CA2144072A1 - Paper products containing a chemical softening composition - Google Patents

Abstract

Fibrous cellulose materials useful in the manufacture of soft, absorbent paper products such as paper towels, facial tissues, and toilet tissue are disclosed. The paper products contain a chemical softening composition comprising a mixture of a quater-nary ammonium compound and a polyhydroxy compound. Preferred quaternary ammonium compounds include dialkyldimethy-lammonium salts such as di(hydrogenated) tallow dimethyl ammonium chloride and di(hydrogenated) tallow dimethyl ammoni-um methyl sulfate. Preferred polyhydroxy compounds are selected from the group consisting of glycerol, and polyethylene glycols and polypropylene glycols having a weight average molecular weight from about 200 to 4000. The chemical softening compositions are prepared by first mixing the polyhydroxy compound into the quaternary ammonium compound at a specific temperature range wherein the polyhydroxy compound is miscible with the quaternary ammonium compound and then diluting the mixture with water at an elevated temperature to form an aqueous vesicle dispersion suitable for treating the fibrous cellulose material.

Description

W094/10381 2lDs~ 172 PCI/U593/09452 PAPER PRODUCTS CONTAINING A
CHEMICAL SOFTENING COMPOSITION

FIELD OF THE INVENTION

This invention relates to tissus paper webs. More particularly, it relates to soft, absorbent tissue paper webs which can be used in toweling, napkin, facial 15 tissue, and toilet tissue products.

BACKGROUND OF THE INVENTION

Paper webs or sheets, sometimes called tissue or paper tissue webs or 20 sheets, find extensive use in modern society. Such items as paper towels, napkins, facial and toilet tissues are staple items of commerce. It has long been recognized that three important physical attributes of these products are their softness; their absorbency, particularly their absorbency for a~ueo~ls systems; and their strength, particularly their strength when wet. Research and development 25 sfforts have been directed to the improvement of each of these anributes without seriously affecting the others as well as to the improvement of two or three attributes simultaneously.
Softness is the tactile sensation perceived by the consumer as he/she holds a part;cular product, rubs it across his/her skin, or cnJmples it within hisÇher hand.
30 This tactile sensation is a combination of several physical properties. One of the more important physical properties related to softness is generally considered by those skilled in the art to be the stiffness of the paper web from which the product is made. Stiffness, in turn, is usually considered to be directly dependent on the dry tensile strength of the web and the stiffness of the fibers which make up the 3~ web.

Wo94/10381 ~14~a72 Pcr/uss3/os4s2 Strength is the ability of the product, and its constituent webs, to maintain physical integrity and to resist tearing, bursting, and shredding under use conditions, particularly when wet.
Absorbency is the measure of the ability of a product, and its constituent webs, to absorb quantities of liquid, particularly aqueous solutions or dispersions. Overall absorbency as perceived by the human consumer is generally considered to be a combination of the total quantity of liquid a given mass of tissue paper will absorb at saturation as well as the rate at which the mass absorbs the liquid.
The use of wet strength resins to enhance the strength of a paper web is widely known. For example, Westfelt described a number of such materials and discussed their chemistry in Cellulose Chemistry and Technology, Volume 13, at pages 813-825 (1979). Freimark et al. in U.S. Pat. No. 3,755,220 issued August 28, 1973 mention that certain chemical additives known as debonding agents interFere with the natural fiber-to-fiber bonding that occurs during sheet formation in papermaking processes. This reduction in bonding leads to a softer, or less harsh, sheet of paper. Freimark et al. go on to teach the use of wet strsngth resins to enhance the wet strength of the sheet in conjunction with the use of debonding agents to off-set undesirable effects of the wet strength resin. These debondingagents do reduce dry tensile strength, but there is also generally a reduction in wet tensile strength.
Shaw, in U.S. Pat. No. 3,821,068, issued June 28, 1974, also teaches that chemical debonders can be used to reduce the stiffness, and thus enhance the softness, of a tissue paper web.
Chemical debonding agents have been disclosed in various references 26 such as U.S. Pat. No. 3,554,862, issued to Hervey ~t al. on January 12,1971.
These materials include quaternary ammonium salts such as trimethylcocoammonium chloride, trimethyloleylammonium chloride, di(hydrogenated) tallow dimethyl ammonium chloride and trimethylstaaryl ammonium chloride.
Emanuelsson et al., in U.S. Pat. No. 4,144,122, issued March 13, 1979, teach the use of complex quaternary ammonium compounds such as bis(alkoxy(2-hydroxy)propylene) quaternary ammonium chlorides to soften webs. These authors also attempt to overcome any decrease in absorbency caused by the debonders through the use of nonionic surfactants such as ethylene oxide and propylene oxide adducts of fatty alcohols.
Armak Company, of Chicago, Illinois, in their bulletin 76-17 (1977) disclose that the use of dimethyl di(hydrogenated) tallow ammonium chloride in ::

W O 94/10381 ~ ~ ~ 4 ~ 7 2 PC~r/US93/09452 combination with fatty acid esters of polyoxyethylene glycols may impart both softness and absorbency to tissue paper webs.
One exemplary result of research directed toward improved paper webs is described in U.S. Pat. No. 3,301,746, issued to Sanford and Sisson on January 31, 1967. Despite the high quality of paper webs made by the process describ~d in this patent, and despite the commercial success of products formed from these webs, research efforts directed to finding improved products have continued.
For example, Becker et al . in U.S. Pat. No. 4,158,594, issued January 19, 1979, describe a method they contend will form a strong, soft, fibrous sheet. More specifically, they teach that the strength of a tissue paper web (which may havebeen softened by the addition of chemical debonding agents) can be enhanced by adhering, during processing, one surface of the web to a creping surface in a fine patterned arrangement by a bonding material (such as an acrylic latex rubber emulsion, a water soluble resin, or an elastomeric bonding material) which has been adhered to one surface of the web and to the creping surface in the flne patterned arrangement, and creping the web from the creping surface to form a sheet material.
It is an object of this invention to provide a soft, absorbent tissue paper products.
It is a fur~her object of this invention to provide soft, absorbent towel paper products.
It is also a further object of this invention to provide a process for making soft, absorbent tissue and towel paper products.
These and other objects are obtained using the present invention, as will become readily apparent from a reading of the following disclQslJre.

SUMMARY OF THE INVENTION

The present invention provides soft, absorbent paper product. Briefly, the paper products comprise a sheet of cellulose material and from about 0.005% to about 5.0% by weight of the fibrous cellulose material of a chemical softening composition comprising a mixture of:

(a) a quaternary ammonium compound having the formula 2 1 ~ 7 2 PCI /US93/09~52 N+ X~

wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group, or mixture thereof; each R1 substituent is a C14 - C22 hydrocarbyl group, or mixture thereof; and X~ is a compatible anion; and (b) a polyhydroxy compound selected from the group consisting of glycerol, and polyethylene glycols and polypropylene glycols having a weight average molecular weight from about 200 to 4000;
wherein the weight ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from about 1: 0.1 to 0.1: 1; and wherein said polyhydroxy compound is miscible with the quaternary ammonium compound at a temperature of at least 40 C . Preferably, the mixture of the quaternary ammonium and the polyhydroxy compound is diluted with a liquid carrier to a concentration of from about 0.01% to about 25.0% by weight of the chemical softening composition before being added to the fibrous cellulosa material.
Pre~erably, at least 20% of the polyhydroxy compound added to the fibrous cellulose is retained.
Examples of quaternary ammonium compounds suitable for use in tha present invention include the well-known dialkyldimethylammonium salts such as ditallowdimethyl ammonium chloride, ditallowdimethyl ammonium methyl sulfate, di~hydrogenated) tallowdimethyl ammonium methylsulfate, di(hydrogenated tallow) dimethyl ammonium chloride.
Examples of polyhydroxy compounds useful in the present invention include glycerol and polyethylene glycols having a weight average molecular weight of from about 200 to about 4000, with polyethylene glycols having a weight average molecular weight of from about 200 to about 600 being preferred.
A particularly preferred tissue paper embodiment of the present inven~ion comprises from about 0.03% to about 0.5% by weight of the mixture of ~uaternary ammonium compound and the polyhydroxy compound.

