteristics. For instance, the
fibrous web bulk may also vary from about 1-20 cc/g, such as from
about 3-15 cc/g or from about 5-12 cc/g.
[0135] In multiple-ply products, the basis weight of each fibrous
web present in the product can also vary. In general, the total
basis weight of a multiple ply product will generally be the same
as indicated above, such as from about 20 gsm to about 200 gsm.
Thus, the basis weight of each ply can be from about 10 gsm to
about 60 gsm, such as from about 20 gsm to about 40 gsm.
[0136] Once the aqueous suspension of fibers is formed into a
fibrous web, the fibrous web may be processed using various
techniques and methods. For example, referring to FIG. 4, shown is
an apparatus related to the method for making through-dried fibrous
sheets. (For simplicity, the various tensioning rolls schematically
used to define the several fabric runs are shown, but not numbered.
It will be appreciated that variations from the apparatus and
method illustrated in FIG. 4 can be made without departing from the
general process.) Shown is a twin wire former having a papermaking
headbox 34, such as a layered headbox, which injects or deposits a
stream 36 of an aqueous suspension of papermaking fibers onto the
forming fabric 38 positioned on a forming roll 39. The forming
fabric serves to support and carry the newly-formed wet web
downstream in the process as the web is partially dewatered to a
consistency of about 10 dry weight percent. Additional dewatering
of the wet web can be carried out such as by vacuum suction, while
the wet web is supported by the forming fabric.
[0137] The wet web is then transferred from the forming fabric to a
transfer fabric 40. In one aspect, the transfer fabric can be
traveling at a slower speed than the forming fabric in order to
impart increased stretch into the web. This is commonly referred to
as a "rush" transfer. Preferably the transfer fabric can have a
void volume that is equal to or less than that of the forming
fabric. The relative speed difference between the two fabrics can
be from 0-60%, more specifically from about 15-45%. Transfer is
preferably carried out with the assistance of a vacuum shoe 42 such
that the forming fabric and the transfer fabric simultaneously
converge and diverge at the leading edge of the vacuum slot.
[0138] The web is then transferred from the transfer fabric to the
throughdrying fabric 44 with the aid of a vacuum transfer roll 46
or a vacuum transfer shoe, optionally again using a fixed gap
transfer as previously described. The throughdrying fabric can be
traveling at about the same speed or a different speed relative to
the transfer fabric. If desired, the throughdrying fabric can be
run at a slower speed to further enhance stretch. Transfer can be
carried out with vacuum assistance to ensure deformation of the
sheet to conform to the throughdrying fabric, thus yielding desired
bulk and appearance if desired. Suitable throughdrying fabrics are
described in U.S. Pat. No. 5,429,686 issued to Kai F. Chiu et al.
and U.S. Pat. No. 5,672,248 to Wendt et al., which are incorporated
by reference.
[0139] In one aspect, the throughdrying fabric contains high and
long impression knuckles. For example, the throughdrying fabric can
have from about 5 to about 300 impression knuckles per square inch
which are raised at least about 0.005 inches above the plane of the
fabric. During drying, the web can be macroscopically arranged to
conform to the surface of the throughdrying fabric and form a
three-dimensional surface. Flat surfaces, however, can also be used
in the present disclosure.
[0140] The side of the web contacting the throughdrying fabric is
typically referred to as the "fabric side" of the paper web. The
fabric side of the paper web, as described above, may have a shape
that conforms to the surface of the throughdrying fabric after the
fabric is dried in the throughdryer. The opposite side of the paper
web, on the other hand, is typically referred to as the "air side".
The air side of the web is typically smoother than the fabric side
during normal throughdrying processes.
[0141] The level of vacuum used for the web transfers can be from
about 3 to about 15 inches of mercury (75 to about 380 millimeters
of mercury), preferably about 5 inches (125 millimeters) of
mercury. The vacuum shoe (negative pressure) can be supplemented or
replaced by the use of positive pressure from the opposite side of
the web to blow the web onto the next fabric in addition to or as a
replacement for sucking it onto the next fabric with vacuum. Also,
a vacuum roll or rolls can be used to replace the vacuum
shoe(s).
