Method for enhancing the bulk softness of tissue paper and product therefrom

Tissue paper having an enhanced bulk softness through incorporation of an effective amount of a polyhydroxy compound is disclosed. Preferably, from about 0.1% to about 2.0% of the polyhydroxy compound, on a dry fiber weight basis. These nonionic compounds have high rates of retention when applied to wet tissue paper webs according to the process described herein. Tissue embodiments of the present invention may further comprise a quantity of strength additive, such as starch, to increase paper strength.

FIELD OF THE INVENTION 
This application relates to tissue papers, in particular pattern densified 
tissue papers, having an enhanced tactile sense of softness. This 
application particularly relates to tissue papers treated with 
water-soluble polyhydroxy compounds. 
BACKGROUND OF THE INVENTION 
Paper webs or sheets, sometimes called tissue or paper tissue webs or 
sheets, find extensive use in modern society. These include such staple 
items as paper towels, facial tissues and sanitary (or toilet) tissues. 
These paper products can have various desirable properties, including wet 
and dry tensile strength, absorbency for aqueous fluids (e.g., 
wettability), low lint properties, desirable bulk, and softness. The 
particular challenge in papermaking has been to appropriately balance 
these various properties to provide superior tissue paper. 
Although somewhat desirable for towel products, softness is a particularly 
important property for facial and toilet tissues. Softness is the tactile 
sensation perceived by the consumer who holds a particular paper product, 
rubs it across the skin, and crumples it within the hand. Such tactile 
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 velvet, silk or flannel. This tactile sensation is 
a combination of several physical properties, including the flexibility or 
stiffness of the sheet of paper, the frictional properties of the web, as 
well as the texture of the surface of the paper. 
Stiffness of paper is typically affected by efforts to increase the dry 
and/or wet tensile strength of the web. Increases in dry tensile strength 
can be achieved either by mechanical processes to insure adequate 
formation of hydrogen bonding between the hydroxyl groups of adjacent 
papermaking fibers, or by the inclusion of certain dry strength additives. 
Wet strength is typically enhanced by the inclusion of certain wet 
strength resins, that, being typically cationic, are easily deposited on 
and retained by the anionic carboxyl groups of the papermaking fibers. 
However, the use of both mechanical and chemical means to improve dry and 
wet tensile strength can also result in stiffer, harsher feeling, less 
soft tissue papers. 
Certain chemical additives, commonly referred to as debonding agents, can 
be added to papermaking fibers to interfere with the natural 
fiber-to-fiber bonding that occurs during sheet formation and drying, and 
thus lead to softer papers. These debonding agents are typically cationic 
and have certain disadvantages associated with their use in softening 
tissue papers. Some low molecular weight cationic debonding agents can 
cause excessive irritation upon contact with human skin. Higher molecular 
weight cationic debonding agents can be more difficult to apply at low 
levels to tissue paper, and also tend to have undesirable hydrophobic 
effects on the tissue paper, e.g., result in decreased absorbency and 
particularly wettability. Since these cationic debonding agents operate by 
disrupting interfiber bonding, they can also decrease tensile strength to 
such an extent that resins, latex, or other dry strength additives can be 
required to provide acceptable levels of tensile strength. These dry 
strength additives not only increase the cost of the tissue paper but can 
also have other, deleterious effects on tissue softness. In addition, many 
cationic debonding agents are not biodegradable, and therefore can 
adversely impact on environmental quality. 
Examples of cationic debonding agents include conventional quaternary 
ammonium compounds such as the well known dialkyl dimethyl ammonium salts 
(e.g. ditallow dimethyl ammonium chloride, ditallow dimethyl ammonium 
methyl sulfate, di(hydrogenated) tallow dimethyl ammonium chloride etc . . 
. ). However, as mentioned above, these cationic quaternary ammonium 
compounds soften the paper by interfering with the natural fiber-to-fiber 
bonding that occurs during sheet formation and drying. In addition to 
decreasing tensile strength, these quaternary ammonium compounds also tend 
to have undesirable hydrophobic effects on the tissue paper, e.g., 
resulting in decreased absorbency and wettability. 
Mechanical pressing operations are typically applied to tissue paper webs 
to dewater them and/or increase their tensile strength. Mechanical 
pressing can occur over the entire area of the paper web, such as in the 
case of conventional felt-pressed paper. More preferably, dewatering is 
carried out in such a way that the paper is pattern densified. Pattern 
densified paper has certain densified areas of relatively high fiber 
density, as well as relatively low fiber density, high bulk areas. Such 
high bulk pattern densified papers are typically formed from a partially 
dried paper web that has densified areas imparted to it by a foraminous 
fabric having a patterned displacement of knuckles. See, for example, U.S. 
Pat. No. 3,301,746 (Sanford et al), issued Jan. 31, 1967; U.S. Pat. No. 
3,994,771 (Morgan et al), issued Nov. 30, 1976; and U.S. Pat. No. 
4,529,480 (Trokhan), issued Jul. 16, 1985. 
Besides tensile strength and bulk, another advantage of such patterned 
densification processes is that ornamental patterns can be imprinted on 
the tissue paper. However, an inherent problem of patterned densification 
processes is that the fabric side of the tissue paper, i.e. the paper 
surface in contact with the foraminous fabric during papermaking, is 
sensed as rougher than the side not in contact with the fabric. This is 
due to the high bulk fields that form, in essence, protrusions outward 
from the surface of the paper. It is these protrusions that can impart a 
tactile sensation of roughness. 
The softness of these compressed, and particularly patterned densified 
tissue papers, can be improved by treatment with various agents such as 
vegetable, animal or synthetic hydrocarbon oils, and especially 
polysiloxane materials typically referred to as silicone oils. See Column 
1, lines 30-45 of U.S. Pat. No. 4,959,125 (Spendel), issued Sep. 25, 1990. 
These silicone oils impart a silky, soft feeling to the tissue paper. 
However, some silicone oils are hydrophobic and can adversely affect the 
surface wettability of the treated tissue paper, i.e. the treated tissue 
paper can float, thus causing disposal problems in sewer systems when 
flushed. Indeed, some silicone softened papers can require treatment with 
other surfactants to offset this reduction in wettability caused by the 
silicone. See U.S. Pat. No. 5,059,282 (Ampulski et al), issued Oct. 22, 
1991. 