W O 94/10381 2 1 ~ 4 ~ P~r/US93/094S2 Briefly, the process for making the tissue webs of the present inven~ion comprises the steps of formation is a papermaking furnish from the aforementioned components, deposition of the papermaking furnish onto a foraminous surface such as a Fourdrinier wire, and removal of the water from thedeposited furnish.
All percentages, ratios and proportions herein are by weight unless otherwise specified.

BRIEF DESCRIPTION OF THE DRAWINGS
While the Specification concludes with claims particularly pointing out and and distinctly claiming the present invention. it is believed the invention is better understood from the following description taken in conjunction with the associated drawings, in which:
Figure 1 is a phase diagram of DODMAMS and DT~MAMS.
Figure 2 is a phase diagram of DODMAMS/pure PEG-400 system.
Figure 3 is a phase diagram of PEG-400/methyl octanoate system.
Figure 4 is a cryo-transmission micro-photograph taken at X 66,000 of a vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium methyl sulfate and PEG-400 system.
Figure 5 is a cryo-transmission micro-photograph taken at X 66,000 of vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium methyl sulfate and glycerol system.
Figure 6 is a cryo-transmission micro-photograph taken at X 66,000 of vesicle dispersion of a 1: 1 by weight r~tio of a di(hydrogenated) tallow dimethyl ammonium chloride and PEG-400 system.
Figure 7 is a cryo-transmission micro-photograph taken at X 66,000 of vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium chloride and glycerol systsm.
The present invention is described in more detail below.

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 wo 94/10381 ~14 '1~ 7 ~ PCI/US93/09452 the invention can be better understood from a reading of the following detailed description and of the appended examples.
As used herein, the terms tissue paper web, paper web, web, paper sheet and paper product ali refer to sheets of paper made by a process comprising the 5 steps of forming an aqueous papermaking furnish, depositing this furnish on a foraminous surface, such ac 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 10 papermaking fibers and the chernicals described hereinafter.
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), and a mixture of at least one quaternary ammonium and at least one polyhydroxy compound, all of which will be hereinafter1 5 described.
It is anticipated that wood pulp in all its varieties will ncrmally comprise thepapermaking 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 20 pulps as well as rnechanical pulps including for example, ~round wood, thermomechanical pulps and chemically modi~led thermomechanical pulp (CTMP).
Pulps derived from both deciduous and coniferous trees can be used. Also applicable to the present invention are nbers derived from recycled paper, whichmay contain any or all of the above categories as well as other non-fibrous 25 materials such as fillers and adhesives used to facilita~e the original papermaking.
Preferably, the papermaking fibers used in this inv~ntion comprise Kraft pulp derived from northem softwoods.
Chemlcal Softener Colr ,~ oslllons The present invention contains as an essen~ial component 'rom about 30 0.005% to about 5.0%, more preferably from about Q.03% to 0.5% by wei~ht, on a dry fiber basis of a mixture of a quaternary ammonium compound and a polyhydroxy compound. The ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from about 1: 0.1 to 0.1: 1; preferably, the weight ratlo of the quaternary ammonium compound to th~ polyhydroxy compound is 35 about 1: 0.3 to 0.3: 1; more preferably, the weight ratio of the quaternary ammonium compound to the polyhydroxy compound is about 1: 0.7 to 0.7: 1, WO 94/1038t ~ t~ , PCr/US93/09452 dep~ndin~ upon the molecular wei~ht ot the particular polyhdroxy compound and/or quaternary ammonium compound us~d.
Each of these types of compounds will bs d~scnbed in detail below.

A. Quaternary Ammonium Compound The chemical softening composition contains as an essential component a quaternary ammonium compound having the formula:

\/

In the structure named above each R1 is C14-C22 hydrocarbon Qroup, pr6f~rabiy tallow, R2 is a C1 - C6 alkyl or hydroxyalkyl ~roup, preferably C1-C3 alkyl, X- is a compatible anion, such as an halide (e.~ chloride or bromide) or methyl sulfat~
As discussed in Swen, Ed~ in Bailey's Industrial Oil and Fat Products, Third Edition, John Wlley and Sons (Naw Yorlc 1964), tallow is a naturally occurring material having a variable composition. Table 6~13 in the above identifisd reference edited by Swem indicates that typically 78% or more of the fatty acids of tallow contain 16 or18 carbon atoms~ Typically, half of the fatty acids pres~nt in tallow ars unsaturated, primarily in the form of oleic acid. Synthetic 85 well as natural tallows fall within the sc~pe of the present invention.
Pr~ferably, each R1 is C16-C18 alkyl, most preferabty each R1 is strai~ht-chain C18 alkyL P-eferably, each P.2 is methyl and X~ is chloride or methyl sulfats~
Examples of quaternary ammonium compounds suitable for use in the pres~nt invention include the well-known dialkyldimethylammonium salts such as ditallowdimethylammonium chlonde, ditallowdimethylammonium methyl sulfats, di(hydrogenated) tallow dimethyl ammonium chloride; with di(hydro~enated) tallowdimethyl ammonium methyl sulfate bein~ preferred. This panicular material is available commercially from Sherex Chemical Company Inc. of Dublin, Ohio under the tradename 'Varisoft R 137~
Biodegradable mono and di-ester variations of the quaternar~r ammonium compound can also ba used, and are meant to fall within the scope ot the pres~ntinvention. These compounds have the forrnula:

wo 94/1038~ 7 2 PCr/US93/Og452 \ /
j N+ X~

and \/
N+ X~

/ \

In the structures named above each R1 is an aliphatic hydrocarbon radical 25 selected from ths group consisting of alkyl having from about 14 to about 22 carbon atoms, such as tallow, R2 is a C1 - C6 a!kyl or hydroalkyl group, X~ is acompatible anion, such as an halide (e.g., chloride or bromide) or methyl sulfate.
Preferably, each R1 is C16-C18 alkyl, most preferably each R1 is straight-chain C18 alkyl, and R2 is a methyl.
30 B. Polyhydroxy Compound The chemical softening composition contains as an essential component a polyhydroxy compound.
Examples of polyhydroxy compounds useful in the present invention include glycerol, and polyethylene glycols and polypropylene glycols having an weight 35 average molecular weight of f.om about 200 to about 4000, preferably from about 200 to about 1000, most preferably from about 200 to about 600. Polyethylene WO 94/10381 Z 1~4 ~ Pcr/us93/o9452 glycols having an weight average molecular weight of from about 200 to about 600are especially preferred.
A particularly preferred polyhydroxy compound is polyethylene glycol having an weight average molecular weight of about 400. This material is available 5 commercially from the Union Carbide Company of Danbury, Connecticut under the tradename "PEG-400n.
The chemical softening composition described above i.e. mixture of a quaternary ammonium compounds and a polyhydroxy compound are preferably added to the aqueous slurry of papermaking fibers, or furnish, in the wet end of the 10 papermaking machine at some suitable point ahead of the Fourdrinier wire or sheet forming stage. However, applications of the above described chemical chemical softening composition subsequent to formation of a wet tissue web and prior to drying of the web to completion will also provide significant softness,absorbency, and wet strength benefits and are expressly included within the scope 15 of the present invention.
It has been discovered that the chemical softening composition are more effective when the quaternary ammonium compound and the polyhydroxy compound are first pre-mixed together before being added to the papermaking furnish. A preferred method, as will be described in greater detail hereinafter in 20 Example 1, consists of first heating the polyhydroxy compound to a temperatura of about 66 C (150 F), and then adding the quatemary ammonium compound to the hot polyhydroxy compound to form a fluidized melt~. The weight ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from about 1: 0.1 to 0.1: 1; preferably, the weight ratio of the quaternary ammonium 25 compound to the compound is about 1: 0.3 to 0.3: 1; more preferably, the weight ratio of the quaternary ammonium compound to the compound is about 1: 0.7 to 0.7: 1, although this ratio will vary depending upon the molecular weight of theparticular compound and/or quaternary ammonium compound used. The quaternary ammonium compound and polyhydroxy compound melt is then diluted 30 to the desired concentration, and mixed to form an aqueous solution containing a vesicle dispersion of the quaternary ammonium compound / polyhydroxy compound mixture which is then added to the papermahng furnish. Preferably, the mixture of the quaternary ammonium compound and polyhdroxy compound is diluted with a liquid carrier such as water to a concentration of from about 0.01% to 35 about 25% by weight of the softening composition before being added to the papermaking furnish. The temperature of the liquid carrier preferably ranges from about 40 C to about 80 C. The mixture of the quaternary ammonium compound ~ ~ ;

WO 94/10381 ~ 7 ~ PCI/US93/09452 and the polyhdroxy compound are present as particles dispersed in the liquid carrier. The average particle size preferably ranges from about 0.01 to 10 microns, most preferably from about 0.1 to about 1.0 micron. As shown in Figures 4 - 6, the dispersed particles are in the form of vesicle particles.
The quaternary ammonium compound and the polyhdroxy compound are mixed at an elevated temperature of at least 40 C, more preferably from about 56 C to about 68 C. At the preferred temperature range, di(hydrogenated) tallow dimethyl ammonium chloride is in a liquid phase and is miscible with the polyhdroxy compound. Di(hdyrogenated) tallow dimethyl methyl sulfate, on the other hand, is in a liquid-crystal phase and is miscible with the polyhydroxy compound. The physcial states of di(hdryogenated) tallow dimethyl ammonium methyl sulfate will be discussed in greater detail hereinafter.
The papermaking furnish can be readily formed or prepared by mixing techniques and equipment well known to those skilled in the papermaking art.
It has unexpectedly been found that the adsorption of the polyhydroxy compound onto paper is significantly enhanced when it is premixed Yvith the quaternary ammonium compound before being added to the paper. In fact, at least 20% of the polyhydroxy compound added to the fibrous cellulose is retained, and preferably, the retention level of the polyhydroxy compound is from about 50%
to about 90% by weight of the dry fibers.
Importantly, adsorption occurs at a concentra~ion and within a time frame that are practical for use during paper making. In an effort to better understand the surprisingly high retention rate of polyhydroxy compound onto the paper, the physical science of the melted solution and the aqueous dispersion of a di(hydrogenated) tallow dimethyl ammonium methyl sulfats and polyethylene glycol 400 were studied.
Without wishing to be bound by theory, or to otharwise limit the present invention, the following discussion is offered for explaining how the quaternaryammonium compound promotes the adsorption of the polyhydroxy compound onto paper.
Information on the physical state of DTDMAMS Di(hyhrogenated)Tallow dimethyl Ammonium Methyl Sulfate, R2N+(CH3)2,CH3OSO3-) and on DODMAMS is provided by X-ray and NMR data on the commsrcial mixture.
DOD!~AAMS (DiOctadecyl Dimethyl Ammonium Methyl Sulfate, (C18H37)2N+(CH3)2.CH3OSO3-) is a major component of DTDMAMS, and serves as a model compound for the commercial mixture. It is useful to consider 21~4072 WO 94/10381 ~ i. PCI`/US93/09452 first the simpler DODMAMS system, and then the more complex commercial DTDMAMS mixture.
Depending on the temperature, DODMAMS may exist in any of four phase states (Figure 1): two polymorphic crystals (xl~ and Xa), a lamellar (Lam) liquid crystal, 5 or a liquid phase. The X~ crystal exists from below room temperature to 47 C. At this temperature it is transformed into the polymorphic X crystal, which at 72 C is transformed into the Lam liquid crystal phass. This phase, in tùm, is transformed into an isotropic liquid at 150 C. DTDMAMS is expected to resemble DODMAMS in its physical behavior, except that the temperatures of the phase transitions will be10 lowered and broadened. For exampls, the transition from the X~ to the XC~ crystal occurs at 27 C in DTDMAMS instead of 47 C as in DODMAMS. Also, c~lorimetric data indicate that several crystal --->Lam phase transitions occur in DTDMAMS rather than one as in DODMAMS. The onset temperature of the highest of these transitions is 56 C, in good agreement with the X-ray data, but calorimetry displays two peaks 15 with onset temperatures of 59 and 63 C.
DODMAC ((DiOctadecyl Dimethyl Ammonium Chloride) displays qualitatively different behavior from DODMAMS in that the Lam liquid crystal phase does not exist in this compound. This diff~rence, however, is believed not to be important to the use of this compound (or its commercial analog i~TDMAC) in the treatment of 20 paper. (Laughlin et al., Journal of Physical Chemistry, Physlcal Sclence of the Dloctadecyldlmethylammonlum Chlorlde-Water System. 1. Equll7brium Phaso Behavior, 1990, volume 94, pages 2546-2552, incorporated herein by reference.
Mixtures of DTDMAMS with PEG 400.
A 1:1 weight ratio mixture of these two materials is studied, and a plausible model for the phase behavior of this system is suggested in Figure 2. In this diagram DODMAMS and PEG are shown to be immiscible at high temperatures, where they coexist as two liquid phases. As mixtures of the two liquids within this region are cooled, a Lam phase separates from tha mixture. This study therefore shows that these two materials while immiscible at high temperatures do become miscible at lower temperatures within the Lam liquid crystal phase. At still lower temperatures crystal phases are expected to separate from the Lam phase, and the compounds are again immiscible.
These studies therefore suggest that in order to form good dispersions of DTDMAMS and PEG -400 in water, the premix that is diluted with water should be held within the intermediate temperzture range where the two compounds are miscible.

