CA1318115C - Hydraulically entangled wet laid base sheets for wipes - Google Patents

Abstract

ABSTRACT

A cloth-like nonwoven material useful for wiping and having strength, toughness, abrasive resistance and resistance to certain solvents and/or chemicals is made from mixtures of wood pulp and staple fibers randomly distributed and hydraulically entangled with each other to form a coherent entangled fibrous structure having a thickness index of at least about 0.008 and a ratio of machine direction strength to cross machine direction strength of at least about 1.5.

Description

FIELD OF THE INVENTION ~ 3 ~ 3 The ~eld o~ the prasent inv~ntion include8 nonwovQn compo~ite mat~rials, for exampl~ hydroentangled material5 containing ~i mixtures oX wocd pulp fibers and staple ~ibers, whieh may be used as wipers for indu~trial and other applications.
J~ 5 BACKGROUND OF THE INVENTION
~, Nonwov~n material~ such a~, ~or exa~ple, m~ltblown or spunbonded polypropylene may bQ used a~ wiper~. In c~rtain applications such as automobile ~inishing the wiper i~ usually moistened with 10 onQ or moro volatile or semi-volatile solve~ts such as, ~or example, isopropyl alcohol/water, n-h~ptane, naphtha, and C5 to 1 C7 aliphatic hydrocarbons in order to remove grea~e, fingerprints ¦ and/or smudgee from th~ automobile fini~h before painting or priming. So~e solvents and/or other chemicals cause some , 15 compon~nt~ such as, for example, low molecular weight polyole~ina to leach out onto the wiped surface rendering that ~ surface unsuitable for painting. Many nonwoven materials are ¦ hydrophobic and require treatment with one or more surfa¢tants to j beccm~ wettable. Th~ surfactant may also be transferred to the ~ 20 wiped s~r~aca rendering that surface unsui able for painting or :~ priming.
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Some nonwoven materials have a low tendency to shed fibers and may ba used a~ wipers in applicatis)n~ where lint and dust are 25 unde~irable such a~, fo~ example, micro-electronic manu~acturing clean rooms. However, such wipes are typically treated with sur~act~nt~ to provid~ ths absorbance and clean wiping char~ct~ri~tic de~ired in Ruch applications. Surfactant treat~ent~ typically comprise an anionic surfactant such as, for ~¦ 30 axample sodium dioctyl sul~osuccinatQ which has a high metallic ion content. These metallic ion~ provide special problems since, . if pre~ent in su~icient concentrations, they may adversely a~fect the electrical properties of metal oxide semiconduc:tors.

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Additionally, certain nonwov0n material~ have a slow rate o~
electrical charge dissipation which r~ult~ in static build-up.
Static build~up on a wip~r may cause problems such as, for example, discom~ort for the us~r, hazards with flammable solvent~ or damage to sen~i~ive elec~ronic equipment.

Nonwoven material~ used in wiping application3 t~pically require som~ bonding to maintain the integrity o~ the nonwoven web.
~ Thermal bonding can reduce the content o~ "active" fibers 3 available ~or absorption. Thermal bonding also results in a 10 stiffer material which may scratch or abrad~ a soft surface such ~ a~ newly applied paint. Chemical bonding offer~ potential '~ problems with extractabla bonding agents.
' Nonwsven materials such as, for exa~ple, bonded oar~ed webs and I 15 air laid web~ ca~ be hydroentangled into a coherent web structure :,1 and u~ed as wipers. However, thesa materials typically havQ high j strength in only one direction becau~e khe fiber3 in the web are :~ oriented in only ona direction during the initial web forming ;~ proce s. That ic, tha materials have high strength in one ~ 20 direction such a~, for exa~ple, the machine direction and . relatively low strength in the cros~ machine direction. This inequality of strength i~ undesirable because the material is . mora likely to tear in the weak direction and because the material must be much stronger than necessary in one direction in 25 order to ~et minimu~ str~ngth requiremsnt~ in the weak direction.
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Compo3it~ hydroQntangled material~ containing stapl~ fibers and . wood pulp ~i~ers are typically mad~ by overlaying a wood pulp : 30 tissue layer on a staple fiber web and hydraulically en~angling : the two layers. Each sid~ of th~ resulting hydroentangled :`~ material usually has a noticeably different level of abrasion re~i~tanc~ from the other side becaus~ of the way the matQrial is produced. : :

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Wood pulp and combinationi~ oP wood pulp and 5tapl~ ~lbers can be proco~ Qd to maka paper tisisue and pap0r item~ which may be used as wlp0r~. Although ths~ wiper~ hav~ de~irable absorbency, ''economy, and rei~i~tanc~ to certain golvantis and chemicals, they 15 generally hav~ low strength (particularly when wet), low ~,toughne33, low abrasion resii~tance and undesirablc levels of lint. Such wip~r~ al90 have poor visual and tactile aesthetics.
~For exampl~, these materials are typically thin and sh~et-like ihaving a thickne~ ind~x o~ about O.01 or typically le~s than 0.01. Some phy~ical properties of the~ materials such as, for example, strength and abra~ion resistancs may be improved by ~'adding binder~. However, bindar~ increa~e thQ CoBt of the wiper ~iand may laave reiidue on the surface to be wipe~O
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-~15 Wip~rs may also be formed from woven material~. Depending on ~he mat~rial used, the wip~rs may have desirablQ absorbency and i~strength but typically aro exp~n~ive and mu~3t be reused in order to be aconomical. Reusable cloths are not de~irable bes:ause they may retain foreign, pos3ibly in~urious objects from previous 2 0 use~ . Cloth mads ~rvm natural f iber~ ha~ the disad~rantage that many natural iber~ surh as, for example, cotton have natural :~oils such a~, for exampl~, cotton oil khat can b~ ex~racted by ¦some solvent~ and depo~ited onto the wiped surface. Cloth made ¦fro~ man-made f~bers such a~, for example, polyester may not be able to ab orb water unlesi3 th~ fibers are treated with a sux~actant 50 that the fib~rs are wettable. The ~presence of sur~aGtants i~ unde~lrable ~or the reason~ noted a~o~e.
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DEFINITIONS
The term "Peak Load" as u~ed her~ln is de~ined as the maxi~u~
amount o~ load or force encountered ln elongating a material to : br~ak~ Peak Load is expres ed in units of force, i.e., g~.
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Tha term "Peak Enerqy Absor~d" (Peak EA) aB u~ed h~x~in is daflned a~ thl3 ar~a und~r a load ver~u~ elongation (strQ~ versus straln) curve up to the polnt o~ "p~ak'~ or maximum load. Peak EA
i9 expra~d in units o~ work, i.e., ~g-mm.

