U.S. patent application number 10/766538 was filed with the patent office on 2004-09-30 for low viscosity bilayer disrupted softening composition for tissue paper.
This patent application is currently assigned to The Procter & Gamble Company. Invention is credited to Frankenbach, Gayle Marie, Hamilton, Amy Jo, McFarland, James Robert, McKay, David D., Rice, John Ernest, Vinson, Kenneth Douglas, Wahl, Errol Hoffman.
Application Number | 20040188045 10/766538 |
Document ID | / |
Family ID | 32736618 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040188045 |
Kind Code |
A1 |
McKay, David D. ; et
al. |
September 30, 2004 |
Low viscosity bilayer disrupted softening composition for tissue
paper
Abstract
Disclosed is a composition for softening a wet laid cellulosic
structure. A particularly preferred structure is an absorbent
tissue. Further disclosed are tissue structures softened using the
composition. The composition includes an effective amount of a
softening active ingredient; a vehicle in which the softening
active ingredient is dispersed; an electrolyte dissolved in the
vehicle; and a bilayer disrupter. The electrolyte and the bilayer
disrupter cooperate to cause the viscosity of the composition to be
less than the viscosity of a dispersion of the softening active
ingredient in the vehicle alone. Preferably, the softening active
ingredient is a quaternary ammonium compound with the formula:
(R.sub.1).sub.4-m--N.sup.+--[(CH.sub.2).sub.n--Y--R.sub.3].sub.m
X.sup.- the vehicle is water, the electrolyte is calcium chloride,
and the bilayer disrupter is a nonionic surfactant. Also disclosed
is a method of using the compound by adding it at a use
concentration to the wet end of a papermaking process.
Inventors: |
McKay, David D.;
(Wilmington, OH) ; Rice, John Ernest; (Koenigstein
im Ts., DE) ; Vinson, Kenneth Douglas; (Cincinnati,
OH) ; McFarland, James Robert; (Cincinnati, OH)
; Hamilton, Amy Jo; (Mason, OH) ; Wahl, Errol
Hoffman; (Cincinnati, OH) ; Frankenbach, Gayle
Marie; (Cincinnati, OH) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY
INTELLECTUAL PROPERTY DIVISION
WINTON HILL TECHNICAL CENTER - BOX 161
6110 CENTER HILL AVENUE
CINCINNATI
OH
45224
US
|
Assignee: |
The Procter & Gamble
Company
|
Family ID: |
32736618 |
Appl. No.: |
10/766538 |
Filed: |
January 28, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10766538 |
Jan 28, 2004 |
|
|
|
09586270 |
Nov 30, 2000 |
|
|
|
Current U.S.
Class: |
162/158 ;
162/123; 162/179; 162/181.2 |
Current CPC
Class: |
D21F 11/145 20130101;
D21F 11/14 20130101; D21H 21/24 20130101 |
Class at
Publication: |
162/158 ;
162/179; 162/181.2; 162/123 |
International
Class: |
D21H 021/22; D21H
021/24 |
Claims
What is claimed is:
1. A cellulosic structure, said structure comprising cellulosic
fibers and a chemical softening composition, said chemical
softening composition comprising: a softening active ingredient,
wherein said softening active ingredient comprises a quaternary
ammonium compound; an electrolyte; and a bilayer disrupter.
2. The cellulosic structure of claim 1 wherein said quaternary
ammonium compound has the
formula:(R.sub.1).sub.4-m--N.sup.+--[(CH.sub.2).sub.n--Y-
--R.sub.3].sub.m X.sup.-wherein Y is --O--(O)C--, or --C(O)--O--,
or --NH--C(O)--, or --C(O)--NH--; m is 1 to 3; n is 0 to 4; each
R.sub.1 is a C.sub.1-C.sub.6 alkyl or alkenyl group, hydroxyalkyl
group, hydrocarbyl or substituted hydrocarbyl group, alkoxylated
group, benzyl group, or mixtures thereof; each R.sub.3 is a
C.sub.13-C.sub.21 linear or branched alkyl or alkenyl group,
hydroxyalkyl group, hydrocarbyl or substituted hydrocarbyl group,
alkoxylated group, benzyl group, or mixtures thereof; and X.sup.-
is any softener-compatible anion.
3. The cellulosic structure of claim 2 wherein m is 2, n is 2,
R.sub.1 is methyl, R.sub.3 is C.sub.15-C.sub.17 alkyl or alkenyl,
and Y is --O--(O)C--, or --C(O)--O--.
4. The cellulosic structure of claim 3 wherein X.sup.- is chloride
or methyl sulfate.
5. The cellulosic structure of claim 2 wherein said chemical
softening composition further comprises a plasticizer.
6. The cellulosic structure of claim 5 wherein said plasticizer is
selected from a group consisting of polyethylene glycol,
polypropylene glycol and mixtures thereof.
7. The cellulosic structure of claim 1 wherein said electrolyte
comprises a salt selected from the group consisting of the chloride
salts of sodium, calcium, and magnesium.
8. The cellulosic structure of claim 1 wherein said bilayer
disrupter is used at a level of between about 2% and about 15% of
the level of said softening active ingredient.
9. The cellulosic structure of claim 1 wherein said bilayer
disrupter is selected from the group consisting of: 1. nonionic
surfactants derived from saturated and/or unsaturated primary
and/or secondary, amine, amide, amine-oxide fatty alcohol, fatty
acid, alkyl phenol, and/or alkyl aryl carboxylic acid compounds
having from about 6 to about 22 carbon atoms in a hydrophobic
chain, wherein at least one active hydrogen of said compounds is
ethoxylated with .ltoreq.50 ethylene oxide moieties to provide an
HLB of from about 6 to about 20; 2. nonionic surfactants with bulky
head groups selected from: a. surfactants having the formulas:
4wherein Y".dbd.N or O; and each R.sup.5 is selected independently
from the following: --H, --OH, --(CH.sub.2)xCH.sub.3,
--O(OR.sup.2).sub.z--H, --OR.sup.1, --OC(O)R.sup.1, and
--CH(CH.sub.2--(OR.sup.2).sub.z"--H)--CH.-
sub.2--(OR.sup.2).sub.z'--C(O) R.sup.1, x and R.sup.1 are as
defined above and 5.ltoreq.z, z', and z".ltoreq.20; and b.
polyhydroxy fatty acid amide surfactants of the
formula:R.sup.2--C(O)--N(R.sup.1)--Zwherein: each R.sup.1 is H,
C.sub.1-C.sub.4 hydrocarbyl, C.sub.1-C.sub.4 alkoxyalkyl, or
hydroxyalkyl; R.sup.2 is a C.sub.5-C.sub.21 hydrocarbyl moiety; and
each Z is a polyhydroxyhydrocarbyl moiety having a linear
hydrocarbyl chain with at least 3 hydroxyls directly connected to
the chain, or an ethoxylated derivative thereof; and 3. cationic
surfactants having the
formula:{R.sup.1.sub.m--Y--[(R.sup.2--O).sub.z--H].sub.p}.sup.+
X.sup.-wherein R.sup.1 is selected from the group consisting of
saturated or unsaturated, primary, secondary or branched chain
alkyl or alkyl-aryl hydrocarbons; said hydrocarbon chain having
from about 6 to about 22 carbon atoms; each R.sup.2 is selected
from the following groups or combinations of the following groups:
--(CH.sub.2).sub.n-- and/or --[CH(CH.sub.3)CH.sub.2]--; Y is
selected from the following groups: .dbd.N.sup.+-(A).sub.q;
--(CH.sub.2).sub.n--N.sup.+-(A).sub.q;
--B--(CH.sub.2).sub.n--N.sup.+-(A).sub.2;
-(phenyl)-N.sup.+-(A).sub.q; --(B-phenyl)-N.sup.+-(A).sub.q; with n
being from about 1 to about 4, wherein each A is independently
selected from the following groups: H; C.sub.1-5 alkyl; R.sup.1;
--(R.sup.2O).sub.z--H; --(CH.sub.2).sub.xCH.sub- .3; phenyl, and
substituted aryl; where 0.ltoreq.x.ltoreq.about 3; and each B is
selected from the following groups: --O--; --NA-; --NA.sub.2;
--C(O)O--; and --C(O)N(A)-; wherein R.sup.2 is defined as
hereinbefore; q=1 or 2; total z per molecule is from about 3 to
about 50; and X.sup.- is an anion which is compatible with fabric
softener actives and adjunct ingredients.
10. The cellulosic structure of claim 9 wherein said bilayer
disrupter is a nonionic surfactant having a hydrophobic moiety that
is selected from the group consisting of: fatty alcohols having
between about 8 and about 18 carbon atoms and alkyl phenols having
between about 8 and about 18 carbon atoms wherein said hydrophobic
moiety is ethoxylated with between about 3 and about 15 ethylene
oxide moieties.
11. The cellulosic structure of claim 10 wherein said cellulosic
structure comprises a tissue paper, wherein said tissue paper
comprises one or more plies.
Description
[0001] This is a continuation application of U.S. patent
application Ser. No. 09/586,270 filed in the names of McKay, et al.
on Nov. 30, 2000.
TECHNICAL FIELD
[0002] This invention relates, in general, to softening cellulosic
structures with cationic bond inhibiting compounds; and more
specifically, to a composition having rheological properties which
facilitate its use for enhancing the softness thereof. Most
particularly, the invention relates to softening tissue paper webs
and methods of producing such softened webs.
BACKGROUND OF THE INVENTION
[0003] Sanitary paper tissue products are widely used. Such items
are commercially offered in formats tailored for a variety of uses
such as facial tissues, toilet tissues and absorbent towels.
[0004] All of these sanitary products share a common need,
specifically to be soft to the touch. Softness is a complex tactile
impression evoked by a product when it is stroked against the skin.
The purpose of being soft is so that these products can be used to
cleanse the skin without being irritating. Effectively cleansing
the skin is a persistent personal hygiene problem for many people.
Objectionable discharges of urine, menses, and fecal matter from
the perineal area or otorhinolaryngogical mucus discharges do not
always occur at a time convenient for one to perform a thorough
cleansing, as with soap and copious amounts of water for example.
As a substitute for thorough cleansing, a wide variety of tissue
and toweling products are offered to aid in the task of removing
from the skin and retaining such discharges for disposal in a
sanitary fashion. Not surprisingly, the use of these products does
not approach the level of cleanliness that can be achieved by the
more thorough cleansing methods, and producers of tissue and
toweling products are constantly striving to make their products
compete more favorably with thorough cleansing methods.
[0005] Shortcomings in tissue products for example cause many to
stop cleaning before the skin is completely cleansed. Such behavior
is prompted by the harshness of the tissue, as continued rubbing
with a harsh implement can abrade the sensitive skin and cause
severe pain. The alternative, leaving the skin partially cleansed,
is chosen even though this often causes malodors to emanate and can
cause staining of undergarments, and over time can cause skin
irritations as well.
[0006] Disorders of the anus, for example hemorrhoids, render the
perianal area extremely sensitive and cause those who suffer such
disorders to be particularly frustrated by the need to clean their
anus without prompting irritation.
[0007] Another notable case which prompts frustration is the
repeated nose blowing necessary when one has a cold. Repeated
cycles of blowing and wiping can culminate in a sore nose even when
the softest tissues available today are employed.
[0008] Accordingly, making soft tissue and toweling products which
promote comfortable cleaning without performance impairing
sacrifices has long been the goal of the engineers and scientists
who are devoted to research into improving tissue paper. There have
been numerous attempts to reduce the abrasive effect, i.e., improve
the softness of tissue products.
[0009] One area that has been exploited in this regard has been to
select and modify cellulose fiber morphologies and engineer paper
structures to take optimum advantages of the various available
morphologies. Applicable art in this area includes: Vinson et. al.
in U.S. Pat. No. 5,228,954, issued Jul. 20, 1993, Vinson in U.S.
Pat. No. 5,405,499, issued Apr. 11, 1995, Cochrane et al. in U.S.
Pat. No. 4,874,465 issued Oct. 17, 1989, and Hermans, et. al. in
U.S. Statutory Invention Registration H1672, published on Aug. 5,
1997, all of which disclose methods for selecting or upgrading
fiber sources to tissue and toweling of superior properties.
Applicable art is further illustrated by Carstens in U.S. Pat. No.
4,300,981, issued Nov. 17, 1981, which discusses how fibers can be
incorporated to be compliant to paper structures so that they have
maximum softness potential. While such techniques as illustrated by
these prior art examples are recognized broadly, they can only
offer some limited potential to make tissues truly effective
comfortable cleaning implements.
[0010] Another area which has received a considerable amount of
attention is the addition of chemical softening agents (also
referred to herein as "chemical softeners") to tissue and toweling
products.
[0011] As used herein, the term "chemical softening agent" refers
to any chemical ingredient which improves the tactile sensation
perceived by the consumer who holds a particular paper product and
rubs it across the skin. Although somewhat desirable for towel
products, softness is a particularly important property for facial
and toilet tissues. Such tactilely perceivable softness can be
characterized by, but is not limited to, friction, flexibility, and
smoothness, as well as subjective descriptors, such as a feeling
like lubricious, velvet, silk or flannel. Suitable materials
include those which impart a lubricious feel to tissue. This
includes, for exemplary purposes only, basic waxes such as paraffin
and beeswax and oils such as mineral oil and silicone oil as well
as petrolatum and more complex lubricants and emollients such as
quaternary ammonium compounds with long alkyl chains, functional
silicones, fatty acids, fatty alcohols and fatty esters.
[0012] The field of work in the prior art pertaining to chemical
softeners has taken two paths. The first path is characterized by
the addition of softeners to the tissue paper web during its
formation either by adding an attractive ingredient to the vats of
pulp which will ultimately be formed into a tissue paper web, to
the pulp slurry as it approaches a paper making machine, or to the
wet web as it resides on a Fourdrinier cloth or dryer cloth on a
paper making machine.
[0013] The second path is categorized by the addition of chemical
softeners to tissue paper web after the web is dried. Applicable
processes can be incorporated into the paper making operation as,
for example, by spraying onto the dry web before it is wound into a
roll of paper.
[0014] Exemplary art related to the former path categorized by
adding chemical softeners to the tissue paper prior to its assembly
into a web ("wet end" addition) includes U S. Pat. No. 5,264,082,
issued to Phan and Trokhan on Nov. 23, 1993 and in U.S. Pat. No.