[0142] While supported by the throughdrying fabric, the web is
finally dried to a consistency of about 94 percent or greater by
the throughdryer 48 and thereafter transferred to a carrier fabric
50. The dried basesheet 52 is transported to the reel 54 using
carrier fabric 50 and an optional carrier fabric 56. An optional
pressurized turning roll 58 can be used to facilitate transfer of
the web from carrier fabric 50 to fabric 56. Suitable carrier
fabrics for this purpose are Albany International 84M or 94M and
Asten 959 or 937, all of which are relatively smooth fabrics having
a fine pattern. Although not shown, reel calendering or subsequent
off-line calendering can be used to improve the smoothness and
softness of the basesheet.
[0143] In one aspect, the reel 54 shown in FIG. 4 can run at a
speed slower than the fabric 56 in a rush transfer process for
building crepe into the paper web 52. For instance, the relative
speed difference between the reel and the fabric can be from about
5% to about 25% and, such as from about 12% to about 14%. Rush
transfer at the reel can occur either alone or in conjunction with
a rush transfer process upstream, such as between the forming
fabric and the transfer fabric.
[0144] In one aspect, the paper web 52 is a textured web which has
been dried in a three-dimensional state such that the hydrogen
bonds joining fibers were substantially formed while the web was
not in a flat, planar state. For instance, the web can be formed
while the web is on a highly textured throughdrying fabric or other
three-dimensional substrate. Processes for producing uncreped
throughdried fabrics are, for instance, disclosed in U.S. Pat. No.
5,672,248 to Wendt, et al.; U.S. Pat. No. 5,656,132 to Farrington,
et al.; U.S. Pat. No. 6,120,642 to Lindsay and Burazin; U.S. Pat.
No. 6,096,169 to Hermans, et al.; U.S. Pat. No. 6,197,154 to Chen,
et al.; and U.S. Pat. No. 6,143,135 to Hada, et al., all of which
are herein incorporated by reference in their entireties.
[0145] Referring now to FIG. 2, another aspect of a process for
forming wet creped fibrous webs is shown. In this aspect, a headbox
60 emits an aqueous suspension of fibers onto a forming fabric 62
which is supported and driven by a plurality of guide rolls 64. A
vacuum box 66 is disposed beneath forming fabric 62 and is adapted
to remove water from the fiber furnish to assist in forming a web.
From forming fabric 62, a formed web 68 is transferred to a second
fabric 70, which may be either a wire or a felt. Fabric 70 is
supported for movement around a continuous path by a plurality of
guide rolls 72. Also included is a pick up roll 74 designed to
facilitate transfer of web 68 from fabric 62 to fabric 70.
[0146] From fabric 70, web 68, in this aspect, is transferred to
the surface of a rotatable heated dryer drum 76, such as a Yankee
dryer.
[0147] In accordance with the present disclosure, the additive
composition can be incorporated into the fibrous web 68 by
topically applying the additive composition during the drying
process. In one particular aspect, the additive composition of the
present disclosure may be applied to the surface of the dryer drum
76 for transfer onto one side of the fibrous web 68. In this
manner, the additive composition is used to adhere the fibrous web
68 to the dryer drum 76. In this aspect, as web 68 is carried
through a portion of the rotational path of the dryer surface, heat
is imparted to the web causing most of the moisture contained
within the web to be evaporated. Web 68 is then removed from dryer
drum 76 by a creping blade 78. Creping the web as it is formed
further reduces internal bonding within the web and increases
softness. Applying the additive composition to the web during
creping can, in some aspects, increase the strength of the web.
[0148] In addition to applying the additive composition during
formation of the fibrous web, the additive composition may also be
used in post-forming processes. For example, in one aspect, the
additive composition may be used during a print-creping process,
forming patterns including but not limited to those patterns shown
in FIGS. 6 and 7. Specifically, once topically applied to a fibrous
web, the additive composition has been found well-suited to
adhering the fibrous web to a creping surface, such as in a
print-creping operation.