WO 94/10381 ~ 7 2 1 2 PCI /US93/09452 Mlxtures of DTDMAC wlth PEG 400.
Phase studies of these two materials using the step-wise dilution method demonstrate that their physical behavior is considerably different from that of DTDMAMS. No liquid crystal phases are found. These compounds are miscible over a wide range of temperatues, which indicates that dispersions may be prepared from these mixtures over a comparable range of temperatures. No upper temperature limit of miscibility exists.
Preparation of dispersTons.
Dispersions of either of these materials may be prepared by diluting a mixture, that is held at a temperature at which the polyhydroxy compound and thequaternary ammonium salt are miscible, with water. It does not matter greatly whether they are miscible within a liquid crystalline phase (as in the case of DTDMAMS), or in a liquid phase (as in the case of DTDMAC). Neither DTDMAMS
nor DTDMAC are soluble in water, so the dilution of either dry phase with water will precipitate the quaternary ammonium compound as small particles. Both quaternary ammonium compounds will precipitate at elevated temperatures as a liquid-crystal phase in dilute aqueous solutions, regardless of whether the dry solution was liquid or liquid crystalline. The polyhydroxy compound is soluble with water in all propcrtions, so it is not precipitated.
Cryoelectron microscopy demonstrates that the particles present are about 0.1 tc 1.0 micrometers in size, and highly varied in stnucture. Some are sheets (curved or flat), while others are closed vesicles. The membranes of all these particles are bilayers of molecular dimensions in which the head groups are exposed to water, the tails are together. The PEG is presumed to be associated with these particles. The appl~cation of dispersions prepared in this manner to paper results in attachment of the quaternary ammonium ion to the paper, strongly promotes the adsorption of the polyhydroxy compound onto papar, and produces the desired modification of softness and retention of wettability.
State of the disparsions.
When the above described dispersions are cooled, the partial crystallization of the material within the colloidal particles may occur. However, it is likely that the attainment of the equilibrium state will require a long time (perhaps months), so that a disordered particle whose membranes are either a liquid crystal or a disordered crystal phase is interacting with the paper.
It is believed that the vesicles containing DTDMA~S and PEG break apart upon drying of the fibrous cellulosic material. Once the vesicle is broken, the majority of the PEG component penetrates into the interior of the cellulose fibers WO 94/10381 2 1 4~ 7 2 PCI'/US93/09452 .

where it ~nhances the fiber flexibility. Importantly, some of the PEG is retained on the surface of the fiber where it acts to enhance the absorbency rats of the cellulose fibers. Due to ionic interaction, the majority of the DTDMAMS
-component stays on the surface of the ceilulose fiber where it enhances the 5 surface feel and softness of the paper product.
-The second step in the process of this invention is the depositing of the papermaking furnish ùsing the above described chemical softener composition as an additive on a foraminous surface and the third step is the remoYing of the water from the furnish so deposited. Techniques and equipment which can b~ used to 10 accomplish these two processing steps will be readily apparent to those skilled in the papermaking art.
The presPnt 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 15 and its progeny; and high bulk, uncompacted tissue paper such as exemplified by U.S. Patent 3,812,000, Salvucci, Jr., issued May 21, 1974. 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. Tissue structures formed from layered paper webs are described in U.~. Patent 3,994,771, Morgan, 20 Jr. et al. issued November 30, 1976, and incorporated herein by ref~rencs. Ingeneral, a wet-laid composite, soft, bulky and absorbent paper stnucture 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 25 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 layer web is subsequently caused to conform to the surface of an open mesh dryingrlmprinting fabric by the application of a fluid to force to the web and thereafter thermally predried on said fabric as part 30 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 abasis weight of between 10 g/m2 and about 65 g/m2, and density of about 0.60 g/cc or less. Preferably, basis weight will be below about 35 g/m2 or less; and 35 density will be about 0.30 glcc or less. Most preferably, density will be between 0.04 g/cc and about 0.20 gtcc.

, W O 94/10381 214 4 ~ 7 2 PC~r/US93/094~2 ~4 Conventionally prassed tissua pap~r and methods for makin~ such paper are known in the art. Such paper is typicaliy made by depositing pap~rmaking furnish on a foraminous forming wire. This forming wir~ is o~ten referred to in the art as a Fourdrinier wire. Once the furnish is deposited on the forming wire, it is 5 referrad to as a web. The web is dewatered by pressing the web and drying at elevated temperature. The particular techniques and typical equipment for makingwebs 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 10 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 issubjected to pressure developed by opposing mechanical members, for example, cylindrical rolls.
The dewatered web is then further pressed nd 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. 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 batween the drums. The tissue paper structures which are formed are referred to hereinafter as conventional, pressed, tissue paper structures. Such sheets are consider~d to be compacted since the wob is subjected to substantial mechanical compressional forces while the fibersare moist and are then dried (and optionally creped) whil~ 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 altemativsly 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 th~ high bulk field. Prefsrredprocesses for making pattern densified tissue we~s are disclosed in U.S. Patent No. 3,301,746, issued to Sanford and Sisson on January 31, 1967, U.S. Patent Ho. 3,974,025, issued to Peter G. Ayers on August i0,1976, and U.S. Patent No.
4,191,609, issued to Paul D. Trokhan on March 4, 1980, and U.S. Patent 4,637,859, issued to Paul D. Trokhan on January 20, 1987; all of which are incorporated herein by reference.

WO 94/10381 ~ 14 ~ ~ 7~ - PCI/US93/09452 , , ~ ., 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 5 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 10 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 15 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 densifled zones, dewatering, and optional predrying, the web is dried to completion, preferably still avoiding mechanical pressing. Pre~erably, from about 8% to about ~5% of the tissue paper 20 surface comprises densified knuckles having a relativa density of at least 125% of the density of the hish bulk field.
Tne array of supports is preferably an imprinting carrier fabric havin~ a patterned displacement of knuckles which operate as the array of supports which facilitate the formation of the densified zones upon application of pr9ssure. The 2~ pattern of knuckles constitutes the array of supports previously refarred to.Imprinting carrier fabrics are ~isclosed in U.S. Patent No. 3,301,746, Sanford and Sisson, issued January 31, 1967, U.S. Patent No. 3,821,068, Salvucci, Jr. et al ., issued May 21, 1974, U.S. Patent No. 3,974,025, Ayers, issued August 10,1976, U.S. Patent No. 3,573,164, Friedberg et al ., issued March 30, 1971, U.S. PatentNo. 3,473,576, Amneus, issued October 21, 1969, U.S. Patent No. 4,239,065, Trokhan, issued December 16, 1980, and U.S. Patent Ho. 4,528,239, Trokhan, issued July 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 aforaminous supporting carrier which also operates as an imprinting fabric. Once formed, the wet web is dewatered and, preferably, thermally predried to a selected wo 94/10381 2 1 4 4 ~ 7 ~ 6 PCr/US93/09452 fiber consistency of between about 40% and about 80%. Dewatering can be performed with suction boxes or other vacuum devices or with blow-through drvers. 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, ~y pressing a nip roll which supports the imprinting fabric against the face of a drying drum, such as a Yanke~ dryer, wherein the web is disposed between the nip roll and drying dn~m. Also, preferably, the web is molded against the imprinting fabric prior to completion of drying by application of fluid 10 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 15 U.S. Patent No. 3,812,000 issued to Joseph L. Salvucci, Jr. and Peter N. Yiannos on May 21, 1974 and U.S. Patent No. 4,208,459, issued to Henry E. Becker, AlbertL. McConnell, and Richard Schutte on June 17, 1980, both of which are incorporated herein by reference. In general, uncompacted, non pattem densified tissue paper structures are prepared by depositing a papermaking furnish on a 20 foraminous forming wire such as a Fourdrinier wire to form a wet web, drainin~ 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 stn~cture isa soft but weak high bulk sheet of relatively uncompacted fibers. Bonding material 25 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-pattern-densified 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 30 the web and removing additional water with the aid of a uniform mechanical compaction (pressing) until the web has a consistency of 25-~0%, 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, 3~ 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. One particularly advantageous use ~4~72 W O 94/10381 PC~r/US93/094~2 of the tissue paper web of this invention is in paper tow~l 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 December 3, 1968 and which is incorporated herein by reference~ to form 2-ply paper towels.