Tissue paper has also been treated with softeners by "dry web" addition 
methods. One such method involves moving the dry paper across one face of 
a shaped block of wax-like softener that is then deposited on the paper 
surface by a rubbing action. See U.S. Pat. No. 3,305,392 (Britt), issued 
Feb. 21, 1967 (softeners include stearate soaps such as zinc stearate, 
stearic acid esters, stearyl alcohol, polyethylene glycols such as 
Carbowax, and polyethylene glycol esters of stearic and lauric acids). 
Another such method involves dipping the dry paper in a solution or 
emulsion containing the softening agent. See U.S. Pat. No. 3,296,065 
(O'Brien et al), issued Jan. 3, 1967 (aliphatic esters of certain 
aliphatic or aromatic carboxylic acids as the softening agent). A 
potential problem of these prior "dry web" addition methods is that the 
softening agent can be applied less effectively, or in a manner that could 
potentially affect the absorbency of the tissue paper. Indeed, the '392 
patent teaches as desirable modification with certain cationic materials 
to avoid the tendency of the softener to migrate. Application of softeners 
by either a rubbing action or by dipping the paper would also be difficult 
to adapt to commercial papermaking systems that run at high speeds. 
Furthermore, some of the softeners (e.g., the pyromellitate esters of the 
'065 patent), as well as some of the co-additives (e.g., dimethyl 
distearyl ammonium chloride of the '532 patent), taught to be useful in 
these prior "dry web" methods are not biodegradable. 
Accordingly, it would be desirable to be able to soften tissue paper, in 
particular high bulk, pattern densified tissue papers, by a process that: 
(1) uses a "wet web" method for adding the softening agent; (2) can be 
carried out in a commercial papermaking system without significantly 
impacting on machine operability; (3) uses softeners that are nontoxic and 
biodegradable; and (4) can be carried out in a manner so as to maintain 
desirable tensile strength, absorbency and low lint properties of the 
tissue paper. 
It is an object of this invention to provide soft, absorbent toilet tissue 
paper products. 
It is an object of this invention to provide soft, absorbent facial tissue 
paper products. 
It is an object of this invention to provide soft, absorbent paper towel 
products. 
It is also a further object of this invention to provide a process for 
making soft, absorbent tissue (i.e., facial and/or toilet tissue) and 
paper towel products. 
These and other objects are obtained using the present invention, as will 
become readily apparent from a reading of the following disclosure. 
SUMMARY OF THE INVENTION 
The present invention provides soft, absorbent tissue paper products. 
Briefly, the soft tissue paper products comprise: 
a) wet-laid cellulosic fibers; and 
b) from about 0.01% to about 5% of a water soluble polyhydroxy compound, 
based on the dry fiber weight of said tissue paper; 
wherein said tissue paper has a basis weight of from about 10 to about 65 
g/m.sup.2 and a density of less than about 0.60 g/cc and wherein said 
polyhydroxy compound having being applied to a least one surface of a wet 
tissue paper web. 
The present invention further relates to a process for making these 
softened tissue papers. The process includes the steps: 
a) wetlaying an aqueous slurry containing cellulosic fibers to form a web; 
b) applying to said web at fiber consistency of from about 10% to about 
80%, total web weight basis, a sufficient amount of a water soluble 
polyhydroxy compound to impart a bulk softness to said structure; and 
c) drying and creping said web. 
Suprisingly, it has been found that these nonionic polyhydroxy compounds 
have high rates of retention even in the absence of cationic retention 
aids or debonding agents when applied to wet tissue paper webs in 
accordance with the process disclosed herein. This is especially 
unexpected because the polyhydroxy compounds are applied to the wet webs 
under conditions wherein they are not ionically substantive to the 
cellulose fibers. Importantly, the wet web process allows the polyhydroxy 
compounds to migrate to the interior of the paper web where they act to 
enhance the tissue paper absorbency and softness. 
Surprisingly, it has been found that significantly improved tissue 
softening benefits can be achieved by much lower levels of these 
polyhydroxy compounds when applied to a wet web, as compared to a dry web 
(e.g., during the converting operation). In fact, an important feature of 
the process disclosed herein, is that the polyhydroxy compound level is 
low enough to be economical. 
Tissue paper softened according to the present invention has good 
flexibility. It is especially useful in softening high bulk, pattern 
densified tissue papers, including tissue papers having patterned designs. 
Surprisingly, even when the softener is applied only to the smoother 
(i.e., wire) side of such pattern densified papers, the treated paper is 
still perceived as soft. The present invention can be carried out in a 
commercial papermaking system without significantly impacting on machine 
operability, including speed. The improved softness benefits of the 
present invention can also be achieved while maintaining the desirable 
tensile strength, absorbency (e.g., wettability), and low lint properties 
of the paper. 
All percentages, ratios and proportions herein are by weight unless 
otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION 
While this specification concludes with claims particularly pointing out 
and distinctly claiming the subject matter regarded as the invention, it 
is believed that the invention can be better understood from a reading of 
the following detailed description and of the appended examples. 
As used herein, the term "comprising" means that the various components, 
ingredients, or steps, can be conjointly employed in practicing the 
present invention. Accordingly, the term "comprising" encompasses the more 
restrictive terms "consisting essentially of" and "consisting of". 
As used herein, the terms teissue paper web, paper web, web, paper sheet 
and paper product all refer to sheets of paper made by a process 
comprising the steps of forming an aqueous papermaking furnish, depositing 
this furnish on a foraminous surface, such as a Fourdrinier wire, and 
removing the water from the furnish as by gravity or vacuum-assisted 
drainage, with or without pressing, and by evaporation. 
As used herein, an aqueous papermaking furnish is an aqueous slurry of 
papermaking fibers and the chemicals described hereinafter. 
As used herein, the term "consistency" refers to the weight percentage of 
the cellulosic paper making fibers (i.e., pulp) in the wet tissue web. It 
is expressed as a weight percentage of this fibrous material, in the wet 
web, in terms of air dry fiber weight divided by the weight of the wet 
web. 
The first step in the process of this invention is the forming of an 
aqueous papermaking furnish. The furnish comprises papermaking fibers 
(hereinafter sometimes referred to as wood pulp). It is anticipated that 
wood pulp in all its varieties will normally comprise the papermaking 
fibers used in this invention. However, other cellulose fibrous pulps, 
such as cotton liners, bagasse, rayon, etc., can be used and none are 
disclaimed. Wood pulps useful herein include chemical pulps such as Kraft, 
sulfite and sulfate pulps as well as mechanical pulps including for 
example, ground wood, thermomechanical pulps and chemically modified 
thermomechanical pulp (CTMP). Pulps derived from both deciduous and 
coniferous trees can be used. 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. Preferably, the 
papermaking fibers used in this invention comprise Kraft pulp derived from 
northern softwoods and/or tropical hardwoods. The aqueous papermaking 
furnish is formed into a wet web on a foraminous forming carrier, such as 
a Fourdrinier wire, as will be discussed hereinafter. 