[0149] For example, once a fibrous web is formed and dried, in one
aspect, the additive composition may be applied to at least one
side of the web and the at least one side of the web may then be
creped. In general, the additive composition may be applied to only
one side of the web and only one side of the web may be creped, the
additive composition may be applied to both sides of the web and
only one side of the web is creped, or the additive composition may
be applied to each side of the web and each side of the web may be
creped.
[0150] The additive composition can penetrate the fibrous web. The
degree of such penetration is dependent upon degree of solubility
of the additive composition. In general, a water soluble additive
composition has a higher degree of penetration. On the other hand,
the precipitate of a LCST polymer at the hot Yankee dryer's surface
and has a much reduced degree of penetration. Creping the fibrous
web increases the softness of the web by breaking apart
fiber-to-fiber bonds contained within the fibrous web.
[0151] In one aspect, fibrous webs made according to the present
disclosure can be incorporated into multiple-ply products. For
instance, in one aspect, a fibrous web made according to the
present disclosure can be attached to one or more other fibrous
webs for forming a wiping product having desired characteristics.
The other webs laminated to the fibrous web of the present
disclosure can be, for instance, a wet-creped web, a calendered
web, an embossed web, a through-air dried web, a creped through-air
dried web, an uncreped through-air dried web, an airlaid web, and
the like.
[0152] In one aspect, when incorporating a fibrous web made
according to the present disclosure into a multiple-ply product, it
may be desirable to only apply the additive composition to one side
of the fibrous web and to thereafter crepe the treated side of the
web. The creped side of the web is then used to form an exterior
surface of a multiple-ply product. The untreated and uncreped side
of the web, on the other hand, is attached by any suitable means to
one or more plies.
[0153] Like cellulose, the materials used for the inventive creping
chemistries are classified as humectants. This means they promote
the adsorption and retention of water, including water vapor from
the atmosphere. It is hypothesized that the creping chemistries
used in this invention retain a higher percentage, by-weight, of
water than cellulose under a given set of conditions (temperature,
relative humidity). Under conditions of 23.degree. C. and 50%
relative humidity, for example, wood pulp fibers typically
equilibrate at about 5% moisture by weight. Humectant creping
chemistries in the tissue sheet that equilibrate at a higher level
of moisture than cellulose will serve to bring, and hold,
additional water within the structure. It is further hypothesized
that the humectant creping chemistries are present in a
concentration gradient within the tissue structure, having a high
concentration on the creped tissue surface and decreasing in
concentration as you move in the z-direction away from the creped
surface. This chemical concentration gradient will result in an
adsorbed moisture concentration gradient within the tissue
thickness. The dryer side of the tissue, containing the highest
concentration of humectant creping chemistry will have the highest
localized moisture content.
[0154] Tissue sheets made according to the present disclosure may
possess a desirable crepe structure. The crepe structure is very
fine, where the crepe folds are small in both frequency and
amplitude. This results in a smoother and softer tissue sheet. The
crepe structure is characterized using tissue images and the STFI
mottling program, as described in the Test Method section.
[0155] Tissue sheets made according to the present disclosure may
possess a desirable surface structure. In addition to having a fine
crepe structure, individual fibers protrude from the surface of the
tissue while still being attached. These individual fibers
protruding from the surface are called free fiber ends and provide
enhanced softness, due to both the fuzziness of the tissue surface,
as well as by the softening of the fibers from the coating of the
additive composition. This results in a velvety soft tissue sheet.
Evidence for free fiber ends are provided by visual images
generated with SEM and the "Fuzz on Edge" test, as described in the
Test Method section. See FIGS. 12-14.
[0156] Tissue sheets made according to the present disclosure may
possess a desirable lubricious hand feel. The additive composition
disposed on the fibers provides a smooth and slippery quality.
Lubricious or lubricated hand feel is demonstrated by a significant
reduction in coefficient of friction on a skin stimulant of
collagen film, as described in the Test Method section.
