CA2165536A1 - Multi-layered tissue paper web comprising biodegradable chemical softening compositions and binder materials and process for making the same - Google Patents

Abstract

Multi-layered tissue paper webs comprising biodegradable chemical softener compositions and binder materials are disclosed. The multi-layered tissue webs are useful in the manufacture of soft, absorbent paper products such as facial tissues and/or toilet tissues. The multi-layered tissue paper products contain a biodegradable chemical softening composition, preferably comprising a mixture of an ester-functional quaternary ammonium compound and a polyhydroxy compound. Preferred ester-functional quaternary ammonium compounds include diester dialkyl dimethyl ammonium salts such as diester di(touch hardened)tallow dimethyl ammonium chloride, diester di(hydrogenated)tallow dimethyl ammonium chloride. Preferred polyhydroxy compounds are selected from the group consisting of glycerol, sorbitols, polyglycerols having a weight average molecular weight of from about 150 to about 800, polyoxyethylene glycols and polyoxypropylene glycols having a weight average molecular weight from about 200 to 4,000. The multi-layered tissue paper webs also contain an effective amount of binder materials to control linting and/or to offset the loss in tensile strength, if any, resulting from the use of the chemical softening compositions. The binder materials are selected from the various wet and dry strength additives, and retention aids used in the paper making art. Preferably, the majority of the biodegradable chemical softening compositions will be disposed on the outer layers of the multi-layered tissue paper products where they are most effective. The binder materials alo typically dispersed throughout the multi-layered product to control linting. In other words, the chemical softening compositions and the binder materials can be selectively distributed within the multi-layered tissue paper web to enhance the softness, absorbency, and/or lint resistance of a particular layer or ply.

Description

~6~536 MULTI-LAYERED TISSUE PAPER WEB COMPRISING
BIODEGRADABLE CHEMICAL SOFTENlN~i COMPOSITIONS AND
BINDER MATERIALS AND PROCESS FOR MAKING THE SAME

FIELD OF THE INVENTION

This invention relates to multi-layered tissue paper web. More particularly, it relates ~o multi-layered tissue paper web comprising bio~e~r~dable chemical sottener cGillpositions and binder materials. The treated tissue webs can be used to make sott, absorbent and lint res;slance paper products such as tacial tissue, and toilet tissue products.

~ACKGROUND OF THE INVENTION

Paper webs or sheets, sG"-eti--,es called tissue or paper tissue webs or sheets, find extensive use in modern society. Such items as facial and toilet tissues are staple items o1 commerce. It has long been reco~nized that 10ur important physical anributes ot these products are their ~lren~,tl" their sollness, their absGn,ency, particularly their absGrl,ency tor a~ eous systems; and their lint resistance, particularly their lint resisl&nce when wet. Research and develo,G",ent eftorts have been directed to the improvement of each ol these attributes without seriously af1ecting the others as well as to the i""crov6."ent ot two or three attnbutes simultaneously.
Strength is the ability of the product, and its constituent webs, to main~ain physical integrity and to resist tearing, bursting, and shredding under use conditions, particularly when wet.
Softness is the tactile sensalion perceived by the consumer as he/she holds a particular product, rubs it across his/her skin, or crumples it within his/her hand.
This tactile sensa~ion is provided by a combination o~ several physical properties.
One of the most important physical properties related to softness is generally ~1~5~6 considered by those skilled in the art to be the stitfness of the paper web fromwhich the product is made. Sti~n~ss, in turn, is usually considered to be directly dependent on the dry tensile strength of the web and the stif~ness of the fiberswhich make up the web.
Absorbency is the measure of the ability of a product, and its constituent webs, to absorb quantities ot liquid, particularly aqueous solutions or d;spersions.
Overall absorbency as perceived by the consumer is generally considered to be a combination of the total quantity of liquid a given mass ot multi-layered tissuepaper will absorb at saturation as well as the rate at which the mass abso~s theliquid.
Lint res;slance is the ability ot the fibrous product, and its constituent webs,to bind together under use conditions, particularly when wet. In other words, the higher the lint res;slance is, the bwer the propensity of the web to lint will be.
The use of wet slrer~tl- resins to enhance th~ slrer,ytil of a paper web is widely known. For example, Westfeit describ~d a number ot such ,-atenals and discussed their che.llistry in Cellulose Che~ lry 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 debGnJ;ng agents interfer~ with the natural fiber-to-fiber bonding that occurs dunng sheet fG~ ti~n in paper making processes This red~tiQn in bonding leads to a softer, or bss harsh, sheet ! paper. Freimark et al. 9O on to teach the use ot wet ~l~r~lh resins in conjunction with the use of debonding agents to off-set the undasirdble effects of the debonding agents. These debonding agents do reduce both dry tensib strength and wet tensi~e ~tr~th.
Shaw, in U.S. Pat. No. 3,821,068, issued June 28,1974, also teaches that chemical debonders can be used to reduce the slillness, and thus enhance the so~lness, of a tissue paper web.
Chemical debondin9 agents have been disclQsed in vanous references such as U.S. Pat. No. 3,554,862, issued to Hervey et al. on January 12, t971.
These materials include quaternary ammonium salts such as cocotrimethylammonium chloride, oleyltrimethylammonium chloride, di(hydro~enated)tallow dimethyl ammonium chlorid~ and stearyltrimethyl a"").on um 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 surfaclants such as ethylene oxide and propylene oxide adducts ot fatty alcohols.
Armak Company. of Chicago, Illinois, in their bulletin 76-17 (1977) disclose the use of dimethyl di(hydrogenated)tallow ammonium chloride in coi"binalion with tatty acid esters of polyoxyethylene glycols to impart both softness and absorbency to tissue paper webs.
One exemplary result ot research directed toward improved paper webs is described in U.S. Pat. No. 3,301,746, issued lo Sanford and Sisson on January 31, 1967. Despite the high quality of paper webs made by the prv~ss des~ib~l in this patent, and despite the cG"-",erc;al success of products formed from these webs, research efforts directed to findin~ 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 conlend will form a strong, soft, fibnDus sheet. More sps~ r~cAlly, they teach that the slrengtll of a tissue paper web (which may have been soflened by the addition of chemical debondin9 a~ents) can be enhancad by adhering, dunng proc~ssing, 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 bondin~ material) which has been adhered to one surface of the web and to the creping surface in the fine patterned anangement, and creping the web from the creping surface to forrn a sheet i"atenal.
Conventional quaternary a"""on-um compounds such as the well known dialkyl dimethyl ammonium salts (e.9. ditallow dimethyl ammonium chloride, dit~l'Du- dimethyl ammonium methyl sulfate, di(hydro~enated)tallow dimethyl ammonium chloride etc ...) are effective chemical debonding agents. However, these quaternary ammonium compounds are hydrophobic and not biode~rd~ble, and can adversely affect the absorbency of the treated paper webs.. Applicants have discovered that mixing the biod~,adable quaternary a"""on Lm compound with a polyhdroxy compound (e.g., glycerol, sorbitols, polyglycerols or polyoxyethylene ~Iycols) will enhance both soflness and absorbency rate of fibrous cellulose ",a~erials.
Unfortunately the use of biodegradable chemical softenin~ CG"~pOSilions c~",prising a biodegradable quaternary ammonium compound and a polyhydroxy compound can decrease the lint r~s;stance ot the treated paper webs. Applicants have discovered that the lint resistance can be improved through the use of suitable binder materials such as wet and dry strength resins and retention aid resins known in the paper making art.

21~SS3~

The present invention is applicable to tissue paper in general, but particularily applicable to muni-layered tissue tissue paper products such as those described in U.S. Patent 3,994,771, issued to Morgan Jr. et al. on November 30, 1976, and incorporated herein by reference.
It is an object o~ this invention to provide soft, absorbent and lint resistanc~multi-layered tissue paper products.
It is also a further object of this invention to provide a process for makin~
soft, absorbent, lint .t,s;slance multi-layQred tissue paper products.
These and other objects are obtained usin~ the presen~ invention, as wTII
become readily appar~rlt from a reading of the fo"~ n~ d~ e.

SUMMARY OF THE INVENTION

The present invention provides soft, absorbent, lint resistant multi-layered tissue paper products comprisin~ paper makin~ fibers, biod~radable chemical softening c;".posi~ions and binder ..~t~fials. Briefly, the bio~,~Jable chemicalsoftenin~ co",position o~".pris~s a mixture of:

(a) trom about 0.01% to about 3.0% of a biodegradable q~at~.-,e.ry ammonium compound. preferabiy havin~ the formuh R2 (CH2)n Y- R3 \/

N' X

R~ (CH2)n- Y R3 or R2 (CH2)n- Y - R3 \/
N~ X
/\

216~536 Or R3 - Y - CH2 \

CH - CH2 - N~ - (R2)3 X-R3 ~ y wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group, benzyl group or mixtures ll,ereo~, each R~ subst;tuent is a C12 - C22 hJJ~oc~b~l ~roup, or svbstituted hydrocarbyl group or mixtures thereof; each R3 substituent is a C11 - C21 hyJ~ocarl,yl group, or substitutQd hyJ~oca,l~l or mixtures thereof; Y is - O - C ~O) - or - C (O) - O - or - NH - C (O) - or - C
(O) - NH -, and mixtures ll~reof, n is 1 to 4 and X is a surtable anion, tor example, chloride, bromide"..atl,ylsulfate, ethyl sulfate, nitrate and the like; and (b) from about 0.01% to about 3.0% of a polyhJ~dloxy compound; pref~ra~selected trom the group con~sling o~ glyo~rol, sorbitols, polygly~rols having a weight avera~e .,.ole~r,Jla weight of from about 150 to about 800 and polyoxyetl,ylGne glycols and polyof~propJlene glycols having a weight average ",Q'ec.ul- ~ weight from about 200 to 4000.