Molecular Weight Determlnation A. Introduction The essential distinguishing characteristic of polymeric materials is their molecular size. The properties which have enabled polymers to be used in a diversity of applications derive almost entirely from their macro-molecular nature.
In order to characterize fully these materials it is essential to have some means of defining and determining their molecular weights and molecular weight distributions. It is more correct to use the term relative molecular mass rather the molecular weight, but the latter is used more generally in polymer technology. It is not always practical to determine molecular weight distributions. However, this is becoming more common practice using chromatographic techniques. Rather, recourse is made to expressing molecular size in terms of molecular weight averages.

B. Molecular welght averages If we consider a simple molecular weight distribution which represents the weight fraction (wj) of molecules having relative molecular mass (Mj), it is possible to define several useful average values. Averaging carried out on the basis of the number of molecules (Nj) of a particular size (Mj) gives the Number Average Molecular Weight ~n = ~NiMi ~: Ni An important consequence of this definition is that the Number Average - Molecular Weight in grams contains Avogadro's Number of molecules.
This definition of molecular weight is consistent with that of monodisperse molecular species, i.e. molecules having the same molecular weight. Of more significance is the recognition that if the number of molecules in a given mass of a WO 94/10381 2 1 4 ~ ~ 7 2 PCI /US93/09452 polydisperse polymer can be determined in some way ~hen Mn, can be calculated readily. This is the basis of colligative property measurements.
Averaging on the basis of the weight fractions (VVj) of molecules of a given mass (Mj) leads to the definition of Weight Averase Molecular Weights Mw = ~W!Ni z ~NiM~i ~ Wj ~: Nj Mj Mw is a more useful means for expressing polymer molecular weights than Mn 10 since it reflects more accurately such properties as melt viscosity and mechanical properties of polymers and is therefor used in the present invention.
Analytical and TestTng Procedures Analysis of the amount of treatment chemicals used herein or retained on tissue paper webs can be performed by any method accepted in the applicable art.For example, the level of the quaternary ammonium compound, such as DTDMAMS, retained by the tissue paper can be determined by solvent extraction of the DTDMAMS by an organic solvent followed by an anionicJcationic titration using Dimidium Bromide as indicator; the level of the polyhydroxy compound, suchas PEG-400, can be determined by extraction in an aqueous solvent such as 20 water followed by gas chromato~raphy or colorimetry techniques to determinc the level of PEG-400 in the extract. Thess 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.
Hydrophilicity of tissue pap~r rafers, in general, to the propensity of the 25 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 pariod of time is referred to as ~wetting time~. In order to provide a consistent and repe~t~ble test for wetting time, the following procedure may ba used for wetting time detarminations: first, a 30 conditioned sample unit sheet (the cnvironmental conditions for testing of paper samples are 23~1C and 50+2% R.l~. as specified in TAPPI Method T 402), approximately 4-3/8 inch x 4-3/4 inch (about 11.1 cm x 12 cm) of tissue paper structure is provided; sscond, the sheet is folded into four (4) juxtaposed quarters, and then crumpled into a ball approximately 0.75 inches (about 1.9 cm) to about 1 35 inch (about 2.5 cm) in diameter; third, the balled sheet is placed on the surface of a body of distilled water at 23 i 1C and a timer is simultaneously started; fourth, 0 ~ 2 the timer is stopped and read when wetting of th~ balled sheet is completed.
Complete wetting is observed visually.
Hydrophilicity characters of tissue paper embodiments of the present invention may, of course, be determined immediately af~er manufacture. Howevet, 5 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 utwo week wetting times.~
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. Caliper of the tissue paper, as used herein, is the thickness of the paper when subjected to a compressive load of 95 glin2 (15.5 g/cm2) Optional Ingredients Other chemicals commonly used in papermaking can be added to tha papermaking furnish so long as they do not significantly and adversely affect the softening, absorbency of the fibrous material, and enhancing actions of the 20 chemical softening composition.
For example, surfactants may be used to treat tha 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 paper. The surfactants preferably have alkyl chains with eight or more carbon atoms.
25 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, NY); alkylglycoside ethers as described in U.S. Patent 4.011,389, issued to W. K. Langdon, et al. on March 8, 1977; and alkylpolyethoxylated esters 30 such as pegosperse 200 ML available from Glyco Chemicals, Inc. (Greenwich, CT) and IGEPAL RC-520 available from Rhone Poulenc Corporation (Cranbury, N.J.).
Other types of chemicals which may be added, include dry strength additives to increase the tensila strength of the tissue webs. Examples of dry strength additives include carboxymethyl cellulose, and cationic polymers from the 35 ACCO chemical family such as ACCO 771 and ACC0 514, with carboxymethyl cellulose (CMC) being preferred. This material is available commercially from the Hercules Company of Wilmington, Delaware under the tradename HERCULESR

WO 94/10381 ~ 4 ~ 7,~ PCl`/US93/09452 CMC. The level of dry strength additive, if used, is preferably from about 0.01 % to about 1.0%, by weight, based on the dry fiber weight of the tissue paper.
Other types of chemicals which may be added, include wet strength additives to increase the wet burst of the tissue webs. The present invention may 5 contain as an optional component from about 0.01% to about 3.0%, more preferably from about 0.3% to about 1.5% by weight, on a dry fiber weight basis, of a water-soluble permanent wet strength resin.
Permanent wet strength resins useful herein can be of several types.
Generally, those resins which have previously found and which will hereafter find 10 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 15 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 20 papermaking fibers. Cross-linking or curing does not normally occur so long as substantial amounts of water are present.
Of particular utility are the various polyamide-epichlorohydrin resins. These materials are low molecular weight polymers provided with re~ctive functional groups such as amino, epoxy, and azetidinium groups. The patent literature is 25 replete with descriptions of processes for making such materials. U.S. Pat. No.
3,700,623, issued to Keim on October 24, 1972 and U.S. Pat. No. 3,772,076, issued to Keim on November 13,1973 are examples of such patents and both are incorporated herein by reference.
Polyamide-apichlorohydrin resins sold under the trademarks Kymene 5S7H
30 and Kymene 2064 by Hercules Incorporated of Wilmington, D~laware, 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 presen invention are sold under the Santo Res trademark, such as Santo Res 31, by 35 Monsanto Compar:y of St. Louis, Missouri. These types of materials are generally described in U.S. Pat. Nos. 3,855,158 issued to Petrovich on December 17,1974;
3,8g9,388 issued to Petrovich on August 12, 1975; 4,129,528 issued to Petrovich 2~4~2 WO 94/10381 ~ i . PCI/US93/09452 on December 12, 1978; 4,147,586 issued to Petrovich on April 3, 1979; and 4,222,921 issued to Van Eenam on September 16, 1980, all incorporated herein by reference.
Other water-soluble cationic resins useful herein are the polyacrylamide 5 resins such as those sold under the Parez trademark, such as Parez 631 NC, by American Cyanamid Company of Stanford, Connecticut. These materials are generally described in U.S. Pat. Nos. 3,556,932 issued to Coscia et al . on January 19, 1971; and 3,556,933 issued to Williams et al . on January 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. Patent 3,844,880, Meisel, Jr. et al ., issued October 29, 1974, incorporated herein by reference.
Still other water-soluble cationic resins finding utility in this invention are the 15 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 20 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, the25 term Upermanent 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.
The above-mentioned wet strength additives typically result in paper products with permanent wet strength, i.e., paper which when placed in an 30 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 35 hydrolysis-resistant streng~h 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.