(A) Polyhydroxy Compounds 
The present invention contains as an essential component from about 0.01% 
to about 5.0%, preferably from 0.1% to about 2.0%, more preferably from 
about 0.1% to about 1.0%, of a water soluble polyhydroxy compound, based 
on the dry fiber weight of the tissue paper. 
Examples of water soluble polyhydroxy compounds suitable for use in the 
present invention include glycerol, polyglycerols having a weight average 
molecular weight of from about 150 to about 800 and polyoxyethylene and 
polyoxypropylene having a weight-average molecular weight of from about 
200 to about 4000, preferably from about 200 to about 1000, most 
preferably from about 200 to about 600. Polyoxyethylene having an weight 
average molecular weight of from about 200 to about 600 are especially 
preferred. Mixtures of the above-described polyhydroxy compounds may also 
be used. For example, mixtures of glycerol and polyglycerols, mixtures of 
glycerol and polyoxyethylenes, mixtures of polyglycerols and 
polyoxyethylenes, etc. are useful in the present invention. A particularly 
preferred polyhydroxy compound is polyoxyethylene having an weight average 
molecular weight of about 400. This material is available commercially 
from the Union Carbide Company of Danbury, Conn. under the trade name 
"PEG-400". 
(B) Tissue Papers 
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 in the aforementioned U.S. 
Patent by Sanford-Sisson and its progeny; and high bulk, uncompacted 
tissue paper such as exemplified by U.S. Pat. No. 3,812,000, Salvucci, 
Jr., issued May 21, 1974. The tissue paper may be of a homogenous or 
multi-layered construction; and tissue paper products made therefrom may 
be of a single-ply or multi-ply construction. Tissue structures formed 
from layered paper webs are described in U.S. Pat. No. 3,994,771, Morgan, 
Jr. et al. issued Nov. 30, 1976, U.S. Pat. No. 4,300,981, Carstens, issued 
Nov. 17, 1981, U.S. Pat. No. 4,166,001, Dunning et al., issued Aug. 28, 
1979, and European Patent Publication No. 0 613 979 A1, Edwards et al., 
published Sep. 7, 1994, all of which are incorporated herein by reference. 
In general, a wet-laid composite, soft, bulky and absorbent paper 
structure is prepared from two or more layers of furnish which are 
preferably comprised of different fiber types. The layers are preferably 
formed from the deposition of separate streams of dilute fiber slurries, 
the fibers typically being relatively long softwood and relatively short 
hardwood fibers as used in tissue papermaking, upon one or more endless 
foraminous screens. The layers are subsequently combined to form a layered 
composite web. The layered web is subsequently caused to conform to the 
surface of an open mesh drying/imprinting fabric by the application of a 
fluid force to the web and thereafter thermally predried on said fabric as 
part of a low density papermaking process. The layered web may be 
stratified with respect to fiber type or the fiber content of the 
respective layers may be essentially the same. The tissue paper preferably 
has a basis weight of between 10 g/m.sup.2 and about 65 g/m.sup.2, and 
density of about 0.60 g/cc or less. Preferably, basis weight will be below 
about 35 g/m.sup.2 or less; and density will be about 0.30 g/cc or less. 
Most preferably, density will be between 0.04 g/cc and about 0.20 g/cc. 
Conventionally pressed tissue paper and methods for making such paper are 
known in the art. Such paper is typically made by depositing 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. The web is dewatered by pressing 
the web and 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 25% (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 steam heated 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. Vacuum may also be applied to the web as it is 
pressed against the Yankee surface. 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 compressional forces while the fibers are moist and are 
then dried (and optionally creped) while in a compressed state. 
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 Peter G. Ayers on Aug. 10, 1976, and U.S. Pat. No. 
4,191,609, issued to Paul D. Trokhan on Mar. 4, 1980, and U.S. Pat. No. 
4,637,859, issued to Paul D. Trokhan on Jan. 20, 1987, U.S. Pat. No. 
4,942,077 issued to Wendt et al. on Jul. 17, 1990, European Patent 
Publication No. 0 617 164 A1, Hyland et al., published Sep. 28, 1994, 
European Patent Publication No. 0 616 074 A1, Hermans et al., published 
Sep. 21, 1994; all of which are incorporated herein by reference. 
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. 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. 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 55% of 
the tissue paper surface comprises densified knuckles having a relative 
density of at least 125% of the density of the high bulk field. 
The 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, Sanford and Sisson, issued Jan. 31, 1967, U.S. Pat. 
No. 3,821,068, Salvucci, Jr. et al., issued May 21, 1974, U.S. Pat. No. 
3,974,025, Ayers, issued Aug. 10, 1976, U.S. Pat. No. 3,573,164, Friedberg 
et al., issued Mar. 30, 1971, U.S. Pat. No. 3,473,576, Amneus, issued Oct. 
21, 1969, U.S. Pat. No. 4,239,065, Trokhan, issued Dec. 16, 1980, and U.S. 
Pat. No. 4,528,239, Trokhan, issued Jul. 9, 1985, all of which are 
incorporated herein by reference. 
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 can be performed with suction boxes or 
other vacuum devices or with blow-through dryers. 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. 
Uncompacted, nonpattern-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 containing a debonding agent 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. 
Compacted non-pattern-densified tissue structures are commonly known in the 
art as conventional tissue structures. In general, compacted, 
non-patterndensified tissue paper structures are prepared by depositing a 
papermaking furnish on a foraminous wire such as a Fourdrinier wire to 
form a wet web, draining the web and removing additional water with the 
aid of a uniform mechanical compaction (pressing) until the web has a 
consistency of 25-50%, transferring the web to a thermal dryer such as a 
Yankee and creping the web. Overall, water is removed from the web by 
vacuum, mechanical pressing and thermal means. The resulting structure is 
strong and generally of singular density, but very low in bulk, absorbency 
and in softness. 
The tissue paper web of this invention can be used in any application where 
soft, absorbent tissue paper webs are required. Particularly advantageous 
uses of the tissue paper web of this invention are in paper towel, toilet 
tissue and facial tissue products. For example, two tissue paper webs of 
this invention can be embossed and adhesively secured together in face to 
face relation as taught by U.S. Pat. No. 3,414,459, which issued to Wells 
on Dec. 3, 1968 and which is incorporated herein by reference, to form 
2-ply paper towels. 