[0157] Tissue sheets made according to the present disclosure may
possess a desirable quality whereby some of the additive
composition chemistry is transferred to moist surfaces, such as
human skin. Additive compositions of the present disclosure are
able to transfer PEG to (moist) skin, which is perceived to be
smooth and having lotion. The method used to determine the amount
of water soluble creping blend component transferred from the
facial tissue to a skin stimulant of collagen film is described in
the Test Method section.
[0158] Tissue sheets made according to the present disclosure may
possess a desirable water absorption rate. The water absorption
rate of cellulose based tissue products affects functional
performance. In one example, facial tissue must be sufficiently
strong in use and also wet out very fast in order to absorb
liquids, such as nasal discharge. Facial tissue with outstanding
softness but delayed absorbent (wet out) rate may not be acceptable
for optimum performance. Absorbent rate is measured as described in
the Test Method section.
[0159] By using readily water soluble Yankee dryer coating
chemicals, in the additive composition of the present disclosure,
to improve softness, we have maintained very quick water wet out
rate. Hydrophobic topical chemicals tend to reduce water absorption
rate and capacity, especially when a significant amount of the
surface fiber area is coated with hydrophobic chemicals. Additive
compositions of the present disclosure are readily water
soluble.
EXAMPLES
I. Example 1
Sample Preparation
[0160] In this example, fibrous webs were made generally according
to the process illustrated in FIG. 2. In order to adhere the
fibrous web to a creping surface, which in this example comprised a
Yankee dryer, additive compositions made according to the present
disclosure were sprayed onto the dryer prior to contacting the
dryer with the web. The samples were then subjected to various
standardized tests.
[0161] For purposes of comparison, samples were also produced using
a conventional creping chemistry treatment as a control. In
addition, samples were also produced using an additive composition
having a water insoluble polyolefin dispersion as described in U.S.
Pat. Pub. 2007/0144697, incorporated herein to the extent that it
is consistent with the present invention. Finally, various
commercially available products were also sampled.
[0162] For reference, tissues manufactured with additive
compositions made according to the present disclosure will be
referred to as Technology A tissues. Likewise, tissues manufactured
with conventional creping chemistry will be referred to as
Technology B tissues. Finally, tissues manufactured with an
additive composition having a water insoluble polyolefin dispersion
as described in U.S. Pat. Pub. 2007/0144697 will be referred to as
Technology C tissues. Competitive commercially available products
are not classified.
[0163] In this example, 2-ply facial tissue products were produced
and tested according to the same tests described in the Test
Methods section. The following tissue manufacturing process was
used to produce the samples.
[0164] Initially, northern softwood kraft (NSWK) pulp was dispersed
in a pulper for 30 minutes at 4% consistency at about 100.degree.
F. The NSWK pulp was then transferred to a dump chest and
subsequently diluted to approximately 3% consistency. The NSWK pulp
was refined at 4.5-5.5 hp-days/metric ton. The softwood fibers were
used as the inner strength layer in a 3-layer tissue structure. The
NSWK layer contributed approximately 34-38% of the final sheet
weight.
[0165] Two kilograms KYMENE.RTM. 6500 and 2-5 kilograms
Hercobond.RTM. 1366 (Ashland, Incorporated, Covington, Ky., U.S.A.)
per metric ton of wood fiber was added to the NSWK pulp prior to
the headbox.
[0166] Aracruz ECF, a eucalyptus hardwood Kraft (EHWK) pulp
(Aracruz, Rio de Janeiro, RJ, Brazil) was dispersed in a pulper for
30 minutes at about 4% consistency at about 100 degrees Fahrenheit.
The EHWK pulp was then transferred to a dump chest and subsequently
diluted to about 3% consistency. The EHWK pulp fibers were used in
the two outer layers of the 3-layered tissue structure. The EHWK
layers contributed approximately 62-66% of the final sheet
weight.
[0167] Two kilograms KYMENE.RTM. 6500 per metric ton of wood fiber
was added to the EHWK pulp prior to the headbox.
[0168] The pulp fibers from the machine chests were pumped to the
headbox at a consistency of about 0.1%. 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 in a Crescent Former, as depicted similar to the
process illustrated in FIG. 3 of U.S. Pat. No. 6,379,498.
