CA2697560A1 - A soft absorbent web material - Google Patents

Abstract

A web comprised of lyocell fibers. The web may be a homogeneous blend of fibers with lyocell fibers having a length of less than about 6 mm as a portion of the blend. The web may be a multi layered single ply with lyocell fibers in one or more layers. The web may be composed of multiple plies, with component plies composed of multiple layers. The length and proportion of the lyocell fibers in the respective layers of the component plies may vary intentionally from layer to layer.

Description

FIELD OF THE INVENTION:
The present invention relates to absorbent, fibrous web materiale.
Speeifically, the present invention relates to sotft, absorbent, fibrous web materials comprised of lyocell fibers. The fibrous tweb materials may be used to produce soft, atmng absorbent paper products.

BACKGROUND OF THE IIVVENTION:
Paper webs or sheets, sometimes called tissue or paper tissue webs or sheets, find extensive use in modern society. Such items as paper towels, facial and toilet tisaes are staple items of commerce. It has long been recognized that four important physical attributes of these products are their strength, their sofbiess, their absorbency, including their absorbency for aqueous systems; and their lint resistance, including their lint resistanee when wet. Research and development efforts have been direoted to the improvement of each of these attributes without seriously affecting the others as well as to the improvement of two or three attributes simultaneously.
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, partieularly when wet.
Softness is the tactile sensation perceived by the consumer as helshe holds a patticular product, rubs it across his/her skin, or crrmples it within his/her hand. This tactile aensation is provided by a combination of several physical praperties. Important physieal properties related to sothsess are generally considered by those akilled in the ert to be the stiffneas, the surfaoe smoothness and lubricity of the paper web from which the product is made.
Sti$hess, in tura, 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 web.
Absorbency is the measure of the ability of a product, and its constituent webs, to absorb quantities of liquid, particularly aqueous solutions or dispmsions. Oveiratl absorbency as perceived by the 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.

Lint resistance is the ability of the fibrous product, and its constituent webs, to bind together undcr use conditions, including when wet. In other words, the higher the lint resistance is, the lower the propensity of ft web to lint will be.
It is an objective of this invention to provide a soft, absorbent web material that is also strong both when wet and dry, and that has good lint resistanee.

SCTMMARY OF THE INVENTION:
A soft, absorbent, strong web rnaterial comprised of lyacell fibers. The web may be a homogeneous blend of lyocell and other types of fibers, whereia no more than 600A by weight of the lyocell fi'bers of the blend have a len.gth greater than, or equal to, 6 mm. The web may be a layered, single ply web wherein one or more layers of the ply are oomprised of lyoeell fibers.
Such a layered web may have lyocxll fibers of different lengths and varying amounts in differeat layers. Optionally, the web may be a multi ply web of multi layered plies, wherein one or more of the layers of such are comprised of lyocell fibers. Such multiple plies may be laminated together with layers coruprised of lyocell fibers on the outer surfaces of the web.
Alternatively, svah a web may have layers comprised of lyocell disposed in the interior of the web. It is further possible that all the layers of such a multi ply, multi layer web be comprised of lyocell fibers sueh tbat different lengths of lyocell fibers in varying quantities are present in the outer layers of the multi ply web, and the interior of the niulti ply web.

All percentages, ratios and proportions herein are by weight unless otherwise specified.
DESCRIPTION OF THE DRAWINGS:
FIG. I is a schematic cross-sectional view of a two-ply, two-layer tissue paper in accordaaoe with the present invention.
FIG. 2 is a schematic representation of a papcrmaldng machine useful for producing a soft tissue paper in accordance with the present invention.

DETAILED DESCRIl'TION OF THE INVENTION:
The physical characteristics of a paper web are intluenced by many factors.
These factora include, but are not limited to, the length, denier, and type of fibers present in the web, the proportions of the respective fiber types, chemical additives, and the method of making the paper.
Applicants have smprisingly found that a sott, absorbent, strong paper web can be produced,

2 usiag conventionat and through air drying pape,r machines, &+ough the additlon of pacticautar pmportions of lyocell fibers having part[cular lengtha. Bmbodimeats of the inventfcn hm improved soflnoes with abwxbmy at least equivalent to a tppical papcx web. Tha webe of t6e invettion may also hsve an impmved rstio of wet burst atregW to total tensils streagth when conopared to apaW web withcxrt lyoceU tibers. The webs naay alao have impro"d sofRness with high lin# reaia6me.
LyoceH fibeca are solvent spim cellatose fibers pmduaod by ecttvding a eolution of eellulo9e into s coagatating bath, Lyoeell Sbec is to be distingaiahed from eellu,lose fiber amde by otta~r lozown procesge:4 which roly on tbo fornadon of a aolnble cheinioal derivative of celtnloe and fts aubsequent dccomposition to regenerate tha cellulosa, far exaniple the macose pmess.
Lyoceit is a generic term fos fibers apun directly from a sohdm of celiutoee in an amine oxide.
The production of lyocdl fiben is the subjoct matter of many patents. Examples of solveutr spiming processes for the prodnetion of lyocell fibers are described in: U.S.
Pat No. 4,246,221:
U.S. Pat. No. 5,725,821: U.S.Pat. No. 6,042,769; US Pat.6,258,304; US Pat.
6y41,927; US Pat 6,235,392; US Pat.6,210,801; US Pat. 6,153,136; US Pat. 6,103,162; US Pat.
5,939,000; US Pat.
5,919,412; US Pat. 5,766,530.
The practice of the preaent invention is not lirnited to the use of lyoaell tibcrs produced according to the patenta of the preceding iist. The non-eahaustiva list is intended to provide eaamples of processes for the manufacture of lyocall fibers. Lyocell fiben ere available in a broad range of fiber lengds and di.amatera. Tha fiben used in the embodimeate of the pmeent invcntion range from 0.5 mm to 8 mm and from 0.8 to 5.0 daWer, optionally 1 to 4 denier, and alternatively 1.5 to 3 denier.
As used hes+tin, the tmms "tisaue paW web, paper web, web, paper eheet and paper product" all refer to sheets of paper, or sheet-hlm materiala, made by a prnoeas aompnsing "
steps of forming an aqueous paper meldng fianish, depositing thia fianish aa a fasminous surface, such as a Foutdrinier wirc, and removing the water fnnm the famish as by gravity or vacnnm-assisted drainago, with or without pressing, and by evaporattoa As used herein, an "aquoaus paper maktng furnish" is an aqueous shury of paper nalcmg fiben and the chemioale deacri'bed henrinaReor.
As uacd herein, the term "multi-layered time paper web, mnlti-layered paper web, muiti-layered web, multrlayea+ed paper sheet and multi-layerod paper pnaduat" all refer to s2wb of Paper pepared $roam two layen of aqueous paper maldng fumish wbich are preferably comprised of different fiber types. The layers may be formed from the deposition of sepsrabe streams of dilute fiber shuries, upon one or more endless foraminova screas. If the individual layers are