F~e~erably the weight ratio of the biodegradable qu~ter--ary ammonium compound to the polyhydroxy compound ranges 1rom about 1.0: 0.1 to 0.1: 1Ø
It has been discovered that the b odeg..~dable chemical softening cG",position is more eftective when the polyhydroxy compound is mixed with said biodegradable quaternary ammonium compound at a temperature wherein said biodeg,adabl~
qua~ernary ammonium compound and said polyhydroxy compound are miscible.
Examples o~ preferred ester-fufi~,tional quaternary ammonium compounds suitable for use in the pres6nt invention include compounds having the formulas:

(CH3)2 - N+ - ((CH2)2 - O - C - R3k Cl-W O 95/01479 PCTrUS94/06916 and (CH3)2 - N+ - (CH2 )2- 0 C - R3 Cl and (CH3) (HO-(CH2)2) - N~ - ((CH2)2- 0 - C - R3)2 CH3S04-and R3-~ o-cH2 CH - Ct~2 N+ - (R2)3 C~

O

wherein each R2 substituent is a C1 C6 alkyl or hydroxyalkyl group, benzyl group or mixtures thereof; each R1 su~stituent is a C12 - Cæ hydrecarl,~rl group, or substituted hyJrucarl,~l group or mixtures thereof; each R3 substituent is a C11 -C21 hyd~ JI group, or substnuted hydrocarbyl or mixtures thereo~.
These compounds can be considered to be mono or diester variations of the well-known dialkyWi.netl-yla""non um salts such as diester ditallow dimethyl ammonium chloride, diester distearyl dimethyl ammonium chloride, I"Gnoesler ditallow dimethyl ammonium chloride, diester di(hydrogenated)tallow di.ll~
ammonium methylsulfate, diester di(hydrogenated)tallow dimethyl ammonium chloride, monoester di(hydrogenated)tallow dimethyl ammonium chloride, and mixtures 1hereof, with the diester variations of di(non hydrogenated)tallow dimethyl ammonium chloride, Di(Touch Hydrogenated)Tallow DiMethyl Ammonium Chloride (DEDTHTDMAC) and Di(Hydrogenated)Tallow DiMethyl Ammonium Chloride 5 :3 6 WO 95/0147g PCT/US94/06916 (DEDHTDMAC), and mixtures thereof being preferred. Depending upon the product characteristic requirements the saturation level ot the dit~llow can be tailored from non hydrogenated (soft) to touch partially or completely hydrogenaled (hard).
Without being bound by theory it is believed that the ester moiety(ies) lends biodegradability to these compounds. Importantly the ester-functional quatemary ammonium compounds used herein biodegrade more rapidly than do conventional dialkyl dimethyl a",i"on um chemical softeners.
Examples ot polyhydroxy compounds usetul in the present invention include glycerol, sorbitols, polyglycerols having a weight average I.Oll~Jl'lr weight ot trom about 150 to about 800 and polyoxyethylene glycols having a weight average mo'~ ?~ weight ot from about 200 to about 4000, with polyoxyethylene glycols having a weight average ~IQ'ecu~ weight of from about 200 to about 600 being prefer.~d.
The term binder reters to the various wet and dry slter~th aWiti~s, and retention aids known in the art. These ~,~t2rials illl~ro~G the lint resistance ot the tissue paper webs o~ the presenl in~ont;on as well as cu,nleracting any Je~e~s~
in tensile strength c~used by biodeg~ ~b!~ chemical so~;en;ng c~ posiUons.
Examples ot suitable binder materials include permanent wet sl,en~th resins r~.e.
Kymene ~ 557H marketed by Hercubs Incorporated ot Wilmin~ton, DE), temporary wet st,en~th resins (i.e. ~alional starch 78 0080 marketed by Nd~;onalStarch and Chemical cGi~or~tion ot New-York NY) dry al,ens~th resins (i.e. Acco ~ 514, Acco ~ 711 marketed by American Cyanamid cG~pan~A ot Wayne, New Jersey) and retention aid resins (i.e. Percol ~'175 marketed by Allied Colbids ot Sul~olk, Virginia).
Brieny, the process tor maWng the multi-layered tissue paper webs ot the present invention co,nprises the steps of to~lion of a multi-layered paper making tumish trom the ato-e",ention~ c~",ponerits, depos;tion ot the mulb-byered papermaking tumish onto a toraminous sur~ace such as a Fourdrinier wire, and rtu..oJal ot the water from the deposited tumish.
All percentages. ratios and proportions herein are by weight unless otherwise sp~ ed BRIEFDESCRlPTlON OFTHEDRAWINGS

While the Speciticalion concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the invention is better WO 95/01479 PCT/I)S94/06916 216553~

understood Irom the following description taken in conjunction with the ~ssoci~ted drawings, in which:
Figure 1 is a schematic cross-sectional view ol a three-layered single ply toilet tissue in accordance with the present invention.
Figure 2 is a sche",atic cross-sectional view of a two-layered two-ply facial tissue in accordance with the present invention.
The present invention is described in more detail ~elow.

DETAILED DESCRIPTION OF THE INVENTION

While this specification concludes with claims particularlr poinling ou1 and distinctly claiming the sut~ject maner regardsd as the invention, it is ' Elie~d that the invention can be better understood from a reading ot the fOI~DWjn9 detailed description and of the append6d examples.
As used herein, the term lint ~esislanca' is the ability of the fibrous product, and its constituent webs, to bind to~etl,er under use corJ;t;ons, particulariy when wet. In other words, the higher the rlnt r~s;~tafic~ is, the bwer the p.~pensily of the web to lint will be.
As used herein, the term ~Dinder~ refers to the various wet and dry slier~th resins and retention aid resins known In the paper making art.
As used herein, the term 'water soluble~ refers to matGrials that are solubb in water ~o at least 3% at 25 C.
As used herein, the temms ~tissu~ paper web, paper web, web, paper sheet and paper product- all refer to sheets ol paper made by a pr~ss c4lllpfising thesteps of forming an ~queous papermakin5 turnish, depositin9 this furnish on a foraminous surface, such as a Four~l~ir er wire, and removing the water from thefumish as by gravity or vacuum-ass;sled dl~nage, with or without prassing, and by evaporation.
As used herein, an ~queous paper making furnish' is an e~lueous slurry of paper mah'ng fibers and the chemicals desclibed her~ind~l~r.
As used herein, the term ~multi-layered tissue paper web, multi-layered paper web, muîti-layered web, multi-layered paper sheet and mu!ti-layered paper product~ all refer to sheets o~ paper prepared from two or more layers of ~ueouspaper making fumish which are pref6rably comprised of different fiber types, thefibers typically being relatively long sollv:ood and relatively shorl hardwood fibers as used in tissue paper making. The layers are prelerably formed from the deposition of separate streams of dilute fiber slurries upon one or more endless -wo 95/01479 2 i ~ 5 5 3 ~ PCT/IJS94/06916 loraminous screens. If the indidual layers are initially formed on separate wires, the layers are subsequently combined when wet to form a layered composite web.
The first step in the process of this invention is the forming of an aqueous paper making furnish. The furnish comprises paper making fibers ~hereinafter sometimes referred to as wood pulp), and a mixture of at least one biodegradablequaternary ammonium compound, a polyhydroxy compound and binder materials all of which will be hereinafter described.
It is a,lticipated that wood pulp in all its varieties will normally cc""prise the paper making fibers used in this invention. I lo-- ev~r, other cellulose fibrous pulps, such as cotton liners, b~sse, rayon, etc., can be ùsed and none are disclaimed.
Wood pulps useful here,in include chemical pulps such as Kraft, sulfite and sulfate pulps as well as mechanical pulps including tor example, ground wood, thermomechanical pulps and Chemi-ThermoMechanical Pulp (CTMP). Pulps derived from both deciduous and conileruus trees can be used.
Both hardwood pulps and sottwood pulps as well as blends of the two may be employed. The, terms hardwood pulps as used herein refers to fibrous pulp deriv~d trom the woody slJ~Iance o? deciduous trees ~angiosper",s): wherein soll~vood pulps are fibrous pulps derived trom the woody suL.~lanc~ ot eoniferous trees ~g~",nGsperms). I lar~J pulps such as eucalyptus are particular~ly suitable for the outer layers ot the multi-byered tissue webs des~,il~d hereinafter, whereas northem softwood Kraft pulps are prele.r-ed tor the inner byer(s) or ply(s). Also applicable to the prssent inve,Ytion are fibers derived from recyeled paper, which may contain any or all of the above categones as well as other non-fibrous materials such as fillers and adhesives used to facilitate the onginal paper making.
Biode~radable chemlcal soflener compositions The present in~G.~iOn contains as an essential component a mixture of a biodegri~?~!e quaternary ammonium compound and a polyhydroxy compound.
The ratio of the biodegradable quaternary ammonium compound to the polyhydroxy compound ranges from about 1.0: 0.1 to 0.1: 1.0; preferably, the weight ratio of the biodegradable quaternary ammonium compound to the polyhydroxy compound is about 1.0: 0.3 to 0.3: 1.0; more preferably, the we~i~htratio of the biodegradable quaternary ammonium compound to the polyhydroxy compound is about 1.0: 0.7 to 0.7: 1.0, although this ratio will vary depending upon ~h~ molecular weighl of the particular polyhydroxy compound and/or biodeg,ddable quaternary ammonium compound used.
Each of these types of compounds will be described in detail below.