[0169] The wet sheet, about 10-20% consistency, was adhered to a
Yankee dryer, traveling at about 2000 to about 5000 fpm, (600
mpm-1500 mpm) through a nip via a pressure roll.
[0170] The consistency of the wet sheet after the pressure roll nip
(post-pressure roll consistency or PPRC) was approximately 40%. The
wet sheet is adhered to the Yankee dryer due to the additive
composition that is applied to the dryer surface. Spray booms
situated underneath the Yankee dryer sprayed the creping/additive
composition, described in the present disclosure, onto the dryer
surface at addition levels ranging from 50 to 1000 mg/m2.
[0171] The creping compositions of GLUCOSOL 800, PEG 8000, and
POLYOX N3000 that were applied to the Yankee dryer were prepared by
dissolution of the solid polymers into water followed by stirring
until the solution was homogeneous. Each polymer was dissolved and
pumped separately to the process. Glucosol 800 and PEG 8000 were
prepared at 5% solids. POLYOX N3000 was prepared at 2% solids. The
flow rates of the GLUCOSOL 800, PEG 8000, or POLYOX N3000 solutions
were varied to deliver a total addition of 50 to 1000 mg/m.sup.2
spray coverage on the Yankee Dryer at the desired component ratio.
Varying the flow rates of the polymer solutions also varies the
amount of solids incorporated into the base web. For instance, at
100 mg/m.sup.2 spray coverage on the Yankee Dryer, it is estimated
that about 1% additive composition solids is incorporated into the
tissue web. At 200 mg/m.sup.2 spray coverage on the Yankee Dryer,
it is estimated that about 2% additive composition solids is
incorporated into the tissue web. At 400 mg/m.sup.2 spray coverage
on the Yankee Dryer, it is estimated that about 4% additive
composition solids is incorporated into the tissue web.
[0172] The sheet was dried to about 95%-98% consistency as it
traveled on the Yankee dryer and to the creping blade. The creping
blade subsequently scraped the tissue sheet and a portion of the
additive composition off the Yankee dryer. The creped tissue
basesheet was then wound onto a core traveling at about 1570 to
about 3925 fpm (480 mpm to 1200 mpm) into soft rolls for
converting. The resulting tissue basesheet had an air-dried basis
weight of about 14.2 g/m2. Two or three soft rolls of the creped
tissue were then rewound, calendared, and plied together so that
both creped sides were on the outside of the 2- or 3-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. See
Table 1 for the Inventive Sample Code Descriptions.
TABLE-US-00004 TABLE 1 Total Water- Additional Add-on soluble Film
Water-soluble Water-soluble Rate (mg/m2 Sample Forming Modifier
Film Forming of Dryer Code Component Component Component surface) 1
GLUCOSOL CARBOWAX 100 800 (13%) PEG 8000 (87%) 2 GLUCOSOL CARBOWAX
1000 800 (13%) PEG 8000 (87%) 3 GLUCOSOL CARBOWAX POLYOX N3000 200
800 (30%) PEG 8000 (10%) (60%) 4 GLUCOSOL CARBOWAX POLYOX N3000 400
800 (30%) PEG 8000 (10%) (60%) 5 GLUCOSOL CARBOWAX POLYOX N3000 100
800 (22%) PEG 8000 (14%) (64%) 6 GLUCOSOL CARBOWAX POLYOX N3000 157
800 (22%) PEG 8000 (14%) (64%)
[0173] For purposes of comparison, a 2-ply sample was also produced
according to the same process. Instead of using an additive
composition in accordance with the present disclosure, however, a
conventional creping chemistry (Technology B) was applied to the
Yankee dryer. Thus, the samples that were tested included Sample
Codes 1 to 6 containing the additive composition in amounts from 1%
by weight to 10% by weight, and a Control not containing the
additive composition. In addition, commercially available facial
tissues were also tested. Particularly, standard KLEENEX.RTM.
facial tissues, PUFFS.RTM. facial tissues, PUFFS PLUS.RTM. facial
tissues, HOMELIFE Whisper Soft facial tissues, and SCOTTIES.RTM.
facial tissues were also tested. All of the commercially available
facial tissues contain 2 plies. PUFFS PLUS.RTM. facial tissue is
treated with a silicone. See Table 2 for sample descriptions.
