U.S. patent application number 09/788739 was filed with the patent office on 2002-08-22 for soft absorbent tissue.
Invention is credited to Carlow, Geoffrey Fenn, Ferguson, Timothy Dale, Fortune, Amber Marie, Liu, Kou-Chang, Van Wychen, Heath David, VanderHeiden, Daniel John, Wendler, Roger Edward JR..
Application Number | 20020112835 09/788739 |
Document ID | / |
Family ID | 25145400 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112835 |
Kind Code |
A1 |
Liu, Kou-Chang ; et
al. |
August 22, 2002 |
SOFT ABSORBENT TISSUE
Abstract
A tissue product having improved hand feel and good wettability
is produced by printing onto one or both sides of the tissue an
aqueous emuslion containing a hydrophilically-modified
amino-functional polydimethylsiloxane. The hydrophilically-modified
amino-functional polydimethylsiloxane structure has one or more
pendant groups containing a terminal amine functionality and at
least one pendant group containing an ethylene oxide moiety.
Inventors: |
Liu, Kou-Chang; (Appleton,
WI) ; Fortune, Amber Marie; (Kaukauna, WI) ;
Carlow, Geoffrey Fenn; (Neenah, WI) ; Ferguson,
Timothy Dale; (Appleton, WI) ; Wendler, Roger Edward
JR.; (Sherwood, WI) ; Van Wychen, Heath David;
(Kimberly, WI) ; VanderHeiden, Daniel John;
(Menasha, WI) |
Correspondence
Address: |
Gregory E. Croft
Kimberly-Clark Worldwide, Inc.
Patent Department
401 North Lake Street
Neenah
WI
54956
US
|
Family ID: |
25145400 |
Appl. No.: |
09/788739 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
162/164.4 |
Current CPC
Class: |
D21H 17/56 20130101;
D21H 17/13 20130101; Y10T 428/31663 20150401; D21H 19/32 20130101;
Y10T 442/2484 20150401; D21H 21/22 20130101 |
Class at
Publication: |
162/164.4 |
International
Class: |
D21H 011/00 |
Claims
We claim:
1. A tissue having a Wet Out Time of about 10 seconds or less and
containing at least about 2 dry weight percent of a
hydrophilically-modified amino-functional polydimethylsiloxane
having the following structure: 5wherein: X is hydrogen, hydroxy,
amino, C.sub.1-C.sub.8 straight chain, branched, cyclic,
unsubstituted or hydrophilically substituted alkyl or alkoxyl
radical; m=20-100,000; p=1-5000; q=0-5000; R.sub.1=a
C.sub.1-C.sub.6, straight chain, branched or cyclic alkyl radical;
R.sub.2=a C.sub.1-C.sub.10 straight chain or branched, substituted
or unsubstituted alkylene diradical; 6wherein R.sub.5 is an
unsubstituted or a hydrophilically substituted C.sub.1-C.sub.10
alkylene diradical; r=1-10,000; s=0-10,000; and Z=hydrogen,
C.sub.1-C.sub.24 alkyl group, or a G-group, where G is selected
from the following: -R.sub.6COOR.sub.7; -CONR.sub.8R.sub.9;
-SO.sub.3R.sub.8; and PO R.sub.8R.sub.9, where R.sub.6 is a
substituted or unsubstituted C.sub.1-C.sub.6 alkylene diradical;
R.sub.7, R.sub.8, and R.sub.9 are independently a hydrogen radical
or a substituted or unsubstituted C.sub.1-C.sub.8 alkyl radical;
and 7wherein R.sub.10, R.sub.11, and R.sub.12 are independently an
unsubstituted or a hydrophilically substituted C.sub.1-C.sub.8
alkylene diradical; t=0-10,000; u=0-10,000; w=0-10,000; and
R.sub.13, R.sub.14 and R.sub.15 are independently a hydrogen
radical, an unsubstituted or a hydroxyl, carboxyl or other
functionally substituted C.sub.1-C.sub.10 straight chain, branched,
or cyclic alkyl radical.
2. The tissue of claim 1 wherein the Wet Out Time is about 8
seconds or less.