2165~3~

A. Blodegradable quaternary ammonlum compound The biodegradable chemical so~ening composition contains as an essenlial component trom about 0.01% to about 3.00% by weight, preferably from about 0.01% to about 1.00% by weight ot a biodegradable quaternary ammonium compound, preferably biodegradable quaternary ammonium compounds having the tormula:

R2 /(CH2)n Y- R3 \N~ X~

R~ \(CH2)n - Y R3 or R2 (C~2)n - Y - R3 N~ X
/\

or /CH - CH2 - N+ - ~R2)3 X~

o wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group, benzyl group or mixtures thereof; each R1 substituent is a C12 - Cæ hydrocar~,yl group, or substituted hydrocarbyl group or mixtures thereot; each R3 substituent is a C11 -WO 95/01479 216 ~ 5 3 6 PCT/US94tO6916 C2- hydrocarbyl group, or substituted hydrocarbyl or mixtures lhereot; Y is - O -C(O) or C(O) - O - or - NH - C(O) or - C(O) - NH - or mixtures ~hereot; n is 1 to 4 and X- is a suitable anion, for example, chloride, bromide, methylsul~ate, ethyl sulfate, nitrate and the like.
As discussed in Swern, Ed. in Bailey's Industrial Oil and Fat Products, Third Edition, John Wiley and Sons (New York 1964), tallow is a naturally occurring material having a variable composition. Table 6.13 in the above-identified re~erence edited by Swem indicates that typically 78% or more of the 1atty adds of tallow contain 16 or 18 carbon atoms. Typically, half of the fatty ac~ds present in tallow are unsaturated, pfimarily in the 1crm of oleic add. Sy.~tl.~lic as well as natural ~,allov.s' fall within the scope of the ~resenl invention. It is also known that depenJing upon the product characteristic requirements, the saturation level of the ditallow can be tailored 1rom non hyd~oganated (soft) to touch, partially or completely hyd~.,genaled (hard). All of above~escribed levels of saturations aree)tpressly meant to be included within the scope of the present invention.
It will be underaloGd that substituenls Rl, R2 and R3 may optionally be sub~tituted with various groups such as alkoxyl, hydroxyl, or can be branched, but such ,.,alenals are not ~r~fe. Ied herein. rl Jferabl~, each R1 is C12 - Cls alkyl and /
or alkenyl, most preferably each R1 is straight-chain C16- C1s alkyl and / or alkenyl. ~leferdbly~ each R2 is methyl or hydroxyethyl. rleferabkJ R3 is C13 -C17 alkyl and / or alkenyl. most pr~ferab~y R3 is straight chain C15 - C17 alkyl and / or alkenyl, and X~ is chloride or methyl sulfate. Furthermore the ester-functional quatemary a---",Gn um compounds can optionally contain up to about 10% of the mono(bng chain alkyl) derivatives, e.g., (R2)2 - N+ - ((CH2)20H) ((CH2)20C(O)R3)X as minor ingredients. Thsse minor ingrQdients can act as emulsifiers and are useful in the presenl invention.
Specific examples ol ester-functional quaternary a",-"on um compounds having the stnuctures named above and suitable tor use in the presen~ invQntion include the well-known diester dialkyl dimethyl ai"",on um salts such as diesterditallow dimethyl ammonium chlori-b, monoester dit~l'DW dimethyl ammonium chloride, diester ditallow dimethyl ammonium methyl sulfate, diester di(hydrogenated)tallow dimethyl ammonium methyl sulfate, diester di(hydlogenated)tallow dimethyl a"""Gn!um chloride, and mixtures thereof. Diester ditallow dimethyl ammonium chloride and diester di(hydrogenated)tallow dimethyl ammonium chloride are particularly preferred. These particular materials are available commercially trom Sherex Chemical Company Inc. of Dublin, Ohio undor the tradename ~ADOGEN DDMC ~.

WO 95/01479 PCT/US94tO6916 2165~3~

Di-quat variations ot the ester-tunctional quaternary ammonium compound can also be used, and are meant to tall within the scope of the present invention.
These compounds have the tormula:

O (R2)2 (R2)2 0 R3 - C - O - (CH2)2 - N~ - (CH2)n- N~ - (CH2)2 - O - C - R3 2 X

In the structure named above each R2 is a C1 - C6 alkyl or hyd.~xyalkyl group, R3 is C11-C21 hy~llocsrbyl group, n is 2 to 4 and X is a suitable anion, such as an halide (e.g., chloride or bromide) or methyl sulfate. rldlerably~ each R3 is C13-C17 alkyl and / or alkenyl, most preterably each R3 is straight~hain C1s -C17 alkyl and / or alkenyl, and R2 is a methyl.

B. Polyhydroxy Compound The biodeslddable chemical sottening cGil~positiGn contains as an essential component from about 0.01% to about 3.00% by weight, preterably from about 0.01% to about 1.00% by weight o~ a polyhydroxy compound.
Examples ot polyhyJ~oxy compounds usetul in the present invention includc glycerol, sGrl,itGls, polyglycerols having a weight average molecubr weight ot trom about 150 to about 800 and polyoxyeUIyl~ne glycols and polyoyp~pybne glycols having a weigM average molecular weight ot from about 200 to about 4000, preterab~ trom about 200 10 about 1000, most preter;~bly trom about 200 to about600. Polyoxyethylene glyccls having an weight average mobcular weight ot from about 200 to about 600 are especi~lly prele"ed. Mixtures o~ the above~eso~il~
polyhydroxy compounds may also be used. For example, mixtures of ~Iyc&r~l and polyoxyethylene glycols having a weight average molecular weight trom about 200 to 1000, more preterably trom about 200 to 600 are usetul in the present invention. Preferably, the weight ratio of glycerol to polyoxyethylene glycol ranges trom about 10 :1 to 1:10.
A particularly pre~ened polyhydroxy compound is polyoxyethylene glycol having an weight average l.l~le CL'I^~ weight of about 400. This .~lenal is available commercially trom the Union Carbide Company of Danbury, Conn~ti~n under the tradename ~PEG-400~. -The biodegradable chemical softening composition described above i.e.
mixture of a biodegradable quaternary ammonium compounds and a polyl,~d,oxy compound are preferably diluted to a desired concentration to form a d;spersion of the quat and polyhydroxy compounds before being added to the ~queous slurry of WO 95/01479 ` PCTfUS94/06916 ~65536 paper making fibers, or furnish, in the wet end ot the paper makin~ machine at some suitable point ahead ot the Fourdrinier wire or sheet torming stage.
However, applications ot the above described biodegradable chemical so~ening composition subsequent to tormation ot 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 of the present invention.
It has been discovered that the biodegradable chemical sottenin4 composition is more effective when lhe biodegradable quatemary a",..,Gnlum compound and the polyhydroxy compound are first pre-mixed tog~ther before being added to the papQr making furnish. A preferred ,nethod, as will be descnbe~
in grea~er detail hereinatter in Example 1, consisls of first heating the polyhydroxy compound to a temperature of about 66 C (150 F), and then adding the biodegradable quat~rn&ry a"""Gn Lm compound to the hot polyhydroxy compound to form a ho",ogenous fluid. The weight ratio of the quaternary ammonium compound to the polyhydroxy compound ranges from about 1.0: 0.1 to 0.1: 1.0;
preferably, the weight ratio ot the biodegradable quatQrnary ammonium compound to the poly~,yJ~o~y compound is about 1.0: 0.3 to 0.3: 1.0; more preferably, the weight ratio of thQ biodegradable quaternary ammonium compound to th~ polyhydroxy compound is about 1.0: 0.7 to 0.7: 1.0, although this ratio will vary depending upon the molecular weight of the polyhydroxy compound and/or biod6~.~dable ql,dternary ammonium compound used.
It has unexp6~,led;f been found that the adsorption of the polyhJJ~o~y compound onto paper is significantly enhanced when it is pr~".ix~d with the biodegradable quaternary ~"""Gn-um compound and added to the paper by the above descnbed proc~ss. In fact, at least 20% of the polyhydroxy compound and the biodegradabb quatemary ammonium compound added to the fibrous cellulose are retainQd; preferably, the ret~ntion level o~ biodegradable quaternary ammonium compound and the polyhydroxy compound is from about 50% to about 90% of the add~d levels.
I",pG,lanlly, a-JsG,I~tion occurs at a concent-ation and within a 1ime frame that are pr~ctical for use during paper making. In an effon to better und~rstand the surprisingly high retention rate of polyhydroxy compound onto the papQr~ the physical science of the melted solution and the aqueous dispersion of a DiEster Di(Touch Hardened)Tallow DiMethyl Ammonium Chloride (DEDTHTDMAC), and polyoxyethylene glycol 400 wer~ stu0ed.

216~3g Without wishing to be bound by theory, or to otherwise limit the present invention, the tollowing discussion is ottered ~or explaining how the ester-functional quaternary ammonium compound promotes the adsorption ot the polyhydroxy compound onto paper.
DEDTHTDMAC (DiEster Di(Touch Hardened)Tallow DiMethyl Ammonium Chloride) exist as a mixture of liquid crystalline and crystalline phases, at equilibrium. X-ray data indicate that commercial DEDTHTDMAC is, in fact, a liquid crystalline phase showing no evidence of crystalline states.
Mlxtures of DEDTHTDMAC wlth PEG~W0.
Phase studies of these two materials using the step-wise dilution ..,~tl.~
demonstrate that their physical behavior is similar to that o~ di(h~J~analed)tallow dimethyl a"""on um chloride. These compounds are miscible over a wide range of temperatures (2 50 C), which indicates that dispersions may be prepar~d 1rom these mixtures over a comparable range of temperatures. No upper te",perature limit of miscibility exists. The X-ray data show that a mixture ot crystal and liquid phases do, in fact, exist in DEDTHTDMAC/PEG-400 mixtures.
Mixtures of DEDTHTDMAC with gly~rol.
A 1: 1 weight ratio mixture of DEDTHTDMAC and glycerol appea.a (from direct observation and X-ray data) to be a liQuid phase. While glyo~r~l is capable of forming liquid aystal phases in combination with other surfactants, it app~a.not to do so in this system at this cG",posiUon.
Mlxtures ot DEDi~DMAC wlth PEG~K0.
Phase studies ot these two materials using the step-wise dilution method demonstrate that their physical behavior is similar to that of DEDTHTDMAC.
These compounds are miscible over a wide range of temperatures (~ 67 C), which indicates that dispersions may be prepared from these mixtures over a comparable range of te",pe,d~ures. No upper temperature limit of Illisc~bility exists.
Physlcal state ot mlxtures of quats I ~olyh~droxy compounds I water.
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 theQster-functional quaternary ammonium salt are miscible, with water. Neither DEDTHTDMAC nor DEDHTDMAC are soluble in water, so the dilution of either dry phase with water will precipitate the ester-functional quaternary ammonium compound as small particles. The polyhydroxy compound is soluble with water in all proportions, so it is not prec;pit~ed The addition of mixtures of about equal parts ot DEDTHTDMAC and polyhydroxy compounds (e.g. glycerol, PEG-400 etc....) to water, so as to form a WO 95/01479 ~ 5 ~ Ei PCT/US94106916 mixture containing about 1% of DEDTHTDMAC will precipitate ~he DEDTHTDMAC. Most likely, the DEDTHTDMAC phase near room temperature wili be the lamellar liquid crystal.
Colloldal structure o1 disperslons.
The liquid crystal phase in the diluted mixtures exists as vesicles which, for the most part, are closed and spherical. The for",ation of such dispers;on likely results trom the large os",o~ic pressure gradients that momentarily exist during the process. The origin of these pressure gradients is the spatial gradients in the cGillposition (and thermodynamic activity) of water that are creal~d. Since the liquid phase of D E D TH T D M A C / glycerol mixtures may exist over a wide range of temperature, one may also produce dispersions over a wide ran~e of temperatures.
Cryoelectron mic,oscopy demonstrates that the particles present are about 0.1 to 1.0 micrometers in size, and highly varied in structure. Some are sheets (curved or flat), while others are closed v~s c'es. 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 application of dispersions prepared in this ,--ann~r to paper results in atlac~"-~ent of the ester-functiGnal quaternary ammonium ion tothe paper, strongly promotes the adsG,I~tion of the polyhydroxy compound onto paper, and produces the desired --odificalion of softness and rat~n~;on of wenability.
State of the dlsF~rsi~n~.
When the above described dispe~ions are cooled, the partial crystalrlzation of the ",at~rial within the colloidal particles may occur. I low6vcr, it is likely that the attainment ot 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. Preferabq~ the biodegradable chemical softenin~ co"~posi1ions described herein are used bsfore the equilibrium state has been anained.
It is believed that the vesicles containing biodegradable quats and polyhydroxy compounds (e.g. glycerol, PEG-400 etc....) break apart upon drying of the fibrous cellulosic material. Once the vesicle is broken, the ",ajority of the PEG component may penetrate into the interior of the cellulose fibers where it enhances the fiber flexibility. Importantly, some of the PEG is retained on the surface of the fiber where it acts to snhance the absorbency rate of the cellulose fibers. Due to ionic interaction, the cationic portion of the biodegradable quats WO 95/0147g PCT/US94/06916 ~a53~ 16 component stays on the surlace of the cellulose fiber, where it enhances the surface feel and softness of the paper product.