3 initially formed on separate wires, the layers are subsequently combined (while wet) to form a layered composite web.
As used herein the terms "multiply tissue paper product, and multi-ply web"
refers to a paper consisting of at least two plies. Each individual ply in turn can consist of single-layered or multi-layered tissue paper webs. The nniltiply structures are formed by bonding together two or more tissue webs such as by gluing or embossing.
The paper web may be blended. By blended it is meant that the paper web comprises a homogeneous mixture of fibers. The lyocell fibers can comprise from about 3%
tio about 70% by weight of the fiber mixwm. Optionally, the lyocell fibers may eomprise from about 70A to about 60% of the fiber mixture. Altematively, the lyocell fibers may comprise from about 10% to about 50% of the fiber mixture. In another alternative, the lyocell fibers may comprise from about 12%
to about 40% of the total fiber mixture. In still anotlw alternative, the lyocell fibers may comprise from about 15% to about 35% of the fiber mixhme. In yet another alternative, the lyocell fibers may comprise from about 17% to about 30% of the total fiber mixture. In yet one more alternative, the lyocell fibers may oomprise from about 20% to about 25% of the total fiber mixtvre.
The lyocell fibers of the preseat invention may have a lower fiber length limit of about 0.5 mm. The lower fiber length limit is the fiber length comspond'mg to the shorbest fibers intentionally present in the web of the invention. Those skilled in the art will recognize that "fine.s", fibers of short fiber length, will be unintenntionally present in the web. Optionally, the lower fiber length limit may be about 1 mm. Alternatively, the lower linut may be about 1.5 mm.
In another alternative, the lower limit may be about 2 nun. In still another altemative, the lower limit may be about 2.5 mm. Similarly; the lyocell fibers have an upper fiber length limit corresponding to the longest fiber length intentionally present in the webs of the present invention. The upper fiber length limit may be about 8 mm. The upper fiber length limit may alternatively be about 6 mm. Optionally; tiw upper limit may be about 5.5 mm.
Alternatively, the upper limit may be about 5 mm. In another alternative, the upper limit may be about 4.5 mm. In yet another altexnative, the upper liniit may be about 4 mm In still another altemative, the upper limit ntay be about 3.5 mm. In still yet another alternative, the upper limit may be about 3 nun.
Up to about 60% by weight of the lyocell fibers in a homogeneously blended web may have a length of about 6 mm or greater, the remaining lyocell fibera having lengths less than about 6 mm. Optionally, up to about 50% by weight of the lyocell fibers may have a length of about 6 mm or greater. Altematively, up to about 40% by weight of the lyocell fibers may have a length of about 6 mm or greater. In another alternative, up to about 30% by weight of the lyocell fibers