3. The tissue of claim 1 wherein the Wet Out Time is about 6
seconds or less.
4. The tissue of claim 1 wherein the Wet Out Time is about 5
seconds or less.
5. The tissue of claim 1 wherein the Wet Out Time is from about 4
to about 6 seconds.
6. The tissue of claim 1 having from about 0.5 to about 15 dry
weight percent of the hydrophilically-modified amino-functional
polydimethylsiloxane.
7. The tissue of claim 1 having from about 1 to about 10 dry weight
percent of the hydrophilically-modified amino-functional
polydimethylsiloxane.
8. The tissue of claim 1 having from about 1 to about 5 dry weight
percent of the hydrophilically-modified amino-functional
polydimethylsiloxane.
9. The tissue of claim 1 having from about 2 to about 5 dry weight
percent of the hydrophilically-modified amino-functional
polydimethylsiloxane.
10. The tissue of claim 1 wherein the ratio of the Wet Out Time to
the add-on amount of the hydrophilically-modified amino-functional
polydimethylsiloxane is about 3 seconds per weight percent or
less.
11. The tissue of claim 1 wherein the ratio of the Wet Out Time to
the add-on amount of the hydrophilically-modified amino-functional
polydimethylsiloxane is about 2 seconds per weight percent or
less.
12. The tissue of claim 1 wherein the ratio of the Wet Out Time to
the add-on amount of the hydrophilically-modified amino-functional
polydimethylsiloxane is from about 1 to about 3 seconds per weight
percent or less.
13. The tissue of claim 1 wherein the ratio of the Differential Wet
Out Time to the add-on amount of the hydrophilically-modified
amino-functional polydimethylsiloxane is about 2 seconds per weight
percent or less.
14. The tissue of claim 1 wherein the ratio of the Differential Wet
Out Time to the add-on amount of the hydrophilically-modified
amino-functional polydimethylsiloxane is about 1 second per weight
percent or less.
15. The tissue of claim 1 wherein the ratio of the Differential Wet
Out Time to the add-on amount of the hydrophilically-modified
amino-functional polydimethylsiloxane is about 0.5 second per
weight percent or less.
16. The tissue of claim 1 wherein the tissue is an uncreped
throughdried tissue.
17. The tissue of claim 1 wherein both sides of the tissue are
printed with the same hydrophilically-modified amino-functional
polydimethylsiloxane.
18. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane printed on one side of the
tissue is different than the hydrophilically-modified
amino-functional polydimethylsiloxane printed on the other side of
the tissue.
19. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane has the following structure:
8
20. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane has the following structure:
9
21. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane has the following structure:
10
22. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane has the following structure:
11
23. The tissue of claim 1 wherein the hydrophilically-modified
amino-functional polydimethylsiloxane has the following structure:
12
Description
BACKGROUND OF THE INVENTION
[0001] In the field of soft tissues, such as facial tissue and bath
tissue, it is well known that the application of polysiloxanes to
the surface of the tissue can impart an improved surface feel to
the tissue. However, polysiloxanes are also known to impart
hydrophobicity to the treated tissue. Hence it is difficult to find
a proper balance between softness and absorbency, both of which are
desirable attributes for tissue, particularly bath tissue.
SUMMARY OF THE INVENTION
[0002] It has now been discovered that the softness of a tissue can
be improved with minimal negative impact on the absorbency or
wettability of the tissue by treating one or both outer surfaces of
the tissue with a particular group of hydrophilically-modified
amino-functional polydimethylsiloxanes. More specifically, suitable
polysiloxane structures have one or more pendant groups which
contain a terminal amine and at least one ethylene oxide moiety.