Binder materials The present invention contains as an essential component from about 0.01%
to about 3.0%, preferably from about 0.01% to about 1% by weight of a binder material selected from the group consisting of permanent wet strength resins, temporary wet strength resins, dry stren~th resins, reten~ion aid rcsins and mixtures Shereof. The binder materials act to control linting and also to offs~t tho loss in tensile slrer,~th, if any, resulting from the biodegradable chemical sc~ten~r compositions.
If permanent wet strength is desired, the binder materials can be chosen from the ~ollowing group ot chemicals: polyamide-epichlorohydrin, polyacrylamides, styrene-butadiene latexes; insolubilized poly~n~l abohol; urea-1Ormaldshyde; poly~lhyl~neimine; chitosan polymers and mixtures thereof.
Polyamide-epichlorohydrin resins are cationic wet strength resins which have been ~ound to be of particular utility. suitablQ types of such resins are des~ri~d in U.S. Patent No. 3,700,623, issued on October 24, 1972, and 3,772,076, issued on Novomber 13, 1973, both issued to Keim and both boing heroby inctl.~Grd~d by reterence. One commorcial source of a usetul polyamide-epichlorohJJnn resins is Hercules, Inc. ot Will"inyton, Delaware, which markets such resin under the markKymeme 0 557ff.
Polyacrylamide resins have also been tound to be of utility as wet sS,~nJth resins or re~ention aids. These resins are described in U.S. Patent No. 3,~556,93~
issued on January 19, 1971, to Coscia, et al. and 3,556,933, issued on January 19, 1971, to Williams et al., both paten~s being incor~orated herein by refer~noe.
One commerdal source of polyacrylamide resins is American Cyanamid Co. o1 Stantord, Connecticut, which markets one such resin under the mark Pare~ ~ 631 NC. Other commercial sources of calionic polyacrylamide resins aro Allied Colloids of Sulfolk, Virginia, and Hercules, Inc. of Wilmington, Delav ar~, which markets such resins under the marks Percol ~9 175 and Reten ~D 1232.
Still other water-soluble cation ~ resins finding utility in this in~ention are urea formaldehyde and melamine formaldehyde resins. The more cG"""on functional groups of these polyfunctional resins are nitrogen containing groups such as amino groups and methylol groups attached to nitrogen. Polyethylenimine type resins may also find utility in the present invention.

WO 95tO1479 216 ~ 5 3 ~ PCT/US94/06916 If temporary wet strength is desired, the binder materials can be chosen from the following group of starch-based temporary wet strength resins: cationicdialdehyde starch-based resin (such as Caldas produced by Japan Carlet or Cobond 1000 produced by National Starch); dialdehyde starch; and/or the resin described in U.S. Patent No. 4,981,557 issued on January 1, 1991, to Bjorkquist and incorporated herein by reference.
11 dry strength is desired, the binder materials can be chosen from the following group of materials: polyacrylamide (such as combinations of Cypro 514 and Accostrength 711 produced by American cyanamid of Wayne, N.J.); starch (such as corn starch or potato starch); polyvinyl alcohol (such as Airvol 540 produced by Air Products Inc of All~ntown, PA); guar or locust bean gums;
polyacrylate latexes; and/or carboxymethyl cellu'2se (such as Aqualon CMC-T
from Aqualon Co., Wilmington, DE). In general, suitable starch for pra~ the present Invention is characterized by water solubility, and hydrophilicity.
Exemplary starch ,-atenals include corn starch and potato starch, albeit it is not intended to thereby limit the scope of suitable starch -,alerials; and waxy comstarch that is known industrially as amioca starch is particularly pr~fer.~J. Amioca starch differs from co,-""on corn starch in that it is entirely a-"ylope~tin, whereas common corn starch contains both amplcpectin and amylose. Various unique characteristics of amioca starch are further described in ~Amioca - The Starch from Waxy Corn~, H. H. Schop",eyer, food Industries, December 1945, pp. 106-108 (Vol. pp. 1476-1478). The starch can be in granular or dispersed fom albeit granular form is pr~fer.~d. The starch is preferably sufficiently cooked to induce swelling of the granules. More prefera~ly, the starch granules are sw~l'en, as by cooking, to a point just prior to d;spersion of the starch granule. Such highly s~ n starch granules shall be r~fer-ed to as being ~fully cooked~. The con~l~onsfor disper~;on in general can vary depending upon the size of the starch granules, the degree of crystallinity of the granules, and the amount of amylose pre-~ent.Fully cooked amioca starch, for example, can be prepared by heating an A~ueous slurry of about 4X consister~ of starch granules at about 190 F (about 88 C) for between about 30 and about 40 minutes. Other exemplary starch materials which may be used include ",odified calion ~ starches such as those modified to have nitrogen containing groups such as amino groups and methylol groups allached to nitrogen, available from National Starch and Chemical Company, ~Bridgewater, New Jersey). Such modified starch materials are used primarily as a pulp furnishadditive to increase wet and/or dry strength. Considering that such modified starch ~16sS~36 materials are more expensive than unmodlfied starches, the latter have generallybeen preferred.
Methods of application include, the same previously described with reference to app"c~ion of other chemical additives preferably by wet end addition, spraying; and, less preferably, by printing. The binder may be applied to the tissue paper web alone, simultaneously with, prior to, or subsequent to the addition ofsoftener, absorbency, and/or aesthetic additives. At least an effective amount of a binder, preferably starch, to provide lint control and conc~",itant st~en~th incr~ase upon drying relative to a non-binder treated but otherv~ise identical sheet is preferably applied to the sheet. Preferably, bet~een about 0.01% and about 3.0YOof a binder is retained in the dried sheet, calculated on a dry fiber weight basis;
and, more preferably, between about 0.1% and about 1.0% of a binder ".d1~rial, preferably starch-based, is retained.

The second step in the process of this invention is the depositing o~ the multi-layered paper making furnish using the above described chemical softener composition and binder materials as additives on a foraminous surface and the third step is the re~moving ot the water from the fumish so deposited Techniquesand equipment which can be used to accomplish these two pr.~c~ssing steps will be readily apparent to those skilled in the paper making an. Preferred multi-layered tissue paper embodiments of the present invention contain from about 0.01% to about 3.0%, more preferably from about 0.1% to 1.0% by weight, on a dry fiber basis of the biodegradable chemical softening composition and binder materials described herein.
The present invention is applicable to multi-layered tissue paper in general, including but not limited to conventionally felt-pressed multi-layered tissue paper;
high bulk pattern densified mult lay¢red tissue paper; and high bulk, unco",pa,led multi-layered tissue paper. The multi-layered 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. Patent 3,994,771, Morgan, Jr. et al. issued November 30, 1976, and incorporated herein by refe~rence. 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 multi-layered tissue paper making, upon one or more endless foraminous screens. If the individual layers are 21~36 initially formed on separate wires, the layers are subsequently combined when wet to form a layered composite web. The layered web is subsequently caused to conform to the surface of an open mesh dryin9rlmprintin9 fabric by the app'ication of a fluid force to the web and thereafter thermally predried on said fabric as pan ot a low density paper making process. The layered web may be stratified with respect to fiber type or the fiber content of the respective layers may be essen~ially the same. The multi-layered tissue paper preferably has a basis weight of between 10 9lm2 and about 65 g/m2, and density of about 0.60 g/cm3 or bss. Preter~bty, basis weight will be below about 35 g/m2 or less; and density will be about 0.30 9/
cm3 or less. Most preferabl~, density will be betw~Gn 0.04 g/cm3 and 0.20 g/cm3.The multi-layered tissue paper webs of the present invention compnse at least two superposed layers, a first layer and at least one second layer contiguous with the first layer. Preferably, the multi-layered tissue papers CG,-,prise three superposed layers, an inner or center layer, and two outer layers, with the inner layer located bet~sn the two outer layers. The two outer layers pralerdbl~
comprise a primary filamentary constituent of about 60% or more by weight of relatively short paper making fibers having an avera~e fiber between about 0.2 and about 1.5 mm. These short paper makin~ fibers are typically hardwood fibers,pref~rably, eucalyptus fibers. Attematively, low cost sources of short fibers such as sulfite fibers, ther~-.G",echan r' pulp fibers, chemi-ll,er",G",echanical pulp fibers, recycled fibers including fibers fla~vtiGnated from recycled fibers, and mixtures thereof can be used in one or both of the outer layers or ~lended in the inner byer, if desired. The inner byer prelerably comprises a primary fila~enlary constituent of about 60% or more by weight ot relatively long paper making fibers having an average fiber length of least about 2.0 mm. These bng paper making fibers are typically softv~ood fibers, preferabty, northern sofl~ood Kraft fibers. Figure 1 is a schematic cross-sectional view of a three-layered single ply toilet tissue in accordance with the present invention. Refe~-ing to figure 1, the three layered single ply web 10, comprises three superposed layers, inner layer 12, and two outer layers 11. Outer layers 11 are co~ ,ised primarily of short paper making fibers 16; whereas inner layer 12 is cG."plised primarily of long paper making fibers 17.
In an alternate preferred embodiment of the present invention, multi-ply tissue paper products are formed by placing at least two mutti-layered tissue paper webs in juxtaposed relation. For example, a two-ply tissue paper product can be made co"~prising a first two-layered tissue paper web and a second two-layered tissue paper web in juxtaposed relation. In this example, each pty is a ~16553~