TABLE-US-00005 TABLE 2 Sample Code Sample Description Manufacturer
Carton Code Technology 1 Invention Kimberly- N/A A Clark
Corporation 2 Invention Kimberly- N/A A Clark Corporation 3
Invention Kimberly- N/A A Clark Corporation 4 Invention Kimberly-
N/A A Clark Corporation 5 Invention Kimberly- N/A A Clark
Corporation 6 Invention Kimberly- N/A A Clark Corporation Control 1
KLEENEX .RTM. Kimberly- H1257A B Facial Tissue Clark Corporation
Control 2 KLEENEX .RTM. Kimberly- H092021 C Facial Tissue Clark
Corporation Control 3 KLEENEX .RTM. Kimberly- 2Y19691 C Facial
Tissue Clark Corporation Control 4 PUFFS .RTM. Procter &
9133U0201N191524 unknown Facial Tissue Gamble Control 5 PUFFS
Procter & 9108U0201501510 unknown PLUS .RTM. Facial Gamble
Tissue Control 6 HOMELIFE Clearwater L2111209S1883 unknown Whisper
Soft Paper Facial Tissue Control 7 SCOTTIES .RTM. Irving Tissue
39066340156 unknown Hypoallergenic Facial Tissue
[0174] Prior to testing, all of the samples were conditioned
according to TAPPI standards. In particular, the samples were
placed in an atmosphere at 50% relative humidity and 23.degree. C.
for at least four hours.
[0175] The following results are shown in Table 3. (Note that
Controls 1-7 are the same in all of the test results show in Tables
3-5 and 7-9.)
TABLE-US-00006 TABLE 3 Conditioned Basis Conditioned Sample Weight
Single Sheet Sheet Bulk Code (gsm) Caliper (um) (cc/g) GMT (g/3'')
1 27.06 180 6.7 609 2 29.96 201 6.7 530 3 28.90 194 6.7 732 4 28.60
185 6.5 727 5 27.6 173 6.3 617 6 27.9 173 6.2 703 Control 1 27.7
180 6.5 639 Control 2 29.2 203 7 739 Control 3 29.6 193 6.5 776
Control 4 29.83 274 9.2 686 Control 5 27.23 322 11.8 902 Control 6
30.77 188 6.1 767 Control 7 29.84 173 5.8 761
[0176] Some of the water soluble additive composition (of the
present disclosure) is transferred to the tissue web during the
creping process and is disposed on portions of the web/pulp fibers.
At least a portion of the additive composition will dissolve in the
presence of water. Additive compositions of the present invention,
when applied at levels greater than 100 mg/m2, have water soluble
extractives greater than 0.35%, as measured by the test method
described in the Test Method section. See Table 4 for test
results.
TABLE-US-00007 TABLE 4 Water Soluble Sample Extractables Code (% by
weight) 1 0.51 2 3.97 3 NA 4 1.01 5 0.76 6 1.14 Control 1 0.27
Control 2 0.35 Control 3 0.22 Control 4 0.28 Control 5 0.24 Control
6 0.24 Control 7 0.28
[0177] The tissue sheets made according to the present disclosure
possess an equivalent or faster water absorbent rate, as well as
several other unique properties. Tissue sheets made according to
the present disclosure may possess a desirable water absorption
rate. The water absorption rate of cellulose based tissue products
affects functional performance. In one example, facial tissue must
be sufficiently strong in use and also wet out very fast in order
to absorb liquids, such as nasal discharge. Facial tissue with
outstanding softness but delayed absorbent (wet out) rate may not
be acceptable for optimum performance. Absorbent rate is measured
as described in the Test Method section.
[0178] Technology C tissues have slow wet out times, likely due to
the water insoluble creping chemistry that is transferred to the
surface of the tissue. Compared to Technology B (conventional
creping chemistry) and other competitive commercially available
tissues, Technology C tissues have a wet out time that is at least
2 times slower. By contrast the wet out times of the Technology A
tissues are all under 3 seconds. Technology A tissue wet out time
is independent of the spray application rate.