The terminal amine group and the ethylene oxide moieties can be
parts of the same pendant group or different pendant groups. A
general structure is as follows: 1
[0003] wherein:
[0004] X is hydrogen, hydroxy, amino, C.sub.1-C.sub.8 straight
chain, branched, cyclic, unsubstituted or hydrophilically
substituted alkyl or alkoxyl radical;
[0005] m=20-100,000;
[0006] p=1-5000;
[0007] q=0-5000;
[0008] R.sub.1=a C.sub.1-C.sub.6, straight chain, branched or
cyclic alkyl radical;
[0009] R.sub.2=a C.sub.1-C.sub.10 straight chain or branched,
substituted or unsubstituted alkylene diradical; 2
[0010] wherein R.sub.5 is an unsubstituted or a hydrophilically
substituted C.sub.1-C.sub.10 alkylene diradical;
[0011] r=1-10,000;
[0012] s=0-10,000; and
[0013] Z=hydrogen, C.sub.1-C.sub.24 alkyl group, or a G-group,
where G is selected from the following: -R.sub.6COOR.sub.7;
-CONR.sub.8R.sub.9; -SO.sub.3R.sub.8; and PO R.sub.8R.sub.9, where
R.sub.6 is a substituted or unsubstituted C.sub.1-C.sub.6 alkylene
diradical; R.sub.7, R.sub.8, and R.sub.9 are independently a
hydrogen radical or a substituted or unsubstituted C.sub.1-C.sub.8
alkyl radical; and 3
[0014] wherein R.sub.10, R.sub.11, and R.sub.12 are independently
an unsubstituted or a hydrophilically substituted C.sub.1-C.sub.8
alkylene diradical;
[0015] t=0-10,000;
[0016] u=0-10,000;
[0017] w=0- 10,000; and
[0018] R.sub.13, R.sub.14 and R.sub.15 are independently a hydrogen
radical, an unsubstituted or a hydroxyl, carboxyl or other
functionally substituted C.sub.1-C.sub.10 straight chain, branched,
or cyclic alkyl radical.
[0019] Representative species within the foregoing general
structure include the following (the values of "m", "p" and "q" are
as defined above; the terms "EO" and "PO" are shorthanded
representations of "ethylene oxide" and "propylene oxide" moieties,
respectively): 4
[0020] The hydrophilically-modified amino-functional
polydimethylsiloxanes described above can be applied to the tissue
web alone or in conjunction with other chemicals, such as bonders
or debonders. They can be applied to the tissue web, particularly
an uncreped throughdried web, by spraying or printing. Rotogravure
printing of an aqueous emulsion is particularly effective. Add-on
amounts can be from about 0.5 to about 15 dry weight percent, based
on the weight of the tissue, more specifically from about 1 to
about 10 dry weight percent, still more specifically from about 1
to about 5 weight percent, still more specifically from about 2 to
about 5 weight percent. The distribution of the deposits of the
hydrophilically-modified amino-functional polydimethylsiloxanes is
substantially uniform over the printed surface of the tissue, even
though the surface of the tissue, such as in the case of uncreped
throughdried tissues, may be highly textured and three-dimensional.
The printing does limit the deposits to the high points of the
textured tissue sheets, thereby ensuring a soft hand feel.
[0021] The Wet Out Time (hereinafter defined) for tissues of this
invention can be about 10 seconds or less, more specifically about
8 seconds or less, still more specifically about 6 seconds or less,
still more specifically about 5 seconds or less, still more
specifically from about 4 to about 6 seconds. As used herein, "Wet
Out Time" is related to absorbency and is the time it takes for a
given sample to completely wet out when placed in water. More
specifically, the Wet Out Time is determined by cutting 20 sheets
of the tissue sample into 2.5 inch squares. The number of sheets
used in the test is independent of the number of plies per sheet of
product. The 20 square sheets are stacked together and stapled at
each corner to form a pad. The pad is held close to the surface of
a constant temperature distilled water bath (23+/-2.degree. C.),
which is the appropriate size and depth to ensure the saturated
specimen does not contact the bottom of the container and the top
surface of the water at the same time, and dropped flat onto the
water surface, staple points down. The time taken for the pad to
become completely saturated, measured in seconds, is the Wet Out
Time for the sample and represents the absorbent rate of the
tissue. Increases in the Wet Out Time represent a decrease in
absorbent rate.
[0022] The "Differential Wet Out Time" is the difference between
the Wet Out Times of a tissue sample treated with a
hydrophilically-modified amino-functional polydimethylsiloxane and
a control tissue sample which has not been treated. The
Differential Wet Out Time, for purposes of this invention, can be
about 5 seconds or less, more specifically about 4 seconds or less,
still more specifically about 3 seconds or less, still more
specifically about 2 seconds or less, and still more specifically
about 1 second or less.
[0023] The ratio of the Wet Out Time, expressed in seconds, to the
add-on amount of the hydrophilically-modified amino-functional
polydimethylsiloxane in the tissue, expressed as dry weight percent
of the weight of the tissue, can be about 3 seconds per weight
percent or less, more specifically about 2 seconds per weight
percent or less, still more specifically from about 1 to about 3
seconds per weight percent.
[0024] The ratio of the Differential Wet Out Time to the add-on
amount of the hydrophilically-modified amino-functional
polydimethylsiloxane can be about 2 seconds per weight percent or
less, more specifically about 1 second per weight percent or less,
still more specifically about 0.5 second per weight percent or
less.
[0025] Tissue sheets useful for purposes of this invention can be
creped or uncreped. Such tissue sheets can be used for facial
tissues or bath tissues. They can have one, two, three or more
plies. The basis weight of the tissue product can be from about 25
to about 50 grams per square meter. If used for bath tissue, a
single ply tissue having a basis weight of from about 30-40 grams
per square meter is particularly suitable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic diagram of an uncreped throughdried
process for making bath tissue in accordance with this
invention.
[0027] FIG. 2 is a schematic diagram of the post-manufacturing
method of handling the uncreped throughdried web and the
rotogravure coating process used to apply the
hydrophilically-modified amino-functional polydimethylsiloxane
emulsion in accordance with this invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0028] Referring to FIG. 1, shown is a schematic flow diagram of a
throughdrying process for making uncreped throughdried tissue
sheets. Shown is the headbox 1 which deposits an aqueous suspension
of papermaking fibers onto an inner forming fabric 3 as it
traverses the forming roll 4. Outer forming fabric 5 serves to
contain the web while it passes over the forming roll and sheds
some of the water. The wet web 6 is then transferred from the inner
forming fabric to a wet end transfer fabric 8 with the aid of a
vacuum transfer shoe 9. This transfer is preferably carried out
with the transfer fabric traveling at a slower speed than the
forming fabric (rush transfer) to impart stretch into the final
tissue sheet. The wet web is then transferred to the throughdrying
fabric 11 with the assistance of a vacuum transfer roll 12. The
throughdrying fabric carries the web over the throughdryer 13,
which blows hot air through the web to dry it while preserving
bulk. There can be more than one throughdryer in series (not
shown), depending on the speed and the dryer capacity. The dried
tissue sheet 15 is then transferred to a first dry end transfer
fabric 16 with the aid of vacuum transfer roll 17. The tissue sheet
shortly after transfer is sandwiched between the first dry end
transfer fabric and the transfer belt 18 to positively control the
sheet path. The air permeability of the transfer belt is lower than
that of the first dry end transfer fabric, causing the sheet to
naturally adhere to the transfer belt. At the point of separation,
the sheet follows the transfer belt due to vacuum action. Suitable
low air permeability fabrics for use as transfer belts include,
without limitation, COFPA Mononap NP 50 dryer felt (air
permeability of about 50 cubic feet per minute per square foot) and
Asten 960C (impermeable to air). The transfer belt passes over two
winding drums 21 and 22 before returning to pick up the dried
tissue sheet again. The sheet is transferred to the parent roll 25
at a point between the two winding drums. The parent roll is wound
onto a reel spool 26, which is driven by a center drive motor.
[0029] Particularly suitable methods of producing uncreped
throughdried basesheets for purposes of this invention are
described in U.S. Pat. No. 6,017,417 issued Jan. 25, 2000 to Wendt
et al. and U.S. Pat. No. 5,944,273 issued Aug. 31, 1999 to Lin et
al., both of which are herein incorporated by reference.
[0030] FIG. 2 illustrates a suitable method for applying the
hydrophilically-modified amino-functional polydimethylsiloxane to
the tissue basesheet. Shown is the parent roll 25 being unwound and
passed through two calender nips between calender rolls 30a and 31a
and 30b and 31b. The calendered web is then passed to the
rotogravure coating station comprising a first closed doctor
chamber 33 containing the hydrophilically-modified amino-functional
polydimethylsiloxane emulsion to be applied to a first side of the
web, a first engraved steel gravure roll 34, a first rubber backing
roll 35, a second rubber backing roll 36, a second engraved steel
gravure roll 37 and a second closed doctor chamber 38 containing
the hydrophilically-modified amino-functional polydimethylsiloxane
emulsion to be applied to the second side of the web. If both sides
of the web are to be treated, the two emulsions can be the same or
different. The calendered web passes through a fixed-gap nip
between the two rubber backing rolls where the
hydrophilically-modified amino-functional polydimethylsiloxane
emulsion is applied to the web. The treated web is then passed to
the rewinder where the web is wound onto logs 40 and slit into
rolls of bath tissue.
EXAMPLES
Example 1
[0031] In order to further illustrate this invention, an uncreped
throughdried tissue was produced using the methods described in
FIGS. 1 and 2 and treated with a hydrophilically-modified
amino-functional polydimethylsiloxane as set forth in structure
(17) described herein above.
[0032] More specifically, a single-ply, three-layered uncreped
throughdried bath tissue was made using eucalyptus fibers for the
outer layers and softwood fibers for the inner layer. Prior to
pulping, a quaternary ammonium softening agent (C-6027 from
Goldschmidt Corp.) was added at a dosage of 4.1 kg/Mton of active
chemical per metric ton of fiber to the eucalyptus furnish. After
allowing 20 minutes of mixing time, the slurry was dewatered using
a belt press to approximately 32% consistency. The filtrate from
the dewatering process was either sewered or used as pulper make-up
water for subsequent fiber batches but not sent forward in the
stock preparation or tissuemaking process. The thickened pulp
containing the debonder was subsequently re-dispersed in water and
used as the outer layer furnishes in the tissuemaking process.
[0033] The softwood fibers were pulped for 30 minutes at 4 percent
consistency and diluted to 3.2 percent consistency after pulping,
while the debonded eucalyptus fibers were diluted to 2 percent
consistency. The overall layered sheet weight was split 30%/40%/30%
among the eucalyptus/refined softwood/ eucalyptus layers. The
center layer was refined to levels required to achieve target
strength values, while the outer layers provided the surface
softness and bulk. Parez 631NC was added to the center layer at 2-4
kilograms per tonne of pulp based on the center layer.
[0034] A three layer headbox was used to form the wet web with the
refined northern softwood kraft stock in the two center layers of
the headbox to produce a single center layer for the three-layered
product described. Turbulence-generating inserts recessed about 3
inches (75 millimeters) from the slice and layer dividers extending
about 1 inch (25.4 millimeters) beyond the slice were employed. The
net slice opening was about 0.9 inch (23 millimeters) and water
flows in all four headbox layers were comparable. The consistency
of the stock fed to the headbox was about 0.09 weight percent.
[0035] The resulting three-layered sheet was formed on a twin-wire,
suction form roll, former with forming fabrics (12 and 13 in FIG.
1) being Lindsay 2164 and Asten 867a fabrics, respectively. The
speed of the forming fabrics was 11.9 meters per second. The
newly-formed web was then dewatered to a consistency of about 20-27
percent using vacuum suction from below the forming fabric before
being transferred to the transfer fabric, which was travelling at
9.1 meters per second (30% rush transfer). The transfer fabric was
an Appleton Wire T807-1. A vacuum shoe pulling about 6-15 inches
(150-380 millimeters) of mercury vacuum was used to transfer the
web to the transfer fabric.
[0036] The web was then transferred to a throughdrying fabric
(Lindsay Wire T1205-1) previously described in connection with FIG.
2 and as illustrated in FIG. 9). The throughdrying fabric was
travelling at a speed of about 9.1 meters per second. The web was
carried over a Honeycomb throughdryer operating at a temperature of
about 350.degree. F. (175.degree. C.) and dried to final dryness of
about 94-98 percent consistency. The resulting uncreped tissue
sheet was then wound into a parent roll.
[0037] The parent roll was then unwound and the web was calendered
twice. At the first station the web was calendered between a steel
roll and a rubber covered roll having a 4 P&J hardness. The
calender loading was about 90 pounds per lineal inch (pli). At the
second calendering station, the web was calendered between a steel
roll and a rubber covered roll having a 40 P&J hardness. The
calender loading was about 140 pli. The thickness of the rubber
covers was about 0.725 inch (1.84 centimeters).
[0038] The calendered single-ply web was then fed into the
rubber-rubber nip of the rotogravure coater to apply the
hydrophilically-modified amino-functional polydimethylsiloxane
emulsion to both sides of the web. The aqueous emulsion contained
25.0% WETSOFT.RTM. CTW (Kelmar Industries), 8.3% surfactant, 0.25%
antifoaming agent, 0.2% acetic acid, 0.1% aloe, 0.1% Vitamin E,
0.05% preservative, and the balance water. The gravure rolls were
electronically engraved, chrome over copper rolls supplied by
Specialty Systems, Inc., Louisville, Kentucky. The rolls had a line
screen of 200 cells per lineal inch and a volume of 6.0 Billion
Cubic Microns (BCM) per square inch of roll surface. Typical cell
dimensions for this roll were 140 microns in width and 33 microns
in depth using a 130 degree engraving stylus. The rubber backing
offset applicator rolls were a 75 Shore A durometer cast
polyurethane supplied by American Roller Company, Union Grove,
Wisconsin. The process was set up to a condition having 0.375 inch
interference between the gravure rolls and the rubber backing rolls
and 0.003 inch clearance between the facing rubber backing rolls.
The simultaneous offset/offset gravure printer was run at a speed
of 2000 feet per minute using gravure roll speed adjustment
(diferential) to meter the polysiloxane emulsion to obtain the
desired addition rate. The gravure roll speed differential used for
this example was 1000 feet per minute. This process yielded an
add-on level of 2.5 weight percent total add-on based on the weight
of the tissue. The tissue was then converted into bath tissue
rolls. Sheets from the bath tissue rolls had a silky, lotiony hand
feel and a Wet Out Time of 5.0 seconds. (Similarly made tissues
without the treatment of this invention had a Wet Out Time of about
4.0 seconds.) The ratio of the Wet Out Time to the weight percent
add-on amount was 2.0.
Example 2
[0039] An uncreped throughdried tissue was made substantially as
described above with the following exceptions: (1) the overall
layered weight is split 20%160%120% among the eucalyptus/refined
softwood/eucalyptus layers; (2) no Parez was added to the center
layer; (3) the add-on level of the hydrophilically-modified
amino-functional polydimethylsiloxane was 3.0 weight percent; (4)
the structure of the hydrophilically-modified amino-functional
polydimethylsiloxane was as set forth in structure (14) herein
above; and (5) the hydrophilically-modified amino-functional
polydimethylsiloxane constituted 40 weight percent of the aqueous
emulsion used to deliver the hydrophilically-modified
amino-functional polydimethylsiloxane to the tissue. The resulting
bath tissue product obtained had a silky, lotiony hand feel and a
Wet Out Time of 7 seconds.
Example 3
[0040] An uncreped throughdried tissue was produced similarly as
described in Example I with the following exceptions: (1) prior to
pulping, an amino functionalized polydimethylsiloxane (AF2340 from
Kelmar Industries) was added to the eucalyptus fibers at a dosage
of 2 kg/Mton of active chemical per metric ton of fiber; (2) the
add-on level of the hydrophilically-modified amino-functional
polydimethylsiloxane was 1.5 weight percent; (3) the structure of
the hydrophilically-modified amino-functional polydimethylsiloxane
printed onto the tissue was as set forth in structure (10) herein
above; and (4) the hydrophilically-modifie- d amino-functional
polydimethylsiloxane constituted 20 weight percent of the aqueous
emulsion used to deliver the hydrophilically-modified
amino-functional polydimethylsiloxane to the tissue. The resulting
bath tissue product obtained had a silky, lotiony hand feel and a
Wet Out Time of 4.8 seconds.
[0041] It will be appreciated that the foregoing example and
discussion is for purposes of illustration only and is not to be
construed as limiting the scope of this invention, which is defined
by the following claims and all equivalents thereto.
* * * * *