two-layer tissue sheet co"~prising a first layer and a second layer. The first layer preferably comprises the shon hardwood fibers and the second layer preferably comprises the long so~twood fibers. The two plys are combined in a manner such that the short hardwood fibers of each ply face outwardly and the layers containing the long sofl~vood fibers tace inwardly. Figure 2 is a sche"-alic cross-sectional view of a two-layered two-ply tacial tissue in accordance with the present invention. Referring to figure 2 the two-layered two- ply web 20, is comprised ot two plies 15 in juYt~posed relation. Each ply 15 is cGi"prised of inner byer 19,and outer layer 18. Outer layers 18 are comprised pri",anly of short paper making fibers 16; whereas inner byers 19 are cG",pnsed p,i".arily of bng paper making fibers 17. Similarly three-ply tissue paper products can be made by pladn~
three multi-layered tissue paper webs in plYt~osed relation.
It should not be inferred from the above discussiQn that the present invention is limited to tissue paper products col"prising threo layers -- single ply or two-plys -- two layers, etc. Tissue paper products cons,sting of three or more plys in combination with each ply consisling of one or more layers are also e~,r~ssly meant to be included within the scope of the p~ nt inJontion.
Preferably, the majority of thc biodegradable quatsrnary ammonium compound and the polyhydroxy compound is contained in at least one of the outer layers of the multi layGred tissue paper web of the present invention. More pre~erably, the majority of the biodegradable quaternary a.,-",onj~m compound and the polyhydroxy compound is contained in both of the outer layers. It has been discovered that the biodeg,adable chemical sonening coi,.~ositicn is most effective when added to the outer layers or plies of the tissue paper products.
There, the mixture of the biodegradable quaternary compound and potyhdroxy compound act to enhance both the softness and the absorbency of the multi-layered tissue products of the present invention. nefer-ing to figures 1 and 2, the biodegradable chemical softening composition comprising a mixture ot the biodegradable quaternary a,n",on Lm compound and the pclyhd~uxy compound is schematically represented by dark circles 14. It can be seen in figures 1 and 2 that the majority of the biodegradable chemical softening coi"position 14 is contained in outer layers 11 and 18, respe~ti~ely.
However, it has also been discovered that the lint resistance of the multilayered tissue paper products decreases with the inclusion of the biodegradable quaternary ammonium compound and the polyhdroxy compound.
Therefore binder materials are used for linting control and to increase the tensile slrenyth. Preferably the binder is contained in the inner layer and at least one ol Wo 95/01479 2 16 5 5 3 6 PCT/US94/06916 the outer layers of the multi-layered tissue paper webs ot the present invention.
More preferably the binder is contained throughout the multi-layered product i.e.
in the inner and outer layers. Referring to figures 1 and 2 the binder materials are schematically represented by white circles 13. It can be seen in figures 1 and 2that the ",ajority ot the binder materials 13 are contained in inner layers 12 and 19 respectively. In an alternate preferred ei"bod;."ent (not shown), the majority ot the binder is contained in at least one of the outer layers more pfeferabl) both of the two outer layers of the mu~i-byered product.
The combination of the biodegradable chemical softening colllpositiGn cGi"~rising a bioJe~radable quaternary a~",onium compound and a polyhdr~xy compound in conjunction with a binder material results in a tissue paper producthaving superior softness, absorbency. and lint resistance properties. Selectively adding the majority of the biodegradable chemical softening co"~position to the outer layers or plys of the tissue paper, enhances its effectiveness. Typically the binder materials are dispersed throughout the tissue sheet to control linting.
However, like the biodegrddable chemical softening co..-roti1icn, the binder ".~teria:s can be selectively added where most needed.
CGn~on~ionally pressed multi hyered tissue paper and --elllG~ for making such paper are known in the art. Such paper is typically made by deF ositing paper making furnish on a foraminous torming wire. This torming v~rire is onen ref~,-ed to in the art as a Fourd~ifi sr wire. Once the fumish is depos;ted on the forrnin~ wire, it is refened to as a web. Th~ web is dewatered by transferring to a dewal~rin9 felt, pressing the web and drying at elevated temperature. The particular techniques and typical equipment for making webs according to the process JUst dsscribed are well known to those skilled in the art. In a typical process a bw consistency pulp turnish is provided in a pressurized headbox. The headbo~ has an opening ~or delivering a thin deposit of pulp turnish onto the Fourdrinier wire to form a wet web.
The web is then typically dewatered to a fiber consislency of bet~asn about 7%
and about 25% (total web weight basis) by vacuum dewatering and turther dewatered by pressing operations wherein the web is subjected to pressure developed by opposing ,-.echan ~l "~s~ber~, for example, cylindrical rolls.
The dewatered web is then turther pr~ssed during t-ans~er and being 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 maybe employed, whereby additional pressing is optionally incurred between the WO 95/0147g ~ 5 ~; 3 6 22 PCT/US94/06916 drums. The multi-lay~red tissue paper structures which are lormed are referred to hereinafter as conventional, pressed, multi-layered tissue paper structures. Such sheets are considered to be compacted since the web is subjected to substantial mechanical compression forces while the fibers are moist and are then dried while in a compressed state.
Pattern densified multi-layered 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 altemativelyreferred to as knuckle regions. The densified zones may be discretely sp~ced within the high bulk field or may be interconnected, either fully or partially, within the hi~h bulk field. Preferred processes for making panern densified tissue websare disclosed in U.S. Patent No. 3,301,746, issued to Sanford and Sisson on January 31, 1967, U.S. Patent No. 3,974,025, issued to Peter G. Ayers on August 10,1976, 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 in;l~Grsted herein by rGf~rence.
In general, patlern densified webs are preferably prepared by depos;ting a paper makin~ turnish on a toraminous forming wire such as a FourJ~ifi-~r wire toform a wet web and then juYtarosing 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 lo~tions geographically conesponding to the points of contaR
bet~re&n the array of supports and the wet web. The ren,aindGr of the web not co",pressed during this opera~ion is r~fe.,eJ to as the high bulk field. This high bulk field can be further JeJensified by application of fluid pressure, such as with a vacuum type device or a blow-through dryer. The web is deu~alered, and optional~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 pr~ssinS~
the web against an array of supports wherein the high bulk field is not compressed. The opa.~t;ons of dewatering, optional predrying and for,"~tion of the densified zones may be integrated or partially integrated to reduce the total number ot processing steps pe,~Gr",ed. Subsequent to formation of the densified zones, dewatering, and optional predrying, the web is dried to completion, preferably still avoiding mechanical pressing. Preferably, trom about 8% to about 55% of the multi-layered tissue paper surface compnses densified knuckles havinga relative density of at least 125% of the density of the high bulk field.

216S~36 WO 95/01479 ~ ` PCTrUS94/06916 The array of supports is pre~erably an imprinting carrier fabric having a panerned displ~cement of knuckles which operate as the array ot supports which tacilitate the formation of the densified zones upon application ot pressure. The pattern of knuckles constitutes the array of supports previously referred to.
Imprinting carrier fabrics are disclosed in U.S. Patent No. 3,301,746, Sanford and Sisson, issued January 31,1967, U.S. Patent No. 3,821,068, Salvuoci, 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 st al ., issued March 30,1971, U.S. Patent No. 3,473,576, Amneus, issued o~tober 21,1969, U.S. Patent No. 4,239,065, Trokhan, issued Dece".ber 16,1980, and U.S. Patent No. 4,528,239, Trokhan, issued July 9, 1985, all of which are irH c ,~Grtted herein by r~fer~
r,eferably, the turnish is first formed into a wet web on a foraminous - forming carrier, such as a Fourdrinier wire. The web is de.:itered and transle--~l to an imprinting fabric. The furnish may alternately be initially d~posi1~ on a foraminous suppo,ting carrier which also operales as an imprinting fabric. Once formed, the wet web is dewat0red and, prel~rably, thermally pr6d~iod to a sslected fiber consislericJ of between about 40% and about 80%. Dewatsring can be performed with suction boxes or other vacuum devices or with blow-through dryers. The knuckle imprint of the imprintin9 fabric is impressed in the web as discussed above, prior to dry;ng the web to CG" plet:on. One method for acrG",plishing this is through application of mechanical pressurs. This can be done, for exampb, by pressing a nip roll which supports the i",printing fabric against the tacc of a drying drum, such as a Yankee dryer, wherein the web iS
J;sposed between the nip roll and drying dnum. Also, preferab~J, thc 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 bbw-through dryer. Fluid pressure may be ~Fplied to induce impression of den~ied zones during initial dewatering, in a separate, subsequent process stage, or a combination thered.
UncGI"pa~,1ed, nonpattern-densified multi-layered tissue paper structures are dssclil~d in U.S. Patent No. 3,812,000 issued to Joseph L Sahrucci, Jr. and Peter N. Yiannos on May 21, 1974 and U.S. Palent No. 4,208,459, issued 10 Henry E. Becker, Albert L. McConnell, and Richard Schutte on June 17, 1980, both of which are inco",oraled herein by reference. In general, unco",pacted, non pattern densified multi-layered tissue paper structures are prepared by depo~i~ing a paper making fumish on a foraminous forming wire such as a Fourdrinier wire toform a wet web, draining the web and removing additional water without mechanical compression until the web has a fiber consistency of at least 80% andcreping the web. Water is removed from the web by vacuum dewatering and thermal drying. The resulting structure is a sott but weak high bulk sheet ot relatively uncompacted fibers. Bonding material is preferably applied to portions of the web prior to creping.
The multi-layered tissue paper web of this invention can be used in any application where soR absorbent multi-layered tissue paper webs are required.
Particularly advanta~e!ous uses of the multi-layered tissue paper web of this invention are in toilet tissue and fadal tissue products. For exarnple, two multi-layered tissue paper webs of this invention can be ply-bond6d to forrn 2-ply fadal or toilet tissue prodwts.