WO 94/10381 X ~ 3 7 2 PCI/US93/09452 Decay of the wet strength facilitates flow of the paper product throuQh 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 5 National Starc'n and Chemical Corporation (New York, New York). This t~pe of wet strength agent can be made by reacting dimethoxyethyl-N-methyl-chloroacetamide with cationic starch polymers. Modified starch temporary wet strength agents arealso described in U.S. Pat. No. 4,675,394, Solarek, et al ., issued June 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 January 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 1 5 invention.
Mixtures of compatible wet strength resins can also be used in the practice of this invention.
The above listings of optional chemical additiv~s is intended to be merely exemplary in nature, and are not meant to limit the scope of the invention.
The following examplas illustrate the practice of the present invention but are not intended to be limiting thereof.

The purpose of this example is to illustrate a method that can be used to make-up a ch~mical softener composition comprisin~ a mixture of Di(hydrogenated) Tallow Dim~thyl Ammonium Methyl Sulfate (DTDMAMS) and Polyethylene Glycol 400 (PEG-400).
A 1% solution of the chemical softener is prepared according to the following procedure: t. An equivalent weight of DTDMAMS and PEG-400is weighed separately; 2. PEG is heated up to about 66 C (150 F); 3.
DTDMAMSis dissolved in PEG to form a melted solution at 66 C (150 F); 4.
Shear stress is applied to form a homogeneous mixture of DTDMAMS in PEG; 5.
The dilution water is heated up to about 66 C (150 F); 6. The melted mixture of DTDMAMS and PEGis diluted to a 1% solution; and 7. Shear stress is applied to form an aqueous solution containing a vesicle dispersion or suspension of theDTDMAMS/PEG mixture; 8. The particle size of the DTDMAMS/PEG vesicle WO 94/10381 2 1 4 ~ ~ 7 2 ~ PCr/US93/09452 ~ . ,~ . ~

dispersion is determined using an optical microscopic technique. The particle size range is from about 0.5 to 1.0 micron.
Figure 4 illustrates a cryo-transmission micro-photograph taken at X
66,000 of a vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium methyl sulfate and PEG-400 system. From figure 4, it indicates that particles having membranes one or two bilayers thick, whose geometry ranges from closed/open vesicles, to disc-like structures and sheets.

The purpose of this example is to illustrate a method that can be used to make-up a chemical softener composition which comprises a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Methyl Sulfate (DTDMAMS) and Glycerol.
1~ A 1% solution of the chemical softener is prepared according to the following procedure: 1. An equivalent weight of DTDMAMS and Glycerol is separately weighed; 2. Glycerol is heated up to about 66 C (150 F); 3.
DTDMAMS is dissolved in Glycerol to form a melted solution at 66 C (150 F); 4.Shear stress is applied to form a homogeneous mixture of DTDMAMS in Glycerol;
5. The dilution water is heated up to about 66 C (150 F); 6. The melted mixture is diluted to a 1% solution; and 7. Shear stress is applied to form an aqueous solution containing a vesicle dispersion or suspension of DTDMAMS/Glycerol mixture. 8. The particle size of the DTDMAMS/Glycerol vesicle dispersion is determined using an optical microscopic technique. The particle size range is from about 0.1 to 1.0 micron.
Figùre 5 illustrates a cryo-transmission micro-photograph taken at X
66,000 of a vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium methyl sulfate and Glycerol systam. From figure 5, it indicates that particles having membranes one or two bilayers thick, whose geometry ranges from closed vesicles, to disc-like structures.

The purpose of this example is to illustrate a method that can be used to make-up a chemical softener composition comprising a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Chloride (DTDMAC) and Polyethylene glycol 400 (PE(i-400).

WO 94/10381 21 4 4 ~ 7 2 PCI /US93/09452 A 1% solution of the chemical softener is prepared according to the following procedure: 1. An equivalent weight of DTDMAC and PEG-400 is separately weighed; 2. PEG is heated up to about 60 C (140 F); 3. DTDMAC
is dissolved in PEG to form a melted solution at 60 C (140 F); 4. Shear stress5 is applied to form a homogeneous mixture of DTDMAC in PEG; 5. The dilution water is heated up to about 60 C (140 F); 6. The melted mixture is diluted to a 1% solution; and 7. Shear stress is applied to form an aqueous solution containing a vesicle dispersion or suspension of DTDMAC/PEG mixture; 8. The particle size of the DTDMAC/PEG vesicle dispersion is determined using an 10 optical microscopic technique. The particle size range is from about 0.5 to 1.0 micron.
Figure 6 illustrates a cryo-transmission micro-photograph taken at X 66,000 of a vesicle dispersion of a 1: 1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium chloride and PEG-400 system. From figure 6, it indicates that 15 particles having membranes one or two bilayers thick, whose geometry ranges from closed vesicles, to disc-like structures.

The purpose of this example is to illustrate a method that can be used to make-up a chemical softener composition comprising a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Chloride (DTDMAC) and glycerol.
A 1% solution of the chemical softener is prepared according to the following procedure: 1. An equivalent weight of DTDMAC and glycerol is separately weighed; 2. Glycerol is h~ated up to about 60 C (140 F); 3.
DTDMAC is dissolved in glycerol to form a melted solution at 60 C (140 F); 4.
Shear stress is applied to form a homogeneous mixture of DTDMAC in glycerol;
5. The dilution water is heated up to about 60 C~ (140 F); 6. The melted mixture is dilute~ to a 1% solution; and 7. Shear stress is applied to form an aqueous solution containing a vesicle dispersion or suspension of DTDMAClglycerol mixture; 8. The particle size of the DTDMAC/glycerol vesicle dispersion is determined using an optical microscopic technique. The particle size range is from about 0.5 to 1.0 micron.
Figure 7 illustrates a cryo-transmission micro-photograph taken at X 66,000 of a vesicle dispersion of a 1:1 by weight ratio of a di(hydrogenated) tallow dimethyl ammonium chloride and glycerol system. From figure 7, it indicates that W O 94/10381 2~1~4~ 0.7~ PC~r/US93/09452 particles having mcmbranes one or two bilayers thick, whose geometry ranges from closed vesicles, to disc-like structures.