5 The term "Total En~rgy Ab~orb~d" (T~A~ a~ us~d herein is de~ined . a~ the total area under a load ver~us elongation (stress versus :, strain) curv~ up to th~ point where th2 mat~rial breaks. TEA is 1 expre~ad in units o~ work, i.a.~ kg-mm.
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lO The ter~ '~Peak Percentag~ Elon~ation'l as used herein is defined as relativ~ increa~e in length o~ a sp~ci~en when a material is extend~d to up ~o the poin~ o~ "pea~" or maximu~ load. Peak .~ perc~ntage elongation is expr~s~ a~ a percentagq of the original length of ~he material, i.e., [(increa~e in 15 lengt~3/~original length)] X lOO.

Th~ ter~ "Total Percentage ~long2tion" as u~d her~in i~ defined a~ the r~lativ~ increas~ in length o~ a spQcimen when a material is extandQd to up to the point wh~re the mat~rial breaksO Total 20 percentage elongation is expre~d as a percentag~ of the original length o~ the mat~rial~ i.e., ~(increase in . length~/(original length); X lOO.

Th~ tQrm "Thickness Index" as used herein is de~ined as the 25 valuQ repre~entsd by th~ ratio of the thickne~ and ths basis ~ weight of a m~8rial wh~re the thickness is described in :l millimetsr~ (~m) and thQ ba~is wei~ht is described in grams per ~,~ squar~. me~r (gs~. For example, the ~hickness index may be expr~sod a~ ~ollowsO
Thickneg~ IndQx 3 ~thicknes~(mm)/ba~is weight(gsm~3 . '.':
ThQ t~rm "machin~ direction" as used herein is defined as the - direction of trav~l of the for~in~ surface onto which fibers are deposited during ~ormation of compo~ite nonwoven material. ~:
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Th~ tQr~ "cro~-mac:hinQ direction" a~3 u~sd herein i~ de~ined a~
the diraction whlch is perpendicular to thQ machine dlrection.
f 5 Th~ t~3rm "I~otropic Strength Index" a~ u ed herein is defined as the valu~ r~pre~snt~d by th~ ratio of th~ peak load of a material in orl~ direction such a~, for exampl9, th~ machine dir~ction with the p~ak load of th~ matQrial in th~ perp~ndicular direction, for axampl~, the cros~-machin~ direction- The index 10 is 1:ypically ~xpres~3~d a~ the ratio o~ th~ mach~n~ dir~ction peak load with th~ cros3 machinQ direction peak load. Materials usually hav~ an index o~ great~r tha~ on~ ~1) unless a compari~on of peak load in a particu:Lar dir~ction i~ ~pecif ied .
An i~atropic strength ind~x n~ar one ( 1 ) indicates an isotropic 15 material . An isotropic strength index signif icantly gr~ater than on~ ( 1) indicate~ an anisotropic material .

The tern~ "staplQ fiber" as~ u3ed herein refers to natural or : synth~atic f ib~ra having an approximate a~Qrage length of from 20 about 1 ~ to abou~ 24 mm, for ~xample, from aboul: 6 mm to about 15 mm, and an approximat~ denier of about 0. 5 to a~ou~ 3, for : exampls, from about 0 . 7 to about 1. 5 denier.
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. The t~nQ "Total Ab~orptlve Capac:ity" as used herein refers to the 2 5 capacity o~ a material ~o absorb liq~lid and is ralat~d to the total amount o~ l~quid ~eld by a material at saturation. Total Ab~orptiv~ Capa~ y i determin~d by measuring tha increase in theL. w~ight oi~ a material sampl~ r~ulting from the absorption oiE
. a li~id and i9 expre~sed, in percent, a~ the weight o~ liquid . 30 absorbed divided by the weight og .th~ sample. That is, Total Absorpl:ive Capacity = t (saturat~d sample weight - sample weight) /sa~npl~ weight] X 100 .

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The term "Mop Up Capacity" as used herein refers to the capacity of a material to absorb liquid after the material has been saturated and wrung to simulate the mult:iple use of a wiper. The mop up capacity is related to the amount of liquid remaining in a material after liquid is removed ; from a saturated material by wringing. Mop up capacity is determined by measuring the difference between the saturated weight and the wrung out weight of a material , sample and dividing that amount by the weight of the dry sample. It is expressed, in percent, as the weight of ¦ liquid removed from the sample by wringing divided by the weight of the dry sample. That is, [(saturated sample ~ weight - wrung out sample weight)/weight of dry sample] x ,, 100.
Generally the present invention relates to a hydraulically entangled coherent fibrous structure which is capable of being elongated at least 104 percent in at least 3; one direction. The structure may contain wood pulp fiber ~ and it may include up to 100 percent by weight of staple i 20 fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers. The structure has a hot water leachable sodium ion content of at least about 150 parts per million and low levels of ¦ materials extractable in organic solvents.
According to one aspect of the invention, the structure has a thickness index of at least about 0.008 and the structure comprises from about 10 to about 50 percent by weight wood pulp fibers and from about 50 to about 90 percent by weight of the staple fibers. Alternatively the structure may comprise from about 0 to 50 percent by weight of wood pulp fibers and from about 50 to about 100 percent by weight of inelastic staple fibers. More specifically, the structure may have a water absorption capability of at least about 375 percent without the use of surface -i 35 modification treatments. Also, in a specific embodiment, the structure has an oil absorption capacity of at least "'i : ' -':

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about 300 percent without the use of surface modification treatments.
Accordiny to another aspect of the present invention, the structure has an isotropic strength index less than about 1.5, and the structure includes from about 10 to about 50 percent by weight wood pulp fibers and from about 50 to about 90 percent by weight staple fibers.
Alternatively, the structure may contain from about 0 to about 50 percent by weight of wood pulp fibers and from 10 about 50 to about 100 percent by weight staple fibers. A
speci~ic embodiment of the structure may have an oil absorption capacity of at least about 300 percent without the use of surface without the use of surface modification ~¦ treatments.
! 15 The materials of the present invention may be made in i a two step process. The materials are ormed by conventional wet-forming techniques using an inclined I wire. The materials are then hydroentangled using ¦ conventional hydroentangling techniques at pressures 20 ranging from about 500 to about 2000 pounds per square inch l (psi) and at speeds ranging from about 20 to about 300 ! meters per minute to form a coherent web structure without the use of thermal or chemical bonding.
As indicated above, wet-formed materials of the ¦ 25 present invention contain randomly distributed mixtures of wood pulp fibers and staple fibers. Typical materials contain from about 50 to about 90 percent by weight staple fiber and from about lO to about 50 percent by weight wood I pulp fibers. Materials may contain up to about 100 percent ~, 30 staple fibers. The cloth-like nonwoven materials of the present invention ~ave basis weights from about 30 to about 150 gsm.
I Staple fibers used in the invention may have a denier in the range of about 0.7 to about 3 and an average length in the range of about 5 mm to about 18 mm. The staple fibers may be one or more of rayon, cotton, polyester, 1 .;~1 ~j :
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polyamides ~nd polyolefins such as, for e~ample, one or more of polyethylen~, polypropylene, polybutene, ethylene copolymers, propylene copolymers and butene copolymers.
Long fiber wood pulps such as hardwood pulps are also particularly useful. Mixtures of long fiber and short fiber wood pulps may also be used.

DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention there is provided a cloth-like composite nonwoven material having strength, toughness, abrasion resistance, resistance to certain solvents, and good visual and tactil~ aesthetics.
The cloth-like nonwoven material is made from a dispersion of wood pulp fibers and staple ~ibers which is formed into a layer of randomly distributed fibers on a foraminous surface by conventional wet-laying techniques , using an inclined wire. Exemplary wet-forming processes ¦ are described in, for example, U~S. Patent No. 2,414,833 to , Osborne.
i 20 In the headbox of the wet-forming apparatus, the dispersion of fibers may be dilute, for example, containing about 2.5 grams of dry fiber per liter of fiber and water ~ mixture. The consistency of the uniform lay~r of fibers `~ after formation on the foraminous surface may range from about 10 to about 30 weight percent fiber solids in water.
For example, the consistency may be about 25 ' ~ ' ., ~'.
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percent by weight ~olid~ . The uni~or~ lay~r o~ f ibQrs may be tr~n~i~err~d t~s a different sur~ace for entangling. The entangling 3urfac~ may be, for example, a wir~ screen of from abou~ 35 to about 100 m6!~h. The entangled material may b~
tran~ferred ~o ano~her surface for patt*rning. Mesh ~ize and/or 5 the texture of ths ~oraminou~ patterning surface can be varied to ', creat~ dif~erent v i~ual and tact~le propertles. A coarse mesh such as, for exa~ple, fror~ about 14 to about 35 m~h can be used to impart a textile or cloth-llke appearance and feel.

10 Ths newly formed layer of randomly distributed fibers is hydraulically entangled to form a nonwoven material. ~xemplary hydraulic entangling process~ are de c:ribed in, for example, ;', U.S. Pat6~nt No. 3,485,706 to Evan~, th~ disclosure o~ which is hereby inco~porated by reference. For example, entangling may be 15 e~f~cteal with a mani~old produced by Hon~ycomb Systems, Incsrporated containing a strip having O . 005 inch diaDIleter ori~ice~, 40 holes per inch and 1 row of hole~. Other manifold .i conrigurat~on~ may also be used~ The wet-formed materials may be run under the strip at speed~ ranging from about 2û to about 300 20 metar~ per minut~ to be entangled by jet~ o~ liquid at pr~s~3ures ranging fro~ about 500 to about 2000 psi. It ha~ been found that j qreater strength ma~erial~ have been ob~ained by hydro~ntangling the base sh~et~ a~ slower speeds and/or higher pressures.
~ Additional pa~e3 through the hydroentangling eguip~ent also .~ 25 yield~ i~prov~d ~trength.

Patt~rning ~ay be accomplished by tran~ferring th~ entangled m~terial to a coar3e m~sh ~uch a~, for exa~ple, 14 to about 35 me h and ru~nlng th~ matsrial under the hydraulic entangling : 30 apparatus at pressures ~rom about 200 to about 1000 psi.
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The nonwoven material formed by hydraulic entangliny may be dried utilizing one or more conventional drying ~ethod3 such as, .
~or ~xample, ~orce~ air, vacuum, heat or pressur~. The nonwoven ''' l ~' ~ . ,_ 1 3 ~
material ~ay b~ dried on a foraminou~ surface such as, for exa~Dpl~, a wirs mesh. Alt~rnatively, the nonwoven material may be dri~d on an un-tQxtured ~ur~ac~ by conv~ntional drying methods.
Mat~srial~s dr~ ed on a foraminous sur~ace are so~ter and more drapeablQ than materials dri~d on an un-textured surface.
5 Additionally, ma~arial dried on a ~oraminous surfaca can be expectlad to hav~ lower p~ak load~ but great~r peak elongations than materials~ dried on an un-textured ~urface.

In connection with this ~e~cription c6~rtain test procedurea have 10 baen employed to determin~ oil and watQr ab~orption capacity and rate, linting, abra~ion resistance, static decay, drape stif ~ne~3~, sodium ion concentration, level o~ extractables, peak ~, load, p~ak energy absorbQd, total energy ab~orbed, peak .i~ elongation, and total elongation.
Lint t~3~;ts~ wer~ carri~d out u~3ing a CllmstT~ par1:icle countar model Cl-250 available from the Climet Instrument Company, :l, Redland~, California~ T~st w~re conducted essentially in :~ accordance wi~h INDA Standard Test 160. 0 - 83 with the following .1 . 20 change: (1) the sampl~ ~i.ze wa 6 inches X 6 inchlas; and (2~ the '1 background count wa~ not d~tanninEad for each individual specimen te~t2d. This t~t employed a mechanical paxticl~ generator which .~ applied b~ndin~, twisting and crushing forces to sample specimens. Sample. werQ plac:ed in machine direction alignment in 25 an enclosure and twi~ted through an angle of 150~ for a distance ~¦ o~ 4 . 2 inc:h2s at a :rat~ o~ about 70 cycle~ per minute. The encio~ur~ is connect2d by tubing to the particle counter which draw~ the particle~ to the counter at a rate of about 20 cu}:~ic ot per hour. The ~low rat~ tllrough ths in~tr~unen~ sensor is ::30 1. 0 cubic feet p-3r hour. Eac:h count take~ 3~ second~ and repre~ent!3 the num~er o~ particle~ o~ the speci~ied ~ize in 0.01 CUbiG fe~t o~ air.
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Grab ~ensile Te~t were conduct~d Q88Qntia11Y in accordanc~ with Mathod 5100 o~ Federal Te~t Method Standard No. l91A, utilizing ~ampla~ o~ tho entangled material haviny a width o~ about 4 inche~ and a length o~ about 6 inche~. The ~ample~ wer~ held at opposlte ends by a one (1) square inch gripping ~ur~ace. The 5 ~ample~ w~re tasted with an IntellQct II Mod~l t~nsile testing ~, apparatu~ available ~rom Thwlng Albert and with an Ins~ron Model 1122 Unlver~al Ta3ting In~trument, aach having a 3 inch jaw span and a cros~head ~poed o~ about 12 inche~ per minuta. Values for peak load, p~ak en~rgy absorbed, p~ak porcentage elongatio~, 10 total energy absorbed and total percantagu elongakion were determined.
¦ The r~te o~ slectrical charg~ dissipation of the material wa~
I determined e~sentially in accordance with Method 4046 o~ Federal ¦ 1 5 TQ3t Method Standard No. lOlB. Te~t rasul~s were obtain~d with ¦ an Electro/~chTM Calibratsd Electro~tatic Charge Det0ctor with ¦ High Voltage Sampl~ Holder u~ing rectangular ~ample~ mea~uring 5-~ 2 inch~ X 3-1/2 inches.
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~: 20 The rata that the material absorbed oil wa~ deterMin~d as ~ollow~: A aample mQasuring 300 mm in thQ cro~s-machine direction and a~out 150 mm in the m~chin~ direction wa3 placed : ~lat on th~ liquid ~urface of an oil bath containing SAE 20W/50 ~ motor oll. A stopwatch was U9Qd to record the timo for the : 25 sample to compl~tely w~t-ou~, ~hat i~, total ~aturation o~ 99parc~nt o~ th~ 9Ur~aCQ area o~ the ~ampl~. Non absorbent ~treak~
o~ th~ mate~i~l are not acceptable under th~ de~inition o~
compl~t~ w~t-out but non absorbent individual fibers are ; accapt~bla. The rat~ that the material absorb~d water was 30 de~rmingd by the same procedures utilized for oll except that distill~ wat~r was u~ed instead Or oil.

ThR capacity o~ the material to absorb oil was d~tQrmined as follGws: A dry 15 cm X 30 cm standard felt available from the ~ 10 : ~
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1'~ 5 Briti~h Papa~ and Board Indu~try Federation, London, England was sub~erg~d ~or at l~ast 24 hour~ in an oil bath containing SAE
20W/50 ~otor oil. The weight o~ a 10 cm X 10 cm material sample w~ d~t~r~ d to th~ neares~ O.01 gram. The sample wa~ then subm~rged in the oil bath ovQr the piece o~ ~lt until the sample 5 was completQly saturated (at lea~t 1 minute). The ~elt and sample ware re~oved and suspended over thQ bath until the observad drainage of oil from ~he sample Wa~ complete. i.e., when tha 3a~ple as~u~ed a singla overall color or appearance. The drain~d ~ampl~ wa~ weighed to the neare~t 0.01 gra~ and the total 10 ab~orptiv~ capacity was calc~lated.

Th~ mop up capacity of the material was de~erm~ned from the ~, sampla in the total a~sorptive capacity test by folding the saturated sample in half, and thsn in half again. The ~a~ple wa~
~ 15 then gragp~d between the thumb and for~ finger on oppo~ite edge~
;¦ and twisted a~ far as po~ible to wring oil fro~ thQ sampl~. The oil wa~ allowed to drain ~hile the sampl~ wa~ twistQd~ When no further oil dxained ~ro~ the twi~ted sample the ampla was ~ untwi~ted. The sample wa~ weighed to thQ neare t 0.01 gram and 3 20 the mop up capacity was detar~ined.

~ The capacity o~ the material to absorb and mop up water wasj determin~d by ~he sa~Q procedure~ utilized ~or oil excep~ that distilled watQr was used instead of oil.
~ 25 ;~ Th~ drap~ ~ti~n~ mea~ur~m~nt~ were performed using a Shirley .~ Sti~ne~ Te~t~r available from Shirley Developments Limited, l Manche~t~r, EnglandO Ts~t r~sult~ were obtained e~sent$ally in .~ accordanc~ with ASTM S~andard Tes~ D l3a8 except tha~ th~ sample 30 9iZQ wa~ 1 inch X 8 inche~ with the larger dim~nsion in the direction boing te~ted.
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: The l~v~13 o~ (1) extractable~ in isopropyl alcohol, 1,1,1-i trichloroethan~ and distilled water and (2) ~he concentration of : 35 11 '' : ' " ' ~
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1 3 ~ 5 sodlum ion~ wa~ detarmined by th~ following procedure. Duplicate sample~ o~ ~h~ wipe~ wsighing approx~mately 2 gra~s were re~luxed i for 4 hour~ in 200 mL o~ solv~nt u~ing a soxhlet extraction apparatu~. The 901v~nt was evapo~ated to dryne~s and the percent extractablQ~ wa~ calculated by determining the 5 differenco in the weight o~ th~ contain~r beforQ and after evaporation. The perc~nt extractables i~ axpre sed a~ weigh~
perc~nt o~ the starting material. The quantity of odium in the sampl~ wa3 d~t~rminsd by ~ea~uring th~ conc~ntration of sodium ions in w~tar obtain~d fro~ th~ ~oxhl~t extraction apparatus lO a~ter tho water ~xtractable~ test. A Perkin-ElmQr Model 380 ato~ic ab~o~ptlon sp~ctrophotometer wa~ used to measure the ~ sodium ion concentration in tha water.
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7 The abrasion resistance o~ the material wa3 determined 15 e5g~ntially in accordanca with Brlti~h Standard ~t ~thod 5693:
i 197~ with th~ ~ollowing c~ange~: (1) th~ abra~ion machin~ used was availabl~ und~r tha trade de~ignation ~artindale W~ar and ~ Abrai~ion Te~er Model No, 103 ~rom Ahiba-~athi~, Charlotte, North :~ Carolina; (2~ th~ sample~ werQ ubjected to 100 abra ion cycl2R
20 under a pre~ure o~ 1.3 pound~ per square inch (p~i) or 9 ¦ kilopa~cal~ (kPa); (3) a 1.5 inch diameter abradant was a cut .~ fro~ a 36 inch X ~ inch X 0.050 (+0.005) inch piecs o~ glass ~i fib~r reinforced iliconQ rubbQr having a ~urface hardnes~ o~ 81A
.~ Durom~ter, 81+9 Shore A available from Flight Insulation 25 Incorporated, Marie~ a, Georgia, distributors for ConnectiGut ~: Hard Rubber; and (4) the samples were examined for the presence ~r~ 0~ ~ur~aca fuzzing (~iber lo~ting), pilling, roping, or hole~.
-: The ~a~ple~ wQr~ compared to a visual scale and assigned a wear nu~ber ~rom 1 to 5 with 1 indicat~ng little or no visi~le ~:~ 30 abrasion and 5 indicating a hole worn through the sample.
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: E%AMPLE 1 ~ A mixture o~ about 50 percent by weight hardwood pulp a~ailable :~. from th~ Weyerhauser Company under the trade designation Grade ` 35 12 ,'"' ,.~
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Regular and about 50 percent by waight uncrimp~d polye~ter ~tapl~ er ( 1 . 5 denier x 12 mm~, was dispersed to a con~l~tency o~ about 0.5 perc~nt by weight solid and then formed into hand~ha~t~ o~ about 7S gsm on a ~tandard 94 x 100 mesh ~ pla~tic screen.
.` 5 . A manifold availahle from Honeycomb Sy~te~, Incorporated wasutilized to entangl~ tha hand~h~et~. The handsheets were transfQrr~d to a standard 100 x 92 mesh stainles~ steel wire.
The manifold wa~ po~itioned approximately one-half (1/2) inch 10 abov~ tha ~tainle~ steel wire mesh. Th~ manifold contained a ~trip having 0.005 inch diameter orifices, 40 holes per inch and 1 row o~ holes. The strip wa~ inserted into the manl~old with the conical ~haped hole~ diverginy in the direction of the wire.
Entanglement was performed with th~ handsheet tr velling at a lS speed o~ about 20 meter~ per minut~.
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The hand~heot~ were entangled at pressures o~ 200, 400, 600, 800, 1200 and 1400 p~i on one sida o~ th~ sheat and at pressure~ of 1200 and 1400 p~i on the opposit~ side o~ th~ ~heet. The flow 20 rate of th~ entangling wa~er was 1.054 cubic meters per hour per inch o~ strip. The entangled sheet~ were air dried at ambient ~3 temperature. The dried material had a ba~is weight of about 70 j g~m.

.' 25 S~mplc~ o~ th~ entangled material having a width of abGut 4 inche~ w~r~ t2~tQd u~ing an Intellect II tensile ~e~ting apparatU~ availabl~ fro~ Thwing Alb~rt and an In5tron Model 1122 . Unive~ Q~ting Instrument, each ha~ing a 3 inch jaw span and a ;- cro~h~ad spe~d o~ about 12 inchss per ~inute. Value~ ~or Peak 30 Load, Peak EA, Peak Percentage Elongation, TEA and Total ~ P~rcentaga Elongation for the dry samples ar~ rep~rted in Table 1 :~ for th8 machine direction and th~ cros3machine direction.
Similar data wa-~ collected for wet samples in the machine ~ direction only and is also repor~ed in Table 1.
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EX~PLE 2 A mixture O~e about 20 percent by weight hardwood pulp available ~rom the Weyerhau~er Company under th~ trad~ designation Gr~de 5 Regular, about 40 percent by weight uncrimped polye~ter taple ~ib~r (1.5 denisr x 12 mm) and about ~0 peroent by weight uncrimpad rayon stapl~ ~$b~r ( 1. 5 deniQr x 12 mm) wa~ dispersed .~, and th~n for~ed into handsheets of about 75 g~m on a standard 94 x 100 me3h pla~tic ss~re~n.

The handsheet wa~ entangled using th~ equipm~nt and proceLdure of Example 1 on a standard 100 x 92 m~h ~tainlas~ steal wire at pr~sure~ o~ 600, 900, 1200 and 1500 psi on on~ aide of t~e sheet and at pre~3ures of 1200 and 1500 psi on the oppo~it~ ~idQ oS the 15 shee~:. 'rh~ ~low rate o~ th~ ~ntangling water wa~ 0 . 808 cul~ic . r~et~r~ per hour per inch oî s~rip. Th~ ~ntanglad sh~ets wer~ air dried at a~ nt temperature. ThQ dried materlal had a ba~i~
weight of about 73 q~m.
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: 2 0 Samples o~ thQ entangled material having a width of about 4 ~;~ inche~3 ware tested using the equipment and procedure~ of }~xample ~ 1. Valul33 for Peak Load, Peak EA, PeaX Percentag~ Elongation,;. TEA and Total Perc~ ag~ Elongation f~r the dry sample are report3d in q: able 2 ~or the machina direction and t~e c:ros~s 2 5 machine direction .

; A mixtur~ of about 1~.5 pe~c:snt by w~ight hardwood pulp available ~; îro~ th~ Weyerhaua~r Company under tha tra~e de~ignation Grade. 30 Regular, abou~ 78 . 5 perc~nt by weight uncrimpQd polyest~r stapl f iber ( 1. 5 d~niier x 12 mm) and about 3 percent by weight poly~rinyl alcohol binder ~ib~r wa~ dispersed and th~n formed . ~ con~inuously onto a îoraminou~i surfac~ at about 60 g~m. The web wa~3 forDIsd utiliæing a con~inuou2~ inclined wir~ psper making : 3 5 1 '~ . ~.
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mach~n~. Th~ web was dri~d ovQr a geries oP ~tea~n heated can3.
Polyvinyl alcohol wa3 add~d to ~acilitat~ reeling and handling.
, The dri~d web wa~ re-wetted and thell entangled u~ing the equipm~nt and procedure o~ Exampla 1 on a standard 100 x 92 me~h 5 ~tainlesg ~t:e31 wir~ e~ploylng 6 pasRQ~ at pressures o~ 1800 psi on each sid~ o~ th~ shaQt. Th~ ~low rate o~ the entangling water wa~ . 2 . 04 cubic m~or~ per hour p~r inch of ~trip. The entangled shQets wera air driad at ambient tempar~ture. Th~ dried material had a basl~ weigh~ o~ about 53 g~m.

Sampl~3 oS the ~rltangled mat~rial having a width of about 4 inche~ wer~3 te~ted us~ing the equipment and procedure~ of Example 1. Value3 for Peak Load, Peak EA, P~ak Perc~ntage Elongation, TEA and Total Perc~ntage El~3ngation for thQ drf sample~ ar~
15 reported in Table 3 ~or th~ machine c~irection and the cro~s-`: 1 . ~achin~3 direction.

: EXAMP~E 4 . A mixtur~3 oî about 19 percent by weight hardwood pulp available 20 from ~he Wey~rhauser Company under the trade de~nation Grade . ¦ Regular, about 39 pQrcent by weight uncrimp~d polye3ter staple ~: fiber (1.5 deni~r x 12 m~), about 39 perc~nt by w~ight uncrimped rayon 3taple îiber ~1. 5 denier x 12 mm) and about 3 psrcent by weight polyvirlyl alcohol binder ~iber wa~ di~persed and then 25 ~orm~d continuou~ly ont~ a foraminou~ surface at about 60 gs~.
Th~ w~b wa~ for~d utilizing a con~inuous inclin~ wire pa~per making ~nachin~. The web was dried over a seriQs o~ steam h~a~ed can~. Polyvinyl alcohol wa3 addad to facilitate re~linq and han~ling.
Tho drled wQb was pre wetted and then entangled using the . equipment and procedure o~ Example 1 on a standard 100 X 92 mesh . stainlQ~E~ stael wir~. PrQ-WQtting was donè on one side at : pre ~ure~ o~ 200, 400 and 600psi. Entangling on tha~ side was ::. lS
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pQr~ormed at pressure~ o~ ~00, 1000, 1200 and thre~ pass~s at 1500 p3i~ The other sid~ o~ th~ material wa~ entangled by 3 pas~ at 1500 p~i. The entangl~d ~heet~ w~re air dried at ambi~nt t~mperatur~. The dri~d mat~rial had a basi~ weight o~
~about 53 g~m.

',Sample~ of tha dried and the entangled material having a width Iof about 4 inches were te~ted using an Intallect II ten~ile tasting appara~u~ with a 3 inch ~aw span and a.cro~shead spesd of about 10 inch~ per minute. Valuesl ~or Peak load, Paak EA and 10 Peak Strain are reported in Table 4 for the machine direction and thQ cro~ machine direction ~or dry sample~. Similar results are al~o report~d in Tabl~ 4 for wet samples.

:I For comparative purposes, Table S li~t~ the Thickne~ Index, `~, 15 Isotropic Strength IndQx, abra~ion te~t result~, and drapQ
:~ stifPneqs test results Sor the entangled mat¢rial o~ Exa~ple3 2, tha ~ntangled and unentangled mat~rial of Example 4, and two co~m~rclally availabl~ mat~rial~ which can b~ used or wiping.
~! Wiper A iB a hydraulically entangl~d nonwov~n material having the .- 20 tradQ de~ignation Sontara, grad~ 80Q5 available E.I. duPont De ~ Ne~our~ and Company. Wiper B is mad~ from a wood pulp/staple : fi~er blend ~ormed by laylng a wood pulp web over a staple Siber . web and then hydroentangling the web~. Wipsr B ha~ ~hs ~rade de~ignation Mohair Bleu and is availabl~ in Franc~ ~rom ~aury o~
25 Nante~, Fran~ and ~ro~ Sodav~ o~ Angers, France. Table 5 also list~ th~ thic~n~ ind~x and th~ isotropic strength index for : t~ ~d3nti~ied mater$als.
. ., As ca~ b~ seen from Tabla 5, ths hydroentangled material~ from . 30 Exa~ples 2 and 4 have a ~reater thicknes~ index than the ;unentangled material o~ ~xa~ple 4, Wiper A and Wiper ~. The material~ Prom Example~ 2 and 4 also have a greater isotropic ~-stran~th index than Wipers A and 8.

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-Tabl~ 6 provid~3 result~ of teRting ~or the ab~orption rate, total ab~orptivo capacity and mop-up capacity o~ the material from ~a~pl~ 4 ~or oil and watEr. The material o~ Example 2 had a total abMo~ptiv~ capacity and mop~up capaci~y for both oil and wat~r which i~ significantly gr~ater than thQ values for Wiper B.
Table~ 7, 8 and 9 provide test re~ult~ Por the materials o~ the presQnt invention and ~or variou~ other wiper~ that are commier~ially available in Europe. wi.per CWl is made e~ a meltblown polypropylene ~abr~c. wiper cW2 is a laminat~ o~
10 spunbonded polypropyl~n~/meltblown polypropylene/spunbonded polypropylene. Thi~ wiper available under the tradQ de3ignation MIRACLE WIPES is made o~ hydroQntangled stapl~ and cellulo5ic ,fiber Th~ wiper available undQr th~ trade de~ignation CLEAN
ROOM WIPE~ made of wet ~or~ed ~tapl~ and callulo~ic fibers.
~ 15 The wiper availabl~ under tha trade dei~ignation DURX i~ mada o~
!hydrosntangl~d staplQ and cellulosic iber~. Th0 wip~r availabla ~'~under the trade d~igna~ion LA~X i~ made of we~-~ormed s~aple and cellulo~ic ~iber~. The wiper availabla undsr the trade de~ignation TEXWIPE i~ mads of a 100 percent cotton woven fabric.
20 The wiper ava~lable under the trade de~ignation MICRONWIPE i~
mad~ o~ hydro2ntangled staple and cellulosic fiberr. The wiper availablo und~r th~ trad~ designation TEXBOND is made o~ a : spunbonded nylsn ~abric~ Th~ wip~r available under ~h~ trade :~de~ignation TECHNI-CLOTH i9 made o~ hydroentangled staple and . 25 cellulo~ic fiber~.
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For co~para~iv~ purpo~es, Tabl~ 7 lists the results o~
:~ extr~abl~ ta~ts and sodium lon t~t~ for the material of .Exampl~ 2 and ~or som~ o~ the abovs-~ention~d wipers. Also - 30 included in Table 7 are result~ ~or two materials mad~ according ~: Example 2... Material H contains about 80 percen~ by weight rayon staplo ~ibers and about 20 percent by weight wood pulp. Material i F contains about 80 percent by weight polye~ter stapl~ fibers and :~ about 20 percent by weight wood pulp. ~able 8 list3 the results 3~ 17 .' .
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o~ electrical charge dissipation te~t~ ~or thQ material o~
Exa~pl~9 2, Wiper A and for ~ome oi~ th~ abov~-mentioned wip~rs.
Table 9 li~t~ the re~3ult~ o~ Cli~elt~M lint t~5t5~ ~or the mat~ria~ rom Example 2, the entangled and untanglsd material ~rom Exa~ple 4, Wiper A, and for some o~ the above-mentioned ;~, 5 wip~r~.

-~, As shown in Tabla 7, th2 materials of ths pre~ent invention ha~e levels o~ extractables which compar~ ~avorably with many ~i commercial wiper~. Fro~ Table ~, it can be seen that the 10 mater$al3 o~ th~ present invention without any anti-Rtatic trea~lnent have a static: decay which i~ c:omparable with many ! c:ommarcial wipers. From Table 9, it can b~ sQ~n that the :! matarial~ o~ the preaent invention have relatively low l int lavels and co~para ~avorably with many co~rcial wiper~.
' ~ Thu~, it i3 apparent that the prasent inv~ntion pro~rides a wiper that satisf ies problem associated with previous wiper~ . While -~ th9 invent~ on has~ been described in con~unction wi~h speci~ic 3 embodiment~, th~ di~closad embodiments ar~ intend~d to illustrate '~ 2 0 and not to liDiit the invention. It î~; underqtoo~ that tho~ o~
skill in th~ art should b~ capableof making numerous . modi~ication~ without departing ~rom the ~3 spirit and ~cope of th~ invention.
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CROSS-~ MACHINE MACHINE
::1 DRY DIRECTION DIRECTION
-I Peak Load (g) 11,677 8699 -Peak Energy Absorbed (kg-mm) 106 62 Peak Strain (%) 68.5 53.8 Total Energy Absorbed (kg-mm)198 146 .
Total Strain ~%) 131 122 -: :.
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Peak Load (9) 7214 , Peak Energy Absorbed (kg-mm) 117 ;;
: Peak Strain (%) 120 :
~` Total Energy Absorbed (kg-mm)196 : . .
Total Strain (%) 217 . ~ .":
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I DRY DIRECTION UIRECTION
Peak Load (g) 9125 8749 ~ Peak Energy Absorbed (kg-mm) 55 55 -¦ Peak Strain (%) 46 49 Total Energy Absorbed (kg-mm) 114 110 Total Strain (%) 100 104 'i .

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DRY DIRECTION DIRECTION
I Peak Load (9) 5035 4081 Peak Energy Absorbed (kg-mm) 63 71 Peak Strain (%) 89 118 Total Energy Absorbed (kg-mm) 124 99 Total Strain (%) 174 160 ' ;'~
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.j DRY DIRECTION DIRECTION
Peak Load (9) 4529 4133 1, Peak Energy Absorbed (kg-mm) 83 79 -~ Peak Strain (%) 39 49 WET
Peak Load (g) 4014 Peak Energy Absorbed (kg-mm) 62 Peak Stra;n (%) 37 .~ .

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I BASE SHEET
¦ EXAMPLE 2 EXAMPLE 4EXAMPLE 4 WIPER A WIPER B ~.
l Isotropic Strength .¦ Index 1.04 1.096 1.0 2.37 1.45 ~ Thickness (mm) 0.79 0.73 0.36 0.44 0.31 .1 Basis Weight (gsm~ 73 53 60 65 75 Thickness Index 0.011 0.014 0.006 0.007 0.004 Drape Stiffness (cm) .
Side 1 3.6 3.4 7.7 Side 2 3.2 2.8 4.8 Martindale Abrasion . Rating Side 1 1 2 2 3 Side 2 1 2 1 1 .
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:~, Absorption Rate (sec. ) 1.0 <1 Total Absorptive Capacity (%) 553 347 Mop-Up Capacity (%) 258 151 'I
OIL
Absorption Rate (sec.l 9 0 7~0 ~:
Total Absorptive Capacity (/O) 596 230 Mop-Up Capacity (%) 250 33 .~ .

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', EXTRACTABLES

'~ % in % in % in hot water isopropyl 1,1,1-tri- hot leachabl e I PRODUCT/CODE alc _olchloroethane watersodium (ppm) ~W1 0.8 0.7 2.5 43 CW2 ~.8 3.5 0.2 47 Miracle Wipes~ 1003 <0.1 1.7 0.2 20 Clean Room Wipers~ 8025 2.1 1.6 1.0 391 ¦ Durx~ 670 <0.1 <0.1 0.3 41 ~. -DurxX 770 0.2 0.1 0.4 177 :~
Labx~ 123 <0.1 <0.1 1.1 206 --Texwipe~ 309 0.3 <0.1 3.1 47 .
Micronwipe~ 500 <0.1 <0.1 3.4 1030 :
Texbond~ 909 5.4 3.4 0.3 1640 ; Techni-Cloth~ 609 <0.1 4.3 1.4 43 ~ Techni-Cloth~ II 1009 <0.1 0.4 2~5 43 .
Example 2 0.1 0.1 1.5 126 Wiper Material H 0.2 0.1 1.0 133 .
Wiper Material F 0.2 0.1 0.6 116 ~ .
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ELECTRICAL PROPERTIES
static decay PRODUCT/CODE (sec) CW1 14.7 ~W2 19.8 Miracle Wipes~ 1003 0,3 Clean Room Wipers~ 8025 4.5 ~
Durx~ 670 5.8 :
Labx~ 123 1,3 ~.
Texwipe~ 309 1.1 Micronwipe~ 500 0.9 Texbond~ 909 6.5 Techni-Cloth~ 609 15.2 Techni-Cloth~ II 1009 1.6 Example 2 7.0 - -Wiper ANo Dissipation Wiper B 3.6 Notes:1. Higher static decay times indicate increased tendency for .static charge accumulation.
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CEIMET LINE (# PARTICLES) PRODUCT~CODE 10 u 0.5 CW1 0.4 112 CW2 o.1 9 Miracle Wipes~ 1003 0.2 56 Clean Room Wipes0 8025 0.2 4 Drux~ 670 0.4 442 Labx~ 123 0.4 42 Texwipe~ 309 2.6 5130 Micronwipe~ 500 0.7 498 Texbond~ 909 0.0 7 Teohni-Cloth~ 609 0.6 358 Techni-Cloth~ II 1009 0.4 8 Example 2 2 65 Example 4 (Entangled) 0.8 76 Example 4 (Base Sheet) 2 72 Wiper A 0.8 51 Wiper B . 0.2 286 Example 1 0.2 328 ~ :''.

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Claims (12)

1. A hydraulically entangled coherent fibrous structure having a thickness index of at least about 0.008 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 10 to about 50 percent by weight wood pulp fibers; and from about 50 to about 90 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers; and wherein said structure has a hot water leachable sodium ion content of less than about 150 parts per million and low levels of materials extractable in organic solvents.

2. A hydraulically entangled coherent fibrous structure having an isotropic strength index less than about 1.5 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 10 to about 50 percent by weight wood pulp fibers; and from about 50 to about 90 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers; and wherein said structure has a hot water leachable sodium ion content of less than about 150 parts per million and low levels of materials extractable in organic solvents.

3. A hydraulically entangled coherent fibrous structure having a thickness index of at least about 0.008 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 0 to about 50 percent by weight wood pulp fibers; and from about 50 to about 100 percent by weight inelastic staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers;
and wherein said structure has a hot water leachable sodium ion content of less than about 150 parts per million and low levels of materials extractable in organic solvents.

4. A hydraulically entangled coherent fibrous structure having an isotropic strength index less than about 1.5 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 0 to about 50 percent by weight wood pulp fibers; and from about 50 to about 100 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide, and polyolefin staple fibers; and wherein said structure has a hot water leachable sodium ion content of less than about 150 parts per million and low levels of materials extractable in organic solvents.

5. The structure of claim 1 wherein the staple fibers have a denier in the range of about 0.7 to about 3 and an average length in the range of about 5 mm to about 18 mm.

6. The structure of claim 1 wherein the material has an oil absorption capacity of at least about 300 percent.

7. The structure of claim 1 wherein the material has a water absorption capacity of at least about 375 percent.

8. A hydraulically entangled coherent fibrous structure having a thickness index of at least about 0.008 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 10 to about 50 percent by weight wood pulp fibers; and from about 50 to about 90 percent by weight inelastic staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers;
and wherein said structure has a water absorption capacity of at least about 375 percent without the use of surface modification treatments, a hot water leachable sodium ion content of less than about 150 parts per million, and low levels of materials extractable in organic solvents.

9. A hydraulically entangled coherent fibrous structure having an isotropic strength index less than about 1.5 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 10 to about 50 percent by weight wood pulp fibers; and from about 50 to about 90 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers; and wherein said structure has an oil absorption capacity of at least about 300 percent without the use of surface modification treatments, a hot water leachable sodium ion content of less than about 150 parts per million, and low levels of material extractable in organic solvents.

10. A hydraulically entangled coherent fibrous structure having a thickness index of at least about 0.008 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 0 to about 50 percent by weight wood pulp fibers; and from about 50 to about 100 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers; and wherein said structure has a water absorption capacity of at least 375 percent without the use of surface modification treatments, a hot water leachable sodium ion content of less than about 150 parts per million, and low levels of materials extractable in organic solvents.

11. A hydraulically entangled coherent fibrous structure having a thickness index of at least about 0.008 and which is capable of being elongated at least 104 percent in at least one direction, said structure comprising:
from about 0 to about 50 percent by weight wood pulp fibers; and from about 50 to about 100 percent by weight staple fibers selected from the group consisting of rayon, cotton, polyester, polyamide and polyolefin staple fibers; and wherein said structure has an oil absorption capacity of at least about 300 percent without the use of surface modification treatments, a hot water leachable sodium ion content of less than about 150 parts per million, and low levels of materials extractable in organic solvents.

12. The structure of claim 8 wherein the staple fibers have a denier in the range of about 0.7 to about 3 and an average length in the range of about 5 mm to about 18 mm.