Mclecular Weight Determination A. Introduc~lon The essential distinguishing characlerislic of polymeric materials is their molecular size. Ths properties which have enabled polymers to be used in a diversity of aFp' e-~ions derive almost entirely from their macro ~, Dlecul^- nature.
In order to characterize fully these materials it is essential to havel some means of defining and determining their molecular weights and molecular weight distributions. It is more correct to use the term relative ",Dlec~JI^ mass rather the molecular weight but the latter is used more generally in polymer techr.a'o~y. n is not always prd~tical lo determine ",o~ecul~ weight distributions. 110~\6~er, this is becoming more common practice using chromatographic techniques. Rather recourse is made to expressing molecular size in terms of molecu'a~ weight averages.
B. Molecùlar welght averages If we consider a simple ",o'ecul~ weight distribution which represents the weight fraction (w~) of molecu'es 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 MOIQCU!~ Weight Mn - ~NiM
~:Ni An important consequence of this definition is that the Number Average Molecular Weight in grams contains Avogadro~s Number of " ~'e~uls~

wo 95/01479 21 ~ 5 5 3 6 PCT/US94106916 This definition of molecular weight is consistent wilh that of monodisperss molecular species, i.e. molecules having the same molecular weight. Of more significance is the recognition that it the number ot molecules in a given mass of a polydisperse polymer can be determined in some way then M n. can be calculated readily. This is the basis of colligative prope.ly measure",ents.
Averaging on the basis of the weight fractions (Wj) of molQ~les of a given mass (Mj) leads to the definition of Weight Average Molecular Wdi~hts Mw = Wi Ni_c Ni Mi2 Wj Nj Mj Mw is a more useful means for expr~ssing poly",~r molecular ~6ights than Mn since it reflects more accurately such pr~pe,ties as melt viscosity and mechanical prope ties of poly.,.ers and is tl,erefor used in the present in~enl;on.

Analytlcal ~nd Testln~ . . ~eJ~Jre~

Analysis of the amount of biodes,ddable t,~at-"ent chemicals used herein or retained on tissue paper webs can be pe"~r-"~d by tny illetl,Gd ~ pt~ in the applicabb art.
A. Quantllatlve analysls for ester-functlonal quatQrnary ammonlum and polyh~droxy CG.-IpOUndS
For example, the level of the ester-functional quaternary ammonium compound, such as DiEs1er Di(Hydrogenated)Tallow DiMethyl Ammonium Chloride (DEDHTDMAC) (i.e., ADOGEN DDMC~, retained by the tissue paper can be determined by solvent extraction of the DEDHTDMAC by an or~,an ~
solvent followed by an anionic~cationic litralion using Dimidium Bromide as indicator; the level of the polyhydroxy compound, such as PEG-400, can be determined by e~l-d~liGn in an aqueous solvent such as water followed by gas chromatography or colorimetry techniques to determine the level of PEG-400 in the extract. These Illelllods are exemplary, and are not meant to e~rclude othermethods which may be usetul for determining levels ot particular co")ponents retained by the tissue paper.
B. Hydrophlllcity (absorbency) Hydrophilicity of multi-layered tissue paper refers, in general, 1O the propensity of the multi-layered tissue paper to be wetted with water. Hydrophilicity of multi-layered tissue paper may be somewhat quantified by determining the WO 95/01479 ` ` PCT/US94/06916 --216~53~

period of time required for dry multi-layered 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 tor wening 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 23+1 C and 50 1 2%
R.H. 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 multi-layered tissue paper structure is provided;
second, the sheet is folded into four (4) juxtarosed quarters, and then cnumpledinto a ball approxi"~t~ly 0.75 inches (about 1.9 cm) to about 1 inch (about 2.5 cm) in diameter; third, the balled sheet is placed on the surface ol a body of distillsd water at 23 ~ 1C and a timer is simultaneously started; fourth, the timer is stopped and read when wetting of the balled sheet is compleled. Complete wettingis observed visually.
Hydrophilicity characters ot multi-layered tissue paper embodiments of the present invention may, of course, be determined i"""edia1ely after manufacture.
However, substantial increases in hydrophobicity may occur during the first two weeks after the multi-byered tissue paper is made: i.e., after the papsr has agsd two (2) weeks ~olb~ its manu~acturs. Thus, the wetting times are prefer~f measured at the end of such two week period. Accordingly, wetting times measured at the end ol a two week aging period at room temperature are r~fe.,a~
to as two week wetting times'.
C. Biodegradable Suitable substantially waterless self-emulsifiable biodegradable chemical softening c~",pGsition for use in the present invention are biadeol~dable. As used herein, the tsrm ~biodsgradability- rsfers to the complete breakdown ot a substance by microorganisms to carbon dioxide, water, b oi"ass, and inor~-n-c materials. The biodeglada~ion poten1ial can be estimated by measuring carbon dioxide evolution and dissolv0d or~an c carbon removal from a medium containing the substance being tested as the sole carbon and energy sourc~ and a dilute bacterial inoculum obtained from the supernatant of homogenized acti~a1ed sludge. See Larson, 'L~1i",at;Gn of Biodegradation Potential of Xenobiotic Organic Chemicals,' ~,~lied ~nd Fnvjronment~l Microbiolo~y. Volume 38 (1979), pages 1153-61, which describes a suitable method for estimating biodegradability. Using this method, a substance is said to be readily biodegradable if it has greater than 70% carbon dioxide evolution and greater than 90% dissolved organic carbon removal within 28 days. The sofleners used in the present invention meet such biodegradability criteria 2tG553~

C. Denslty The density ot multi-layered 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 multi-layered tissue paper, as used herein, is the thickness ot the paper when subjected to a compressive load of 95 g/jn2 (15.5 g/cm2).
D. Llnt Dry llnt Dry lint can be measured using a Sutherland Rub Tester, a piece of black felt, a four pound weight and a Hunter Color meter. The Sull,eilar~ tester is a motor-driven instnument which can stroke a weighted sample back and fonh across a stationary sample. The piece of black felt is attached to the four pound weight. The tester then nubs or moves the weighted felt over a stationary issue sample for five strokes. The Hunter Color L value of the black felt is determined before and after rubbing. The difference in the two Hunter Color readings constitutes a measurement of dry linting. Other "~ett,ods known in the prior ansfor measuring dry lint also can be used.
Wet llnl A suitabb procedure for measuring the wet lin1ing pr~,pg.ly of tissue samples is described in U.S. Patent No. 4,950,545; issued to Walter et al., on August 21, 1990, and inco.~,oraled herein by reference. The procedure essentially involves pass;ng a tissue sample through two steel rolls, one of which is panially su6",erged in a water bath. Lint from the tissue sample is transle.-ed to the steel roll which is ",oislaned by the water bath. The continued rotation of the steel roll deposits the lint into the water bath. The lint is recovered and then counted. See col. 5, line 45 col. 6, line 27 of the Walter et al. patent. Other methods known in the prior an for rneasuring wet lint also can be used.

Optional I~ ents Other chemicals commonly used in paper making can be added to the biodegradable chemical softening cG",position described herein, or to the paper making ~urnish so long as they do not significantly and adversely affect the softening, absorbency ot the fibrous material, and enhancing actions of the biodegradable chemical soflening composition.
For example, surfactants may be used to treat the multi-layered tissue paper webs of the present invention. The level of surfactant, if used, is pre~er~bly WO 9~/01479 - PCT/US94/06916 21fiS~3~

trom about 0.01% to about 2.0% by weight, based on the dry fib~r weight ot ths multi-layered tissue paper. Ths surfac1ants preferably have alkyl chains with sight or more carbon atoms. Exemplary anionic surtactants are linear alkyl sultonates,and alkylbenzene sulfonates. Exemplary nonionic su~actants are alkylglycosides including alkylglycosids 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 such as Pegosperse 200 ML available from GIYQO
Chsmicals, Inc. (Grssnwich, CT) and IGEPAL RC-520 availabl~ from Rhon~
Poulenc Corporation (Cranbury, N.J.).
The above listings of optional chemical aWili~s is inlend~d to bs mer~ly exemplary in nature, and ars not meant to limit the scope ot the invention.
The tollowing examples illustrate the practics of the prsssnt invsntion but are not intended to bs limiting thereof.

E~CAMPLE 1 The purpose ot this example is to illustrate a method that can be used to make-up a substantially waterless ~olf ~"~ulsifiable biodegradabl~ che."ic~l softsnsr cG",pos;tion OG",pnsin9 a mixtur~ ot DiEster Di(Touch Hardsned)Talbw DiMethyl Ammonium Chloride (DEDTHTDMAC) and Polyoxyethylene Glycol 400 (PEG-400).
A waterless sslf-emulsir?t~e biode~radable chemical softensr colllpGsitiGn is prepared according to the following procedure: 1. An equivalent weight of DEDTHTDMAC and PEG-400 is weighed separately; 2. PEG is heated up to about 66 C (150 F); 3. DEDTHTDMAC is d;ssolved in ths PEG to 1Orm a melted solution at about 66 C (150 F); 4. ~de~u~te mixing is provided to torm a homogenous mixture of DEDTHTDMAC in PEG; 5. The hGi"Ggenous mixturs ot (4) is cooled down to a solid form at room temperature.
The substantially waterless selt-emulsifiable biodegradabls chemical softener composition ot (5) can be pre-mixed (steps 1-5 above) at the chemical supplier (e.g. Sherex company of Dublin, Ohio) and then econG",~ y shipped to ths ultimate ussrs ot the biodegradable chemical softening composition where it can then be diluted to the desired concentration.