5,543067, issued to Phan on Aug. 6, 1996, the disclosure of each
being incorporated herein by reference. Such methods have found
broad use in the industry. However, such prior art compositions are
either solids or viscous liquids at room temperature. As a result,
such prior art chemical softening composition must be heated before
dilution to a use concentration for addition to the papermaking
furnish. Such heating adds complexity to the papermaking process
and poses an additional capital requirement for the necessary
equipment.
[0015] Further exemplary art related to the addition of chemical
softeners to the tissue paper web during its formation includes
U.S. Pat. No. 5,059,282, issued to Ampulski, et. al. on Oct. 22,
1991 incorporated herein by reference. The Ampulski patent
discloses a process for adding a polysiloxane compound to a wet
tissue web (preferably at a fiber consistency between about 20% and
about 35%). Such a method represents an advance in some respects
over the addition of chemicals into the furnish for the papermaking
machine. For example, such means target the application to one of
the web surfaces as opposed to distributing the additive onto all
of the fibers of the furnish. However, when such softening
compositions are used there may be a loss of control of the sheet
as it is creped from the Yankee dryer. A widely believed theory is
that the additives interfere with the coating on the Yankee dryer
so that the bond between the wet web and the dryer is weakened.
[0016] Considerable art has also been directed toward the
application of chemical softeners to already-dried paper webs
either at the so-called dry end of the papermaking machine or in a
separate converting operation subsequent to the papermaking step.
Exemplary art from this field includes U.S. Pat. No. 5,215,626,
issued to Ampulski, et. al. on Jun. 1, 1993; U.S. Pat. No.
5,246,545, issued to Ampulski, et. al. on Sep. 21, 1993; U.S. Pat.
No. 5,525,345, issued to Warner, et. al. on Jun. 11, 1996, and U.S.
patent application Ser. No. 09/053,319 filed in the name of Vinson,
et al. on Apr. 1, 1998 all incorporated herein by reference. The
'626 Patent discloses a method for preparing soft tissue paper by
applying a polysiloxane to a dry web. The '545 Patent discloses a
similar method utilizing a heated transfer surface. The '345 Patent
discloses methods of application including roll coating and
extrusion for applying particular compositions to the surface of a
dry tissue web. Finally, the Vinson, et al. application discloses
compositions that are particularly suitable for surface application
onto a tissue web.
[0017] While each of these references represent advances over the
prior art, there is a continuing need for soft tissue paper
products having good strength properties. There is also a need for
improved softening compositions that can be applied to such tissue
products to provide the requisite softness without adding
additional complexity and capital expense to the manufacture of
such products.
[0018] Such improved products, compositions, and methods are
provided by the present invention as is shown in the following
disclosure.
SUMMARY OF THE INVENTION
[0019] The present invention describes softening compositions that,
when added to the wet end of a wet laid process for producing
cellulosic structures, reduce the fiber to fiber bonding thereof,
providing a structure with improved softness while providing
acceptable strength and absorbency. The softening composition
comprises:
[0020] an effective amount of a softening active ingredient;
[0021] a vehicle in which the softening active ingredient is
dispersed;
[0022] an electrolyte dissolved in the vehicle, the electrolyte
causing the viscosity of the composition to be less than the
viscosity of a dispersion of the softening composition in the
vehicle alone; and
[0023] a bilayer disrupter to further reduce the viscosity of the
softening composition.
[0024] The term "cellulosic structure" as used herein is defined as
a wet laid fabric, web, or sheet comprised of fibers containing
cellulose. In its broadest sense, such structures possess a basis
weight ranging from 10 g/m.sup.2 to about 1 kg/m.sup.2 and possess
densities ranging from about 0.1 g/cc to as high as about 1 g/cc.
The cellulosic structures of the present invention preferably
derive at least a portion of their strength from the natural fiber
to fiber bonds which form when a web of short cellulosic fibers is
drained and dried from a aqueous slurry. Consequently, so called
wet laid papermaking is the most common process employing the
present invention.
[0025] The softening compositions of the present invention have
desirable low viscosity at room temperature allowing dilution as a
part of the papermaking process without the complexity and added
cost of a heating step.
[0026] The term "vehicle" as used herein means a fluid that
completely dissolves a chemical papermaking additive, or a fluid
that is used to emulsify a chemical papermaking additive, or a
fluid that is used to suspend a chemical papermaking additive. The
vehicle may also serve as a carrier that contains a chemical
additive or aids in the delivery of a chemical papermaking
additive. All references are meant to be interchangeable and not
limiting. The dispersion is the fluid containing the chemical
papermaking additive. The term "dispersion" as used herein includes
true solutions, suspensions, and emulsions. For purposes for this
invention, all terms are interchangeable and not limiting.
[0027] The amount of the softening composition added to the
cellulosic structure is preferably about 0.01% to about 10%, more
preferably between about 0.03% and about 1% based on the total
weight of the softening composition compared to the total weight of
the resulting cellulosic structure.
[0028] The cellulosic structure is preferably a tissue paper, most
preferably a tissue paper having a basis weight of from about 10 to
about 100 g/m.sup.2 and a fiber density of less than about 0.6
g/cc.
[0029] All percentages, ratios and proportions herein are by
weight, unless otherwise specified.
BRIEF DESCRIPTION OF THE FIGURES
[0030] While the specification concludes with claims particularly
pointing out and distinctly claiming the present invention, it is
believed that the present invention will be better understood from
the following description in conjunction with the appended example
and with the following drawing, in which like reference numbers
identify identical elements and wherein:
[0031] FIG. 1 is a schematic representation illustrating a creped
papermaking process of the present invention for producing a
strong, soft tissue paper comprising papermaking fibers using the
softening composition of the present invention.
[0032] FIG. 2 is a schematic representation illustrating the steps
for preparing the aqueous papermaking furnish for a creped
papermaking process, according to one embodiment of the present
invention.
[0033] The present invention is described in more detail below.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Briefly, the present invention provides a composition useful
for softening cellulosic structures. Preferably, it is added to the
wet end of a process for making the cellulosic structure. Most
preferably, the cellulosic structure is a tissue paper. The
resulting tissue paper comprising the composition of the present
invention has enhanced tactilely perceivable softness. The
softening composition, a method for producing the combination, and
a method of adding it to wet end of a paper-making process are
described.
[0035] The composition of the present invention is a dispersion of
a softening active ingredient in a vehicle. Importantly, the
composition also comprises a bilayer disrupter which allows the
composition to have both a particularly high level of ingredients
effective in softening tissue paper webs and, at the same time, a
low viscosity at room temperature. Such compositions are
particularly desirable for addition to the wet end of a papermaking
process so as to provide paper made using such a process with
desirable softness. Such compositions are especially desirable for
use in processes used in the production of tissue paper products
used for personal cleaning.
[0036] Tissue Paper
[0037] The present invention is applicable to tissue paper in
general, including but not limited to: conventionally felt-pressed
tissue paper; pattern densified tissue paper such as exemplified by
Sanford-Sisson and its progeny; and high-bulk, uncompacted tissue
paper such as exemplified by Salvucci. The tissue paper may be of a
homogenous or multilayered construction; and tissue paper products
made therefrom may be of a single-ply or multi-ply construction.
The tissue paper preferably has a basis weight of between about 10
g/m.sup.2 and about 100 g/m.sup.2, and density of about 0.60 g/cc
or less. Preferably, the basis weight will be between about 10
g/m.sup.2 and about 80 g/m.sup.2, and the density will be about
0.30 g/cc or less. Most preferably, the density will be between
about 0.04 g/cc and about 0.20 g/cc.
[0038] Conventionally pressed tissue paper and methods for making
such paper are known in the art. Such paper is typically made by
depositing a papermaking furnish on a foraminous forming wire. This
forming wire is often referred to in the art as a Fourdrinier wire.
Once the furnish is deposited on the forming wire, it is referred
to as a web. Overall, water is removed from the web by vacuum,
mechanical pressing and thermal means. The web is dewatered by
pressing the web and by drying at elevated temperature. The
particular techniques and typical equipment for making webs
according to the process just described are well known to those
skilled in the art. In a typical process, a low consistency pulp
furnish is provided in a pressurized headbox. The headbox has an
opening for delivering a thin deposit of pulp furnish onto the
Fourdrinier wire to form a wet web. The web is then typically
dewatered to a fiber consistency of between about 7% and about 45%
(total web weight basis) by vacuum dewatering and further dried by
pressing operations wherein the web is subjected to pressure
developed by opposing mechanical members, for example, cylindrical
rolls. The dewatered web is then further pressed and dried by a
stream drum apparatus known in the art as a Yankee dryer. Pressure
can be developed at the Yankee dryer by mechanical means such as an
opposing cylindrical drum pressing against the web. Multiple Yankee
dryer drums may be employed, whereby additional pressing is
optionally incurred between the drums. The tissue paper structures
which are formed are referred to hereinafter as conventional,
pressed, tissue paper structures. Such sheets are considered to be
compacted, since the web is subjected to substantial overall
mechanical compression forces while the fibers are moist and are
then dried while in a compressed state. The resulting structure is
strong and generally of singular density, but very low in bulk,
absorbency and in softness.
[0039] Pattern densified tissue paper is characterized by having a
relatively high-bulk field of relatively low fiber density and an
array of densified zones of relatively high fiber density. The
high-bulk field is alternatively characterized as a field of pillow
regions. The densified zones are alternatively referred to as
knuckle regions. The densified zones may be discretely spaced
within the high-bulk field or may be interconnected, either fully
or partially, within the high-bulk field. Preferred processes for
making pattern densified tissue webs are disclosed in U.S. Pat. No.
3,301,746, issued to Sanford and Sisson on Jan. 31, 1967, U.S. Pat.
No. 3,974,025, issued to Ayers on Aug. 10, 1976; and U.S. Pat. Nos.
4,191,609 and 4,637,859, issued to Trokhan on Mar. 4, 1980 and on
Jan. 20, 1987 respectively; the disclosure of each of which is
incorporated herein by reference.
[0040] In general, pattern densified webs are preferably prepared
by depositing a papermaking furnish on a foraminous forming wire
such as a Fourdrinier wire to form a wet web and then juxtaposing
the web against an array of supports as it is transferred from the
forming wire to a structure comprising such supports for further
drying. The web is pressed against the array of supports, thereby
resulting in densified zones in the web at the locations
geographically corresponding to the points of contact between the
array of supports and the wet web. The remainder of the web not
compressed during this operation is referred to as the high-bulk
field. This high-bulk field can be further dedensified by
application of fluid pressure, such as with a vacuum type device or
a blow-through dryer, or by mechanically pressing the web against
the array of supports. The web is dewatered, and optionally
predried, in such a manner so as to substantially avoid compression
of the high-bulk field. This is preferably accomplished by fluid
pressure, such as with a vacuum type device or blow-through dryer,
or alternately by mechanically pressing the web against an array of
supports wherein the high-bulk field is not compressed. The
operations of dewatering, optional predrying and formation of the
densified zones may be integrated or partially integrated to reduce
the total number of processing steps performed. Subsequent to
formation of the densified zones, dewatering, and optional
predrying, the web is dried to completion, preferably still
avoiding mechanical pressing. Preferably, from about 8% to about
65% of the tissue paper surface comprises densified knuckles, the
knuckles preferably having a relative density of at least 125% of
the density of the high-bulk field.
[0041] The structure comprising an array of supports is preferably
an imprinting carrier fabric having a patterned displacement of
knuckles which operate as the array of supports which facilitate
the formation of the densified zones upon application of pressure.
The pattern of knuckles constitutes the array of supports
previously referred to. Imprinting carrier fabrics are disclosed in
U.S. Pat. No. 3,301,746, issued to Sanford and Sisson on Jan. 31,
1967, U.S. Pat. No. 3,821,068, issued to Salvucci, Jr. et al. on
May 21, 1974, U.S. Pat. No. 3,974,025, issued to Ayers on Aug. 10,
1976, U.S. Pat. No. 3,573,164, issued to Friedberg, et al. on Mar.
30, 1971, U.S. Pat. No. 3,473,576, issued to Amneus on Oct. 21,
1969, U.S. Pat. No. 4,239,065, issued to Trokhan on Dec. 16, 1980,
and U.S. Pat. No. 4,528,239, issued to Trokhan on Jul. 9, 1985, the
disclosure of each of which is incorporated herein by
reference.
[0042] Preferably, the furnish is first formed into a wet web on a
foraminous forming carrier, such as a Fourdrinier wire. The web is
dewatered and transferred to an imprinting fabric. The furnish may
alternately be initially deposited on a foraminous supporting
carrier which also operates as an imprinting fabric. Once formed,
the wet web is dewatered and, preferably, thermally predried to a
selected fiber consistency of between about 40% and about 80%.
Dewatering is preferably performed with suction boxes or other
vacuum devices, with blow-through dryers, or combinations thereof.
The knuckle imprint of the imprinting fabric is impressed in the
web as discussed above, prior to drying the web to completion. One
method for accomplishing this is through application of mechanical
pressure. This can be done, for example, by pressing a nip roll
which supports the imprinting fabric against the face of a drying
drum, such as a Yankee dryer, wherein the web is disposed between
the nip roll and drying drum. Also, preferably, the web is molded
against the imprinting fabric prior to completion of drying by
application of fluid pressure with a vacuum device such as a
suction box, or with a blow-through dryer. Fluid pressure may be
applied to induce impression of densified zones during initial
dewatering, in a separate, subsequent process stage, or a
combination thereof.
[0043] Uncompacted, non pattern-densified tissue paper structures
are described in U.S. Pat. No. 3,812,000 issued to Joseph L.
Salvucci, Jr. and Peter N. Yiannos on May 21, 1974, and U.S. Pat.
No. 4,208,459, issued to Henry E. Becker, Albert L. McConnell, and
Richard Schutte on Jun. 17, 1980, both of which are incorporated
herein by reference. In general, uncompacted, non pattern-densified
tissue paper structures are prepared by depositing a papermaking
furnish on a foraminous forming wire such as a Fourdrinier wire to
form a wet web, draining the web and removing additional water
without mechanical compression until the web has a fiber
consistency of at least 80%, and creping the web. Water is removed
from the web by vacuum dewatering and thermal drying. The resulting
structure is a soft but weak high-bulk sheet of relatively
uncompacted fibers. Bonding material is preferably applied to
portions of the web prior to creping.
[0044] The softening composition of the present invention can also
be useful for softening uncreped tissue paper. Uncreped tissue
paper, a term as used herein, refers to tissue paper which is
non-compressively dried, most preferably by through air drying.
Resultant through air dried webs are pattern densified such that
zones of relatively high density are dispersed within a high bulk
field, including pattern densified tissue wherein zones of
relatively high density are continuous and the high bulk field is
discrete.