[0179] Tissue sheets made according to the present disclosure may
possess a desirable crepe structure. The crepe structure is very
fine, where the crepe folds are small in both frequency and
amplitude. This results in a smoother and softer tissue sheet. The
crepe structure is characterized using tissue images and the STFI
mottling program, as described in the Test Method section.
[0180] Tissue sheets made according to the present disclosure may
possess a desirable surface structure. In addition to having a fine
crepe structure, individual fibers protrude from the surface of the
tissue while still being attached. These individual fibers
protruding from the surface are called free fiber ends and provide
enhanced softness, due to both the fuzziness of the tissue surface,
as well as by the softening of the fibers from the coating of the
additive composition. This results in a velvety soft tissue sheet.
Evidence for free fiber ends are provided by visual images
generated with SEM and the "Fuzz on Edge" test, as described in the
Test Method section. See Table 5 for test results.
[0181] The Fine Crepe Structure values of the Technology A tissues
are all better (lower) than or equal to the Control codes.
Additionally, the Fuzz on Edge values of the Technology A tissues
are all much higher (better) than any of the Control codes.
TABLE-US-00008 TABLE 5 Wet-out Fine Crepe Fuzz on Sample Time
Structure (% COV Edge Code (sec) @ 0.28-0.55 mm) (PR/EL) 1 1.8 NA
NA 2 2.2 NA NA 3 2.0 NA NA 4 2.2 NA NA 5 2.2 25.0 1.43 6 2.3 23.8
1.32 Control 1 3.3 35.4 0.93 Control 2 14.8 28.7 1.20 Control 3
60.3 26.9 0.75 Control 4 5.7 30.3 0.81 Control 5 106.6 27.7 0.78
Control 6 2.3 30.8 0.78 Control 7 2.4 24.7 0.95
[0182] The moisture sensitivity (water solubility) of the creping
composition, present on the creped tissue, enables the coating to
be used for controlled delivery of ingredients that have been mixed
into the composition. Under low moisture conditions ingredients
remain trapped within the composition's matrix. Under high moisture
conditions, the ingredients are released as the composition
dissolves.
Example 2
[0183] Tissue sheets were prepared as described in Example 1.
[0184] Tissue sheets made according to the present disclosure may
possess a desirable quality whereby some of the additive
composition chemistry is transferred to moist surfaces, such as
human skin. Additive compositions of the present disclosure are
able to transfer PEG to moist skin, which is perceived to be smooth
with the feel of lotion. The method used to determine the amount of
water soluble creping blend component transferred from the facial
tissue to a skin stimulant of collagen film is described in the
Test Method section. See Table 6 for test results.
TABLE-US-00009 TABLE 6 PEG Transfer with collagen PEG Transfer
Sample at 50% RH with collagen at Code (ug/ml) 100% RH (ug/ml) 1 0
0 2 0 0 3 0 24 4 0 76
[0185] These results indicate that PEG 8000 is transferred to the
skin model material (collagen film), but only when the film is well
hydrated (100% RH equilibration) and when PEO (POLYOX N3000) is
incorporated into the creping blend. Because the creping blend
consists of water soluble components the transfer is enabled by
contact with a slightly moist surface, as in the samples
equilibrated at 100% RH.
[0186] A possible explanation for the PEG transfer happening only
when PEO is incorporated is that the blend with high molecular
weight PEO has higher viscosity so more of the creping blend
remains on the tissue surface where it can be transferred to the
skin.
Example 3
[0187] Tissue sheets made according to the present disclosure may
possess a desirable lubricious hand feel. The additive composition
disposed on the fibers provides a smooth and slippery quality.
Lubricious or lubricated hand feel is demonstrated by a significant
reduction in coefficient of friction on a skin stimulant of
collagen film, as described in the Test Method section.