~ wo 95/01479 ~16 5 5 3 ~ PCTluss4lo6sl6 The purpose of this example is to illustrate a method that can be used to make-up a substantially waterless self-emulsifiable biodegradable chemical sottener composition which comprises a mixture ol DiEster Di(Touch Hardened)Tallow DiMethyl Ammonium Chloride (DEDTHTDMAC) and a mixture o~ Glycerol and PEG~00.
A substantially waterless self-emulsifiable biodegradable chemical sotlener cGi"pGsition is prepared according to the ~ollowing procedure: 1. A mixture ot Glycerol and PEG-400 is b'ended at about 75: 25 by weight ratio; 2. Equivalent weights of DEDTHTDMAC and the mixture of (1) are weighted sapar;~tsly; 3.
Mixture of (1) is heated up to about 66 C (150 F); 4. DEDTHTDMAC is dissolv6d in (3) to ~orm a melted solution at 66 C (150 F); 5. Ade~uate mixingis provided to torm a homo~enous mixture ol DEDTHTDMAC in (3); 6. The homogenous mixture of (5) is cooled down to a solid lorm at room te",per~t~lre.
The substantially waterless 501~ o."ulsifiable ~ odeDradable chemical softener c~",position ot (6) can be prs-mixed (steps 1-6 above) at the chemical suppl er (e.g. Sherex cGi.lpanf of Dublin, Ohio) and then econG..~ically shipped to the ultimate users of the bioldegradable chemical softening c~".pGsition where jJt can then be diluted to the desired concenl,ation.

The purp~ose of this example is to illustrate a method using blow throu~h drying and layered paper making techniques to make soft, absGrLent and lint resistance toilet multi-layered tissue paper treated with a chemical softener co"~pGsition cG",prisir~ DiEster Di(To~ch Hardened)Tallow DiMethyl Ammonium Chloride (DEDTHTDMAC) and a rolyoxyetl,ylene Glycol 400 (PEG-400) and a temporary wet ~ r,~tl- resin.
A pilot scale Fourdrinier paper making machine is used in the practice of the present invention. First, the chemical sollener co",position is pr~pared according to the procedure in Example 1 wherein the homogenous premix ol DEDTHTDMAC
and polyhydroxy compounds in solid state is re-melted at a temperature ot about 66 C (150F). The mened mixture is then dispersed in a conditioned water tank - (pH - 3 Temperature - 66 C) to ~orm a sub-micron vesicle dispersion. The particle size o~ the vesicle dispersion is determined using an optical mic,.scoptechnique. The particle size range is from about 0.1 to 1.0 micron.

~lfi~3~

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 ot the temporary wet strength resin (i.e. Na~ional starch 78-0080 marketed by National Starch and Chemical corporation of New-York, NY) is added to the NSK stock pipe at a rate ot 0.75% by weight of the dry fibers. The 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 2% solution of the temporary wet strength resin (i.e.
National starch 78~080 marketed by National Starch and Chemical cG"~ordtion ot New-York, NY) is added to the Eucalyptus stock pipe before the stock pump at a rate ot 0.1% by wei~ht of the dry fibers; and a 1% solution of the biodegradablechemical softener mixture is added to the Eucalyptus stock pipe before the in-line mixer at a rate of 0.2% by weight ot the dry fibers. The Eucalyptus slurry is diluted to about 0.2% cons;st~nc~ a1 the fan pump.
The treated tumish mixture (30% of NSK 170% of Eucalyptus) is blended in the head box and deposited onto a Fourdrinier wire to form an embryonic web.
Dewalering occurs through the Fourdrinier wire and is assisle~ by a defl~l~r andvacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave conf~uration having 84 machine-directiGn and 76 cross-machine-direction ",onofi'~ments per inch, respe~,ti~ely. The embryonic wet web is transferred from the photo-pol~l,~r wire, at a fiber consistency of about 15% at the point of transter, 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-waterin~ is accomplished by vacuum assisted drainage until the web has a fi~er consistency of about 28%.
The panerned 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 Abohol (PVA). The fiber consistency is increased to an estimated 96% be~ore the dry creping the web 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 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 minules).
The web is convened into a one ply multi-layered tissue paper product. The multi-layered tissue paper has about 18 #/3M Sq Ft basis weight, contains about 0.2% of the biodegradable chemical softener mixture and about 0.3% of tho --wo 95/01479 21~ 5 ~ ~ ~ PCT/US94/06916 temporary wet strength resin. Importantly, the resulting multi-layered tissue paper is soft. absorbent, has good lint resistance and is suitable for use as facial and/or toilet tissues.

The purpose ot this example is lo illustrate a method using a blow through drying paper making technique to make sott, absGrbent and lint iesislance toiletmulti-layered tissue paper treated with a chemical softener comp~osition c~,-,prts..~g DiEster Di(Touch Hardened)Tallow DiMethyl Ammonium Chloride (DEDTHTDl~JtAC) and a mixture of polyhydroxy compound (Glycerol I PEG-400) and a dry strength aWiliio resin.
A pilot scale Fourdrinier paper making machine is used in the practice ot the present invention. First, the chemical softener compos7tion is pr~par~
according to the procedure in Example 2 wherein the ho",oganous premix of DEDTHTDMAC and polyhydroxy compounds in solid state is re-metted at a temperature of about 66 C (150 F). The melted mixture is then dispersed in a conditioned water tank (pH -3, Te",p*rdture - 66 C) to form a sub-micron vesicle dispersion. The particle size of the vesicle dispersion is determined using an optical micr-scop-c technique. The particle size range is trom about 0.1 to 1.0 micron.
Sscond, a 3% by weight aqueous slurry ot NSK is made up in a conventional re-pulper. The NSK slurry is refined ~ently and a 2Yo solution of the dry slr~rs~tl, resin (i.e. Acco ~ 514, Acco ~D 711 marl~eted by A"-erican Cyanamid company ot Fairtield, OH) is added to the NSK stock pipe at a rate ot 0.2% by weight of the dry fibers. The adsG,IJtion ot 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 tan pump.
Third, a 3% by weight aqueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 2% solution of tho dry strength resin (i.e. Acco ~D 514, Acco ~9 711 marketed by American Cyanamid company ot Fairfield, OH) is added to the Eucalyptus stock pipe betore the stock pump at a rate ot 0.1% by weight ot the dry tibers; and a 1% solution ot the biodegradable chemical sottener mixture is added to the Eucalyptus stock pipe betore the in-line mixer at a rate ot 0.2% byweight ot the dry fibers. The Eucalyptus slurry is diluted to about 0.2% c~nsisler,.,~
at the fan pump.

~16~53~

The treated furnish mixture (30% of NSK / 70% ot Eucalyptus) is blended in the head box and deposited onto a Fourdrinier wire to form an embryonic web.
Dewatenng occurs through the Fourdrinier wire and is assisted by a deflector andvacuum boxes. The Fourdrinier wire is of a 5-shed, satin weave con~iguration having 84 machine-direction and 76 cross-machine-direction monofilaments per inch, respectively. The embryonic wet web is transferred from the photo-poly...er wire, at a fiber consistency of about 15% at the point of transfer, to a photo-polymer fabric having 562 Linear Idaho oells per square inch, 40 pe-,an~ knucklearea and 9 mils of photo-polymer depth. Further de-watering is ac~,.-plished by vacuum assiste~ 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 adl,ered to the surface of a Yankee dryer with a sprayed creping adhesive cG",pris;n~ 0.25% aqueous solution of Polyvinyl Alcohol(PVA). The fiber consistency is incr~ased to an estimated 96% before th~ dry creping the web with a doctor blade. The doctor blade has a bevel angle of about25 degrees and is positioned with respect 10 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 multi-layered tissue paper products and laminating them together usin~ ply bonded technique. The multi-layered tissue paper has about 23 #/3M Sq Ft basis weight, contains about 0.1% of the biodegradable chemical soRener mixture and about 0.2% of the dry strength resin.Importantly, the resulting multi-layered tissue paper is soR, absorbent, has good lint resistance and is suitable for use as facial and/or toilet tissues The purpose of this example is to illustrate a method using a conventional drying paper making technique to make soR, absorbent and lint (esislancs toilet multi-layered tissue paper treated with a chemical softener co",position c ;i"prising DiEster Di(Touch Hardened)Tallow DiMethyl Ammonium Chloride (DEDTHTDMAC) and a Polyoxyethylene Glycol 400 (PEG-400), a dry slren~
additive and a cationic polyacrylamide additive resin (Percol ~9 175) as retention aid.
A pilot scale Fourdrinier paper making machine is used in the practice of the present invention. First, the chemical sonener composition is prepared according 216553fi to the procedure in Example 1 wherein the homogenous premix of DEDTHTDMAC
and PEG-400 in solid state is dispersed in a conditioned water tank (pH ~ 3, Temperature - 66 C) to form a sub-micron vesicle dispersion. The particle size of the vesicle d;sper:,ion is determined using an optical microsc~pic technique. The particle size range is trom about 0.1 to 1.0 micron.
Second, a 3% by weight aqueous slurry o~ 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 ~D 514, Acco ~ 711 marketed by American Cyanamid company of Wayne, New Jersey) is added to the NSK stock pipe at a rate of 0.2%
by weight o1 the dry fibers. The adsG",tion ot the dry strength resin orlto NSK
fibers is enhanced by an in-line mixer. The NSK slurry is diluted to about 0.2%
consistency at the tan pump.
Third, a 3% by weight aqueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 1% solution ot the biodegradable chemical softener mixture is added to th~ Eucalyptus stock pipe belore the stock pump at a rate ot0.2% by weight of the dry fibers; and a 0.05% solution of Percol 0 175 is added to the Eucalyptus byers before the fan pump at a rate of 0.05% by weight of the dryfibers. The adsorption of the biod~radable chemical softener mixture to Eucalyptus fibers can be enhanced by an in-line mixer. The Eucalyptus slurry is diluted to about 0.2% c~nsistency at the fan pump.
The treated hmish mixturs (30YO of NSK / 70% ot Eucalyptus) is blended in the head box and deposited onto a Fourdrinier wire to ~orm an e,nbryonic web.
Dewatering occurs through ths Fourdrinier wire and is assisted by a d~fl~tor andvacuum boxes. The Fourdrinier wire is ot a 5-shed, satin weave configuration having 84 "ach ne-direction and 76 cross-machine-direction .,.Gnnf brnents per inch, respecl;~Gly. Ths s"lbryon:c wet web is transferred from the Fourdrinier wire, at a fiber oons;slericlr of about 15% at the point of transfer, to a conventional feR. Further do watcring is accG..,plished by vacuum assisted drainage until theweb has a fiber cons;slency of about 35%. The web is then aJl,er~d to the surtace of a Yankse dryer. The fiber consistency is increassd to an estimated 96% betoreths dry creping the web with a doctor blade. The doctor blads has a bevel angle of about 25 degrees and is posi~ionsJ with respect to the Yankee dryer to provide an impact angls o~ about 81 degrses; ths Yankee dryer is operated at about 800 fpm (feet per minute) (about 244 meters psr minute). The dry web is formed into roll at a speed ol 700 fpm (214 meters per minutes).
Two plies of the web are formed into multi-layered tissue paper products and laminating thsm together using ply bonded techniqus. Ths multi-laysred 2165~3~