4 may have a length of about 6 mm or greater. In still another altemative, up to about 20% by weight of the lyocell fibm may have a length of about 6 mm or greater. In st01 yet anntber alternative, up to about 100/a by weight of the lyocell fibers may have a length of about 6 mm or gceater. h- another alternative embodiment, up to about 5% by weight of the lyocell fibers may bave a length of about 6 mm or greater.
The paper web according to the present invention may be multi layered. In multi layered embodiments, the length and proportions of lyocell fibers in each layer may be varied. It is possible to make a two-layered web with lyocell fibers in only one of the two layers, or with lyocell fibers present in each layer. The length and relative propartion of lyocell fibe.rs in saeh layers may be varied in the same manner as set forth above for a homogeneously blended web. In a pattieular layered web, the proportion of lyocell fibers in one layer is from about 35% to abont 45% of the weight of ihe fibers in that layer. The rawnder of the fiber weight of each layer is comprised of non lyocell papermaldng fibers.
It is anticipated that wood pulp in all its varieties will normally comprise the balance of the paper malung fibers used in this invention. However, othis cellulose fibrons pulps, such as cotton linters, bagasse, rayon, etc., can be used and none are disclaimed.
Wood pulps useful herein include ehemical pulps such as Kraft, sulfite and sulfate pulps as well as mechanical pulps including for example, ground wood, thermomwhanical pulps and Chemi-1'hennoMecliaaical Pulp (G'TMI'). Pulps denved from both decidnous and eonfferous trees can be used.
Synthetic fibers such as rayon, polyethylene and polypropylene fibers, may also be utilized in combination with the above-identified natural cellnlose fibers, and the lyocell fibers.
One exemplary polyethylene fiber wbich niay be utilized is PULPEX , available from Hercules, Inc. (Wilmington, Del.).
Both hardwood pulpa and softwood puips may be employed. The terms hardwood pulps as used herein refers to fibrous pulp derived from the woody substance of deciduons trees (angiosperms): wherein so8wood pulps are fibrous pulps derived from the woody substanee of coniferous trees (gyainospcrms). Also applicable to the present invention are low cost fibers derived from recycled paper, which may contain any or all of the above categories as well as otha non-fibrous materials such as fillers and adhesives used to facilitate the original paper making.
The present invention is applicable to tissue paper in general, including but not limited to conventionally felt-pressed tissue papa; high bulk pattern densified tissue papar, and high bulk, uncompacted tissue paper. The tissm paper products made therefrom may be of a s'rngle-laytted or multi-layered eonstruotioa Tissue stcactures formed from layered paW webs are described in U.S. Pat. No. 3,994,771, Morgan, Jr. et al. issued Nov. 30, 1976, U.S. Pat.
No. 4,300,981, Carabens, Wued Nov. 17, 1981, U.S. Pai. No. 4,166,001, Dunning et al., issued Aug. 28, 1979, and Buropam Patent Publication No. 0 613 979 Al, Edwards at al., published Sep. 7, 1994.
Pattwn densified tiasae paper is characterized by having a relatively higb bulk field of relativety low fiber density and an etYay of denaified zonee of relatively high fiber deaaity. The high bulk field is altornafively ehuacterind as a field of pillow regiona. The densified zones are alternativety refened to as knuckle regiona. The dcnaiSed zones way be disonetely spaced witbia the lugh bullc field or may be inhrconmected, ecither flWly or partially, within tha bigh bulk field.
Prefared proceasea for maldng pattarn denaified tiasuo weba are disclosed in U.S. Pat No.
3,301,746, issuod to 3anford and Sisson on Jan. 31, 1967, U.S. Pat. No.
3,974,025, iaaud to Peter o. Ayera on Aug. 10, 1976, and U.S. Pat. No. 4,191,609, iaaaed to Pau1 D.
'Iroldisn on Met+eh 4, 1980, and U.S. Pat. No. 4,637,859, issued to Panl D. Trokban on Jan. 20, 1987, U.S. Pat. No.
4,942,077 issued to Wendt et al. on July 17, 1990 , Buropean Patent Publication No. 0 617 164 Al, Hyland et al., pubiiahed Sep. 28, 1994, European Patent Publication No. 0 616074 Al, Hormans et al., published Sep. 21,1994.
In general, pattern denaifial weba are prefembly preperOd by depoaiting a papec malang fucnish on a faraminoua formfug wire anch as a Fwudrimier wire to form a wet web and then juxtaposing the web against an array of sappocta. The web is preased againat the array of supporta, thareby resulting in denaified zonea in tho web at the locations geographically cortvaponding to the points of coutaot betwaoa the axray of augporte and the wet web. The remainder of the web not compressed during this operation is refared to as the high bulk field. Thia high bulk field oan be finther dcdensified by application of fh;dd pressure, such as with a vacuum type clevioe or a blow-tbrougl- dryar. The web is dewatared, and aptionally predried; in eueh a so ea to substantially avoid compreseion of the high bulk field. This is preferabiy accomplished by fluid preasure, such as with a vacuum type devioa or blow tbrough dryer, or alternately by criechanically presaing the web agamst an array of soppons wharom the higb bulk field ia not compressed. The opexatione of dewabering, optional predrying and formation of the densified zones may be integrated or partially integtated to reduce the totat number of procxseing etepa perfornxd. Subseqnent to formation of the densified zones, dewaberusg, and optionat prahying, tha web is driai to coxnpletio.n, prefembly still avoiding uieeheaioal pnsaing. Proferably, from about 8% to about 55% of the aadti-layerad tisaao paper surface oomprlsee deesified ]mvekles having a relative density of at teaat 125% of the dt.naity of the bigb bulk field. Tha optional predrying may be accomplished using throngh air drying as is known in the ast.17w opaating temperature ntilized in the tlrough air drying may be in the range from about 225 degrees Fa>ueaheit to about 525 degmm Fakeaheit. Applieanta bave surprisingly found that the web eompriaed of lyocell Sbaa may be predried to an equivaleat camaisteacy as a non-lyooell eontaining web of similar basia weight, utilizing a lower predrying ftmperataca.
The array of supporta is pceferably an iapinting canier falnic having a pattarned displacement of lmucidea, which operate as the array of supparts, which f3;cilitate the formation of the denaified zonea upon applioation of pmme. The pattern of imncklea constitobea the array of snpports previonaly referred to. Inprinting camter fabriea ara disclosed in U.S. Pat No.
3,301,746, Sanford and Sisson, ismied Jan. 31, 1967, U.S. Pat. No. 3,821,068, Salvacci, Jr. et al., issued May 21, 1974, U.S. Pat. No. 3,974,025, Ayera, issued Aug. 10, 1976, U.S. PaL No.
3,573,164, Friedberg et al., issued Mar. 30, 1971, U.S. Pat. No. 3,473,576, Amneu, issued Oct.
21, 1969, U.S. Pat. No. 4,239,065, Trokhan, isaoad Dec. 16, 1980, and U.S.
Pat. No. 4,528,239, Trokhart, issuad Jul. 9, 1985.
Uncompacted, norVattem-densiSed multi-layered tissue papc strueturas we desaribed in U.S. Pat. No. 3,812,000 isaued to Joseph L. Salvucci, Jr. and Peter N. Yiamios an May 21, 1974 'and U.S. Pat. No. 4,208,459, issued to Henry B. Beclaer, Albert L. MaCemdell, and Ricbard Schutte on Jun. 17, 1980. In gwera1, uncompacted, non patDan densiSed multi layerod tiem papec structures are prepand by depositing a paper making fiamish on a fmminons fornring wire aach as a Fourdinier wira to form a wet web, dtaining the web and removing additional water without meeha ioal eomprassiert _ untll the web has a fiber consistarey of at kast 80%, and creping the web.
Water is renwved 8om tlm web by vacaum dewabaring and ttmuul drying. The resulting struettu+e is a soft but weak high bulk ahed of relatively ttacompected fibers. Bonding mate,risl is preferably appiied to portions of the web prior to excping.
The webs of the invention may be made without the use of a Yankee drier, in accordance with U.S. Pat. 5,772,845, issued June 30,1998 to Parrington, et al.
The webs may be foreshortened by creping, ar by other raeaas sach aa wet micro contraction as is known in the a:t, The webs of the pneaent inventioa may be used in any application whece soft and/or absorbent produats are required. Particularly advantageous, though non-limitiag uses of tbe invcntion are in paper towels, facial and bath tissues. The webs may also be used m absorbe,nt ardcles, for example, diapers, and fieminine hygienc pivducts, as well as in wipea typa products such as pre-moiateaed baby wipes and asulogoua products.
A web prodnad in a papermaking machme has two distinct stufiices, a wire contacdng surface, or wire contacting side, and a fabric cantacting swrfac% or fabric oontia,cting side. The wire contacting sida is the surface of the web in condu,t with the facming wiro of ft nmchirr.
The fabric contnctiag side is that eiufaee ia contwt with the drying fabrie of the paper amchme.
Bmbodiments of the preeait inrention may be produeai with lyocell fibers m the wlre coirtaating layar, the fabric contacting layer or both.
il is possble to join multiple plies of such a layered paper web to each other focming a laminated web. The pliea may be joined anch tlW layers with ehort lyocxll fiben are oriented inward toward each offia in the inddrior of the lanrinated web and layers compised of long lyocell fibe.rs oriented outward. Atbernatively, the layers comprised of long fibers may be oriented inward and the layers comprised of ahod fiben oriented ontward.
FIG. 1 is a sehematic cross-sectional view of a two-layered, two-ply web in accordance with the pssent invention. Referring to FIG. 1, the two-layaed, two- ply web 10, is oompised of two plies 15 in juxtapoaed relation. Bach p}y 15 is eomprisod of imia layec 19, and outer lapar 18.
A mnlti ply papex may be produced from individual mdti layer plies haviog lyocell fiben fa only one layer of each ply. A muld ply paper with lyocell in the oubei layers 18, bmefita from the sofineea of lyocall fibers and ean have a bettar hand feol than a papor having no lyocell in the outor layeta 1 S. A paper with a high parcentage of lyocell fibers in the interia layers 17, benefits from the absorbency of lyocell fiben and caa have a high absorbent capacitlr.
Such a multi ply web compr9sod of multi layer plies may be produced with lyocell fibera in all layers, alternatively with lyocell fiben exchnively in the outer layera and, in another altcrnative, with lyocell fiben ezchnively in the inteaior facing layers.