[0045] To produce uncreped tissue paper webs, an embryonic web is
transferred from the foraminous forming carrier upon which it is
laid, to a slower moving, high fiber support transfer fabric
carrier. The web is then transferred to a drying fabric upon which
it is dried to a final dryness. Such webs can offer some advantages
in surface smoothness compared to creped paper webs.
[0046] The techniques to produce uncreped tissue in this manner are
taught in the prior art. For example, Wendt, et. al. in U.S. Pat.
No. 5,672,248, issued on Sep. 30, 1997 and incorporated herein by
reference, teach a method of making soft tissue products without
creping. In another case, Hyland, et. al. in European Patent
Application 0 617 164 A1, published Sep. 28, 1994 and incorporated
herein by reference, teach a method of making smooth uncreped
through air dried sheets. Finally, Farrington, et. al. in U.S. Pat.
No. 5,656,132 published Aug. 12, 1997, the disclosure of which is
incorporated herein by reference, describes the use of a machine to
make soft through air dried tissues without the use of a
Yankee.
[0047] Furnish
[0048] Papermaking Fibers
[0049] The papermaking fibers utilized for the present invention
will normally include fibers derived from wood pulp. Other
cellulosic fibrous pulp fibers, such as cotton linters, bagasse,
etc., can be utilized and are intended to be within the scope of
this invention. Synthetic fibers, such as rayon, polyethylene and
polypropylene fibers, may also be utilized in combination with
natural cellulosic fibers. One exemplary polyethylene fiber which
may be utilized is Pulpex.RTM., available from Hercules, Inc.
(Wilmington, Del.).
[0050] Applicable wood pulps include chemical pulps, such as Kraft,
sulfite, and sulfate pulps, as well as mechanical pulps including,
for example, groundwood, thermomechanical pulp and chemically
modified thermomechanical pulp. Chemical pulps, however, are
preferred since they impart a superior tactile sense of softness to
tissue sheets made therefrom. Pulps derived from both deciduous
trees (hereinafter, also referred to as "hardwood") and coniferous
trees (hereinafter, also referred to as "softwood") may be
utilized. Also applicable to the present invention are fibers
derived from recycled paper, which may contain any or all of the
above categories as well as other non-fibrous materials such as
fillers and adhesives used to facilitate the original
papermaking.
[0051] Particularly preferred cellulosic pulps include long fibers
such as Northern softwood Kraft (NSK); short fibers, such as
Eucalyptus; and secondary fibers, such as pre and post consumer
white ledger, coated book stock, and office waste. Such fibers may
be used in any desired combination, with or without layering.
[0052] Softening Composition
[0053] In general, the softening composition of the present
invention comprises a dispersion of a softening active ingredient
in a vehicle. When dispersed in a furnish used to produce tissue
paper or other cellulosic structures as described herein, such
compositions are effective in softening the structures. Preferably,
the softening composition of the present invention has properties
(e.g., ingredients, rheology, pH, etc.) permitting easy application
thereof on a commercial scale.
[0054] It is well known to those skilled in the art that quaternary
ammonium compounds which comprise the preferred active ingredient
of the softening composition of the present invention are not
usually readily dispersible in water. The preferred quaternary
compounds are solids at room temperature and when added to water
are difficult to disperse into a uniform dispersion even with the
application of mechanical action. It is also well known that the
desired form for softening composition is a cold-water dispersible
liquid. Previous attempts to solve this conflict have not been
entirely satisfactory.
[0055] One method has been to use highly active organic solvents
capable of solubilizing the quaternary ammonium compound liquid at
room temperature and making it dispersible in water. For example, a
low molecular weight alcohol such as isopropanol can be used. Such
methods are not desired because of the increased process safety and
environmental burden (VOC) concerns raised by the volatility of
such solvents. Solvents which are less active can be employed, but
much larger quantities are required with resulting negative cost
and environmental consequences as well.
[0056] Another method employed historically has been to render the
quaternary ammonium compound more fluid, for example by introducing
more carbon to carbon double bonds in the long alkyl chains of the
preferred quaternary ammonium compounds. These materials are
typically either more costly or burdened by side effects such as
odor.
[0057] Quaternary ammonium compounds can also be made more fluid
and more dispersible by increasing their hydrophilicity by, for
example, ethoxylating the alkyl chains thereof. This method
decreases the effectiveness of the quaternary ammonium compound as
a softening ingredient and involves additional processing cost as
well.
[0058] The composition of the present invention is a highly
concentrated form of a preferred softening active ingredient, a
quaternary ammonium compound, that is still readily water
dispersible. The following discusses each of the components of the
softening composition of the present invention, the properties of
the composition, methods of producing the composition, and methods
of applying the composition.
[0059] Components
[0060] Softening Active Ingredients
[0061] Quaternary compounds having the formula:
(R.sub.1).sub.4-m--N.sup.+--[R.sub.2].sub.m X.sup.-
[0062] wherein:
[0063] m is 1 to 3;
[0064] each R.sub.1 is a C.sub.1-C.sub.6 alkyl group, hydroxyalkyl
group, hydrocarbyl or substituted hydrocarbyl group, alkoxylated
group, benzyl group, or mixtures thereof;
[0065] each R.sub.2 is a C.sub.14-C.sub.22 alkyl group,
hydroxyalkyl group, hydrocarbyl or substituted hydrocarbyl group,
alkoxylated group, benzyl group, or mixtures thereof; and
[0066] X.sup.- is any softener-compatible anion
[0067] are suitable for use in the present invention. Preferably,
each R.sub.1 is methyl and X.sup.- is chloride or methyl sulfate.
Preferably, each R.sub.2 is C.sub.16-C.sub.18 linear or branched
alkyl or alkenyl, most preferably each R.sub.2 is straight-chain
C.sub.18 alkyl or alkenyl. Optionally, the R.sub.2 substituent can
be derived from vegetable oil sources. Several types of the
vegetable oils (e.g., olive, canola, safflower, sunflower, etc.)
can used as sources of fatty acids to synthesize the quaternary
ammonium compound. Branched chain actives (e.g. as can be derived
from the equivalent branched chain fatty acid) are also effective
and have the additional advantage of oxidation resistance. Suitable
branched chain fatty acids that can serve as a starting point for
such quaternary ammonium compounds include: 2-n-heptylundecanoic
acid, 2-n-butyloctanoic acid, 5,7,9-trimethylnonanoic acid,
3,5,7,9-tetramethylnonanoic, alpha-heptyldecanoic acid, and
isostearic acid, with isostearic acid being particularly
preferred.
[0068] Such structures include the well-known
dialkyldimethylammonium salts (e.g. ditallowdimethylammonium
chloride, ditallowdimethylammonium methyl sulfate, di(hydrogenated
tallow)dimethyl ammonium chloride, etc.), in which R.sub.1 are
methyl groups, R.sub.2 are tallow groups of varying levels of
saturation, and X.sup.- is chloride or methyl sulfate.
[0069] As discussed in Swern, Ed. in Bailey's Industrial Oil and
Fat Products, Third Edition, John Wiley and Sons (New York 1964),
tallow is a naturally occurring material having a variable
composition. Table 6.13 in the above-identified reference edited by
Swern indicates that, typically, 78% or more of the fatty acids of
tallow contain 16 or 18 carbon atoms. Typically, half of the fatty
acids present in tallow are unsaturated, primarily in the form of
oleic acid. Synthetic as well as natural "tallows" fall within the
scope of the present invention. It is also known that depending
upon the product characteristic requirements, the saturation level
of the ditallow can be tailored from non hydrogenated (soft) to
touch hydrogenated (partially hydrogenated) or completely
hydrogenated (hard). All of above-described saturation levels of
are expressly meant to be included within the scope of the present
invention.
[0070] Particularly preferred variants of these softening active
ingredients are what are considered to be mono or diester
variations of these quaternary ammonium compounds having the
formula:
(R.sub.1).sub.4-m--N.sup.+--[(CH.sub.2).sub.n--Y--R.sub.3].sub.m
X.sup.-
[0071] wherein
[0072] Y is --O--(O)C--, or --C(O)--O--, or --NH--C(O)--, or
--C(O)--NH--;
[0073] m is 1 to 3;
[0074] n is 0 to 4;
[0075] each R.sub.1 is a C.sub.1-C.sub.6 alkyl group, hydroxyalkyl
group, hydrocarbyl or substituted hydrocarbyl group, alkoxylated
group, benzyl group, or mixtures thereof;
[0076] each R.sub.3 is a C.sub.13-C.sub.21 linear or branched alkyl
group, hydroxyalkyl group, hydrocarbyl or substituted hydrocarbyl
group, alkoxylated group, benzyl group, or mixtures thereof;
and
[0077] X.sup.- is any softener-compatible anion.
[0078] Preferably, Y.dbd.--O--(O)C--, or --C(O)--O--; m=2; and n=2.
Each R.sub.1 substituent is preferably a C.sub.1-C.sub.3, alkyl
group, with methyl being most preferred. Preferably, each R.sub.3
is C.sub.13 -C.sub.17 alkyl and/or alkenyl, more preferably R.sub.3
is straight chain C.sub.15-C.sub.17 alkyl and/or alkenyl,
C.sub.15-C.sub.17 alkyl, most preferably each R.sub.3 is
straight-chain C.sub.17 alkyl. Optionally, the R.sub.3 substituent
can be derived from vegetable oil sources. Several types of the
vegetable oils (e.g., olive, canola, safflower, sunflower, etc.)
can used as sources of fatty acids to synthesize the quaternary
ammonium compound. Preferably, olive oils, canola oils, high oleic
safflower, and/or high erucic rapeseed oils are used to synthesize
the quaternary ammonium compound.
[0079] As mentioned above, X.sup.- can be any softener-compatible
anion, for example, acetate, chloride, bromide, methylsulfate,
formate, sulfate, nitrate and the like can also be used in the
present invention. Preferably X.sup.- is chloride or methyl
sulfate.
[0080] Specific examples of ester-functional quaternary ammonium
compounds having the structures named above and suitable for use in
the present invention include the well-known diester dialkyl
dimethyl ammonium salts such as diester ditallow dimethyl ammonium
chloride, monoester ditallow dimethyl ammonium chloride, diester
ditallow dimethyl ammonium methyl sulfate, diester
di(hydrogenated)tallow dimethyl ammonium methyl sulfate, diester
di(hydrogenated)tallow dimethyl ammonium chloride, and mixtures
thereof. Diester ditallow dimethyl ammonium chloride and diester
di(hydrogenated)tallow dimethyl ammonium chloride are particularly
preferred. The diester ditallow dimethyl ammonium chloride and
diester di(hydrogenated)tallow dimethyl ammonium chloride is
available commercially from Witco Chemical Company Inc. of Dublin,
Ohio under the tradename ADOGEN SDMC.
[0081] As mentioned above, typically, half of the fatty acids
present in tallow are unsaturated, primarily in the form of oleic
acid. Synthetic as well as natural "tallows" fall within the scope
of the present invention. It is also known that depending upon the
product characteristic requirements, the degree of saturation for
such tallows can be tailored from non hydrogenated (soft), to
partially hydrogenated (touch), or completely hydrogenated (hard).
All of above-described saturation levels of are expressly meant to
be included within the scope of the present invention. At least a
minimal level of hydrogenation is preferred in order to remove, in
particular, the multiply unsaturated species (e.g. linolenic
derivatives) which are known to be more susceptible to oxidation
with resulting rancidity.
[0082] It will be understood that substituents R.sub.1, R.sub.2 and
R.sub.3 may optionally be substituted with various groups such as
alkoxyl, hydroxyl, or can be branched. As mentioned above,
preferably each R.sub.1 is methyl or hydroxyethyl. Preferably, each
R.sub.2 is C.sub.12-C.sub.18 alkyl and/or alkenyl, most preferably
each R.sub.2 is straight-chain C.sub.16-C.sub.18 alkyl and/or
alkenyl, most preferably each R.sub.2 is straight-chain C.sub.18
alkyl or alkenyl. Preferably R.sub.3 is C.sub.13-C.sub.17 alkyl
and/or alkenyl, most preferably R.sub.3 is straight chain
C.sub.15-C.sub.17 alkyl and/or alkenyl. Preferably, X.sup.- is
chloride or methyl sulfate. Furthermore the ester-functional
quaternary ammonium compounds can optionally contain up to about
10% of the mono(long chain alkyl) derivatives, e.g.:
(R.sub.1).sub.2--N.sup.+--((CH.sub.2).sub.2OH)((CH.sub.2).sub.2OC(O)R.sub.-
3)X.sup.-
[0083] as minor ingredients. These minor ingredients can act as
emulsifiers and are useful in the present invention.
[0084] Other types of suitable quaternary ammonium compounds for
use in the present invention are described in U.S. Pat. No.
5,543,067, issued to Phan et al. on Aug. 6, 1996; U.S. Pat. No.
5,538,595, issued to Trokhan et al., on Jul. 23, 1996; U.S. Pat.
No. 5,510,000, issued to Phan et al. on Apr. 23, 1996; U.S. Pat.
No. 5,415,737, issued to Phan et al., on May 16, 1995; and European
Patent Application No. 0 688 901 A2, assigned to Kimberly-Clark
Corporation, published Dec. 12, 1995; the disclosure of each of
which is incorporated herein by reference.
[0085] Di-quat variations of the ester-functional quaternary
ammonium compounds can also be used, and are meant to fall within
the scope of the present invention. These compounds have the
formula: 1
[0086] In the structure named above each R.sub.1 is a
C.sub.1-C.sub.6alkyl or hydroxyalkyl group, R.sub.3 is
C.sub.11-C.sub.21 hydrocarbyl group, n is 2 to 4 and X.sup.- is a
suitable anion, such as an halide (e.g., chloride or bromide) or
methyl sulfate. Preferably, each R.sub.3 is C.sub.13-C.sub.17 alkyl
and/or alkenyl, most preferably each R.sub.3 is straight-chain
C.sub.15-C.sub.17 alkyl and/or alkenyl, and R.sub.1 is a
methyl.
[0087] Parenthetically, while not wishing to be bound by theory, it
is believed that the ester moiety(ies) of the aforementioned
quaternary compounds provides a measure of biodegradability to such
compounds. Importantly, the ester-functional quaternary ammonium
compounds used herein biodegrade more rapidly than do conventional
dialkyl dimethyl ammonium chemical softeners.
[0088] The use of quaternary ammonium ingredients as described
herein above is most effectively accomplished if the quaternary
ammonium ingredient is accompanied by an appropriate plasticizer.