tissue paper has abou123 #/3M Sq. Ft. basis weight contains about 0.1% of the biodegradable chemical softener mixture about 0.1% of the dry strength resin andabout 0.05% of the retention aid resin. Importantly the resulting multi-layered tissue paper is son. absorbent. has good lint resistance and is suitable tor use as a facial and/or toilet tissues.

The purpose of this example is to illustrate a method using a blow through drying and layered paper making techn ~l es to make soft, absorbent and lint resistance 1acial multi-layered tissue paper treated with a chemical soflener composition comprising DiEster Di(Touch Hardened)Tallow DiMethyl Ai"",Gn um Chloride (DEDTHTDMAC) and a Polyoxyethylene Glycol 400 (PEG-400) a permanent wet slren!Jtl, resin and a retention aid (Percol ~9 175 ).
A pilot scale Fourdrinier paper making ",acl,;ne is used in the p,a..lice of th~present invention. hrst, the chemical softener co",posit;on is prepared accordin~
to the procedure in Example 1 wherein the homogenous premix ot DEDTHTDMAC
and polyhydroxy compounds in solid state is re-melted at a ten,peiature of about66 C (150F). The melted mixture is then disper~ed in a cor,d;t;Gned water tank(pH - 3, Temperature - 66 C) to hrm a sub-micron vesicle d;sp~rsion. The particle size of the vesicle dispersion is deler~ ned using an optical micr~sccptechnique. The particle size ran~e is from about 0.1 to 1.0 micron.
Second, a 3% by weight ~qveous slurry ol NSK is made up in a conventional re-pulper. The NSK slurry is refined gently and a 2% solution of the permanent wet slrength resin (i.e. Kymene ~!9 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 the temporary wet sl-engtl- resin onto NSK fibers is enhanced by an in-line mixer. The NSK slurry is diluted to about 0.2% consistency a1 the fan pump.
Third a 3% by weight ~ueous slurry of Eucalyptus fibers is made up in a conventional re-pulper. A 1% solution of the biodegradable chemical soflen~r mixture is added to the Eucalyptus stock pipe before the in-line mixer at a rate of 0.2% by weight of the dry fibers; and a 0.5% solution of Percol ~D 175 is added to the Eucalyptus layers before the fan pump at a rate of 0.05% by weight of the dry fibers. The Eucalyptus slurry is diluted to about 0.2% consistency at the fan pump.
The treated fumish mixture (50% of NSK / 50% of Eucalyptus) is blended in the head box and deposited onto a Fourdrinier wire to form an embryonic web.

WO 95/01479 21 fi 5 ~ 3 6 PCTIIJS94/06916 Dewatering occurs through the Fourdrinisr wire and is assisted by a deflector and vaeuum boxes. The Fourdrinier wire is ot a 5-shed, satin weave contiguration having 84 machine-direction and 76 cross-machine-direction monofilaments per inch, respectively. The embryonic wet web is transterred trom the photo-pGly,..~r wire, at a tiber consistency ot about 15% at the point ot transter, Io a photo-polymer tabric having 711 Linear Idaho cells per square inch, 40 percent knucklsarea and 9 mils of photo-polym~r depth. Funher de-waterin9 is a~ comprlsh~d by vacuum assisted drainage until the web has a fibsr consistenc~ of about 28%.
The panerned web is prs-dried by air bbw-through to a fiber consistency of about65% by wei~ht. The web is then adhered to the surfacs of a Yankee dryer ~Hth a sprayed creping adhesive comprising 0.25% aqueous solution of rolyvinyl AJcohol (PVA). The fiber consistency is increased 1O an estimated 96% before the dry creping the web with a doctor blade. The doctor bbde has a bevel angb ol about 25 de~rees and is positioned with respect to the Yankee dryer to provide an impact an~le of about 81 degr~ss; the Yankee dryer is operated at about 800 fprn(teet per minute) (about 244 meters per minute). The dry web is formed into ro~ at a speed of 7001pm (214 meters per minutes).
The web is converted Into a two ply multi-layered ~acial tissue paper. The muni-lay~r~d tissu~ pa~r has about 21 #/3M Sq Ft basis wei9ht, conlains about 1% of the permanent wet strength resin, about 0.2% of the biode~-~dabb chemical sonener mixture and about 0.05% of the retention aid resin. I-,-,oG~ntly, the resulting multi-byered t~sue wer is soft, absG~nl, has good ~nt r~s.~snca and is suitable for use as faclal tissus~ -

Claims (10)

What is Claimed is:

1. A multi-layered tissue paper web characterized in that it comprises at least two superposed layers a first layer and at least one second layer contiguous said first layer said multi-layered web comprising:
a) paper making fibers;
b) from 0.01% to 3.0% by weight of a biodegradable quaternary ammonium compound preferably having the formula X-or X-or X-wherein each R2 substituent is a C1 - C6 alkyl or hydroxyalkyl group benzyl group or mixtures thereof preferably methyl; each R1 substituent is a C12 - C22 hydrocarbyl group or substituted hydrocarbyl group or mixtures thereof, preferably C16 - C18 alkyl or alkenyl; each R3 substituent is a C11 - C21 hydrocarbyl group, or substituted hydrocarbyl or mixtures thereof, preferably C15 - C17 alkyl or alkenyl; Y is - O - C (O) - or - C (O) - O - or - NH - C (O) - or - C (O) - NH - or mixtures thereof; n is 1 to 4 and X- is a suitable anion, preferably chloride or methyl sulfate;
c) from 0.1% to 3.0% of a water soluble polyhydroxy compound;
wherein said polyhydroxy compound is preferably selected from glycerol, sorbitols, polyglycerols having a weight average molecular weight of from 150 to 800, polyoxyethylene glycols and polyoxypropylene glycols having a weight average molecular weight from 200 to 4000, preferably from 200 to 1000, most preferably from 200 to 600, and mixtures thereof;
and d) from 0.01% to 3.0% of a binder material wherein said binder material is preferably selected from permanent wet strength resins, preferably polyamide-epichlorohydrin or polyacrylamide permanent wet strength resins, and mixtures thereof, temporary wet strength resins, preferably a starch-based temporary wet strength resin, dry strength resins, retention aid resins and mixtures thereof.

2. The multi-layered tissue paper web of Claim 1 wherein said multi-layered web comprises three superposed layers, an inner layer and two outer layers, said inner layer being located between two said outer layers, said multi-layered web preferably comprising a single ply, wherein said biodegradable quaternary ammonium compound, said water soluble polyhdroxy compound, and said binder material are each contained in one or more of said layers of said multi-layered web.

3. The multi-layered tissue paper web of Claim 2 wherein the majority of the biodegradable quaternary ammonium compound and the polyhydroxy compound is contained in at least one of said outer layers, preferably in both of said outer layers.

4. The multi-layered tissue paper web of Claim 2 or 3 wherein the majority of the binder is contained in said inner layer.

5. The multi-layered tissue paper web of any of Claims 2 - 4 wherein said inner layer comprises relatively long paper making fibers, preferably softwood fibers, most preferably northern softwood fibers, said long paper making fibers having an average length of at least 2.0 mm and wherein each of two said outer layers comprises relatively short paper making fibers, preferably hardwood fibers, most preferably eucalyptus fibers, said short paper making fibers having an average length between 0.2 and 1.5 mm.

6. The multi-layered tissue paper web of Claim 5 wherein said inner layer comprises mixtures of softwood fibers and low cost fibers, and at least one of said outer layers comprises low cost fibers or mixtures of hardwood fibers and low cost fibers, wherein said low cost fibers are selected from sulfite fibers, thermomechanical pulp fibers, chemi-thermomechanical pulp fibers, recycled fibers, and mixtures thereof.

7. The multi-layered tissue paper web of any of Claims 1 - 6 wherein the biodegradable quaternary ammonium compound is diester di(touch hardened)tallow dimethyl ammonium chloride or diester di(touch hardened)tallow dimethyl methyl sulfate.

8. The multi-layered tissue paper web of any of Claims 1 - 7 wherein the weight ratio of the quaternary ammonium to the polyhydroxy compound ranges from 1.0: 0.3 to 0.3: 1.0, preferably from 1.0:
0.7 to 0.7 : 1Ø

9. A multi-ply tissue paper product comprising at least two juxtaposed multi-layered tissue paper webs of Claim 1, wherein said multi-ply tissue paper product preferably comprises two plies, wherein each of two said plies preferably comprises two superposed layers, and wherein said binder materials are permanent wet strength resins or temporary wet resins, and wherein the majority of said biodegradable quaternary ammonium compound and said polyhdroxy compound are contained in at least one of said outer layers and wherein the majority of said binder material is contained in said inner layer.

10. The multi-layered tissue paper web of any of Claims 1 - 9 wherein said tissue paper web is a toilet tissue or a facial tissue.