CHEMIGAL ADI?.PTIVES:
The attribatea of tha papac webs of the present inveution may be fiather impaeted by the use of ahemical additives. The prooeae for manufachuing the webs may also be made mo~e reliable thmugh the addition of selected chemical additives. Additives for enhancing abeorbenoy, dry strength, sof3nese, and lint resistemce may be mea:porated mrto the webs of the present invention. Temporary and parnnanent wet streY-gth enhancu-g additives and wetting agents may also be incocporated into the webs. The use of euah chemicals is well lmown in tho ark Examples relating the use of snch additives may be found in U.S. Pat 5,538,595, iesued July 23, 1996 to Trohkan, at al. and U.S. Pat 5,573,637, issued November 12, 1996 to Ampulslci et ai.
Wetting ageuta to irnprove the reliability of the manufacturing proeess may also be added.
Two Coaroortat Chemical Softem Comoositiona The present invention may contain a chemical softening composition. Such a soACning cornposition may comprise an ester-fametional quateinaiy ammonimn comPoand, or a quatemary ammonium compound. Alternatively, snah a softening conipound may comlxise an ester-functional quaternary ammonium compound and a polysiloxane compound, or a quaternary ammonium compound and a polysdoaane compound.
A. Estei- mrtjonnl qnatrrnarv ammcmium cOIDD011QdS:
Specific non-liniiting examplea of esler-fimctional quate,rnaty ammonium compounds suitable for use in the present invention include the well-lmown di-ester di(alkyl) dimetbyl ammonium salts such as di-ester ditallow dimethyl ammonium chloride, mono-ester ditallow dinnethyl amnwnium chloride, di-ester ditallow dimethyl ammonium methyl salfate, di-ester di(hydrogenated)tallow dimethyl ammonium methyl sulfate, di-ester di(hydrogenated)tallow dimethyl ammonium chloride, and mixtura thereof.
B. Quatemarv ammonium comggmida:
Examples of quatemary ammonium compounds suitable for use in the present mvention include the well-known dialkyldimethylaxmmonium salts such as ditallow dimethyl ammonium chloride, ditallow dimethylammonium methyl sulfate, and di(hydrogenated)tallow dimethyl ammonium chloride.
C. PolYsiloxane CoMunds=
In general, suitable polysiloxane materials for use in the present invention include those having monomeric siloxane units of the following stcuctme:

4-Si -0-+
Rz wherein, Rt and R2, for each independent siloxane monomeric unit can each independently be hydrogen or any a1kyl, aryl, alkenyl, alkaryl, arakyl, cycloalkyl, halogenated hydrocarbon, or otr radioal. Any of such radicals can be sub,tituted or unaubstitutod. Rl and R2 radicals of any particular monomeric mft may dift Snm ft correspaadina ftmcticanslitiea of the nw acl,johmtg mmommc unit Additiona8y, tlre polysiloxane can be either a saaight chsin, a branched cham or have a cyclic struv~ The rachoala Rt and R2 oan additionally mdependeotly be othw slCaous fimctionalitiee such se, bnt not limited to silomnm polydloxsaa, silaaea, md polysilaars. The radwsle Rl azrd Rz nmy contain say of a variaty of orPtic llinotionelities including, for oaampla, alcohol, carboxylic acid, aldehyde, loetone sad sorina, amide fmuonalities.
Exemplary alkyl radicsls aro methyl, oftl, propyl, bntyl, pentyl, hacyl, octyl, decyl, oetadecyl, and the l0ae. Eaemplary alloenyl radicals are viayi, allyl, and the lilaa. Exemplary aryl radicals are phenyl, dipheayl, naphthyl, md tlye h'los. Saemplary alkaryi radicals ,ee teyl, xylyl.
etttylpharwyl, and the lika. Bxemplary aralcyl radfoals are benayl, alphalhenylethyl, beta phaayletbyl, slpha-phenylbutyl, and the liloe: Bxemplary oyeioalkyl uadieale are oyolobutyl, cyclopentyl, eyclohexyl, and the lilae. Eaemplary halogenatod hydrocarbon radiicals a:+e ehleroznetbql, bromoethyl, tetrafluorethyl, fliwrothyl, triAucredyl, titlaoratayl, basafluoroxylyl, and ft Mce.
Vieeosity of polysilomkaea neeful may vary as widely as ttw viscasity of polysiloxanes in genaral vary, so long as the polysiloaaae is flowable or oaa be amde to be flowable for applioation to the tisaae paper. The polyeiloxane may have an intriaeic viseosity rangmg from about 100 to about 1000 centipoisea. Refa-ence4 disclosing polysiloxanea includa U.S. Pat No. 2,826,551, issaed Mar.11,1958 to Geea; U.S. Pat. No. 3,964,500, issued Jun. 22,19761D
Dralroff-, U.S. Pat No. 4,364,837, ieeued Dec. 21, 1982, Pader, U.S. Pat. No. 5,059,282, issued Uet. 22, 1991 to A.mpulsld et al.; and British Patent No. 849,433, published Sep. 28, 1960 to Woolaton.
Also, Silicon Compounds, pp 181-217, disdrlbuted by Petraroh Systams, Inc., 1984, oontsins an extensive listing and description of polysiloxanes in geieral.

Wet slreaath binder mitaWs:

Tl-e peamonent wet strangth biader matenala are chosen from die following group of chemicals: polyamide-epichlorohydrin, polyacrylamidea, atyrenebutadiene latexea; inaohibilized potyvinyl alcohol; urea formaldehyde; polyetliylsAemiiae; chitoeaa polymws md mixturoe thereof. The perument wet strength bunder materiale may be selected from the group consisting of polyamide-epiohlorohydrin resioa, potyacrylamide tGaitre, aad mixhuee thmwf The pemaneut wet stnength binder materfals act to control linting and also to offset the lose in tmile slrength, if any, resultiag from the chemicai soibaner compositions.
Polyamido-epielilorohydcin reains ara cationie wet strongth rr.sins wbieh have bem fouad to be of patticular utility. Suitable types of such resiw are described in U.S. Pat. Nos. 3,700,623, issuad on Oct. 24, 1972, and 3,772,076, isaued on Nov. 13, 1973, bodi iseued to Relm.
One commercial source of a uaeU polyamide-epichiorohydrin resins is Herculesõ Inc. of Wilmingtan, Del., which markets such resin unda the trade-mark KY11ENE 557H.
Polyaay-larmde resins have also been found to be of utdity as wet stresigdi resins. These resins are descri"bed in U.S. Pat Nos. 3,556,932, issued on Jan. 19, 1971, to Coecia, et al. and 3,556,933, issued on Jut. 19, 1971, to Williams et al.
One commeroisl source of polyacrylamido resins is American Cy-anamid Co. of Stanford, Cooa., which markft one auch resin ander the ftde-merk PAREZ 631 NC. Still other water-soluble catiouic reeine futding op7ity in thia iavention are urea foamaldehyde and aulamine fomoaldehyde resins.

B. Temnorarv wet amgatl- biuder materisls The above-mentioned wet strength additives typicelly result in paper products with pearnanent wet strongth, i.e., paper which when placed in an aqueous medium retaiae a substantial portion of its initial wet strength over time. However, permanent wet strength m some types of paper pvducts can be an uanecessary and undesirable propaty. Paper products such as toilet tissues, etie., are gcnerally disposed of after brief periods of uae into septic syatems and tha lOce.
Clogging of these systeme cau result if the paper product pamanently retsins fts hydt+olysis-resistant strength praperties. More recandy, manufachrera have added tanpo7ary wet strength additives to paper products for which wet strength is safficient for the intended use, but which then decays upon soaking in water. Decay of the wet strength facilitates flow of the paper product through septic systems.
Examples of suitable temporary wet strength reaias include modified starch temporaty wet stmvngth agents, such as National Starch 78-0080, marlaebed by the Nstional Stnch and Chemical Corporation (New Yarkõ N.Y.). This typo of wet atrength agent can be made by reacting dimethoxyetlryl N-methyl-chloroacetacreide with cationio starch polymare.
Modified starch temporary wet strength agents are also docn'bed in U.S. Pat. No. 4,675,394, Solarelc, et al., issaed Jun. 23, 1987. Temporary wet strength resins inclnde those deseribai in U.S. Pak No. 4,981,5S7, Bjorloquisr, issued Jan.1, 1991.