In the following discussion, wherein reference is made to the several 
figures, certain preferred embodiments of processes for making the tissue 
sheet structures of the present invention are described. 
FIG. 1 is 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 82.5, 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 82.5, 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 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. 
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 under 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. Furthermore the forming section and headbox can be 
any system suitable for making tissue such as a twin wire former. 
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 inter-filamentary 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. 
Specifically relating to FIG. 1, spray nozzle 120 is provided opposite 
vacuum dewatering box 98 for application of polyhydroxy compound. 
FIG. 2 shows an alternate papermaking machine which is substantially the 
same as that shown in FIG. 1, except that the rotogravure printer 122 is 
provided between the predryers 100 and the Yankee dryer 108 in place of 
spray nozzle 120. 
FIG. 3 is a side elevational view of an alternate preferred papermaking 
machine for making tissue sheets by conventional papermaking techniques 
which were predominate prior to the invention of processes such as those 
shown in FIGS. 1-2 and described in U.S. Pat. No. 3,301,746, each of which 
utilizes blow through drying and minimizes compression of the tissue 
sheet. To simplify description of the alternate preferred papermaking 
machine of FIG. 3, the components which have counterparts in papermaking 
machine 80, FIG. 1, are identically designated; and the alternate 
papermaking machine 280 of FIG. 3 is described with respect to differences 
therebetween. 
Papermaking machine 280 of FIG. 3 is essentially different from papermaking 
machine 80 of FIG. 1, by virtue of having a duplex headbox 281 comprising 
a top chamber 282 and a bottom chamber 283 in place of a triple headbox 
81; by having a felt loop 296 in place of foraminous carrier fabric 96; by 
having two pressure rolls 102 rather than one; and by not having blow 
through dryers 100. Papermaking machine 280, FIG. 3, further comprises a 
lower felt loop 297 and wet pressing rolls 298 and 299 and means not shown 
for controllably biasing rolls 298 and 299 together. The lower felt loop 
297 is looped about additional turning rolls 101 as illustrated. 
Papermaking machine 280 is considered a dual felt machine by virtue of 
having felt loops 296 and 297. Felt loop 297 can be eliminated, in which 
case papermachine 280 would be considered a single felt machine (not 
shown). Typically if run as a single felt machine at least one of the 
pressure roll (102) applies a vacuum to the wet web at the point of 
transfer to the Yankee dryer (108). 
FIG. 3 further shows a two layered embryonic web 288 having layers 288a and 
288b which becomes paper sheet 270 subsequent to drying at the Yankee 
dryer 108. Paper sheet 270 comprises Yankee side layer 271 and off-Yankee 
side layer 275. 
Still referring to FIG. 3, a preferred embodiment is shown wherein spray 
nozzle 220 for application of the polyhydroxy compound located as shown 
between turning roll 101 and wet pressing roller 298 and 299, i.e . . . 
after embryonic web 88 has been transferred from Fourdrinier were 85 to 
felt loop 296. Though not shown, spray nozzle 220 can be alternately 
located after felt loop 297 and before Yankee dryer 108. Optionally nozzle 
220 can spray into a vacuum box 106 located on the opposite side of felt 
296. 
FIG. 4 is substantially the same a FIG. 3, except that spray nozzle 220 is 
replaced by rotogravure printer 222. 
The level of polyhydroxy compound to be retained by the tissue paper, as a 
minimum, is at least an effective level for imparting a bulk softness to 
the paper. The minimum effective level may vary depending upon the 
particular type of sheet, the method of application, the particular type 
of polyhydroxy compound, surfactant, or other additives or treatments. 
Without limiting the range of applicable polyhydroxy retention by the 
tissue paper, preferably at least about 0.05% of the polyhydroxy compound 
is retained by the tissue paper. More preferably, from about 0.1% to about 
2.0% of the polyhydroxy compound is retained by the tissue paper. 
Analytical and Testing Procedures 
Analysis of the amounts of treatment chemicals herein retained on tissue 
paper webs can be performed by any method accepted in the applicable art. 
For example, the level of the polyhydroxy compound retained by the tissue 
paper can be determined by solvent extraction of the polyhydroxy compound 
with a solvent. In some cases, additional procedures may be necessary to 
remove interfering compounds from the polyhydroxy species of interest. For 
instance, the Weibull solvent extraction method employs a brine solution 
to isolate polyethylene glycols from nonionic surfactants (Longman, G. F., 
The Analysis of Detergents and Detergent Products Wiley Interscience, New 
York, 1975, p. 312). The polyhydroxy species could then be analyzed by 
spectroscopic or chromatographic techniques. For example, compounds with 
at least six ethylene oxide units can typically be analyzed 
spectroscopically by the Ammonium cobaltothiocyanate method (Longman, G. 
F., The Analysis of Detergents and Detergent Products, Wiley Interscience, 
New York, 1975, p. 346). Gas chromatography techniques can also be used to 
separate and analyze polyhydroxy type compounds. Graphitized 
poly(2,6-diphenyl-p-phenylene oxide) gas chromatography columns have been 
used to separate polyethylene glycols with the number of ethylene oxide 
units ranging from 3 to 9 (Alltech chromatography catalog, number 300, p. 
158). 
The level of nonionic surfactants, such as alkyl glycosides, can be 
determined by chromatographic techniques. Bruns reported a High 
Performance Liquid chromatography method with light scattering detection 
for the analysis of alkyl glycosides (Bruns, A., Waldhoff, H., Winkle, W., 
Chromatographia, vol. 27, 1989, p. 340). A Supercritical Fluid 
Chromatography (SFC) technique was also described in the analysis of alkyl 
glycosides and related species (Lafosse, M., Rollin, P., Elfakir, c., 
Morin-AIIory, L., Martens, M., Dreux, M., Journal of chromatography, vol. 
505, 1990, p. 191). The level of anionic surfactants, such as linear alkyl 
sulfonates, can be determined by water extraction followed by titration of 
the anionic surfactant in the extract. In some cases, isolation of the 
linear alkyl sulfonate from interferences may be necessary before the two 
phase titration analysis (Cross, J., Anionic Surfactants--Chemical 
Analysis, Dekker, New York, 1977, p. 18, p. 222). The level of starch can 
be determined by amylase digestion of the starch to glucose followed by 
colorimetry analysis to determine glucose level. For this starch analysis, 
background analyses of the paper not containing the starch must be run to 
subtract out possible contributions made by interfering background 
species. 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. 