The purpose of this example is to illustrate a method using a blow through drying papermaking technique to make soft and absorbent paper towel sheets treated with a chemical softener composition comprising a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Chloride (DTDMAC), a 10 Polyethylene glycol 400 (PEG-400), and a permanent wet strength resin .
A pilot scale Fourdrinier papermaking machine is used in the practice of the present invention. First, a 1% solution of the chemical softener is prepared according to the procedure in Example 3. Second, a 3% by weight aqueous slurry of NSK is made up in a conventional re-pulper. The NSK slurry is refined gently 15 and a 2% solution of a permanent wet strength resin (i.e. Kymene 557H marketed by Hercules incorporated of Wilmington, DE) 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 20 enhance the dry strength of the fibrous substratc. The adsorption of CMC to NSK
can be enhanced by an in-line mixer. Then, a 1% solution of the chemical softener mixture (DTDMAMS / PEG) is added to the NSK slurry at a rate of 0.1%
by weight of the dry fibers. The adsorption of the chemical softener mixture to NSK can also enhanced via an in-line mixer. The NSK slurry is diluted to 0.2% by25 the fan pump. Third, a 3% by weight aqueous slurry of CTMP is made up in a conventional re-pulpcr. A non-ionic surfactant (Pegosperse) is added to the re-pulper at a rate of 0.2% by weight of dry fibers. A 1% solution of the chemical softener mixture is added to the CTMP stock pipe before the stock pump at a rateof 0.1% by weight of the dry fibers. The adsorption of th~ chemical softener 30 mixture to CTMP can be enhanced by an in-line mixer. 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 fonn an embryonic web.
Dewatering occurs through the Foudrinier wirs and is assisted by a deflector andvacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave configuration 35 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-.

26consistency of about 22% at the point of transfer, to a photo-polymer fabric having 240 Linear Idaho cells per square inch, 34 percent knuckle areas and 14 mils of photo-polymer depth. Further de-wataring is accomplished by vacuum assisted drainage until the web has a fiber consistency of about 28%. The patterned web is 5 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 10 is positioned with respect to the Yankee dryer to provide an impact angle of about 81 degrees; the Yankee dryer is operated at abou~ 800 fpm (feet per minute) (about 244 meters per minute). The dry web is formed into roll at a speed of 700fpm ( 214 meters per minutes).
Two plies of the web are ~ormed into paper towel products by embossing 15 and laminating them together using PVA adhesive. The paper to-~rel has about 26 #/3M Sq Ft basis weight, contents about 0.2% of the chemical softener mixture and about 1.0% of the permanent wet strength resin. The resulting paper towel issoft, absorbent, and very strong when wetted.
Table 1 below summarizes the retention levels and the average particle size 20 of the DTDMAC/PEG-400 vesicle dispersion compared to adding PEG-400 only to the furnish slurry.

Tabl~
DTDMAC/PEG
PEG to sluny Vesicle ~
Rctcntion level of PEG 5 9O
in product (%) Retention Icvcl of DTDMAC
in product (%) NA \ 98 Averagc particle size (microns) NA 0.6 2~

The purpose of this example is to illustrate a method using a blow through 30 drying and layered papermaking techniques to make soft and absorbent toilet WO 94/10381 . ~. ~ . PCr/US93/094~2 Di(hydrogenated) Tallow Dimethyl Ammonium M6thyl Sulfate (DTDMAMS) and a Polyethylen~ glycol 400 (PEG-400) and a temporary w~t strength resin.
A pilot scale Fourdrinier papermaking machine is used in the practice of the present invention. First, a 1% solution of the chsmical softener is prepared 5 according to the procedure in Example 1. Second, 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 the temporary wet strength resin (i.e. National starch 78-0080 marketed by National Starch and Chemical corporation of New-York, NY) is added to the NSK stock pipe at a rate of 0.75% by weight of the dry fibers. The 10 adsorption of the temporary wet strength resin onto NSK fibers is enhanced by an in-line mixer. The NSK slurry is diluted to about 0.2% consistency at the fan pump. Third, a 3% by weight aqueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 1% solution of the chemical softener mixture is added to the Eucalyptus stock pipe before the stock pump at a rate of 0.2% by weight of 15 the dry fibers. The adsorption of the chemical softener mixture to Eucalyptusfibers can be enhanced by an in-line mixer. The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
The treated furnish mixture (30% of NSK 170% of Eucalyptus) is blended in the head box and deposited onto a Foudrinier wirs to form an embryonic web.
20 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 confi~uration having 84 machine-direction and 76 cross-machine-direction monofilaments per inch, respectively. The embryonic wet web is transferred from the photo-polymer wire, at a fiber consistency of about 15% at the point of transfer, to a photo-25 polymer fabric having 562 Linear Idaho cells per square inch, 40 percent knucklearea and 9 mils of photo-polymer depth. Further de-wataring is accompOshed byvacuum 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 30 sprayed creping adhssive 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 blad~ has a bevel angle of about25 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 35 (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).

W O 94/10381 2i 4 4 ~ 7 Z PC~r/US93/09452 The web is converted into a one ply tissue paper product. The tissue paper has about 18 #/3M Sq Ft basis weight, contents about 0.1% of the chemical soflener mixture and about 0.2% of the temporary wet strength resin. Importantly, the resulting tissue paper is soft, absorbent and is suitable for use as facial and/or 5 toilet tissues.
Table 2 below summarizes the retention levels and the average particle size of the DTDMAMS/PEG vesicle dispersion compared to adding PEG-400 only to the furnish slurry.

Table2:
DTDMAMS/P~G
PEG to sluny Veslcle dlsperslon Retention level of PEG
in product (%) 85 Reten~ion levcl of DTDMAMS NA 95 in product (%) Average par~icle size (Inir~nc) NA 0.8 The purpose of this example is to illustrate a method using a blow through drying papermaking technique to make soft and absorbent toilet tissue paper treated with a chemical softener composition comprising a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Methyl Sulfate (DTDMAMS), a Polyethylene glycol 400 (PEG-400) and a dry strength additive resin.
A pilot scale Fourdrinier papermaking machin~ is used in the practice of th~
present invention. First, a 1% solution of the chemical softener is prepared according to the procedure in Example 1. Second, 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 the dry strength resin (i~e. Acco 614, Acco 711 marketed byAmerican Cyanamid company of Fairfield, OH) is added to the NSK stock pipe at a WO 94/10381 ~ 1 4 ~ O ~ 2 PCI /US93/09452 rate of 0.2% by weight of the dry fibsrs. The adsorption of the dry strength resin onto NSK fibers is enhanced by an in-line mixer. The NSK slurry is diluted to about 0.2% consistency at the fan pump. Third, a 3% by weight aqueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 1% solution of the 5 chemical softener mixture is added to the Eucalyptus stock pipe before the stock pump at a rate of 0.2% by weight of the dry fibers. The adsorption of the chemical softener mixture to Eucalyptus fibers can be enhanced by an in-line mixer. The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
The treated furnish mixture (30% of NSK / 70% of Eucalyptus) is blended in 10 the head box and deposited onto a Foudrinier wire to form an embryonic web.
Dewatering occurs through the Foudrinier wire and is assisted by a deflector andvacuum 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 photo-polymer 15 wire, at a fiber consistency of about 15% at the point of transfer, to a photo-polymer fabric having 562 Linear Idaho cells per square inch, 40 percent knucklearea and 9 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 20 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 we~ with a doctor blade. The doctor blade has a bevel angle of about25 degrees and is positioned with respect to the Yankee dryer to provide an 25 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).
Two plies of the web are formed into tissue paper products and laminating them together using ply bonded technique. The tissue paper has about 23 #t3M
30 Sq Ft basis weight, contents about 0.1% of the chemical softener mixture and about 0.1% of the dry strength resin. Importantly, the resulting tissue paper issoft, absorbent and is suitable for US9 as facial and/or toilet tissues.
Table 3 below summarizes the retention levels and the average particle size of the DTDMAMS/PEG-400 vesicle dispersion compared to adding PEG-400 only 35 to the furnish slurry.