With respect to the cissm and specific cxamplet of both permanent and temporary wet strength rams listed above, it should be nnderebood that the resims lisbed ara ewnVlary ia nawrrs and are not meant to limit the scope of tMs im-enfiion.
Mixtutea of compati'ble wet stz+atgah ream can also be used in the prwioe of this invention.

2a staLQth binder materials The present invention contains as an optional component fmm about 0.01% to about 3.0 /a, and alternatively from about 0.01% to about 1.0% by weight of a dry sCcngth bindar matcrial chosen flro3n tha foIlowing group of matarials: polyacrylamide (such as oonmbimtiona of CYPRO 4D 514 and ACCOSTRENC3TH 711 produced by American Cyanamid of Wayne, N.J.); starch (stimh as REDIBOND 0 5320 and 2005) available finan Natieaal 3tsn+ch and Chemical Company, Bridgewater, NJ.; polyvinyl alcohol (snch aa AIItVOL (D 540 produced by Air Products Inc of Alleatoa+n, Pa.); guar or locust bean gums; arrd/or carbax~ymethyl cellulose (such as CMC from Herculee, Ine. of Wilmington, Del.). The dry sh+ength binder mataiala may be selected froon the group consisting of earboxymethyl cellalose resins, and unmodified starch based reains and mixtures thereof, The dry suength binder materials act to control lfnmg and also to offset the loss in tensile strength, if any, resultieg fim the clewdcal soRaner Gomposidm.
In geneisl, suitable starch for practicingthe present invention is chmcMrized by water solubility, and lrydrophilieity. Exemplary stsieh rnateriais include eom stareh and potato stanch, albeit it is not intended to thereby linrit tha scope of suitabk starch materiala; and waay corn starch that is lmown industrially as amioca starch is also ueable. Aanioca smrch differa fYom common corn starch in dat it is entirely autylopectin, whoreas common c.an starch eoatains both amplopeetin and amylose. Viriona unique characteristics of amdoea starch are furWer deseribed ia "Amioca-The Starch from Waxy Corn", H. H Sr.hopmeyer, Food In+dustriea, DwxmbCr 1945, pp.
106-108 (Vol. pp. 1476-1478). Tha starch can be in gianaula< or dispersed form. Ttia starch may be sufficiently cooked to indaae awrcJling of the g-anailee. Alternatively, the stac+ch granutes are swollesz, as by cooldng, to a point just prior to disparsion of the starch gramle. Such highly sarollan atgreh graaules shall be referred to as being "fully cooked". The conditiona for dispersion in genenal can vary flcpending upon ffie size of the starcb gtanules, the degree of raystaIlinity of the grannles, and the amount of anrylose present. Fully cooked amioca smrch, for ezample, can be prepared by heating an aqueous slurry of about 4× consistency of starch granules at about 190° F. (about 88° C.) for between about 30 and about 40 minutes.

Wetting agents=
The present invention may contain as an optional ingredient from about 0.1% to about 3.0 fo, alternatively, from about 0.03% to about 1.0% by weight, on a dry fiber basis of a wetting agent. Wetting agents may be used to improve the performance of low grade fiber sourcos, as well as to improve the reliability of the manufacturing process used to make the webs of the invention.
Po)ylvdroxv ConxDgund The chemical softening composition contains as an optional component from about 0.01% to about 3.00% by weight, preferably from about 0.01% to about 1.00% by weight of a water soluble polyhydroxy compound.
Examples of polyhydroxy eonmpounds useful in the present invention include glycerol, polyglycerols having a weight average molecular weight of fi+am about 150 to about 800 and polyoxyethylene glycols and polyoxypropylene glycols having a weight average molecular weight of from about 200 to about 4000, preferably from about 200 to about 1000, most preferably from about 200 to about 600. Polyoxyethylene glycols having an weight average molecular weight of from about 200 to about 60 Oare especially preferred. Mixtux+es of the above-described polyhydroxy compounds may also be used. For eaample, mixtures of glycerol and polyoxyethylene glycols having a weight average molecular weight from about 20 to 1000, more preferably from about 200 to 600 are useful in the present invention. The weight ratio of glycerol to polyoxyethylene glycol may range from about 10:1 to 1:10.

Nonionic Surfactant (Allcoxylated Materials) Suitable nonionic surfactants that can be used as weaing agents in the present invention include addition produots of ethylene oxide and, optionally, propylene oxide, with fatty alcohols, fatty acids, fatty amines, etc.
Any of the alkoxylated materials of the particular type described hereinafter can be used as the nonionic surfactant. Suitable compounds are substantially water-soluble surFactanis of the general formula:
Ra-Y-(C2H4OVC2H4OH