The term plasticizer as used herein refers to an ingredient capable
of reducing the melting point and viscosity at a given temperature
of a quaternary ammonium ingredient. The plasticizer can be added
during the quaternizing step in the manufacture of the quaternary
ammonium ingredient or it can be added subsequent to the
quaternization but prior to the application as a softening active
ingredient. The plasticizer is characterized by being substantially
inert during the chemical synthesis of the quaternary ammonium
compound where it can act as a viscosity reducer to aid in the
synthesis. Preferred plasticizers are non-volatile polyhydroxy
compounds. Preferred polyhydroxy compounds include glycerol and
polyethylene glycols having a molecular weight of from about 200 to
about 2000, with polyethylene glycol having a molecular weight of
from about 200 to about 600 being particularly preferred. When such
plasticizers are added during manufacture of the quaternary
ammonium ingredient, they comprise between about 5% and about 75%
percent of the product of such manufacture. Particularly preferred
mixtures comprise between about 15% and about 50% plasticizer.
[0089] Vehicle
[0090] As used herein a "vehicle" is used to dilute the active
ingredients of the compositions described herein forming the
dispersion of the present invention. A vehicle may dissolve such
components (true solution or micellar solution) or such components
may be distributed throughout the vehicle (dispersion, emulsion, or
sponge phase). The vehicle of a suspension or emulsion is typically
the continuous phase thereof. That is, other components of the
dispersion or emulsion are dispersed on a molecular level or as
discrete particles or molecular aggregates throughout the
vehicle.
[0091] For purposes of the present invention, one purpose that the
vehicle serves is to dilute the concentration of softening active
ingredients so that such ingredients may be efficiently and
economically applied. Such diluted compositions are more readily
diluted to a use concentration without the need for complex
processing equipment.
[0092] Vehicles and softening compositions comprising such vehicles
have also been discovered that are particularly useful for
facilitating the incorporation of softening active ingredients into
webs of tissue on a commercial scale.
[0093] While softening ingredients can be dissolved in a vehicle
forming a solution therein, materials that are useful as solvents
for suitable softening active ingredients are not commercially
desirable for safety and environmental reasons. Therefore, to be
suitable for use in the vehicle for purposes of the present
invention, a material should be compatible with the softening
active ingredients described herein and with the tissue substrate
with which the softening compositions of the present invention will
be used. Further a suitable material should not contain any
ingredients that create safety issues (either in the tissue
manufacturing process or to users of tissue products using the
softening compositions described herein) and not create an
unacceptable risk to the environment. Suitable materials for the
vehicle of the present invention include hydroxyl functional
liquids most preferably water.
[0094] Electrolyte
[0095] While water is a particularly preferred material for use in
the vehicle of the present invention, water alone is not preferred
as a vehicle. Specifically, when softening active ingredients of
the present invention are dispersed in water at a level suitable
for application to a tissue web, the dispersion has an unacceptably
high viscosity. While not being bound by theory, it is believed
that combining water and the softening active ingredients of the
present invention to form such dispersions creates a liquid
crystalline phase having a high viscosity. Compositions having such
a high viscosity are difficult to dilute for use in a process for
producing tissue webs softening the web.
[0096] It has been discovered that the viscosity of dispersions of
softening active ingredients in water can be substantially reduced,
while maintaining a desirable high level of the softening active
ingredient in the softening composition by the simple addition of a
suitable electrolyte to the vehicle. Again, not being bound by
theory, it is believed that the electrolyte shields the electrical
charge around bilayers and vesicles, reducing interactions, and
lowering resistance to movement resulting in a reduction in
viscosity of the system. Additionally, again not being bound by
theory, the electrolyte can create an osmotic pressure difference
across vesicle walls which would tend to draw interior water
through the vesicle wall reducing the size of the vesicles and
providing more "free" water, again resulting in a decrease in
viscosity.
[0097] Any electrolyte meeting the general criteria described above
for materials suitable for use in the vehicle of the present
invention and which is effective in reducing the viscosity of a
dispersion of a softening active ingredient in water is suitable
for use in the vehicle of the present invention. In particular, any
of the known water-soluble electrolytes meeting the above criteria
can be included in the vehicle of the softening composition of the
present invention. When present, the electrolyte can be used in
amounts up to about 25% by weight of the softening composition, but
preferably no more than about 15% by weight of the softening
composition. Preferably, the level of electrolyte is between about
0.1% and about 10% by weight of the softening composition based on
the anhydrous weight of the electrolyte. Still more preferably, the
electrolyte is used at a level of between about 0.3% and about 1.0%
by weight of the softening composition. The minimum amount of the
electrolyte will be that amount sufficient to provide the desired
viscosity. The dispersions typically display a non-Newtonian
rheology, and are shear thinning with a desired viscosity generally
ranging from about 10 centipoise (cp) up to about 1000 cp,
preferably in the range between about 10 and about 200 cp, as
measured at 25.degree. C. and at a shear rate of 100 sec.sup.-1
using the method described in the TEST METHODS section below.
Suitable electrolytes include the halide, nitrate, nitrite, and
sulfate salts of alkali or alkaline earth metals, as well as the
corresponding ammonium salts. Other useful electrolytes include the
alkali and alkaline earth salts of simple organic acids such as
sodium formate and sodium acetate, as well as the corresponding
ammonium salts. Preferred electrolytes include the chloride salts
of sodium, calcium, and magnesium. Calcium chloride is a
particularly preferred electrolyte for the softening composition of
the present invention. While not being bound by theory, it is
believed that the divalent nature of the calcium ion makes it
particularly effective in reducing the viscosity of the vesicular
dispersions of the softening active ingredient. If desired,
compatible blends of the various electrolytes are also
suitable.
[0098] Bilayer Disrupter
[0099] A bilayer disrupter is an essential component of the
invention. While, as has been shown above, the vehicle,
particularly the electrolyte component dissolved therein, performs
an essential function in preparing the cellulosic structures of the
present invention, it is desirable also to maximize the
concentration of softening active ingredient while maintaining an
acceptable viscosity. As noted above, addition of electrolyte
allows an increase in the concentration of softening active
ingredient in the softening composition without unduly increasing
viscosity. However, if too much electrolyte is used, phase
separation can occur. It has been found that adding a bilayer
disrupter to the softening composition allows more softening active
ingredient to be incorporated therein while maintaining viscosity
at an acceptable level. As used herein a "bilayer disrupter" is an
organic material that, when mixed with a dispersion of a softening
active ingredient in a vehicle, is compatible with at least one of
the vehicle or the softening active ingredient and causes a
reduction of the viscosity of the dispersion.
[0100] Not to be bound by theory, it is believed that bilayer
disrupters function by penetrating the palliside layer of the
liquid crystalline structure of the dispersion of the softening
active ingredient in the vehicle and disrupting the order of the
liquid crystalline structure. Such disruption is believed to reduce
the interfacial tension at the hydrophobic-water interface, thus
promoting flexibility with a resulting reduction in viscosity. As
used herein, the term "pallisade layer", it is meant describe the
area between hydrophilic groups and the first few carbon atoms in
the hydrophobic layer (M. J Rosen, Surfactants and interfacial
phenomena, Second Edition, pages 125 and 126).
[0101] In addition to providing the viscosity reduction benefits
discussed above, materials suitable for use as a bilayer disrupter
should be compatible with other components of the softening
composition. For example, a suitable material should not react with
other components of the softening composition so as to cause the
softening composition to lose softening capability.
[0102] Bilayer disrupters useful in the compositions of the present
invention are preferably surface active materials. Such materials
comprise both hydrophobic and hydrophilic moieties. A preferred
hydrophilic moiety is a polyalkoxylated group, preferably a
polyethoxylated group. Such preferred materials are used at a level
of between about 1% and about 15% of the level of the softening
active ingredient. Preferably, the bilayer disrupter is present at
a level of between about 2% and about 10% of the level of the
softening active ingredient.
[0103] Particularly preferred bilayer disrupters are nonionic
surfactants derived from saturated and/or unsaturated primary
and/or secondary, amine, amide, amine-oxide fatty alcohol, fatty
acid, alkyl phenol, and/or alkyl aryl carboxylic acid compounds,
each preferably having from about 6 to about 22, more preferably
from about 8 to about 18, carbon atoms in a hydrophobic chain, more
preferably an alkyl or alkylene chain, wherein at least one active
hydrogen of said compounds is ethoxylated with .ltoreq.50,
preferably .ltoreq.30, more preferably from about 3 to about 15,
and even more preferably from about 5 to about 12, ethylene oxide
moieties to provide an HLB of from about 6 to about 20, preferably
from about 8 to about 18, and more preferably from about 10 to
about 15.
[0104] Suitable bilayer disrupters also include nonionic
surfactants with bulky head groups selected from:
[0105] a. surfactants having the formula
R.sup.1--C(O)--Y'--[C(R.sup.5)].sub.m--CH.sub.2O(R.sub.2O).sub.zH
[0106] wherein R.sup.1 is selected from the group consisting of
saturated or unsaturated, primary, secondary or branched chain
alkyl or alkyl-aryl hydrocarbons; said hydrocarbon chain having a
length of from about 6 to about 22; Y' is selected from the
following groups: --O--; --N(A)-; and mixtures thereof; and A is
selected from the following groups: H; R.sup.1;
--(R.sup.2--O).sub.z--H; --(CH.sub.2).sub.xCH.sub.3; phenyl, or
substituted aryl, wherein 0.ltoreq.x.ltoreq.about 3 and z is from
about 5 to about 30; each R.sup.2 is selected from the following
groups or combinations of the following groups:
--(CH.sub.2).sub.n-- and/or --[CH(CH.sub.3)CH.sub.2]--; and each
R.sup.5 is selected from the following groups: --OH; and
--O(R.sup.2O).sub.z--H ; and m is from about 2 to about 4; 2
[0107] wherein Y".dbd.N or O; and each R.sup.5 is selected
independently from the following:
[0108] --H, --OH, --(CH.sub.2)xCH.sub.3, --O(OR.sup.2).sub.z--H,
--OR.sup.1, --OC(O)R.sup.1, and
--CH(CH.sub.2--(OR.sup.2).sub.z"--H)--CH.-
sub.2--(OR.sup.2).sub.z'--C(O) R.sup.1, x and R.sup.1 are as
defined above and 5.ltoreq.z, z', and z".ltoreq.20, more preferably
5.ltoreq.z+z'+z".ltoreq.20, and most preferably, the heterocyclic
ring is a five member ring with Y".dbd.O, one R.sup.5 is --H, two
R.sup.5 are --O--(R.sup.2O)z--H, and at least one R.sup.5 is the
following structure
--CH(CH.sub.2--(OR.sup.2).sub.z"--H)--CH.sub.2--(OR.sup.2).sub.z'--C(O)
R.sup.1with 8.ltoreq.z+z'+z".ltoreq.20 and R.sup.1is a hydrocarbon
with from 8 to 20 carbon atoms and no aryl group;
[0109] c. polyhydroxy fatty acid amide surfactants of the
formula:
R.sup.2--C(O)--N(R.sup.1)--Z
[0110] wherein: each R.sup.1 is H, C.sub.1-C.sub.4 hydrocarbyl,
C.sub.1-C.sub.4 alkoxyalkyl, or hydroxyalkyl; and R.sup.2 is a
C.sub.5-C.sub.31 hydrocarbyl moiety; and each Z is a
polyhydroxyhydrocarbyl moiety having a linear hydrocarbyl chain
with at least 3 hydroxyls directly connected to the chain, or an
ethoxylated derivative thereof; and each R' is H or a cyclic mono-
or poly- saccharide, or alkoxylated derivative thereof; and
[0111] Suitable phase stabilizers also include surfactant complexes
formed by one surfactant ion being neutralized with surfactant ion
of opposite charge or an electrolyte ion that is suitable for
reducing dilution viscosity.
[0112] Examples of representative bilayer disrupters include:
[0113] (1)--Alkyl or Alkyl-aryl Alkoxylated Nonionic
Surfactants
[0114] Suitable alkyl alkoxylated nonionic surfactants are
generally derived from saturated or unsaturated primary, and
secondary fatty alcohols, fatty acids, alkyl phenols, or alkyl aryl
(e.g., benzoic) carboxylic acid, where the active hydrogen(s) is
alkoxylated with .ltoreq.about 30 alkylene, preferably ethylene,
oxide moieties (e.g. ethylene oxide and/or propylene oxide). These
nonionic surfactants for use herein preferably have from about 6 to
about 22 carbon atoms on the alkyl or alkenyl chain, and are in a
straight chain configuration, preferably straight chain
configurations having from about 8 to about 18 carbon atoms, with
the alkylene oxide being present, preferably at the primary
position, in average amounts of .ltoreq.about 30 moles of alkylene
oxide per alkyl chain, more preferably from about 3 to about 15
moles of alkylene oxide, and most preferably from about 6 to about
12 moles of alkylene oxide. Preferred materials of this class also
have pour points of less than about 70.degree. F. (21.degree. C.)
and/or do not solidify in these softening compositions. Examples of
alkyl alkoxylated surfactants with straight chains include
Neodol.RTM. 91-8, 23-5, 25-9, 1-9, 25-12, 1-9, and 45-13 from
Shell, Plurafac.RTM. B-26 and C-17 from BASF, and Brij.RTM. 76 and
35 from ICI Surfactants. Examples of alkyl-aryl alkoxylated
surfactants include: Surfonic N-120 from Huntsman, Igepal.RTM.
CO-620 and CO-710, from Rhone Poulenc, Triton.RTM. N-111 and N-150
from Union Carbide, Dowfax.RTM. 9N5 from Dow and Lutensol.RTM. AP9
and AP14, from BASF.
[0115] (2)--Alkyl or Alkyl-aryl Amine or Amine Oxide Nonionic
Alkoxylated Surfactants
[0116] Suitable alkyl alkoxylated nonionic surfactants with amine
functionality are generally derived from saturated or unsaturated,
primary, and secondary fatty alcohols, fatty acids, fatty methyl
esters, alkyl phenol, alkyl benzoates, and alkyl benzoic acids that
are converted to amines, amine-oxides, and optionally substituted
with a second alkyl or alkyl-aryl hydrocarbon with one or two
alkylene oxide chains attached at the amine functionality each
having .ltoreq.about 50 moles alkylene oxide moieties (e.g.
ethylene oxide and/or propylene oxide) per mole of amine. The
amine, amide or amine-oxide surfactants for use herein have from
about 6 to about 22 carbon atoms, and are in either straight chain
or branched chain configuration, preferably there is one
hydrocarbon in a straight chain configuration having about 8 to
about 18 carbon atoms with one or two alkylene oxide chains
attached to the amine moiety, in average amounts of .ltoreq.50
about moles of alkylene oxide per amine moiety, more preferably
from about 3 to about 15 moles of alkylene oxide, and most
preferably a single alkylene oxide chain on the amine moiety
containing from about 6 to about 12 moles of alkylene oxide per
amine moiety. Preferred materials of this class also have pour
points less than about 70.degree. F. (21.degree. C.) and/or do not
solidify in these softening compositions. Examples of ethoxylated
amine surfactants include Berol.RTM. 397 and 303 from Rhone Poulenc
and Ethomeens.RTM. C/20, C25, T/25, S/20, S/25 and Ethodumeens.RTM.