WO94/10381 I ~ L` ~ i .. PCl`/US93/09~52 2 ~ 2 Table 3:
DTDMAMS/PEG
PEG to slu~y Vcsicle dispersion ~çt~ntion level of PEG 5 70 in product (%) R~.t~nli~n level of DTDMAMS NA 80 in product (%) Average panicle size (microns) NA 0.8 The purpose of this exampls is to illustrate a method using a conventional drying papermaking technique to make soft and absorbent toilet tissue paper treated with a chemical softener composition comprising a mixture of Di(hydrogenated) Tallow Dimethyl Ammonium Methyl Sulfate (DTDMAMS), a Polyethylene glycol 400 (PEG-400) and a dry strength additive resin .
A pilot scale Fourdrinier papermaking machine is used in the practice of the present invention. First, a 1% solution of the chemical softener is prepared according to the procedure in example 1. Second, 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 the dry strength resin (i.e. Acco 514, Acco 711 marketed byAmerican Cyanamid company of Fairfield, OH) is added to the NSK stock pipQ at a rate of 0.2% by weight of the dry fibers. The adsorption of the dry strength resin onto NSK fibers is enhanced by an in-line mixer. The NSK slurry is diluted ~o about 0.2% consistency at the fan pump. Third, a 3% by weight aqueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 1% solu~ion of the chemical softener mixture is added to the Eucalyptus stock pipe before the stockpump at a rate of 0.2% by weight of tha dry fibers. The adsorption of the chemical softener mixture to Eucalyptus fibers can be enhanced by an in-line mixer. The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
The treated furnish mixture (30% of NSK / 70% of Eucalyptus) is blended in the head box and deposited onto a Foudrinier wire to form an embryonic web.
Dewatering occurs through the Foudrinier wire and is assisted by a deflector andvacuum boxes. The Foudrinier 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 tha Foudrinier wire, WO 94~10381 ;~ ~4 ~ ~`7 ~ PCI/US93/09452 at a fiber consistency of about 15% at the point of transfer, to a conventional felt.
Fur~her de-watering is accomplished by vacuum assisted drainage until ths web has a fiber consistency of about 35%. The web is then adhered to the surface of a Yankee dryer. The fiber consistency is increased to an estimated 96% before 5 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).
Two plies of the web are formed into tissue paper products and laminating them together using ply bonded technique. The tissue paper has about 23 #/3M
Sq Ft basis wei~ht, contents about 0.1% of the chemical softener mixture and about 0.1% of the dry strength resin. Importantly, the resulting tissue paper issoft, absorbent and is suitable for use as a facial and/or toilet tissues.
Table 4 below summarizes the retention levels and the average particle size of the DTDMAMS/PEG-400 vesicle dispersion compared to adding PEG-400 only to the furnish slurry.

Table 4:
PEO to sluny DTDMAMS/PEG
Vesiclc ~ n Rct~ntion level of PEG 5 70 ~ p~duct (%) Retention levcl of DTDMAMS
~n product (%) NA 75 Average pa~iclc sizc (microns) NA 0.8

Claims (12)

What is claimed is:

1. A paper product characterized in that it comprises a sheet of cellulose material and from 0.005% to 5.0% by weight of said fibrous cellulose material of a chemical softening composition comprising a mixture of:
(a) a quaternary ammonium compound having the formula X-wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group or mixture thereof, preferably C1 - C3 alkyl, most preferably methyl;
each R1 substituent is a C14 - C22 hydrocarbyl group, or mixture thereof, preferably C16 - C18 alkyl; and X- is a compatible anion, preferably chloride or methyl sulfate, and (b) a polyhydroxy compound selected from the group consisting of glycerol, and polyethylene glycols and polypropylene glycols having a weight average molecular weight from 200 to 4000, preferably from 200 to 1000, most preferably from 200 to 600, wherein the weight ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from 1:0.1 to 0.1:1 preferably from 1:0.3 to 3:1, most preferably from 1:0.7 to 0.7:1, wherein said polyhydroxy compound is mixed with said quaternary ammonium compound at an elevated temperature wherein said quaternary ammonium compound and said polyhydroxy compound are miscible.

2. The paper product of Claim 1 wherein the quaternary ammonium compound is di(hydrogenated) tallow dimethyl ammonium chloride or di(hydrogenated) tallow dimethyl ammonium methyl sulfate.

3. The paper product of Claim 1 or 2 wherein the polyhydroxy compound is miscible with the quaternary ammonium compound in the liquid-crystal phase or in the liquid phase.

4. The paper product of any of Claims 1 - 3 wherein at least 20%, and preferably from 50% to 90%, of the polyhydroxy compound added to the fibrous cellulose is retained.

5. The paper product of any of Claims 1 - 4 wherein the quaternary ammonium compound is mixed with the polyhydroxy compound at an elevated temperature of at least 40°C, preferably from 56°C to 68°C.

6. The paper product of any of Claims 1 - 5 wherein the mixture of the quaternary ammonium and the polyhydroxy compound is diluted with a liquid carrier to a concentration of from 0.01% to 25.0% by weight of the chemical softening composition.

7. The paper product of Claim 6 wherein the mixture of the quaternary ammonium compound and the polyhydroxy compound is present as particles dispersed in the liquid carrier.

8. The paper product of Claim 7 wherein the average particle size of the quaternary ammonium compound and the polyhydroxy compound ranges from 0.01 to 10 microns, preferably from 0.1 to 1.0 micron.

9. The paper product of any of Claims 1 - 8 wherein said paper product is a towel, toilet tissue, or facial tissue.

10. A chemical softening composition characterized in that it comprises a mixture of:
(a) a quaternary ammonium compound having the formula X-wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group or mixture thereof, preferably C1 - C3 alkyl, most preferably methyl; each R1 substituent is a C14 - C22 hydrocarbyl group, or mixture thereof, preferably C16 - C18 alkyl; and X- is a compatible anion, preferably chloride or methyl sulfate, and (b) a polyhydroxy compound selected from the group consisting of glycerol, and polyethylene glycols and polypropylene glycols having a weight average molecular weight from 200 to 4000, preferably from 200 to 1000, most preferably from 200 to 600, wherein the weight ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from 1:0.1 to 0.1:1 preferably from 1:0.3 to 3:1, most preferably from 1:0.7 to 0.7:1, wherein said polyhydroxy compound is mixed with said quaternary ammonium compound at an elevated temperature wherein said quaternary ammonium compound and said polyhydroxy compound are miscible.

11. The chemical softening composition of Claim 10 wherein the quaternary ammonium compound is di(hydrogenated) tallow dimethyl ammonium chloride or di(hydrogenated) tallow dimethyl ammonium methyl sulfate.

12. The chemical softening composition of Claim 10 or 11 wherein the mixture of the quaternary ammonium and the polyhydroxy compound is diluted with a liquid carrier to a concentration of from 0.01% to 25.0% by weight of the chemical softening composition, and wherein the mixture of the quaternary ammonium compound and the polyhydroxy coumpound is present as particles dispersed in the liquid carrier, wherein the average particle size ranges from .01 to 10 microns, preferably from 0.1 to 1.0 micron.