wherein R2 for both solid and liquid compositions is selected from the group eonsisting of primary, secondary and branched chain aikyl and/or acyl hYdrocabYl groups;
PrmMY, sOcOndgrY
and brmched chain alkenyl hydrocarbyl gtoups; and primsry, seeondary and branched chain, allryl- and alk=yl-substituted phenolic hydrocarbyl groups; said hydroearbyl groups having a hydrocarbyl chain longth of from about 8 to about 20, preferably from about 10 to about 18 earbon atoms. Alternatively the hydrocarbyl ehain length for liquid aompositions is from about 16 to about 18 carbon atoms and for solid compositions from about 10 to about 14 carbon atoms. In the general formula for the ethoxylated nonionic surfaotants herein, Y is typically --0-, --C(O)O--, --C(O)N(R)--, or --C(O)N(R)R-, in which RZ, and R, when present, have the meanings given herein before, and/or R can be hydrogen, and z is at least about 8, preferably at least about 10-11.
Performance and, usnally, skability of the softener composition decrease when fewer ekhoxylate groups are present.
The nonionic surfactants herein are characterized by an HLB
(hydrophiliclipophilic balance) of from about 7 to about 20, preferably from about 8 to about 15. Of course, by deSning RZ and the nnmber of ethoxylate groups, the HLB of the surfactant is, in general, determined.
However, it is to be noted that the nonionic ethoxylated surfactants useful herein, for concenttated liquid compositions, contain: relatively long chain R2 groups and are relatively highly ethoxylated. Wkrile shorter alkyl chain surfactants having short ethoxylated groups may possess the requisite HLB, they are not as effective herein.
Examples of nonionic surfactants follow. The nonionic surfactants of this invention are not limited to these examples. In the examples, the integer defines the number of ethoxyl (BO) groups in the molecule.

Linear Alkoxylated Alcohols A. Linear, Prfmary Alcohol Alkoxylates The deca-, undeca-, dodeca-, tetradeca-, and pentadeea-ethoxylates of n-hexadecanol, and n-octadecanol having an HLB within the range reeited herein are useful wetking agents in the oontext of this invention. Exemplary ethoxylated primary alcohols useful herein as the viscosity/disperslbility modifiers of the compositions are n-Cts EO(10); and n-Cia EO(11). The ethoxylatts of mixed natuial or synthetie alcohols in the "oleyl" chain length range are also uscful herein. Specific examples of such materials inclnde olcylalcohol-EO(11), oleylalcohol-EO(18), and oleylalcohol -EO(25).

B. Linear, Secondary Alcohol Alkoxylabes The deca-, undeca-, dodeca-, tetradeca-, pentadeca-, octadeca-, and nonadeca-ethoxylates of 3-hexadecanol, 2-octadecanol, 4-eicosanol, and 5-eicosanol having and HL,B
within the range recited herein can be used as wetxing agents in the present invention.
Eaemplary athoaylabed secondary alcohols can be used as wetting agents in the present invention are:
2-Ct6 EO(11); 2-C20 EO(11); and 2-C16 EO(14).