T/20 and T25 from Akzo.
[0117] Preferably, the compounds of the alkyl or alkyl-aryl
alkoxylated surfactants and alkyl or alkyl-aryl amine, amide, and
amine-oxide alkoxylated have the following general formula:
R.sup.1.sub.m--Y--[(R.sup.2--O).sub.z--H].sub.p
[0118] wherein each R.sup.1 is selected from the group consisting
of saturated or unsaturated, primary, secondary or branched chain
alkyl or alkyl-aryl hydrocarbons; said hydrocarbon chain preferably
having a length of from about 6 to about 22, more preferably from
about 8 to about 18 carbon atoms, and even more preferably from
about 8 to about 15 carbon atoms, preferably, linear and with no
aryl moiety; wherein each R.sup.2 is selected from the following
groups or combinations of the following groups:
--(CH.sub.2).sub.n-- and/or --[CH(CH.sub.3)CH.sub.2]--; wherein
about 1<n.ltoreq. about 3; Y is selected from the following
groups: --O--; --N(A).sub.q-; --C(O)O--; --(O.rarw.)N(A).sub.q-;
--B--R.sup.3--O--; --B--R.sup.3--N(A).sub.q-;
--B--R.sup.3--C(O)O--; --B--R.sup.3--N(.fwdarw.O)(A)-; and mixtures
thereof; wherein A is selected from the following groups: H;
R.sup.1; --(R.sup.2--O).sub.z--H; --(CH.sub.2).sub.xCH.sub.3;
phenyl, or substituted aryl, wherein 0.ltoreq.x.ltoreq. about 3 and
B is selected from the following groups: --O--; --N(A)-; --C(O)O--;
and mixtures thereof in which A is as defined above; and wherein
each R.sup.3 is selected from the following groups: R.sup.2;
phenyl; or substituted aryl. The terminal hydrogen in each alkoxy
chain can be replaced by a short chain C.sub.1-4 alkyl or acyl
group to "cap" the alkoxy chain. z is from about 5 to about 30. p
is the number of ethoxylate chains, typically one or two,
preferably one and m is the number of hydrophobic chains, typically
one or two, preferably one and q is a number that completes the
structure, usually one.
[0119] Preferred structures are those in which m=1, p=1 or 2, and
5.ltoreq.z.ltoreq.30, and q can be 1 or 0, but when p=2, q must be
0; more preferred are structures in which m=1, p=1 or 2, and
7.ltoreq.z.ltoreq.20; and even more preferred are structures in
which m=1, p=1 or 2, and 9.ltoreq.z.ltoreq.12. The preferred y is
0.
[0120] (3)--Alkoxylated and Non-alkoxylated Nonionic Surfactants
with Bulky Head Groups
[0121] Suitable alkoxylated and non-alkoxylated bilayer disrupters
with bulky head groups are generally derived from saturated or
unsaturated, primary and secondary fatty alcohols, fatty acids,
alkyl phenol, and alkyl benzoic acids that are derivatized with a
carbohydrate group or heterocyclic head group. This structure can
then be optionally substituted with more alkyl or alkyl-aryl
alkoxylated or non-alkoxylated hydrocarbons. The heterocyclic or
carbohydrate is alkoxylated with one or more alkylene oxide chains
(e.g. ethylene oxide and/or propylene oxide) each having
.ltoreq.about 50, preferably .ltoreq.about 30, moles per mole of
heterocyclic or carbohydrate. The hydrocarbon groups on the
carbohydrate or heterocyclic surfactant for use herein have from
about 6 to about 22 carbon atoms, and are in a straight chain
configuration, preferably there is one hydrocarbon having from
about 8 to about 18 carbon atoms with one or two alkylene oxide
chains carbohydrate or heterocyclic moiety with each alkylene oxide
chain present in average amounts of .ltoreq.about 50, preferably
.ltoreq.about 30, moles of carbohydrate or heterocyclic moiety,
more preferably from about 3 to about 15 moles of alkylene oxide
per alkylene oxide chain, and most preferably between about 6 and
about 12 moles of alkylene oxide total per surfactant molecule
including alkylene oxide on both the hydrocarbon chain and on the
heterocyclic or carbohydrate moiety. Examples of bilayer disrupters
in this class are Tween.RTM. 40, 60, and 80 available from ICI
Surfactants.
[0122] Preferably the compounds of the alkoxylated and
non-alkoxylated nonionic surfactants with bulky head groups have
the following general formulas:
R.sup.1--C(O)--Y'--[C(R.sup.5)].sub.m--CH.sub.2O(R.sub.2O).sub.zH
[0123] wherein R.sup.1 is selected from the group consisting of
saturated or unsaturated, primary, secondary or branched chain
alkyl or alkyl-aryl hydrocarbons; said hydrocarbon chain having a
length of from about 6 to about 22; Y' is selected from the
following groups: --O--; --N(A)-; and mixtures thereof; and A is
selected from the following groups: H; R.sup.1;
--(R.sup.2--O).sub.z--H; --(CH.sub.2).sub.xCH.sub.3; phenyl, or
substituted aryl, wherein 0.ltoreq.x.ltoreq.about 3 and z is from
about 5 to about 30; each R.sup.2 is selected from the following
groups or combinations of the following groups:
--(CH.sub.2).sub.n-- and/or --[CH(CH.sub.3)CH.sub.2]--; and each
R.sup.5 is selected from the following groups: --OH; and
--O(R.sup.2O).sub.z--H ; and m is from about 2 to about 4;
[0124] Another useful general formula for this class of surfactants
is 3
[0125] wherein Y".dbd.N or O; and each R.sup.5 is selected
independently from the following:
[0126] --H, --OH, --(CH.sub.2)xCH.sub.3, --(OR.sup.2).sub.z--H,
--OR.sup.1, --OC(O)R.sup.1, and
--CH.sub.2(CH.sub.2--(OR.sup.2).sub.z"--H-
)--CH.sub.2--(OR.sup.2).sub.z'--C(O) R.sup.1, with x R.sup.1, and
R.sup.2as defined above in section D above and z, z', and z" are
all from about 5.ltoreq.to .ltoreq.about 20, more preferably the
total number of z+z'+z" is from about 5.ltoreq.to .ltoreq.about 20.
In a particularly preferred form of this structure the heterocyclic
ring is a five member ring with Y".dbd.O, one R.sup.5 is --H, two
R.sup.5 are --O--(R.sup.2O).sub.z--H, and at least one R.sup.5 has
the following structure
--CH(CH.sub.2--(OR.sup.2).sub.z"--H)--CH.sub.2--(OR.sup.2).sub.-
z'--OC(O)R.sup.1 with the total z+z'+z"= to from about 8.ltoreq.to
.ltoreq.about 20 and R.sup.1 is a hydrocarbon with from about 8 to
about 20 carbon atoms and no aryl group.
[0127] Another group of surfactants that can be used are
polyhydroxy fatty acid amide surfactants of the formula:
R.sup.6--C(O)--N(R.sup.7)--W
[0128] wherein: each R.sup.7 is H, C.sub.1-C.sub.4 hydrocarbyl,
C.sub.1-C.sub.4 alkoxyalkyl, or hydroxyalkyl, e.g., 2-hydroxyethyl,
2-hydroxypropyl, etc., preferably C.sub.1-C.sub.4 alkyl, more
preferably C.sub.1 or C.sub.2 alkyl, most preferably C.sub.1 alkyl
(i.e., methyl) or methoxyalkyl; and R.sup.6 is a C.sub.5-C.sub.31
hydrocarbyl moiety, preferably straight chain C.sub.7-C.sub.19
alkyl or alkenyl, more preferably straight chain C.sub.9-C.sub.17
alkyl or alkenyl, most preferably straight chain C.sub.11-C.sub.17
alkyl or alkenyl, or mixture thereof; and W is a
polyhydroxyhydrocarbyl moiety having a linear hydrocarbyl chain
with at least 3 hydroxyls directly connected to the chain, or an
alkoxylated derivative (preferably ethoxylated or propoxylated)
thereof. W preferably will be derived from a reducing sugar in a
reductive amination reaction; more preferably W is a glycityl
moiety. W preferably will be selected from the group consisting of
--CH.sub.2--(CHOH).sub.n--CH.sub.2OH,
--CH(CH.sub.2OH)--(CHOH).sub.n--CH.- sub.2OH,
--CH.sub.2--(CHOH).sub.2(CHOR')(CHOH)--CH.sub.2OH, where n is an
integer from 3 to 5, inclusive, and R' is H or a cyclic mono- or
poly-saccharide, and alkoxylated derivatives thereof. Most
preferred are glycityls wherein n is 4, particularly
--CH.sub.2--(CHOH).sub.4--CH.sub.2- O. Mixtures of the above W
moieties are desirable.
[0129] R.sup.6 can be, for example, N-methyl, N-ethyl, N-propyl,
N-isopropyl, N-butyl, N-isobutyl, N-2-hydroxyethyl,
N-1-methoxypropyl, or N-2-hydroxypropyl.
[0130] R.sup.6--CO--N.ltoreq. can be, for example, cocamide,
stearamide, oleamide, lauramide, myristamide, capricamide,
palmitamide, tallowamide, etc.
[0131] W can be 1-deoxyglucityl, 2-deoxyfructityl, 1-deoxymaltityl,
1-deoxylactityl, 1-deoxygalactityl, 1-deoxymannityl,
1-deoxymaltotriotityl, etc.
[0132] (4)--Alkoxylated Cationic Quaternary Ammonium
Surfactants
[0133] Alkoxylated cationic quaternary ammonium surfactants
suitable for this invention are generally derived from fatty
alcohols, fatty acids, fatty methyl esters, alkyl substituted
phenols, alkyl substituted benzoic acids, and/or alkyl substituted
benzoate esters, and/or fatty acids that are converted to amines
which can optionally be further reacted with another long chain
alkyl or alkyl-aryl group; this amine compound is then alkoxylated
with one or two alkylene oxide chains each having .ltoreq.about 50
moles alkylene oxide moieties (e.g. ethylene oxide and/or propylene
oxide) per mole of amine. Typical of this class are products
obtained from the quaternization of aliphatic saturated or
unsaturated, primary, secondary, or branched amines having one or
two hydrocarbon chains from about 6 to about 22 carbon atoms
alkoxylated with one or two alkylene oxide chains on the amine atom
each having less than .ltoreq. about 50 alkylene oxide moieties.
The amine hydrocarbons for use herein have from about 6 to about 22
carbon atoms, and are in either straight chain or branched chain
configuration, preferably there is one alkyl hydrocarbon group in a
straight chain configuration having about 8 to about 18 carbon
atoms. Suitable quaternary ammonium surfactants are made with one
or two alkylene oxide chains attached to the amine moiety, in
average amounts of .ltoreq.about 50 moles of alkylene oxide per
alkyl chain, more preferably from about 3 to about 20 moles of
alkylene oxide, and most preferably from about 5 to about 12 moles
of alkylene oxide per hydrophobic, e.g., alkyl group. Preferred
materials of this class also have a pour points below about
70.degree. F. (21.degree. C.) and/or do not solidify in these
softening compositions. Examples of suitable bilayer disrupters of
this type include Ethoquad.RTM. 18/25, C/25, and O/25 from Akzo and
Variquat.RTM.-66 (soft tallow alkyl bis(polyoxyethyl) ammonium
ethyl sulfate with a total of about 16 ethoxy units) from
Witco.
[0134] Preferably, the compounds of the ammonium alkoxylated
cationic surfactants have the following general formula:
{R.sup.1.sub.m--Y--[(R.sup.2--O).sub.z--H].sub.p}.sup.+X.sup.-
[0135] wherein R.sup.1 and R.sup.2 are as defined previously in
section D above;
[0136] Y is selected from the following groups:
.dbd.N.sup.+-(A).sub.q; --(CH.sub.2).sub.n--N.sup.+-(A).sub.q;
--B--(CH.sub.2).sub.n13 N.sup.+-(A).sub.2;
-(phenyl)-N.sup.+-(A).sub.q; --(B-phenyl)-N.sup.+-(A).- sub.q; with
n being from about 1 to about 4.
[0137] Each A is independently selected from the following groups:
H; R.sup.1; --(R.sup.2O).sub.z--H; --(CH.sub.2).sub.xCH.sub.3;
phenyl, and substituted aryl; where 0.ltoreq.x.ltoreq. about 3; and
B is selected from the following groups: --O-; --NA--; --NA.sub.2;
--C(O)O--; and --C(O)N(A)-; wherein R.sup.2 is defined as
hereinbefore; q=1 or 2; and
[0138] X.sup.- is an anion which is compatible with the softening
active ingredient and other components of the softening
composition.
[0139] Preferred structures are those in which m=1, p=1 or 2, and
about 5.ltoreq.z.ltoreq.about 50, more preferred are structures in
which m=1, p=1 or 2, and about 7.ltoreq.z.ltoreq.about 20, and most
preferred are structures in which m=1, p=1 or 2, and about
9.ltoreq.z.ltoreq.about 12.
[0140] (5)--Alkyl Amide Alkoxylated Nonionic Surfactants
[0141] Suitable surfactants have the formula:
R--C(O)--N(R.sup.4).sub.n--[(R.sup.1O).sub.x(R.sup.2O).sub.yR.sup.3].sub.m
[0142] wherein R is C.sub.7-21 linear alkyl, C.sub.7-21 branched
alkyl, C.sub.7-21 linear alkenyl, C.sub.7-21 branched alkenyl, and
mixtures thereof. Preferably R is C8-18 linear alkyl or
alkenyl.