A. Panel Softness 
Ideally, prior to softness testing, the paper samples to be tested should 
be conditioned according to Tappi Method #T402OM-88. Here, samples are 
preconditioned for 24 hours at a relative humidity level of 10 to 35% and 
within a temperature range of 22.degree. to 40.degree. C. After this 
preconditioning step, samples should be conditioned for 24 hours at a 
relative humidity of 48 to 52% and within a temperature range of 
22.degree. to 24.degree. C. 
Ideally, the softness panel testing should take place within the confines 
of a constant temperature and humidity room. If this is not feasible, all 
samples, including the controls, should experience identical environmental 
exposure conditions. 
Softness testing is performed as a paired comparison in a form similar to 
that described in "Manual on Sensory Testing Methods", ASTM Special 
Technical Publication 434, published by the American Society For Testing 
and Materials 1968 and is incorporated herein by reference. Softness is 
evaluated by subjective testing using what is referred to as a Paired 
Difference Test. The method employs a standard external to the test 
material itself. For tactile perceived softness two samples are presented 
such that the subject cannot see the samples, and the subject is required 
to choose one of them on the basis of tactile softness. The result of the 
test is reported in what is referred to as Panel Score Unit (PSU). With 
respect to softness testing to obtain the softness data reported herein in 
PSU, a number of softness panel tests are performed. In each test ten 
practiced softness judges are asked to rate the relative softness of three 
sets of paired samples. The pairs of samples are judged one pair at a time 
by each judge: one sample of each pair being designated X and the other Y. 
Briefly, each X sample is graded against its paired Y sample as follows: 
1. a grade of plus one is given if X is judged to may be a little softer 
than Y, and a grade of minus one is given if Y is judged to may be a 
little softer than X; 
2. a grade of plus two is given if X is judged to surely be a little softer 
than Y, and a grade of minus two is given if Y is judged to surely be a 
little softer than X; 
3. a grade of plus three is given to X if it is judged to be a lot softer 
than Y, and a grade of minus three is given if Y is judged to be a lot 
softer than X; and, lastly: 
4. a grade of plus four is given to X if it is judged to be a whole lot 
softer than Y, and a grade of minus 4 is given if Y is judged to be a 
whole lot softer than X. 
The grades are averaged and the resultant value is in units of PSU. The 
resulting data are considered the results of one panel test. If more than 
one sample pair is evaluated then all sample pairs are rank ordered 
according to their grades by paired statistical analysis. Then, the rank 
is shifted up or down in value as required to give a zero PSU value to 
which ever sample is chosen to be the zero-base standard. The other 
samples then have plus or minus values as determined by their relative 
grades with respect to the zero base standard. The number of panel tests 
performed and averaged is such that about 0.2 PSU represents a significant 
difference in subjectively perceived softness. 
B. Hydrophilicity (Absorbency) 
Hydrophilicity of tissue paper refers, in general, to the propensity of the 
tissue paper to be wetted with water. Hydrophilicity of tissue paper may 
be somewhat quantified by determining the period of time required for dry 
tissue paper to become completely wetted with water. This period of time 
is referred to as "wetting time". In order to provide a consistent and 
repeatable test for wetting time, the following procedure may be used for 
wetting time determinations: first, a conditioned sample unit sheet (the 
environmental conditions for testing of paper samples are 22.degree. to 
24.degree. C. and 48 to 52% R.H. as specified in Tappi Method #T 402), 
approximately 43/8 inch.times.43/4 inch (about 11.1 cm.times.12 cm) of 
tissue paper structure is provided; second, the sheet is folded into four 
(4) juxtaposed quarters, and then crumpled by hand (either covered with 
clean plastic gloves or copiously washed with a grease removing detergent 
such as Dawn.RTM.) into a ball approximately 0.75 inch (about 1.9 cm) to 
about 1 inch (about 2.5 cm) in diameter; third, the balled sheet is placed 
on the surface of a body of about 3 liters of distilled water at 
22.degree. to 24.degree. C. contained in a 3 liter pyrex glass beaker. It 
should also be noted all testing of the paper through this technique 
should take place within the confines of the controlled temperature and 
humidity room at 22.degree. to 24.degree. C. and 48 to 52% relative 
humidity. The sample ball is then carefully placed on the surface of the 
water from a distance no greater than 1 cm above the water surface. At the 
exact moment the ball touches the water surface, a timer is simultaneously 
started; fourth, the second ball is placed in the water after the first 
ball is completely wetted out. This is easily noted by the paper color 
transitioning from its dry white color to a darker grayish coloration upon 
complete wetting. The timer is stopped and the time recorded after the 
fifth ball has completely wet out. 
At least 5 sets of 5 balls (for a total of 25 balls) should be run for each 
sample. The final reported result should be the calculated average and 
standard deviation taken for the 5 sets of data. The units of the 
measurement are seconds. The water must be changed after the 5 sets of 5 
balls (total=25 balls) have been tested. copious cleaning of the beaker 
may be necessary if a film or residue is noted on the inside wall of the 
beaker. 
Another technique to measure the water absorption rate is through pad sink 
measurements. After conditioning the tissue paper of interest and all 
controls for a minimum of 24 hours at 22.degree. to 24.degree. C. and 48 
to 52% relative humidity (Tappi method #T402OM-88), a stack of 5 to 20 
sheets of tissue paper is cut to dimensions of 2.5" to 3.0". The cutting 
can take place through the use of dye cutting presses, a conventional 
paper cutter, or laser cutting techniques. Manual scissors cutting is not 
preferred due to both the irreproducibility in handling of the samples, 
and the potential for paper contamination. 
After the paper sample stack has been cut, it is carefully placed on a wire 
mesh sample holder. The function of this holder is to position the sample 
on the surface of the water with minimal disruption. This holder is 
circular in shape and has a diameter of approximately 4.2". It has five 
straight and evenly spaced metal wires running parallel to one another and 
across to spot welded points on the wire's circumference. The spacing 
between the wires is approximately 0.7". This wire mesh screen should be 
clean and dry prior to placing the paper on its surface. A 3 liter beaker 
is filled with about 3 liters of distilled water stabilized at a 
temperature of 22.degree. to 24.degree. C. After insuring oneself that the 
water surface is free of any waves or surface motion, the screen 
containing the paper is carefully placed on top of the water surface. The 
screen sample holder is allowed to continue downward after the sample 
floats on the surface so the sample holder screen handle catches on the 
side of the beaker. In this way, the screen does not interfere with the 
water absorption of the paper sample. At the exact moment the paper sample 
touches the surface of the water, a timer is started. The timer is stopped 
after the paper stack is completely wetted out. This is easily visually 
observed by noting a transition in the paper color from its dry white 
color to a darker grayish coloration upon complete wetting. At the instant 
of complete wetting, the timer is stopped and the total time recorded. 