Lincar Alkyl Phenoxylated Alcohols As in the case of the alcohol alkoxylates, the heaa- through ootadeoaethoxylates of alkylated phenols, partioularly monohydrio atkylphenols, having an HLB within the range recited herein are useful as the viscosity/dispersibility mod'ifiera of the iaetant eompositions. The hexa through octadeca-ethoxylates of p-tridecylphenol, m-pentadccylphenol, and the 1>7ce, are useful herein. Exemplary ethoxylated alkyiphenols useful as the wetting agents of the mixtnres hercin are: p-tridecylphenol EO(11) andp-pentadecylphenol EO(18).
As used heroin and as generally necognized in the art, a phenylene group ia the nonionic formula is the equivalent of an alkylene group containing from 2 to 4 carbon atoms. For present purposes, nonionics containing a phenylene group are considered to contain an equivalent number of carbon atoms calculated as the sum of the carbon atoms in the alkyl group plus about 3.3 carbon atoms for each phenylene group.
Olefinic Alkoacylates The allcenyl alcohols, both primary and secondary, and alkenyl phenols corresponding to those disclosed immediately herein above can be ethoxylated to an HLB within de range recited herein can be used as wetting agents in the present invention Branched Chain llllaoxylates Branched chain primary and secondary alcohols which are available from the well-known "OXO" process can be ethoxylated and can be used as wetting ageats in the present invention.
The above ethoxylated nonionic surfactants are usefnl in the present invention alone or in combination, and the tcrm "nonionic surfactant" encompasses mixed nonionie sufFace aotive agents.
The level of surfactant, if used, may be from about 0.0 1% to about 3.0% by weight, based on the dry fiber weight of the tissue paper. The surfactants may have alkyl chains with eight or more carbon atoms. Exemplary anionic surfactants are linear alkyl sulfonates, and alkylbenzene snlf'onates. Bxemplary nocionic mwbcbnb ere atkylglyaoidea including alkyiglycoaide eatas such as CRQDBS'TA SL-+40 which is available ftm Croda, ymc. (New Yock, N.Y.);
atk,ylglyceside etbm as deeert'lW m U.S. Pat. No. 4,011,389, isaaed to W. lC.
Langduo, et ai. cn Mar. 8,197 !; mi alkylpolyethoxy4ted esben suah as PEC3O3PBRSB m 200 M[, available frosn Glyco Chearica* l'tx. (CireeYtwich, Conn.). IGEPAL 8$ RC-520, available &om ltlwW Poulenc Corpomtion (G"rsnbtuy, N.J.) is a ps+efeered nufBctant The above listingt of optional ohamical additives is intended to be merely exemVlary in nahu+e, and are net mWmt tu limit the ecope of the im-entioa PAPER MAS.M PRpCESS:
FIG. 2 is a sclmatie repvmtatim nutating a papemlring process foc produciag a soft abmrbent web. Thia pa+ocesa is described in tlre following discussiam, wherein referevice is made to FIG. 2:
M. 2 is a side elevatiooal view of an example of aPRaUmlring maclune 80 for mamifkdmiag papar aemding to ffie preseut invartim Refearing to FIti. 2, pqmmukmg nwhime 80 compisea a layered headbox 81 having a top chamber 82 a ceaber ebambar 82b, and a bottom chamber 83, a slice roof 84, and a Foucdrinier wire 85 which is looped over and about breast roll 86, defleata 90, vacumn suction boxes 91, comh ro1192, and a plurality of tarning rolls 94.
In operation, ow Papmeldng firrnish is pumped tirough top chamber 82 a secaad pqxnmldng fumish is pumped through cseater chamber M, while a tlurd finnish is ptmved through bottom ehamber 83 and thcnce out of tbe slice roof 84 in over and under rebdon ozno Fourdrmia wires 85 to fam thereon an embryonio web 88 aott~Zrising layas SSa, and 88b, and 88o. Dewabering oocute tigoagh the Fourdris-ier wire 85 aad is assisted by deflector 90 and vacanml bozes 91. As ft Fourdrinier wh+e makes its return rua in the direction simm by the arrow, sbowers 95 clean ft prior to ita coomwncing aaother paes over ltteset roll 86. At web teaesfer zone 93, the embryonic web 88 ia transferred to a foraminons carriec fabrie 96 by the actton of vacunm trataft bmc 97. Canier fabuc 96 carries the web from the trm~efer rone 93, tl>c+ough blow throuo predryers 100 and past two turning rolls 101 after which the web is traiortrrod to a Yanioea dryar 108 by the action of prr,se<ae roU 102. The carrier fsbiic 96 is then cleaned and dewatered as it completet its loop by pessing over and aronnd sdcHtionei tnrting rolla 101, showers 103, and vacuunn dewetaring box 105. The predried pqxx web is adhesively secured to the cylndrical surfeoe of Yankee dryer 108 afded by addesive apptied by spray apQHcamr 109.
Drying ia completed on the stemn heated Yankea dryer 108 and by hot air which is heated aed ciueulated #hrough dryrng hood 110 by means not shoarn. The web is then dry creped from the Yankee dryer 108 by doctor blade 111 after which it is "gnated paper sheet 70 cornprising a Yankee-side layer 71 a center layer 73, and an off-Yanlcee-side layer 75.
Paper shect 70 thcn passes between calendar rolls 112 and 113, about a ciroumferential portion of reel 115, and thence is wound into a roll 116 on a core 117 disposed on shaft 118.
Stil1 referring to FIG. 2, the genesis of Yankee-side layer 71 of paper sheet 70 is the fumish pumped through bottom chamber 83 of headbox 81, and whhieh finnish is appliod directly to the Fourdrinicr wire 85 whereupon it becomes layer 88c of embryonic web 88.
The genesis of the ceaiter layer 73 of paper sheet 70 is the ftunish delivered through chamber 82b of headbox 81, and which fiunish forms layer 88b on top of layer 88c. The genesis of the off-Yankae-side layer 75 of paper sheet 70 is the fianish delivexod through top chamber 82 of headbox 81, and which fiunish forms layar 88a on top of layer 88b of embryonic web 88. Although FIG.
2 shows paponnachine 80 having headbox 81 adapted to make a three-layer web, headbox 81 may altcrnatively be adapted to make unlayered, two layer or other multi-layered webs.
Further, with respoct to malcing paper sheet 70 embodying the prosent invention on papennaking machine 80, FIG. 2, the Fourdrinier wire 85 must be of a fine mesh having relatively small spans with respect to the average lengths of the fibecrs consM,uting the short fiber finnish so that good formation will occur; and the foraniinous carrier fabric 96 should have a fine mesh having relatively small opening spans with respect to the average lengths of the fibers constituting the long fiber fiunish to substantially obviate bullQng the fabric side of tlx embryonic web intA
the inter-filamentary spaces of the fabric 96. Also, with respect to the procesa conditions for"
making exemplary paper sheet 70, the paper web is preferably dried to about 80% fiber consistency, and more preferably to about 95% fiber consistency prior to creping.

EXAMPLE:
The following non-limiting example illustrates a paper web of the present invcntion.
Example 1:
Stock chest A contains unrefinod NSK at about 3% solids. Stock tank B contains a nuxWre of 40% by mass of unrefined, 4mm, 1.5 denier lyocell, and 609A unrefined NSK.
This mixture is present in the stock tank at about 1.75% solids. Stock chest C contains CTMP
at about 2.0%
solids. The NSK in stock chest A is pumped out at 11.5 gailons per minute (gpm), and passed through a refining step. A wet strength resin such as KYNgiNE and/or carboxymethyl cellulose is then added to refimned NSK. CTNIP is pumped out of stock chest C
at about 5.5 gpm.

The NSK and CTMP are combined in a first fan pump which also draws water from the wire pit so that the total flow from this pump is about 320 gpm. This mixture is then sent to the fabric side layer of a multi-layer headbox.

The lyocell/NSK mixture is pumped from stock tank B at a rate of about 9 gpm.
Optionally, a strength resin such as KYMENE and/or CMC is added for lint control. This mixture is pumped into a second fan pump where it is combined with water from the wire pit so that the total flow from this pump is about 165 gpm. This mixture is then piped to the wire-side layer of a multi-layer headbox.

'fU sheat is thm fornxd aceardiug to tlis usual papecmaking proca&

The resulting sheet has a basis weight of about 13.7 lb/3000 ft^2. The wire-side layer, cansisting of a 40:60 lyocell:NSK mixture, reprasents about 30% of tlze total sheet weight, or about 4 1b13000fM2.

Optionally, the NSK and lyocell in the fabric layer may be drawn from separate stock chests ratha than baing premixed into a single stock chest. In this case the lyocell is pmsent in the stook tank at about 1.0 fo solids, the NSK at about 3.0% solids. Optionally strength cheniicals may be added to the lyocell, NSK, or both for lint control.

Claims (2)

What is claimed is:

1. A web comprising lyocell fibers, characterized in that no more than about 60% by weight of the lyocell fibers have a length of 6mm or greater.

2. A web according to claim 1 further comprising a wetting agent.