[0188] Lubricious or lubricated hand feel was demonstrated by a
significant reduction in coefficient of friction on a skin
stimulant of collagen film. Samples were produced as described in
Example 1. As shown in the Table below, treatment of the collagen
film skin stimulant results in a significant reduction of kinetic
coefficient of friction indicative of a lubricated hand feel. See
Table 7 for test results.
TABLE-US-00010 TABLE 7 Lubricious % reduction from Sample Handfeel
untreated Code (kinetic COF) collagen film Untreated 163.5 NA
Collagen Film 4 69.8 57.3 5 77.0 52.9 6 69.9 57.2 Control 1 118.4
27.6 Control 2 78.4 52.0 Control 3 102.0 37.6 Control 4 73.1 55.3
Control 5 68.0 58.4 Control 6 114.2 30.2 Control 7 106.2 35.0
Example 4
[0189] Tissues were prepared as described in Example 1. Fibrous
webs made according to the present disclosure (Technology A
tissues) can have a perceived softness and/or strength that is
similar to or better than fibrous webs treated with a conventional
treatment (Technology B tissues) or with recent technology
treatments (Technology C tissues). See Table 8 for test
results.
TABLE-US-00011 TABLE 8 Softness Sample IHR Softness Statistical
Wet-out Time Code (Log Odds) Grouping GMT (g/3'') (sec) 5 6.223 AB
617 2.2 6 6.536 A 703 2.3 Control 1 0.267 G 639 3.3 Control 2 4.757
DE 739 14.8
[0190] The data from the IHR Softness test show that the tissues of
the present invention (Technology A tissues) have higher Log Odds
and Highest Statistical Groupings than Control 1 or 2, which are
Technology B and C tissues respectively. This is achieved with GMT
strengths which are about equal to or greater than the control
tissue codes. Additionally, this is achieved with wet-out times
which are lower than the control codes.
[0191] In a separate test, this softness ranking was verified as
shown in Table 9.
TABLE-US-00012 TABLE 9 Softness Sample IHR Softness Statistical
Code (Log Odds) Grouping 3 0.430 AB 4 0.910 A Control 1 -1.561 G
Control 2 0.000 BCD Control 4 -0.955 FG
Example 5
[0192] Tissues were prepared as described in Example 1. Fibrous
webs made according to the present disclosure (Technology A
tissues) can have a perceived softness greater than conventional
tissues largely due to the amount of additive composition available
at the surface of the dryer-side of the tissue surface. This
dryer-side of the tissue is typically the externally-facing surface
of the facial tissue product. See Table 10 for sample
descriptions.
TABLE-US-00013 TABLE 10 Total Water- Additional Add-on soluble Film
Water-soluble Water-soluble Rate (mg/m2 Sample Forming Modifier
Film Forming of Dryer Code Component Component Component surface) 1
GLUCOSOL CARBOWAX 100 800 (13%) PEG 8000 (87%) 2 GLUCOSOL CARBOWAX
1000 800 (13%) PEG 8000 (87%) 7 GLUCOSOL CARBOWAX POLYOX N3000 100
800 (30%) PEG 8000 (10%) (60%)
[0193] Single plies of the fibrous webs made according to the
present disclosure were split into two portions and then analyzed
to determine the amount of PEG in each of the portions, as
described in the Sheet Split PEG Analysis Test Method in the Test
Method section. The resulting data demonstrate that the amount of
PEG in the dryer-side portion is much greater than the felt-side
portion, and can be influenced by the composition of the additive
composition sprayed on the Yankee dryer. See Table 11 for test
results.
TABLE-US-00014 TABLE 11 Sample % PEG Dryer- % PEG Dryer/Felt Code
Side Felt-Side Ratio 1 0.68 0.46 1.48 2 6.28 4.40 1.43 7 1.00 0.43
2.30
[0194] The Dryer/Felt Ratios demonstrate that a larger portion of
the PEG is in the Dryer-Side portion of the tissue sheet, also
meaning that most of the additive composition remains in the
dryer-side portion and less penetrates through to the felt-side.
Finally, the incorporation of POLYOX N3000 also appears to increase
the amount of PEG which is retained in the dryer-side portion. This
is also a benefit as the perceived softness is improved.
* * * * *
References