This total time is the time required for the paper pad to completely wet 
out. 
This procedure is repeated for at least 2 additional tissue paper pads. No 
more than 5 pads of paper should be run without disposing of the water and 
post cleaning and refilling of the beaker with fresh water at a 
temperature of 22.degree. to 24.degree. C. Also, if new and unique sample 
is to be run, the water should always be changed to the fresh starting 
state. The final reported time value for a given sample should be the 
average and standard deviations for the 3 to 5 stacks measured. The units 
of the measurement are seconds. 
Hydrophilicity characteristics of tissue paper embodiments of the present 
invention may, of course, be determined immediately after manufacture. 
However, substantial increases in hydrophobicity may occur during the 
first two weeks after the tissue paper is made: i.e., after the paper has 
aged two (2) weeks following its manufacture. Thus, the wetting times are 
preferably measured at the end of such two week period. Accordingly, 
wetting times measured at the end of a two week aging period at room 
temperature are referred to as "two week wetting times." Also, optional 
aging conditions of the paper samples may be required to try and mimic 
both long term storage conditions and/or possible severe temperature and 
humidity exposures of the paper products of interest. For instance, 
exposure of the paper sample of interest to temperatures in the range of 
49.degree. to 82.degree. C. for 1 hour to 1 year can mimic some of 
potentially severe exposures conditions a paper sample may experience in 
the trade. Also, autoclaving of the paper samples can mimic severe aging 
conditions the paper may experience in the trade. It must be reiterated 
that after any severe temperature testing, the samples must be 
re-conditioned at a temperature of 22.degree. to 24.degree. C. and a 
relative humidity of 48 to 52%. All testing should also be done within the 
confines of the controlled temperature and humidity room. 
C. Density 
The density of tissue paper, as that term 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 to 
convert to g/cc. Caliper of the tissue 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). The caliper is measured with a Thwing-Albert 
model 89-II thickness tester (Thwing-Albert Co. of Philadelphia, Pa.). The 
basis weight of the paper is typically determined on a 4".times.4" pad 
which is 8 plies thick. This pad is preconditioned according to Tappi 
Method #T402OM-88 and then the weight is measured in units of grams to the 
nearest ten-thousandths of a gram. Appropriate conversions are made to 
report the basis weight in units of pounds per 3000 square feet. 
Optional Ingredients 
Other chemicals commonly used in papermaking can be added to the chemical 
softening composition described herein, or to the papermaking furnish so 
long as they do not significantly and adversely affect the softening, 
absorbency of the fibrous material, and softness enhancing actions of the 
quaternary ammonium softening compounds of the present invention. 
A. Wetting Agents 
The present invention may contain as an optional ingredient from about 
0.005% to about 3.0%, more preferably from about 0.03% to 1.0% by weight, 
on a dry fiber basis of a wetting agent. 
Nonionic Surfactant (Alkoxylated Materials) 
Suitable nonionic surfactants can be used as wetting agents in the present 
invention include addition products of ethylene oxide and, optionally, 
propylene oxide, with fatty alcohols, fatty acids, fatty amines, etc. 
Any of the alkoxylated materials of the particular type described 
hereinafter can be used as the nonionic surfactant. Suitable compounds are 
substantially water-soluble surfactants of the general formula: 
EQU R.sub.2 --Y--(C.sub.2 H.sub.4 O).sub.z --C.sub.2 H.sub.4 OH 
wherein R.sub.2 for both solid and liquid compositions is selected from the 
group consisting of primary, secondary and branched chain alkyl and/or 
acyl hydrocarbyl groups; primary, secondary and branched chain alkenyl 
hydrocarbyl groups; and primary, secondary and branched chain alkyl- and 
alkenyl-substituted phenolic hydrocarbyl groups; said hydrocarbyl groups 
having a hydrocarbyl chain length of from about 8 to about 20, preferably 
from about 10 to about 18 carbon atoms. More preferably the hydrocarbyl 
chain length for liquid compositions is from about 16 to about 18 carbon 
atoms and for solid compositions from about 10 to about 14 carbon atoms. 
In the general formula for the ethoxylated nonionic surfactants herein, Y 
is typically --O--, --C(O)O--, --C(O)N(R)--, or --C(O)N(R)R--, in which 
R.sub.2, and R, when present, have the meanings given herein before, 
and/or R can be hydrogen, and z is at least about 8, preferably at least 
about 10-11. Performance and, usually, stability of the softener 
composition decrease when fewer ethoxylate groups are present. 
The nonionic surfactants herein are characterized by an HLB 
(hydrophilic-lipophilic balance) of from about 7 to about 20, preferably 
from about 8 to about 15. Of course, by defining R.sub.2 and the number of 
ethoxylate groups, the HLB of the surfactant is, in general, determined. 
However, it is to be noted that the nonionic ethoxylated surfactants 
useful herein, for concentrated liquid compositions, contain relatively 
long chain R.sub.2 groups and are relatively highly ethoxylated. While 
shorter alkyl chain surfactants having short ethoxylated groups may 
possess the requisite HLB, they are not as effective herein. 
Examples of nonionic surfactants follow. The nonionic surfactants of this 
invention are not limited to these examples. In the examples, the integer 
defines the number of ethoxyl (EO) groups in the molecule. 
Linear Alkoxylated Alcohols 
a. Linear, Primary Alcohol Alkoxylates 
The deca-, undeca-, dodeca-, tetradeca-, and pentadeca-ethoxylates of 
n-hexadecanol, and n-octadecanol having an HLB within the range recited 
herein are useful wetting agents in the context of this invention. 
Exemplary ethoxylated primary alcohols useful herein as the 
viscosity/dispersibility modifiers of the compositions are n-C.sub.18 
EO(10); and n-C.sub.10 EO(11). The ethoxylates of mixed natural or 
synthetic alcohols in the "oleyl" chain length range are also useful 
herein. Specific examples of such materials include oleylalcohol-EO(11), 
oleylalcohol-EO(18), and oleylalcohol-EO(25). 
b. Linear, Secondary Alcohol Alkoxylates 
The deca-, undeca-, dodeca-, tetradeca-, pentadeca-, octadeca-, and 
nonadeca-ethoxylates of 3-hexadecanol, 2-octadecanol, 4-eicosanol, and 
5-eicosanol having and HLB within the range; recited herein can be used as 
wetting agents in the present invention. Exemplary ethoxylated secondary 
alcohols can be used as wetting agents in the present invention are: 
2-C.sub.16 EO(11); 2-C.sub.20 EO(11); and 2-C.sub.16 EO(14). 