[0143] R.sub.1 is --CH.sub.2--CH2--, R.sub.2 is C.sub.3-C.sub.4
linear alkyl, C.sub.3-C.sub.4 branched alkyl, and mixtures thereof;
preferably R.sup.2 is --CH(CH.sub.3)--CH.sub.2--. Surfactants which
comprise a mixture of R.sup.1 and R.sup.2 units preferably comprise
from about 4 to about 12 --CH.sub.2--CH.sub.2-- units in
combination with from about 1 to about 4 --CH(CH.sub.3)--CH.sub.2--
units. The units may be alternating or grouped together in any
combination suitable to the formulator. Preferably the ratio of
R.sup.1 units to R.sup.2 units is from about 4:1 to about 8:1.
Preferably an R.sup.2 unit (i.e. --C(CH.sub.3)H--CH.sub.2--- ) is
attached to the nitrogen atom followed by the balance of the chain
comprising from about 4 to 8 --CH.sub.2--CH.sub.2-- units.
[0144] R.sup.3 is hydrogen, C.sub.1-C.sub.4 linear alkyl,
C.sub.3-C.sub.4 branched alkyl, and mixtures thereof; preferably
hydrogen or methyl, more preferably hydrogen.
[0145] R.sup.4 is hydrogen, C.sub.1-C.sub.4 linear alkyl,
C.sub.3-C.sub.4 branched alkyl, and mixtures thereof; preferably
hydrogen. When the index m is equal to 2 the index n must be equal
to 0 and the R.sup.4 unit is absent.
[0146] The index m is 1 or 2, the index n is 0 or 1, provided that
m+n equals 2; preferably m is equal to 1 and n is equal to 1,
resulting in one --[(R.sup.1O).sub.x(R.sup.2O).sub.yR.sup.3] unit
and R4 being present on the nitrogen. The index x is from 0 to
about 50, preferably from about 3 to about 25, more preferably from
about 3 to about 10. The index y is from 0 to about 10, preferably
0, however when the index y is not equal to 0, y is from 1 to about
4. Preferably all the alkyleneoxy units are ethyleneoxy units.
[0147] Examples of suitable ethoxylated alkyl amide surfactants are
Rewopal.RTM. C.sub.6 from Witco, Amidox.RTM. C5 from Stepan, and
Ethomid.RTM. O/17 and Ethomid.RTM. HT/60 from Akzo.
[0148] Minor Components of the Softening Composition
[0149] The vehicle can also comprise minor ingredients as may be
known to the art. examples include: mineral acids or buffer systems
for pH adjustment (may be required to maintain hydrolytic stability
for certain softening active ingredients) and antifoam ingredients
(e.g., a silicone emulsion as is available from Dow Corning, Corp.
of Midland, Mich. as Dow Corning 2310) as a processing aid to
reduce foaming when the softening composition of the present
invention is used.
[0150] Stabilizers may also be used to improve the uniformity and
shelf life of the dispersion. For example, an ethoxylated
polyester, HOE S 4060, available from Clariant Corporation of
Charlotte, N.C. may be included for this purpose.
[0151] Forming the Softening Composition
[0152] As noted above, the softening composition of the present
invention is a dispersion of a softening active ingredient in a
vehicle. Depending on the softening active ingredient chosen, the
desired application level and other factors as may require a
particular level of softening active ingredient in the composition,
the level of softening active ingredient may vary between about 10%
of the composition and about 50% of the composition. Preferably,
the softening active ingredient comprises between about 25% and
about 45% of the composition. More preferably, the softening active
ingredient comprises between about 35% and about 45% of the
composition. The nonionic surfactant is present at a level between
about 1% and about 15% of the level of the softening active
ingredient, preferably between about 2% and about 10%. Depending on
the method used to produce the softening active ingredient the
softening composition may also comprise between about 2% and about
30%, preferably between about 5% and about 25% of a plasticizer. As
noted above, the preferred primary component of the vehicle is
water. In addition, the vehicle preferably comprises an alkali or
alkaline earth halide electrolyte and may comprise minor
ingredients to adjust pH, to control foam, or to aid in stability
of the dispersion. The following describes preparation of a
particularly preferred softening composition of the present
invention.
[0153] A particularly preferred softening composition of the
present invention (Composition 1) is prepared as follows. The
materials are more specifically defined in the table detailing
Composition 1 which follows this description. Amounts used in each
step are sufficient to result in the finished composition detailed
in that table. The appropriate quantity of water is heated (extra
added to compensate for evaporation loss) to about 165.degree. F.
(75.degree. C.). The hydrochloric acid (25% solution) and antifoam
ingredient are added. Concurrently, the blend of softening active
ingredient, plasticizer, and nonionic surfactant is melted by
heating it to a temperature of about 150.degree. F. (65.degree.
C.). The melted mixture of softening active ingredient,
plasticizer, and nonionic surfactant is then slowly added to the
heated acidic aqueous phase with mixing to evenly distribute the
disperse phase throughout the vehicle. (The water solubility of the
polyethylene glycol probably carries it into the continuous phase,
but this is not essential to the invention and plasticizers which
are more hydrophobic and thus remain associated with the alkyl
chains of the quaternary ammonium compound are also allowed within
the scope of the present invention.) Once the softening active
ingredient is thoroughly dispersed, part of the calcium chloride is
added (as a 2.5% solution) intermittently with mixing to provide an
initial viscosity reduction. The stabilizer is then slowly added to
the mixture with continued agitation. Lastly, the remainder of the
calcium chloride(as a 25% solution) is added with continued
mixing.
1 Composition 1 Component Concentration Continuous Phase Water QS
to 100% Electrolyte.sup.1 0.6% Antifoam.sup.2 0.2% Bilayer
Disrupter.sup.3,5 1.0% Hydrochloric Acid.sup.4 0.04%
Plasticizer.sup.5 19% Stabilizer.sup.6 0.5% Disperse Phase
Softening Active Ingredient.sup.5 40.0% .sup.10.38% from 2.5%
aqueous calcium chloride solution and 0.22% from 25% aqueous
calcium chloride solution .sup.2Silicone Emulsion (10% active)-Dow
Corning 2310 .RTM., marketed by Dow Corning Corp., Midland, MI
.sup.3Suitable nonionic surfactants are available from Shell
Chemical of Houston, TX under the trade name NEODOL 91-8.
.sup.4Available as a 25% solution from J. T. Baker Chemical Company
of Phillipsburg, NJ .sup.5Bilayer disrupter, plasticizer, and
softening active ingredient obtained pre-blended from Witco
Chemical Company of Dublin OH (about 2 parts Neodol 91-8, about 29
parts polyethylene glycol 400, and about 69 parts tallow diester
quaternary) .sup.6Stabilizer is HOE S 4060, from Clariant Corp.,
Charlotte, NC
[0154] The resulting chemical softening composition is a milky, low
viscosity dispersion suitable for application to cellulosic
structures as described below for providing desirable tactile
softness to such structures. It displays a shear-thinning
non-Newtonian viscosity. Suitably, the composition has a viscosity
less than about 1000 centipoise (cp), as measured at 25.degree. C.
and at a shear rate of 100 sec.sup.-1 using the method described in
the TEST METHODS section below. Preferably, the composition has a
viscosity less than about 500 cp. More preferably, the viscosity is
less than about 300 cp.
[0155] The chemical composition is easily handled as a liquid and
is easily shipped from the point of manufacture to point of use
since it has a relatively high concentration of active ingredient.
At point the of use, it is convenient to dilute the concentrate to
a use concentration. This dilution step is necessary in order to
allow proper metering of the softening active ingredient into the
papermaking process. That is, in a commercial papermaking process,
a fairly large quantity of a dispersion having a low concentration
of the softener active ingredient is metered into an appropriate
process stream. It will be recognized that the use concentration
depends on several factors including: process capability for the
metering step, the desired add-on of the softening active
ingredient, the flow rates of the various process steams, and other
factors as will be recognized by those having skill in the art. A
suitable range of use concentrations has been found to be between
about 0.5% and about 10% where the concentration is expressed as
weight percent softening active ingredient. Preferably the use
concentration is between about 0.5% and about 5%, more preferably
between about 0.5% and about 2%. A particularly preferred use
concentration is about 1%.
[0156] Optional Chemical Additives
[0157] Other materials can be added to the aqueous papermaking
furnish or the embryonic web to impart other desirable
characteristics to the product or improve the papermaking process
so long as they are compatible with the chemistry of the softening
composition and do not significantly and adversely affect the
softness or strength character of the present invention. The
following materials are expressly included, but their inclusion is
not offered to be all-inclusive. Other materials can be included as
well so long as they do not interfere or counteract the advantages
of the present invention.
[0158] It is common to add a cationic charge biasing species to the
papermaking process to control the zeta potential of the aqueous
papermaking furnish as it is delivered to the papermaking process.
These materials are used because most of the solids in nature have
negative surface charges, including the surfaces of cellulosic
fibers and fines and most inorganic fillers. One traditionally used
cationic charge biasing species is alum. More recently in the art,
charge biasing is done by use of relatively low molecular weight
cationic synthetic polymers preferably having a molecular weight of
no more than about 500,000 and more preferably no more than about
200,000, or even about 100,000. The charge densities of such low
molecular weight cationic synthetic polymers are relatively high.
These charge densities range from about 4 to about 8 equivalents of
cationic nitrogen per kilogram of polymer. An exemplary material is
Cypro 514.RTM., a product of Cytec, Inc. of Stamford, Conn. The use
of such materials is expressly allowed within the practice of the
present invention.
[0159] The use of high surface area, high anionic charge
microparticles for the purposes of improving formation, drainage,
strength, and retention is taught in the art. See, for example,
U.S. Pat. No. 5,221,435, issued to Smith on Jun. 22, 1993, the
disclosure of which is incorporated herein by reference. Common
materials for this purpose are silica colloid, or bentonite clay.
The incorporation of such materials is expressly included within
the scope of the present invention.
[0160] If permanent wet strength is desired, the group of
chemicals: including polyamide-epichlorohydrin, polyacrylamides,
styrene-butadiene lattices; insolubilized polyvinyl alcohol;
urea-formaldehyde; polyethyleneimine; chitosan polymers and
mixtures thereof can be added to the papermaking furnish or to the
embryonic web. Preferred resins are cationic wet strength resins,
such as polyamide-epichlorohydrin resins. Suitable types of such
resins are described in U.S. Pat. No. 3,700,623, issued on Oct. 24,
1972, and U.S. Pat. No. 3,772,076, issued on Nov. 13, 1973, both to
Keim, the disclosure of both being hereby incorporated by
reference. One commercial source of useful
polyamide-epichlorohydrin resins is Hercules, Inc. of Wilmington,
Del., which markets such resin under the mark Kymene 557H.RTM..
[0161] Many paper products must have limited strength when wet
because of the need to dispose of them through toilets into septic
or sewer systems. If wet strength is imparted to these products,
fugitive wet strength, characterized by a decay of part or all of
the initial strength upon standing in presence of water, is
preferred. If fugitive wet strength is desired, the binder
materials can be chosen from the group consisting of dialdehyde
starch or other resins with aldehyde functionality such as Co-Bond
1000.RTM. offered by National Starch and Chemical Company of
Scarborough, Me.; Parez 750.RTM. offered by Cytec of Stamford,
Conn.; and the resin described in U.S. Pat. No. 4,981,557, issued
on Jan. 1, 1991, to Bjorkquist, the disclosure of which is
incorporated herein by reference, and other such resins having the
decay properties described above as may be known to the art.
[0162] If enhanced absorbency is needed, surfactants may be used to
treat the tissue paper webs of the present invention. The level of
surfactant, if used, is preferably from about 0.01% to about 2.0%
by weight, based on the dry fiber weight of the tissue web. The
surfactants preferably have alkyl chains with eight or more carbon
atoms. Exemplary anionic surfactants include linear alkyl
sulfonates and alkylbenzene sulfonates. Exemplary nonionic
surfactants include alkylglycosides including alkylglycoside esters
such as Crodesta SL-40.RTM. which is available from Croda, Inc.
(New York, N.Y.); alkylglycoside ethers as described in U.S. Pat.
No. 4,011,389, issued to Langdon, et al. on Mar. 8, 1977; and
alkylpolyethoxylated esters such as Pegosperse 200 ML available
from Glyco Chemicals, Inc. (Greenwich, Conn.) and IGEPAL
RC-520.RTM. available from Rhone Poulenc Corporation (Cranbury,
N.J.). Alternatively, cationic softener active ingredients with a
high degree of unsaturated (mono and/or poly) and/or branched chain
alkyl groups can greatly enhance absorbency.
[0163] The cellulosic structures of the present invention can
contain other types of chemical softeners as well. For example,
another class of papermaking-added chemical softening agents
comprise the well-known organo-reactive polydimethyl siloxane
ingredients, including the most preferred amino functional
polydimethyl siloxane.
[0164] Filler materials may also be incorporated into the tissue
papers of the present invention. U.S. Pat. No. 5,611,890, issued to
Vinson et al. on Mar. 18, 1997, and, incorporated herein by
reference discloses filled tissue paper products that are
acceptable as substrates for the present invention.
[0165] The above listings of optional chemical additives is
intended to be merely exemplary in nature, and are not meant to
limit the scope of the invention.
[0166] Addition Method
[0167] Furnish Preparation
[0168] Further insight into preparation methods for the aqueous
papermaking furnish can be gained by reference to FIG. 2, which is
a schematic representation illustrating a preparation of the
aqueous papermaking furnish for the creped papermaking operation
yielding a product according to the present invention. The
following discussion refers to FIG. 2:
[0169] A storage vessel 8 is a repository for the low viscosity
chemical softening composition of the present invention. Pipe 9
provides dilution water for reducing the concentration of the
softening active ingredient to a suitable use concentration. Pump
10 acts to convey the diluted vesicular dispersion of the softening
active ingredient. The dispersion is optionally conditioned in a
mixer 12 to aid in formation of the vesicles. Resultant dispersion
13 is conveyed to a point where it is mixed with an aqueous
dispersion of refined relatively long fiber papermaking fibers.
[0170] Still referring to FIG. 2, a storage vessel 1 is provided
for staging an aqueous slurry of relatively long papermaking
fibers. The slurry is conveyed by means of a pump 2 and optionally
through a refiner 3 to fully develop the strength potential of the
long papermaking fibers. Pipe 27 positioned between pump 2 and
refiner 3 may be used to add a cationic debonder, if desired, to
compensate for charged fines so as to minimize usage of other
materials added at later stages in the process. If desired,
additive pipe 4 conveys a resin to provide for wet or dry strength,
in the finished product. The slurry is then further conditioned in
mixer 5 to aid in absorption of the resin. After mixing with the
vesicular dispersion of softening active ingredient 13, it becomes
the relatively long fiber based aqueous papermaking slurry 17.