Linear Alkyl Phenoxylated Alcohols 
As in the case of the alcohol alkoxylates, the hexa- through 
octadeca-ethoxylates of alkylated phenols, particularly monohydric 
alkylphenols, having an HLB within the range recited herein are useful as 
the viscosity/dispersibility modifiers of the instant compositions. The 
hexa- through octadeca-ethoxylates of p-tridecylphenol, 
m-pentadecylphenol, and the like, are useful herein. Exemplary ethoxylated 
alkylphenols useful as the wetting agents of the mixtures herein are: 
p-tridecylphenol EO(11) and p-pentadecylphenol EO(18). 
As used herein and as generally recognized in the art, a phenylene group in 
the nonionic formula is the equivalent of an alkylene group containing 
from 2 to 4 carbon atoms. For present purposes, nonionics containing a 
phenylene group are considered to contain an equivalent number of carbon 
atoms calculated as the sum of the carbon atoms in the alkyl group plus 
about 3.3 carbon atoms for each phenylene group. 
Olefinic Alkoxylates 
The alkenyl alcohols, both primary and secondary, and alkenyl phenols 
corresponding to those disclosed immediately herein above can be 
ethoxylated to an HLB within the range recited herein can be used as 
wetting agents in the present invention 
Branched Chain Alkoxylates 
Branched chain primary and secondary alcohols which are available from the 
well-known "OXO" process can be ethoxylated and can be used as wetting 
agents in the present invention. 
The above ethoxylated nonionic surfactants are useful in the present 
compositions alone or in combination, and the term "nonionic surfactant" 
encompasses mixed nonionic surface active agents. 
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 paper. The 
surfactants preferably have alkyl chains with eight or more carbon atoms. 
Exemplary anionic surfactants are linear alkyl sulfonates, and 
alkylbenzene sulfonates. Exemplary nonionic surfactants are 
alkylglycosides including alkylglycoside esters such as Crodesta SL-40 
which is available from Croda, Inc. (New York, N.Y.); alkylglycoside 
ethers as described in U.S. Pat. No. 4,011,389, issued to W. K. Langdon, 
et al. on Mar. 8, 1977; and alkylpolyethoxylated esters such as Pegosperse 
200 ML available from Glyco Chemicals, Inc. (Greenwich, Conn.) and IGE 
RC-520 available from Rhone Poulenc Corporation (Cranbury, N.J.). 
B. Strength additives 
Other types of chemicals which may be added, include the strength additives 
to increase the dry tensile strength and the wet burst of the tissue webs. 
The present invention may contain as an optional component an effective 
amount, preferably from about 0.01% to about 3.0%, more preferably from 
about 0.2% to about 2.0% by weight, on a dry fiber weight basis, of a 
water-soluble strength additive resin. These strength additive resins are 
preferably selected from the group consisting of dry strength resins, 
permanent wet strength resins, temporary wet strength resins, and mixtures 
thereof. 
(a) Dry Strength Additives 
The dry strength additives are preferably selected from the group 
consisting of carboxymethyl cellulose resins, starch based resins and 
mixtures thereof. Examples of preferred dry strength additives include 
carboxymethyl cellulose, and cationic polymers from the ACCO chemical 
family such as ACCO 711 and ACCO 514, with ACCO chemical family being most 
preferred. These materials are available commercially from the American 
Cyanamid Company of Wayne, N.J. 
(b) Permanent Wet Strength Additives 
Permanent wet strength resins useful herein can be of several types. 
Generally, those resins which have previously found and which will 
hereafter find utility in the papermaking art are useful herein. Numerous 
examples are shown in the aforementioned paper by Westfelt, incorporated 
herein by reference. 
In the usual case, the wet strength resins are water-soluble, cationic 
materials. That is to say, the resins are water-soluble at the time they 
are added to the papermaking furnish. It is quite possible, and even to be 
expected, that subsequent events such as cross-linking will render the 
resins insoluble in water. Further, some resins are soluble only under 
specific conditions, such as over a limited pH range. 
Wet strength resins are generally believed to undergo a cross-linking or 
other curing reactions after they have been deposited on, within, or among 
the papermaking fibers. Cross-linking or curing does not normally occur so 
long as substantial amounts of water are present. 
Preferably the permanent wet strength resin binder materials are selected 
from the group consisting of polyamide-epichlorohydrin resins, 
polyacrylamide resins, and mixtures thereof. 
Of particular utility are the various polyamide-epichlorohydrin resins. 
These materials are low molecular weight polymers provided with reactive 
functional groups such as amino, epoxy, and azetidinium groups. The patent 
literature is replete with descriptions of processes for making such 
materials. U.S. Pat. No. 3,700,623, issued to Keim on Oct. 24, 1972 and 
U.S. Pat. No. 3,772,076, issued to Keim on Nov. 13, 1973 are examples of 
such patents and both are incorporated herein by reference. 
Polyamide-epichlorohydrin resins sold under the trademarks Kymene 557H and 
Kymene 2064 by Hercules Incorporated of Wilmington, Del., are particularly 
useful in this invention. These resins are generally described in the 
aforementioned patents to Keim. 
Base-activated polyamide-epichlorohydrin resins useful in the present 
invention are sold under the Santo Res trademark, such as Santo Res 31, by 
Monsanto Company of St. Louis, Mo. These types of materials are generally 
described in U.S. Pat. No. 3,855,158 issued to Petrovich on Dec. 17, 1974; 
U.S. Pat. No. 3,899,388 issued to Petrovich on Aug. 12, 1975; U.S. Pat. 
No. 4,129,528 issued to Petrovich on Dec. 12, 1978; U.S. Pat. No. 
4,147,586 issued to Petrovich on Apr. 3, 1979; and U.S. Pat. No. 4,222,921 
issued to Van Eenam on Sep. 16, 1980, all incorporated herein by 
reference. 
Other water-soluble cationic resins useful herein are the polyacrylamide 
resins such as those sold under the Parez trademark, such as Parez 631NC, 
by American Cyanamid Company of Stanford, Conn. These materials are 
generally described in U.S. Pat. No. 3,556,932 issued to Coscia et al. on 
Jan. 19, 1971; and U.S. Pat. No. 3,556,933 issued to Williams et al. on 
Jan. 19, 1971, all incorporated herein by reference. 
Other types of water-soluble resins useful in the present invention include 
acrylic emulsions and anionic styrene-butadiene latexes. Numerous examples 
of these types of resins are provided in U.S. Pat. No. 3,844,880, Meisel, 
Jr. et al., issued Oct. 29, 1974, incorporated herein by reference. 
Still other water-soluble cationic resins finding utility in this invention 
are the urea formaldehyde and melamine formaldehyde resins. These 
polyfunctional, reactive polymers have molecular weights on the order of a 
few thousand. The more common functional groups include nitrogen 
containing groups such as amino groups and methylol groups attached to 
nitrogen. 
Although less preferred, polyethylenimine type resins find utility in the 
present invention. 
More complete descriptions of the aforementioned water-soluble resins, 
including their manufacture, can be found in TAPPI Monograph Series No. 
29, Wet Strength In Paper and Paperboard, Technical Association of the 
Pulp and Paper Industry (New York; 1965), incorporated herein by 
reference. As used herein, the term "permanent wet strength resin" refers 
to a resin which allows the paper sheet, when placed in an aqueous medium, 
to keep a majority of its initial wet strength for a period of time 
greater than at least two minutes. 
(c) Temporary Wet Strength Additives 
The above-mentioned wet strength additives typically result in paper 
products with permanent wet strength, i.e., paper which when placed in an 
aqueous medium retains a substantial portion of its initial wet strength 
over time. However, permanent wet strength in some types of paper products 
can be an unnecessary and undesirable property. Paper products such as 
toilet tissues, etc., are generally disposed of after brief periods of use 
into septic systems and the like. Clogging of these systems can result if 
the paper product permanently retains its hydrolysis-resistant strength 
properties. More recently, manufacturers have added temporary wet strength 
additives to paper products for which wet strength is sufficient for the 
intended use, but which then decays upon soaking in water. Decay of the 
wet strength facilitates flow of the paper product through septic systems. 
Examples of suitable temporary wet strength resins include modified starch 
temporary wet strength agents, such as National Starch 78-0080, marketed 
by the National Starch and Chemical Corporation (New York, N.Y.). This 
type of wet strength agent can be made by reacting 
dimethoxyethyl-N-methyl-chloroacetamide with cationic starch polymers. 
Modified starch temporary wet strength agents are also described in U.S. 
Pat. No. 4,675,394, Solarek, et al., issued Jun. 23, 1987, and 
incorporated herein by reference. Preferred temporary wet strength resins 
include those described in U.S. Pat. No. 4,981,557, Bjorkquist, issued 
Jan. 1, 1991, and incorporated herein by reference. 
With respect to the classes and specific examples of both permanent and 
temporary wet strength resins listed above, it should be understood that 
the resins listed are exemplary in nature and are not meant to limit the 
scope of this invention. 
Mixtures of compatible wet strength resins can also be used in the practice 
of this invention. 
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. 
The following example illustrates the practice of the present invention but 
is not intended to be limiting thereof. 
EXAMPLE 
The purpose of this example is to illustrate tissue paper made by a 
papermaking machine of the type shown in FIG. 1, wherein the wet tissue is 
treated with an aqueous solution of PEG-400. 
A pilot scale Fourdrinier papermaking machine is used in the practice of 
the present invention. A 3% by weight aqueous slurry of NSK is made up in 
a conventional re-pulper. The NSK slurry is refined gently and a 2% 
solution of a permanent wet strength resin (i.e., Kymene 557H marketed by 
Hercules Incorporated of Wilmington, Del.) is added to the NSK stock pipe 
at a rate of 1% by weight of the dry fibers. The adsorption of Kymene 557H 
to NSK is enhanced by an in-line mixer. A 1% solution of Carboxy Methyl 
Cellulose (CMC) is added after the in-line mixer at a rate of 0.2% by 
weight of the dry fibers to enhance the dry strength of the fibrous 
substrate. The NSK slurry is diluted to 0.2% by the fan pump. A 3% by 
weight aqueous slurry of CTMP is made up in a conventional re-pulper. A 
non-ionic surfactant (Pegosperse) is added to the re-pulper at a rate of 
0.2% by weight of dry fibers. The CTMP slurry is diluted to 0.2% by the 
fan pump. The treated furnish mixture (NSK/CTMP) is blended in the head 
box and deposited onto a Foudrinier wire to form a homogenous embryonic 
web. Dewatering occurs through the Foudrinier wire and is assisted by a 
deflector and vacuum boxes. The Fourdrinier wire is of a 5-shed, satin 
weave configuration having 84 machine-direction and 76 
cross-machine-direction monofilaments per inch, respectively. The 
embryonic wet web is transferred from the Fourdrinier wire, at a fiber 
consistency of about 22% at the point of transfer, to a photo-polymer belt 
having 240 Linear Idaho cells per square inch, 34 percent knuckle areas 
and 14 mils of photo-polymer depth. Further de-watering is accomplished by 
vacuum assisted drainage until the web has a fiber consistency of about 
28%. The patterned web is pre-dried by air blow-through to a fiber 
consistency of about 65% by weight. The web is then adhered to the surface 
of a Yankee dryer with a sprayed creping adhesive comprising 0.25% aqueous 
solution of Polyvinyl Alcohol (PVA). The fiber consistency is increased to 
an estimated 96% before the dry creping the web with a doctor blade. The 
doctor blade has a bevel angle of about 25 degrees and is positioned with 
respect to the Yankee dryer to provide an impact angle of about 81 
degrees; the Yankee dryer is operated at about 800 fpm (feet per minute) 
(about 244 meters per minute). The dry web is formed into roll at a speed 
of 700 fpm (214 meters per minutes). 
An aqueous solution is sprayed onto the wet tissue paper through spray 
nozzle 220 which contained an aqueous solution comprising about 50% by 
weight of a polyhydroxy compound. The polyhydroxy compound used is PEG-400 
available commercially from Union Carbide of Danbury, Conn. The wet web 
has a fiber consistency of about 25%, total web basis weight basis when 
sprayed by the aqueous solution containing the polyhydroxy compound. Two 
plies of the web are formed into paper towel products by embossing and 
laminating them together using PVA adhesive. The paper towel has about 26 
#/3M Sq. Ft basis weight, contains about 1% of the PEG-400 and about 0.5% 
of the permanent wet strength resin. The resulting paper towel is soft, 
absorbent, and very strong when wetted.