Optionally, the slurry may be conditioned in mixer 25 to aid in
absorption of the softening active ingredient. The suitably
conditioned slurry is then diluted with white water 7 in a fan pump
6 forming a dilute long papermaking fiber slurry 29. Pipe 20 adds a
cationic flocculant to the slurry 29, producing a flocculated
relatively long fibered slurry 22.
[0171] Still referring to FIG. 2, a relatively short papermaking
fiber slurry originates from a repository 11, from which it is
conveyed through pipe 49 by pump 14 through a refiner 15 where it
becomes a refined slurry of relatively short papermaking fibers 16.
White water 7 is mixed with slurry 16 in a fan pump 18 at which
point the slurry becomes a dilute aqueous papermaking slurry 19.
Pipe 21 directs a cationic flocculant into slurry 19, after which
the slurry becomes a flocculated aqueous relatively short fiber
based papermaking slurry 23.
[0172] In one embodiment of a papermaking process, the flocculated
relatively short-fiber based aqueous papermaking slurry 23 is
directed to the creped papermaking process illustrated in FIG. 1
and is divided into two approximately equal streams which are then
directed into headbox chambers 82 and 83 ultimately evolving into
off-Yankee-side-layer 75 and Yankee-side-layer 71, respectively of
the strong, soft creped tissue paper. Similarly, the aqueous
flocculated relatively long papermaking fiber slurry 22, referring
to FIG. 2, is preferably directed into headbox chamber 82b
ultimately evolving into center layer 73 of the strong, soft creped
tissue paper.
[0173] The Creped Papermaking Process
[0174] FIG. 1 is a schematic representation illustrating a creped
papermaking process for producing a strong, soft creped tissue
paper. These preferred embodiments are described in the following
discussion, wherein reference is made to FIG. 1. FIG. 1 is a side
elevational view of a preferred papermaking machine 80 for
manufacturing paper according to the present invention. Referring
to FIG. 1, papermaking machine 80 comprises a layered headbox 81
having a top chamber 82 a center chamber 82b, and a bottom chamber
83, a slice roof 84, and a Fourdrinier wire 85 which is looped over
and about breast roll 86, deflector 90, vacuum suction boxes 91,
couch roll 92, and a plurality of turning rolls 94. In operation,
one papermaking furnish is pumped through top chamber 82 a second
papermaking furnish is pumped through center chamber 82b, while a
third furnish is pumped through bottom chamber 83 and thence out of
the slice roof 84 in over and under relation onto Fourdrinier wire
85 to form thereon an embryonic web 88 comprising layers 88a, and
88b, and 88c. Dewatering occurs through the Fourdrinier wire 85 and
is assisted by deflector 90 and vacuum boxes 91. As the Fourdrinier
wire makes its return run in the direction shown by the arrow,
showers 95 clean it prior to its commencing another pass over
breast roll 86. At web transfer zone 93, the embryonic web 88 is
transferred to a foraminous carrier fabric 96 by the action of
vacuum transfer box 97. Carrier fabric 96 carries the web from the
transfer zone 93 past vacuum dewatering box 98, through
blow-through predryers 100 and past two turning rolls 101 after
which the web is transferred to a Yankee dryer 108 by the action of
pressure roll 102. The carrier fabric 96 is then cleaned and
dewatered as it completes its loop by passing over and around
additional turning rolls 101, showers 103, and vacuum dewatering
box 105. The predried paper web is adhesively secured to the
cylindrical surface of Yankee dryer 108 aided by adhesive applied
by spray applicator 109. Drying is completed on the steam heated
Yankee dryer 108 and by hot air which is heated and circulated
through drying hood 110 by means not shown. The web is then dry
creped from the Yankee dryer 108 by doctor blade 111 after which it
is designated paper sheet 70 comprising a Yankee-side layer 71 a
center layer 73, and an off-Yankee-side layer 75. Paper sheet 70
then passes between calendar rolls 112 and 113, about a
circumferential portion of reel 115, and thence is wound into a
roll 116 on a core 117 disposed on shaft 118.
[0175] Still referring to FIG. 1, the genesis of Yankee-side layer
71 of paper sheet 70 is the furnish pumped through bottom chamber
83 of headbox 81, and which furnish is applied directly to the
Fourdrinier wire 85 whereupon it becomes layer 88c of embryonic web
88. The genesis of the center layer 73 of paper sheet 70 is the
furnish delivered through chamber 82.5 of headbox 81, and which
furnish forms layer 88b on top of layer 88c. The genesis of the
off-Yankee-side layer 75 of paper sheet 70 is the furnish delivered
through top chamber 82 of headbox 81, and which furnish forms layer
88a on top of layer 88b of embryonic web 88. Although FIG. 1 shows
papermachine 80 having headbox 81 adapted to make a three-layer
web, headbox 81 may alternatively be adapted to make unlayered, two
layer or other multi-layer webs.
[0176] Further, with respect to making paper sheet 70 embodying the
present invention on papermaking machine 80, FIG. 1, the
Fourdrinier wire 85 must be of a fine mesh having relatively small
spans with respect to the average lengths of the fibers
constituting the short fiber furnish so that good formation will
occur; and the foraminous carrier fabric 96 should have a fine mesh
having relatively small opening spans with respect to the average
lengths of the fibers constituting the long fiber furnish to
substantially obviate bulking the fabric side of the embryonic web
into the interfilamentary spaces of the fabric 96. Also, with
respect to the process conditions for making exemplary paper sheet
70, the paper web is preferably dried to about 80% fiber
consistency, and more preferably to about 95% fiber consistency
prior to creping.
[0177] The present invention is applicable to creped tissue paper
in general, including but not limited to conventionally
felt-pressed creped tissue paper; high bulk pattern densified
creped tissue paper; and high bulk, uncompacted creped tissue
paper. One of skill in the art will also recognize that the process
steps described above are exemplary and that other processes are
equally within the scope of the present invention. For example, a
homogeneous furnish can be provided wherein the furnish can
comprise any desired blend of long and short papermaking fibers
that have been treated with a vesicular dispersion of a chemical
softening active ingredient using process steps similar to those
described above. Processes providing tissue structures having two
layers, such as that shown in Examples 3 and 4, are also within the
scope of the present invention.
EXAMPLES
Example 1
[0178] This Example illustrates preparation of a preferred
embodiment of the softening composition of the present
invention.
[0179] Materials used in the preparation of the chemical softening
mixture are:
[0180] 1. Partially hydrogenated tallow diester chloride quaternary
ammonium compound premixed with polyethylene glycol 400 and an
ethoxylated fatty alcohol nonionic surfactant. The premix is about
69% quaternary ammonium compound (Adogen SDMC-type from Witco
incorporated) 29% PEG 400 (available from J.T. Baker Company of
Phillipsburg, N.J.) and 2% nonionic (available from Shell Chemical
of Huston, Tex. as Neodol 91-8). The Blend is available from Witco
as DXP-5429-14.
[0181] 2. Calcium Chloride Pellets: from J. T. Baker Company of
Phillipsburg, N.J.
[0182] 3. Polydimethylsiloxane: 10% active emulsion (DC2310) from
Dow Corning of Midland, Mich.
[0183] 4. Hydrochloric acid (25% solution) from J. T. Baker Company
of Phillipsburg, N.J.
[0184] 5. Stabilizer HOE S 4060, from Clariant Corp., Charlotte,
N.C.
[0185] These materials are prepared as follows to form the
softening composition of the present invention.
[0186] The chemical softening composition is prepared by first
heating the required quantity of water to about 75.degree. C. The
hydrochloric acid and the polydimethylsiloxane are then added to
the heated water. The pH of the water premix is about 4. The premix
of quaternary compound, PEG 400, and nonionic surfactant is then
heated to about 65.degree. C. and metered into the water premix
with stirring until the mixture is fully homogeneous. About half of
the calcium chloride is added as a 2.5% solution in water with
continued stirring. The stabilizer is then added with continued
mixing. Final viscosity reduction is achieved by adding the
remainder of the calcium chloride (as a 25% solution) with
continued mixing. The components are blended in a proportion
sufficient to provide a composition having the following
approximate concentrations of each of the ingredients:
[0187] 40.1% Partially hydrogenated tallow diester chloride
quaternary ammonium compound
[0188] QS Water
[0189] 17.2% PEG 400
[0190] 1.1% Neodol 91-8
[0191] 0.6% CaCl.sub.2
[0192] 0.5% Stabilizer
[0193] 0.02% Polydimethylsiloxane
[0194] 0.02% HCl
[0195] After cooling and addition of make-up water, the composition
has a viscosity of about 300 centipoise as measured at 25.degree.
C. and at a shear rate of 100 sec.sup.-1 using the method described
in the TEST METHODS section.
Example 2
[0196] This example illustrates the effect of nonionic surfactant
chemical composition on a key softening composition
property--viscosity. Chemical softening compositions are made up by
first preparing a master batch containing all of the ingredients of
the softening except a bilayer disrupter. The formula for this
composition is given in Table 1.
2 TABLE 1 Concentration Component (%) Partially hydrogenated tallow
diester 41 chloride quaternary ammonium compound Water 39 PEG 400
19 CaCl.sub.2 0.6 Stabilizer 0.5 Polydimethylsiloxane 0.02 HCl
0.02
[0197] Test softening composition are then prepared by blending
potential bilayer disrupters with the master batch at levels of 1%,
2%, 3%, and 4%. Viscosity of each of the test softening
compositions is measured according to the method described in the
TEST METHODS section below. The viscosity of the master batch is
also measured. Table 2 lists the test materials, their HLB (a
measure of emulsifying effectiveness), and the viscosity for each
of the compositions made.
3 TABLE 2 Concentration Viscosity Nonionic Surfactant HLB (%)
(centipoise) Neodol 23-3.sup.1 7.9 0 1.8 .times. 10.sup.7* 1 6774 2
4375 3 1549 4 1365 NEODOL 23-5.sup.1 10.7 0 2150* 1 335 2 260 3 644
4 1285 NEODOL 91-8.sup.1 13.9 0 1.8 .times. 10.sup.7* 1 166 2 1583
3 9 .times. 10.sup.5 4 8 .times. 10.sup.6 Surfonic N-120.sup.2 14.1
0 6103* 1 193 2 704 3 7595 4 9 .times. 10.sup.6 Acconon CC-6.sup.3
0 6103* 1 450 2 421 3 1194 4 1.7 .times. 10.sup.4 Tween 60.sup.4
14.9 0 6.4 .times. 10.sup.7* 1 215 2 367 3 652 4 2043 Plurafac
B25-5.sup.5 12.0 0 1029* 1 442 2 2100 3 2.9 .times. 10.sup.4 4 1.1
.times. 10.sup.7 *Without being bound by theory, it is believed
that the variability in viscosity is due to intermittent formation
of stable liquid crystal phases due to the high concentration of
softening active ingredient used. As noted above, addition of a
bilayer disrupter is believed to reduce this viscosity by
interrupting the structure of the liquid crystal phase.
.sup.1Ethoxylated fatty alcohol from Shell Chemical, Houston, TX
.sup.2Ethoxylated alkylphenol from Huntsman Corp., Houston, TX
.sup.3Ethoxylated capric/caprylic glyceride from Abitec Corp. of
Columbus, OH .sup.4POE(20) Sorbitan Monostearate from Henkel Corp.
Charlotte, NC .sup.5Modified oxyethylated straight chain alcohol
from BASF Corp., Mt. Olive, NJ
[0198] As can be seen, each of these materials substantially
reduces the viscosity of the dispersion to less than that of the
dispersion without the material.
Example 3
[0199] The purpose of this example is to illustrate a method using
a conventional drying papermaking technique to make soft and
absorbent tissue paper treated with a prior art chemical softener
composition comprising a premix of Di(Hydrogenated)Tallow DiMethyl
Ammonium Methyl Sulfate (DHTDMAMS) and a Polyoxyethylene Glycol 400
(PEG-400) in solid state and a wet strength additive resin.
[0200] A pilot scale S-wrap twin-wire papermaking machine is used
in the practice of the present invention. First, the substantially
waterless self-emulsifiable chemical softener composition is
prepared according to U.S. Pat. No. 5,474,689 wherein the
homogenous premix of DHTDMAMS and PEG400 in solid state is
dispersed in a conditioned water tank (Temperature about 66.degree.
C.) to form a sub-micron vesicle dispersion.
[0201] Second, a 3% by weight aqueous slurry of Deinked Market Pulp
(DMP) is made up in a conventional re-pulper. The DMP slurry is
refined gently and a 0.25% solution of the wet strength resin (i.e.
Kymene 557H as is available from Hercules of Wilmington, Del.) is
added to the DMP stock pipe at a rate of 0.7 pounds resin/ton
(0.04%) by weight of the dry fibers. The adsorption of the wet
strength resin onto DMP fibers is enhanced by an in-line mixer.
DHTDMAMS in the form of a chemical softener mixture according to
U.S. Pat. No. 5,474,689 is also added to the DMP stock pipe (at a
concentration of 1% softening active ingredient) before the stock
pump, but after the wet strength resin, at a rate of about 2.5
pounds/ton (0.125%) by weight of the dry fibers. The adsorption of
the chemical softener mixture to DMP fibers can be enhanced by an
in-line mixer. The DMP slurry is diluted to about 0.2% consistency
at the fan pump.
[0202] Third, a 3% by weight aqueous slurry of Eucalyptus fibers is
made up in a conventional re-pulper. The Eucalyptus slurry is
diluted to about 0.2% consistency at the fan pump.
[0203] The slurries of DMP and eucalyptus are directed into a
multi-channeled headbox suitably equipped with layering leaves to
maintain the streams as separate layers until discharge onto a
traveling S-wrap twin-wire. A three-chambered headbox is used. The
eucalyptus slurry, containing sufficient solids flow to achieve 34%
of the dry weight of the ultimate paper is directed to chambers
leading to the forming wire, while the DMP slurry comprising
sufficient solids flow to achieve 66% of the dry weight of the
ultimate paper is directed to the remaining two chambers. The DMP
and eucalyptus slurries are combined at the discharge of the
headbox into a composite slurry.
[0204] The composite slurry is discharged onto the traveling S-wrap
twin-wire former and is dewatered. Dewatering is assisted by a
deflector and vacuum boxes.
[0205] The embryonic wet web is transferred from the S-wrap
twin-wire former, at a fiber consistency of about 15% at the point
of transfer, to a drying fabric. A suitable drying fabric is a
needle punched batt with a trilayer base fabric as is available
from Albany International of Albany, N.Y. as TRIOVENT. Further
dewatering is accomplished by vacuum assisted drainage until the
web has a fiber consistency of about 28%.
[0206] The semi-dry web is then adhered to the surface of a Yankee
dryer with a sprayed creping adhesive comprising a mixture of
polyvinyl alcohol and a polyamide based resin. The creping adhesive
is delivered to the Yankee surface at a rate of 0.125% adhesive
solids based on the dry weight of the web.
[0207] The fiber consistency is increased to about 96% before the
web is dry creped from the Yankee with a doctor blade.
[0208] The doctor blade has a bevel angle of about 20 degrees and
is positioned with respect to the Yankee dryer to provide an impact
angle of about 76 degrees.
[0209] The percent crepe is adjusted to about 21-25% by operating
the Yankee dryer at a speed of about 1000 fpm (feet per minute)
(about 305 meters per minute), while the dry web is formed into
roll at a speed of about 770 fpm (235 meters per minutes).
[0210] The tissue paper has a basis weight of about 10 pounds/3000
ft.sup.2 (16 grams/m.sup.2), contains about 0.05% of the
substantially waterless self-emulsifiable chemical softener mixture
and about 0.1% of the wet strength resin. Importantly, the
resulting tissue paper is soft, absorbent and is suitable for use
as a facial and/or toilet tissues.
Example 4
[0211] The purpose of this example is to illustrate a method using
a conventional drying papermaking technique to make soft and
absorbent tissue paper treated with a low viscosity chemical
softener composition prepared according to Example 1 of the present
invention and a wet strength resin.
[0212] The makeup of the furnish is substantially the same as that
used in Example 3, the only exception being that a 2.5% dispersion
of the chemical softener mixture from Example 1 was used instead of
the prior art chemical softening composition.
[0213] The separate furnishes are delivered to a headbox, deposited
on a twin-wire former and dried in substantially the same manner as
described in Example 3 to form a dried tissue web.
[0214] The tissue paper has a basis weight of about 10 pounds/3000
ft.sup.2 (16 grams/m.sup.2), contains about 0.05% of the
substantially waterless self-emulsifiable chemical softener mixture
and about 0.1% of the wet strength resin. Importantly, the
resulting tissue paper is soft, absorbent and is suitable for use
as a facial and/or toilet tissues.
Example 5
[0215] This example compares the properties of the tissue papers of
Examples 3 and 4.
4 MD Tensile CD Tensile Softener Basis Weight Strength Strength
Retention Tissue Sample (grams/m.sup.2) (g/cm) (g/cm) (%) Example 3
16 62.6 42.5 17.2 Example 4 16.5 75.2 44.8 16.8
[0216] As can be seen, the tissue papers made in Examples 3 and 4
have substantially the same physical properties.
Test Methods
[0217] Softening Active Ingredient Level on Cellulose Fibers
[0218] Analysis of the amounts of softening active ingredients
described herein that are retained on cellulosic structures can be
performed by any method accepted in the applicable art. These
methods are exemplary, and are not meant to exclude other methods
which may be useful for determining levels of particular components
retained by the tissue paper.
[0219] The following method is appropriate for determining the
quantity of the preferred quaternary ammonium compounds (QAC) that
may be deposited by the method of the present invention. A standard
anionic surfactant (sodium dodecylsulfate--NaDDS) solution is used
to titrate the QAC using a dimidium bromide indicator.
[0220] Preparation of Standard Solutions
[0221] The following methods are applicable for the preparation of
the standard solutions used in this titration method.
[0222] Preparation of Dimidium Bromide Indicator
[0223] To a 1 liter volumetric flask:
[0224] A) Add 500 milliliters of distilled water.
[0225] B) Add 40 ml. of dimidium bromide-disulphine blue indicator
stock solution, available from Gallard-Schiesinger Industries, Inc.
of Carle Place, N.Y.
[0226] C) Add 46 ml. of 5N H.sub.2SO.sub.4
[0227] D) Fill flask to the mark with distilled water and mix.
[0228] Preparation of the NaDDS solution. to a 1 liter volumetric
flask:
[0229] A) Weigh 0.1154 grams of NaDDS available from Aldrich
Chemical Co. of Milwaukee, Wis. as sodium dodecyl sulfate (ultra
pure).
[0230] B) Fill flask to mark with distilled water and mix to form a
0.0004N solution.
[0231] Method
[0232] 1. On an analytical balance, weigh approximately 0.5 grams
of a specimen of the cellulosic fiber structure. Record the sample
weight to the nearest 0.1 mg.
[0233] 2. Place the sample in a glass cylinder having a volume of
about 150 milliliters which contains a star magnetic stirrer. Using
a graduated cylinder, add 20 milliliters of methylene chloride.
[0234] 3. In a fume hood, place the cylinder on a hot plate turned
to low heat. Bring the solvent to a full boil while stirring and
using a graduated cylinder, add 35 milliliters of dimidium bromide
indicator solution.
[0235] 4. While stirring at high speed, bring the methylene
chloride to a full boil again. Turn off the heat, but continue to
stir the sample. The QAC will complex with the indicator forming a
blue colored compound in the methylene chloride layer.
[0236] 5. Using a 50 ml. burette, titrate the sample with a
solution of the anionic surfactant. This is done by adding an
aliquot of titrant and rapidly stirring for 30 seconds. Turn off
the stir plate, allow the layers to separate, and check the
intensity of the blue color. If the color is dark blue add about
0.3 milliliters of titrant, rapidly stir for 30 seconds and turn
off stirrer. Again check the intensity of the blue color. Repeat if
necessary with another 0.3 milliliters. When the blue color starts
to become very faint, add the titrant dropwise between stirrings.
The endpoint is the first sign of a slight pink color in the
methylene chloride layer.
[0237] 6. Record the volume of titrant used to the nearest 0.05
ml.
[0238] 7. Calculate the amount of QAC in the product using the
equation: 1 ( mililitersNaDDS - X ) .times. Y .times. 2 Sample Wt .
( Grams ) = Pounds Per Ton QAC
[0239] Where X is a blank correction obtained by titrating a
specimen without the QAC of the present invention. Y is the
milligrams of QAC that 1.00 milliliters of NaDDS will titrate. (For
example, Y=0.254 for one particularly preferred QAC, i.e.
diestherdi(touch-hydrogenated)tallow dimethyl ammonium
chloride.)
Density
[0240] The density of a cellulosic structure (e.g. paper), as the
term "density" is used herein, is the average density calculated as
the basis weight of that paper divided by the caliper, with the
appropriate unit conversions incorporated therein. Caliper of the
paper, as used herein, is the thickness of the paper when subjected
to a compressive load of 95 g/in.sup.2 (15.5 g/cm.sup.2).
Strength of Tissue Papers
[0241] Dry Tensile Strength
[0242] This method is intended for use on finished paper products,
reel samples, and unconverted stocks. The tensile strength of such
products may be determined on one inch wide strips of sample using
a Thwing-Albert Intelect II Standard Tensile Tester (Thwing-Albert
Instrument Co of Philadelphia, Pa.).
[0243] Sample Conditioning and Preparation
[0244] Prior to tensile testing, the paper samples to be tested
should be conditioned for at least 15 minutes at a relative
humidity of 48 to 52% and within a temperature range of 22 to
24.degree. C. Sample preparation and all aspects of the tensile
testing should also take place within the confines of the constant
temperature and humidity room.
[0245] For finished product, discard any damaged product. Next,
remove 5 strips of four usable units (also termed sheets) and stack
one on top to the other to form a long stack with the perforations
between the sheets coincident. Identify sheets 1 and 3 for machine
direction tensile measurements and sheets 2 and 4 for cross
direction tensile measurements. Next, cut through the perforation
line using a paper cutter (JDC-1-10 or JDC-1-12 with safety shield
from Thwing-Albert Instrument Co. of Philadelphia, Pa.) to make 4
separate stocks. Make sure stacks 1 and 3 are still identified for
machine direction testing and stacks 2 and 4 are identified for
cross direction testing.
[0246] Cut two 1" wide strips in the machine direction from stacks
1 and 3. Cut two 1" wide strips in the cross direction from stacks
2 and 4. There are now four 1" wide strips for machine direction
tensile testing and four 1" wide strips for cross direction tensile
testing. For these finished product samples, all eight 1" wide
strips are five usable units (also termed sheets) thick.
[0247] For unconverted stock and/or reel samples, cut a 15" by 15"
sample which is 8 plies thick from a region of interest of the
sample using a paper cutter (JDC-1-10 or JDC-1-12 with safety
shield from Thwing-Albert Instrument Co of Philadelphia, Pa.). Make
sure one 15" cut runs parallel to the machine direction while the
other runs parallel to the cross direction. Make sure the sample is
conditioned for at least 2 hours at a relative humidity of 48 to
52% and within a temperature range of 22 to 24.degree. C. Sample
preparation and all aspects of the tensile testing should also take
place within the confines of the constant temperature and humidity
room.
[0248] From this preconditioned 15" by 15" sample which is 8 plies
thick, cut four strips 1" by 7" with the long 7" dimension running
parallel to the machine direction. Note these samples as machine
direction reel or unconverted stock samples. Cut an additional four
strips 1" by 7" with the long 7" dimension running parallel to the
cross direction. Note these samples as cross direction reel or
unconverted stock samples. Make sure all previous cuts are made
using a paper cutter (JDC-1-10 or JDC-1-12 with safety shield from
Thwing-Albert Instrument Co. of Philadelphia, Pa.). There are now a
total of eight samples: four 1" by 7" strips which are 8 plies
thick with the 7" dimension running parallel to the machine
direction and four 1" by 7" strips which are 8 plies thick with the
7" dimension running parallel to the cross direction.
[0249] Operation of Tensile Tester
[0250] For the actual measurement of the tensile strength, use a
Thwing-Albert Intelect II Standard Tensile Tester (Thwing-Albert
Instrument Co. of Philadelphia, Pa.). Insert the flat face clamps
into the unit and calibrate the tester according to the
instructions given in the operation manual of the Thwing-Albert
Intelect II. Set the instrument crosshead speed to 4.00 in/min and
the 1st and 2nd gauge lengths to 2.00 inches. The break sensitivity
should be set to 20.0 grams and the sample width should be set to
1.00" and the sample thickness at 0.025".
[0251] A load cell is selected such that the predicted tensile
result for the sample to be tested lies between 25% and 75% of the
range in use. For example, a 5000 gram load cell may be used for
samples with a predicted tensile range of 1250 grams (25% of 5000
grams) and 3750 grams (75% of 5000 grams). The tensile tester can
also be set up in the 10% range with the 5000 gram load cell such
that samples with predicted tensiles of 125 grams to 375 grams
could be tested.
[0252] Take one of the tensile strips and place one end of it in
one clamp of the tensile tester. Place the other end of the paper
strip in the other clamp. Make sure the long dimension of the strip
is running parallel to the sides of the tensile tester. Also make
sure the strips are not overhanging to the either side of the two
clamps. In addition, the pressure of each of the clamps must be in
full contact with the paper sample.
[0253] After inserting the paper test strip into the two clamps,
the instrument tension can be monitored. If it shows a value of 5
grams or more, the sample is too taut. Conversely, if a period of
2-3 seconds passes after starting the test before any value is
recorded, the tensile strip is too slack.
[0254] Start the tensile tester as described in the tensile tester
instrument manual. The test is complete after the crosshead
automatically returns to its initial starting position. Read and
record the tensile load in units of grams from the instrument scale
or the digital panel meter to the nearest unit.
[0255] If the reset condition is not performed automatically by the
instrument, perform the necessary adjustment to set the instrument
clamps to their initial starting positions. Insert the next paper
strip into the two clamps as described above and obtain a tensile
reading in units of grams. Obtain tensile readings from all the
paper test strips. It should be noted that readings should be
rejected if the strip slips or breaks in or at the edge of the
clamps while performing the test.
[0256] Calculations
[0257] For the four machine direction 1" wide finished product
strips, sum the four individual recorded tensile readings. Divide
this sum by the number of strips tested. This number should
normally be four. Also divide the sum of recorded tensiles by the
number of usable units per tensile strip. This is normally five for
both 1-ply and 2-ply products.
[0258] Repeat this calculation for the cross direction finished
product strips.
[0259] For the unconverted stock or reel samples cut in the machine
direction, sum the four individual recorded tensile readings.
Divide this sum by the number of strips tested. This number should
normally be four. Also divide the sum of recorded tensiles by the
number of usable units per tensile strip. This is normally
eight.
[0260] Repeat this calculation for the cross direction unconverted
or reel sample paper strips.
[0261] All results are in units of grams/inch.
[0262] For purposes of this specification, the tensile strength
should be converted into a "specific total tensile strength"
defined as the sum of the tensile strength measured in the machine
and cross machine directions, divided by the basis weight, and
corrected in units to a value in meters.
Viscosity
[0263] Overview
[0264] Viscosity is measured at a shear rate of 100 (s.sup.-1)
using a rotational viscometer. The samples are subjected to a
linear stress sweep, which applies a range of stresses, each at a
constant amplitude.
5 Apparatus Viscometer Dynamic Stress Rheometer Model SR500 which
is available from Rheometrics Scientific, Inc. of Piscatawy, NJ
Sample Plates 25 mm parallel insulated plates are used Setup Gap
0.5 mm Sample Temperature 20.degree. C. Sample Volume at least
0.2455 cm.sup.3 Initial Shear Stress 10 dynes/cm.sup.2 Final Shear
Stress 1,000 dynes/cm.sup.2 Stress Increment 25 dynes/cm.sup.2
applied every 20 seconds Method
[0265] Method
[0266] Place the sample on the sample plate with the gap open.
Close the gap and operate the rheometer according to the
manufacturer's instructions to measure viscosity as a function of
shear stress between the initial shear stress and the final shear
stress using the stress increment defined above.
[0267] Results and Calculation
[0268] The resulting graphs plot log shear rate (s.sup.-1) on the
x-axis, log viscosity, Poise (P) on the left y-axis, and stress
(dynes/cm.sup.2) on the right y-axis. Viscosity values are read at
a shear rate of 100 (s.sup.-1). The values for viscosity are
converted from P to centipoise (cP) by multiplying by 100.
[0269] The disclosures of all patents, patent applications (and any
patents which issue thereon, as well as any corresponding published
foreign patent applications), and publications mentioned throughout
this description are hereby incorporated by reference herein. It is
expressly not admitted, however, that any of the documents
incorporated by reference herein teach or disclose the present
invention.
[0270] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *