Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~;~.l;'XlRF.F. DISPENSER AND ME~HOD F~ DISPENSING
SORBENT NONWOVEN WEBS CONTAINING MICROFIBERS
The present inven~ion pe~ ~s to a ~ . ncP. and method for dispen~ g
5 a nor,wo~.. web co~ g Illiero~c~ ~.
Nonwoven webs that contain ~ rorlbe~ are comrnonly used to as
so~ 3 for so~king up spilled liquids. The nonwoven webs are îul.~shed on
spools that are co-~lAi~l in c~llul3alo~ C~dlJG~ boxes. The 3M Conlp~.y
sells the products as Spooled Sorbents~ M-SB3 160 and P-SB3 160. 3M also
10 ...~l~ts a ~ tel~nr~e Sorbent-Folded product M-FI.550D that is also
fi.-.usl.ed in a cardboard box in a coiled confi~ alion. The webs are di~_.~ed
f from these boxcs by puncturing a p~ t~ area on the box, grasping the web,
~~ and pulling on the web until the desired length of web is wiLlldlawu from the
box. The coiled webs rotate about a central axis when web is withdrawn from
the box. ~lthou~h these known ~l;spens.;rs provide a Svll~ .hdt CGIlveni
way to di~ se nonwoven sorbent webs, the di~;ns_. ~ do have some
drawbacks.
Onc particular drawback is that the dispensers are rather large and
bulky. There are voits in the boxes--namely, at the boxes' corners and at the
spool core that create dead space. These voids are neces~. ~ to allow the
coiled web to rotate to f~ilit~te dispe.~;n~. The additional volume created by
the voids, however, causes an h~cl~ in storage space and adds to slfipping
costs.
Another d~a~ack is that the .li~p~ -~ . a are not flexible. The lack of
2~ fl~Yihility prevents them from bei~lg easily co,~l,lled to fit in a tight area. The
corrugatet c~o~ .1 boxes are also unwieldy, malcing them somewhat diffiC~llt
to rnanage and portage.
A further dla~l~cl~ is that the ~li$p ~ -a require addition~l parts ant
process steps for asse.l,blin~, the ~I,s~.ense- and ~kpenc;~g the wcb. This addsto product cost and creates ad~litiQ~ items, for c~llple, a spool, that must be
disposed of when the dispenser is empty.
The present invention o~e..,ollles the noted drawbacks for articles that
di;,pense sorbent nonwoven webs that contain microfibers. The .liapenser of
~I~FNDED SHEEi~
IP~AIEP
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rel~ el~ easy to m~mlf~ re and when co...pl~lely used leaves less materials
behindl for disposal or recycle. In short, the dispenser of the invention provides
a convenient and relatively simple way to .3iepçnce sorbent nonwoven webs of
mi~; u .r~ r.
In brief sl~mmqry~ the c~icpencpl of the invention comprises: (a) a
flexible en~1os~re having a m~m~ y puncturable region and an interior; and (b)
a nonwoven web disposed in the flexible çnrlosllre~s interior in an lmt~ngled
mann~r, the nonwoven web co..~ g microfiber and having a first end that is
located in the çnr1r)s~lre~s interior at the puncturable region so that when theregion is m~n~lly punctured, a person can readily grasp the first end and pull
thereon to dispense a desired length of nonwoven web from the enclosure in a
tangle-free manner.
The method of the invention is similarly advantageous and briefly
comprises:
(a) providing a dispenser that inrlu~c: (i) a flexible enclosure that has a
m~ml~lly puncturable region and an interior, and (ii) a nonwoven web
co..~ g microfiber that is disposed in the flexible enclosure's interior in an
mt~ngled manner, the first end of the nonwoven web being located in the
enclosure's interior at the puwlu~ble region;
(b) puncturing the ~nrl~s~lre in the m~n~l~lly puncturable region;
(c) grasping the first end of the web and pulling thereon to dispense a
desired length of web from the flexible enclosure's interior, the desired lengthof web being withdrawn from the enclosllre~s interior in a tangle free con~lition
and
(d) sep~ , the desired withdrawn length of web from the web
g in the enClos~re~s interior to create a new first end that can be
~ubse~ ently grasped and pulled thereon to dispense a second length of
nonwoven web.
The inventive dispenser and method differ from known .li~p~ ç, ~ and
methods in that the nonwoven web is disposed in a flexible ~nr.losl~re in a
tangle-free manner, and the flexible enClos~lre has a m~n~l~lly puncturable
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region that allows a person to easily open the Pncl~sllre to grasp an end of thenonwoven web. A desired length of web can be withdrawn from the çnr1~ re,
and the withdrawn portion may be separated from the web rel~A;...I~g in the
~lisi-en~,l. The r~ web's end is located at the ~.un.~ d openil.g so that
5 ~d.1ition~1 web can be readily withdrawn from the co.~ The flexible
nature of the en~los~re ~ es corners that provide dead space. Further,
there is no need for a spool to fi~cilit~te web withdrawal. The enclosure is
r~l~lively lightweight and easily maneuverable so that it can be rotated or
otherwise oriented to allow web to be ~lispPnced
In the dlawl.lgs.
FIG. 1 is a pcl~)eeliv-e view of a rlicp~n~Pr 10 that colllaills a sorbent
nonwoven web 12 that colllaills microfibers;
FIG. 2 is an end view of nonwoven web 12; and
FIG. 3 illustrates a pel~e.;Li~e view of another embodiment of a
15 dispenser 40 in accordance with the present invention.
In the practice of the present invention, a dispenser is provided that
readily lends itself to çffir;ent storage and cl.il....~..~ and .~ ;..s a sorbent
nonwoven web in a safe, clean condition by pl~c~ nt of the nonwoven web in
a flexible çnc1osl.re that is ~ lly~ and preferably, completely closed.
When dispell~illg is desired, however, the flexible Pnclnsllre may be easily
pullcluled using a person's fingers to allow the person to grasp an end of the
nonwoven web. The nollwovell web that colll~ns microfibers can be ~ JPn~ed
through the punctured ope-ullg by grasping the end and pulling thereon.
FIG. 1 illustrates a dispenser 10 that CQI~ a sorbent nonwoven web
12. Nollwovell web 12 is located in a flexible enclosure 14. As the terms are
used herein, the term "nol~wovt:il web" means the fibers are intertangled to
such an extent that the intertangled mass is h~nrllP~hle by itself as a mat, andthe term "flexible" means the Pnrlosllre can be squeP7e~bly col~lll.ed with a
person's hands when the nol~wo~n web is disposed therein and it will return to
e~s~ lly its original configuration when the hand pl'eS~ult; iS removed.
Flexible enclosure 14 has a m~ml~lly puncturable region 16 (note: in FIG. 1,
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region 16 is shown in a punctured condition), which when punctured allows
nol~woven web 12 to be withdrawn from PnC1oSllre 14. The term "m~nllAIIy
puncturable" is used herein to mean able to be pun~ilùred simply by pressillg the
tip of a person's eYt~nded index finger at the pun~iluldble region without using5 n~l-lition~l tools, force, or other means such as a perforation. Rec~ e the
whole ~nCloylre 14 is typically made from a thin, flexible material, it may be
that its entire surface is m~mlAlly puncturable. Thus, to prevent a tear in region
16 from ~YtPnrling outward into the rest of enr~losllre 14, m~mlAlly l~un~iluluble
region 16 plere.~bly is enco...pa~ed by a band 18 that reil~ro.ces the ~nr~losllre
10 about the punctured area. With the exception of band 18, flexible enclosure 14
plere-~bly consists ç,ssçntiAIIy of one type of material such as a thin plastic film,
and thus its whole surface may be m~ml~lly puncturable except for the
.~inrolced area 18.
Nonwoven web 12 is disposed in flexible enclosure in a lmt~r~led
15 manner. In the embodiment illustrated in FIG. 1, the no.,woven web is
disposed in the ~nrlosllre 14 in a se-~;--liile, untA~led pattern. The end 20 ofnonwoven web 12 p-t;rt;.~bly is located in a corner of the flexible enclosure 14.
Before any of the web is withdrawn from the enclosure, no..wovell web 12
Ç~PJ~iAlly fills the whole ~nr~losllre 14; there is little residual dead space. The
20 enr~osllre makes a firm, intim~te contact with the enclQsed web such that itssurface is taut or tightly drawn. The taut condition of enclosure 14 allows
region 16 to be easily punctured by pressing a person's finger therein with
sllffic~nt force. The taut condition also assists in Ill~ lg the u~-l~lgled
contli~ion of the non-woven web. In some in~t~nces, the no..woven web ma
2~ be co"..plessed before the flexible çnclosllre is placed about the web. Thus, the
volume of the Pnrlosed web may be si nific~ntly less in the flexible enclosure
than in an ~ ron~l~lled conr~ition. This provides further volume savings for
storage and sl.ipl)ing.
Af~er region 16 is m~ml~lly punctured, web 12 can be withdrawn from
30 the in~erior of çnclosllre 14 by ~ ,h.g and pulling on end 20. The withdrawn
portion 22 can be s~aled from web le~ g in ~nc~osllre 14 along a
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pe~ro-~lion 24. Upon sep~ling portion 22 from the web in çn~losllre 14
le~ g, a new end is created at punctured region 16. The new-created end
also can be handily ~ed and pulled on to withdraw al~oLl~r desired length
of web from ~icp~nePr 10.
Nonwoven web 12 co~ s microfibers so that mass q~uA~ ;ee of liquid
can be absorbed. The nonwoven web cr~ g microfibers may take a variety
of forms; for c ,)le, the web may be in the form of a folded article shown in
U.S. Patent 5,256,466, or it may be in the form of an çlongAte boom shown in
U.S. Patent 5,360,654; the ~licçlosllres of which are incorporated here by
.~rcr~.~ce.
In FIG. 2, a folded l~GIlwo~en sorbent web is illustrated that has a four
layer fold construction 26. The folded web has a casing-like cover or scrim 28
that assists in ~Ai~ g the integrity of the nonwoven fibers. This kind of
folded construction may be produced in accordance with the te~çhin~s in U.S.
Patent 5,256,466. Four-layer construction 26 has outer quadrants 30 of
mi.;.ufil,.uus sheet material 32 that are folded inwardly; that is, toward the face
of the m~t~ri~l not having scrim 28. These folds are along outer longit~tlin~l
fold lines 34 and are followed by a second fold along a central fold line 36,
which forms a major fold that produces the configuration shown. The folded
no-~wovt;n web 12 can be stabilized in its folded configuration by the use of
int~rmitt~nt bonds 38. Bonds 38 may be in the form of ultrasonic welds or may
be forrned using a hot-melt adhesive. This folded construction can be
subseql.ently opened in a flat configuration by breaking intermittent bonds 38.
Thus, in this embo~liment the web 12 can be opened to form a two-layer or
one-layer configuration that covers ~d~1ition~l surface area. This may be
needed for large liquid spills.
Alternatively, the nonwoven web that cont~ine microfibers may be in
the form of an elongate boom such as disclosed in U.S. Patent 5,360,654. The
elongaled boom ~ieclosed in this patent has a subs~ ;AIIy oval cross-section
and is formed of multiple a~ cçnt microrl~e~ layers that are bonded to each
other by çnt~nglPm~nt of the fibers bc;L~ce.l the a~ cent layers. The boom
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typically has a ~ ,t~r of about 50 millimeters (mm) to 30 cm, has a lineal
weigllt of about 20 to 600 grams per meter (g/m), and has an oil scJlb~,ncy of at
least about 5 grams per gram (g/g). Oil soll,ell~;y may be dete...filled in
accol~c~ with the test oullined in U.S. Patent 5,360,654.
S ~IG. 3 f1icrloses an ~It~rn~tive embodiment of the invention. As shown
in ~IG. 3, a d;el,en~er 40 is provided that co~ e a coiled ~ wov~,n web 42 in
a flexible enc1os~re 44. A m~ml~lly puncturable region 46 is located centrally
in the flexible PnC1osllre 44. A circular reil~ol~,ed band 48 enco...rAc~cs
m~nl~1ly pun~i~ul~le region 46. When m~nll~lly p~ln~;~ul~ble region 46 is
punctured as shown in FIG. 3, a first end 50 of web 42 may be withdrawn from
the d;s~ense.'s interior.
As opposed to the embodiment illustrated in FIG. 1, the embodiment
shown in FIG. 3 has the nonwoven web coiled within the flexible ~nrlosllre. As
shown in both FIGs. 1 and 3, the nonwoven web ess~ lly fills the whole
flexi~le enclosllre. The ~icpPneers are able to consist e~ lly of the
nonwoven web and flexible ~nt~lo~l~re. There are no other items such as spools
that are rc~uhed to diep~n.ce the web. Further, the web ...~ its llnt~led
confi~uration as web is withdrawn from the rnelosllre. The nonwoven web is
not initially dis~osed randomly in the enclosure; nor does it become
20 h~l~hA,~.-dly arranged in the .lieclos~lre thro~l~hout its use. The nonwoven web
preferably is wound in a st;l~ ine or coiled pattern (the term "wound" is used
herein to include either of these orientations). After a portion of the web is
torn or otherwise separated from the re...~ ;..g enclosed web, the newly-
created end resides at the punctured open-llg for subsequçnt h~nrlling by the
25 user and the re...~ g web retains its wound non-random oriPnt~tion
Nonwoven webs used in this invention typically comprise at least 5
weight percent microfiber based on the weight of fibrous material in the
nonu~oven web. A ~lcr~ d nonwoven web comprises at least about 20
weight percent microfiber, more preferably at least about 50 weight percent
30 microfiber, and up to 100 weight percent microfiber. The term microfiber
mea~s a fiber that has a ~ mPter of less than appro~im~tP1y 10 micrometers.
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A l -~Ç~l~d nonwoven web cont~ins microfibers that have an average fiber
...rter of about 5 to 8 micrometers. The fiber ~ P~ can be cz~1rulz~t~
g to the method set forth in Davies, C. N., "The Sep~r~tion of
Airborne Dust and Particles~, Tn.~tih~tinn of M~ll~ni~l F.ngin~erS~ T~n~c~n~
5 ~,c~A;.~s lB, (1952). The nonwoven web preferably has a subst~nti~lly
uniru..l.ly di~ ~d microfibrous structure throughout the whole web. The
nonwoven web, typically, has a lineal weight of 0.5 to 2.0 grams per
cenl;...el~r (g/cm).
The nonwoven web that cont~in~ microfibers preferably has a solidity
less than about 0.2 and generally greater than about 0.001. The term
"solidity" means the volume of fibers per volume of web. Solidity can be
c~1e.l1~tP~ using the following formula:
S = Pb
1~ n
~: Xj Pi
where: Pb iS the bulk density of the web, which is the weight of the web
divided by the volume of the web;
xi is the weight fr~ction of colllpone
Pi is the density of component i;
S is the solidity; and
n is the number of colll~nents.
~re;reldbly, the nonwovell web has a solidity of about 0.02 to 0.15, and
more preferably of about 0.05 to 0.1.
The nonwoven web that cont~in~ microfibers generally has a basis
weight greater than 50 grams per square meter (g/m2) and up to
a~ h~te1y 600 g/m2. Typically, the basis weight is in the range of about
100 to 400 g/m2.
The sorbent capacity of the nonwoven web is generally of 5 to 40
grams H20 per gram web (gH20/g web), and more typically in the range of
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about 15 to 20 gH2O/g web. The sorbent capacity can be measured
accor~ g to the tests described in Tntern~tion~l Publi~tif~n WO 95/00417.
The nonwoven web prer~.dbly has sllffi-~iPnt tensile strength to allow
the web to ~ h~l~;n its inL~i~y during h~n-lling. The web ~er~dbly
5 demol-ctr~tPs a tensile strength when wet which is eccPnti~lly the same as ~e
tensile ~ ;Ih when dry. The nonwoven web th~erore does not
~ig1~ifir~ntly lose strength upon sorbing a liquid. In ~enP~l, the nonwoven
web's dry (and preferably wet) tensile strength is greater than about 0.5
Jns per c~ . trr (N/cm), typically about 1 to 8 N/cm. Tensile
10 strength can be ~el~ Pd using an INSTRON tensile tester Model 4302
(available from Inshron CG~ lion, having a jaw spacing of 25.4 cm and
jaw f,~ces 7.62 cm wide), and a 2.54 cm (one inch) wide dry sample at a
croschP~rl speed of 12.7 cm/min. Wet tensile strength is d~le~ ~ by
~hlr~tinf~ the web in water before placing the web in the tensile tester.
The microfibers in the nonwoven web are ent~nglPd as a cohelent
mass of fibers. The fibers can be ent~nglPIi using, for eY~mplP, a melt-
blowing process, where a molten polymer is forced through a die and the
extruded fibers are ~ Pd by ~ c~nt high velocity air streams to form
an ent~n~led mass of blown microfiber (BMF). A process for making BMF
20 webs is ~iicclose~ in Wente, Van A., "Superfine Therrnopl~ctic Fibers" 48
Indus~-rial Engineering Chemistry, 1342 et seq (1956); or see Report No.
4364 of the Naval Research Lab~ o.;es, published May 25, 1954, entitled
"Manufacture of Super Fine Organic Fibers" by Wente, Van A.; Boone,
C.D.; and Fluharty, E.L. A nonwoven web cc~ microfiber also may
25 be made using sollJtion blown techniques such as di~close~ in U.S. Patent
4,011,067 to Carey or electrostatic techniques such as ~ close~ in U.S.
Paten~ 4,069,026 to Simm et al.
Polymeric co.,.~nenls that may be used to form a BMF web include
polyolefins such as polyethylene, polypropylene, polybutylene, poly(4-
30 mel~lyl~ nten~--l), and polyolefin copolymers; polyesters such as
polyelhylene terephth~l~te (PEI~, polybutylene terephth~l~te, and polye~er
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Wo 96/20884 PCr/US95/14371
ester copolymers such as HYI~EL available from Dupont Co., Ela~
Division, Wilmington, Delaware; poly~l,onales; polyu~ es;
poly~ly~ e; polyamides such as nylon 6 and nylon 66; and thermoplastic
p~ mPr block copolymers such as styrene-but~lip-nprstyrene~ slyl~ne-
isoplenc-styrene, slyl1. c ethylene/butylene-styrene, available from Shell Oil
Col-lpany, ~oUstcln, Texas, under the tr~ PmArk KRATON. CGIllbi..~ Qns
of the above polymeric microfibers, or blends of the polymeric co~
may also be employed. For ~,Y~mple, a blend of polypropylene and poly(4-
methyl-l-pentene) can be used to make a nonwoven web that col~tAin~
microfiber (see U.S. Patent 4,874,399 to Reed et al.), or the web may
contain bic~"l~nent microfiber such as the polypropylene/polyester fibers
(see U.S. Patent 4,547,420 to Krueger et al.) Polymers useful for forming
microfibers from solution include polyvinyl chloride, acrylics and acrylic
copolymers, polystyrene, and polysulfone. A nonwoven web preferably
15 comprises microfibers made from polyolefins, particularly fibers that containpoly~ pylene as a major fiber co"l~onent, for example, greater than ninety
weight percent, because such fibers provide the web with good resilient
pf~lLies in conjunction with good sorptive plup~lLes.
In addition to microfibers, the nonwoven web may contain other
20 fibers such as crimped or lm~rimI)ed staple fibers. The Ad~itio~ of staple
fibers can impart better conformability and improved loft to the nonwoven
web. Staple fibers are fibers of a given ril P~Pss, crimp, and cut length.
Fineness is gPnPrAlly given in units of tex, grams per kilometer (g/km), a
linear density. Crimp is ch~ tPri7~d by the mlmbP~r of bends per unit
2~ length of fiber (crimps/c-pntimptpr). Cut length is the overall length of the cut filAmt~nt~ Staple fibers employed in this invention generally have
finPn~ of about 0.1 to 10 tex, preferably about 0.3 to 4 tex, crimp den~itips
of about 1 to 10 crimps/cm, preferably at least 2 crimps/cm, and cut lengths
in the range of about 2 to 15 cPntimPters~ preferably about 2 to 10
30 cP!ntimPt~rs. Webs that contain staple fibers may. be pfe~alcd accol~ing to
procedures ~ cus~1 in U.S. Patent 4,988,560 to Meyer et al., U.S. Patent
g
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WO 96/20884 PCT/US95/14371
4,118,531 to Hauser, and U.S. Patent 3,016,599 to Perry. When added to a
non~,voven web that collt~in~ microfibers, staple fibers typically comprise
applu~ y 10 to 50 weight percent of the fibrous m~tPri~l in the
nonwoven web.
S A norlwovel~ web that co~ microfibers as carrier fibers (and
optionally staple fibers) may also contain microfiber micr~webs as sorbent
structures in the nonwoven web. Microfiber micr~wel~s have a relatively
dense nucl~us with numerous individual fibers andtor ffber bundles
cYtPn-ling th~nr.ul". The eYtPn~led fibers and fiber bundles provide an
~n~horing means for the microfiber microwebs when they are incol~ldted
into the nonwoven web. The nucl~PNs of the microfiber microwebs
preferably is in the range of about 0.2 to 2 mm. The eYten~ling fibers and/or
fiber bundles preferably extend beyond the mlcl~p~ls to provide an overall
n~P~tpr of about 0.07 to 10 mm, more preferably about 0.2 to 5 mm. The
(li~mPtPr of the microfibers in a microfiber microweb can be similar in
~i~mPter to, or smaller than, the microfibers of the carrier microfiber web.
The microfibers of the microfiber micruwebs can be smaller in ~ mPtPr than
is normally con~i~lP-red suitable for use in microfiber webs because the staple
fibers or the carrier microfibers in the nonwoven webs are major
contributors to the strength of the nonwoven webs. Pl~Ç~dbly smaller in
mPter than the carrier microfibers of the nonwoven web, the microfibers
in the microfiber microwebs can be at least 20 percent smaller and more
preferably at least 50 percent smaller than the carrier microfibers in the
nor.wovel~ web. Fibers having smaller ~ mPterS can increase the capillary
2~ action in the microfiber micr~webs to Pnh~nce sorptive ~ ~lLies for
ret~inin~ liquids. When employed in a nonwoven web that cont~inc
microfibers, microfiber microwebs generally are present in the nonwoven
web in the range of about 10 to 80 weight percent based on the weight of
fibrous m~tPri~l Microfiber micr~webs and their m~mlf~rtllre are described
in U.S. Patent 4,813,948 to Insley, the ~ r1~s--re of which is incol~uldted
here by reference.
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A nonwoven web that contains microfibers and optionally staple
fibers and/or microfiber mi~;luwel~s may also include other ingredients in
:~lAition to the fibrous m~tPri~l. For inct~nr~, the nonwoven web of
microfibers may be loaded with discrete solid particles capable of intP~ctin~
5 with (for eY~mr'e çl~Pmi~lly or physically reacting with) a liquid to which
the particles are e~os~d. Such particles can remove a comro~P,nt from the
liquid by sorption, ch~o-mir~l reartion, or ~m~ m~tinn or a catalyst may be
employed to convert a hazardous fluid to a h~rmlP~ fluid. An eY~mrle of a
particle-loaded nonwoven web of microfiber is di~r,~os~d in U.S. Patent
3,971,373 to Braun, where discreet solid particles of activated carbon,
~lllmin~, sodium bic~ul onate, and/or silver are uniformly dispersed
throughout and are physically held in the web to sorb a fluid; see also, U.S.
Patent 4,100,324 to Anderson et al. and U.S. Patent 4,429,001 to Kolpin et
al. Also, additives such as dyes, pigm~nt~, fillers, surf~ct~nt~, abrasive
15 particles, light stabilizers, fire lel~-rdallls~ absorbents, m~1ir~mrnt.~, et cetera, also may be added to the web by introd~lrin~ such co~ P~ to the
fiber-forming molten polymers or by spraying them onto the fibers after the
web has been c~ll~t~d.
The flexible ~nrlosllre may take the form of ess~nti~lly any m~teri~l
20 capable of providing a m~ml~lly puncturable region and ,~ ;g the no~wovt;.
web therein. Plerel~bly the flexible enclosure is in the form of a ll~l~)&~
plastic so that a person can see how much web relll&il,s in the dispenser. The
l,~lsparel,l plastic can be, for rY~mrle a multi-layer coextruded polyolefin film
that is s~ffici~ntly elastic to resist inadvertent tears but when in taut condition
can be punctured with a person's fingers. The plastic desirably has good cold
flex plope,lies that keep it pliable at low temps (e.g. -40~F) without cracking
or becoming brittle. The plastic also should form a strong seal line that does
not fail under normat use conditions. Typically, the plastic is about 0.006 to
0.05 rnm (apprvx;~ oly 25 to 200 gauge) thick and l l~;rtl~bly has a ball burst
impact s~,ellglll of 5 to 25 joules, more preferably 10 to 20 joules. Preferably,
the plastic has a tensile ~llt;llglh of 70 to 140 mega pascals (~D?a)
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WO 96/208~4 PCT/US95/14371
(appro~ çly 10,000 to 20,000 psi), and more preferably of 80 to 110 MPa
(al~p~ ely 12,000 to 15,000 psi). The plastic preferably also has a tear
l~[oph~ion of 5 to 20, more p.ere.~bly 6 to 16. The modulus of elasticity of
the çnclosllre typica11y is 500 to 1050 MPa (app~oxi~ ely 75,000 to 150,000
psi at ~/3~F), and more ple~-~bly is 650 to 725 MPa (95,000 to 105,000 psi at
73~F).
Preferably the plastic is a heat-shrink material. Heat-shrink plastics can
form 9n erlclos -re that tightly fits about the nonwoven web. The plastic
typically has an u~ ed linear thermal sh~inkage of 10 to 25 percent at
200~F (93~C). An example of a suitable heat-shrink plastic inrllldes Cryovac
Type MPD2055 Film, 100 gauge. This heat-shrink plastic can be lei,~rced
about the m~ml~lly-puncturable region by a lei,lro-~iing tape such as Scotch
Brand, Type 351 tape from 3M.
The following standar~ ed ASTM test metho-l~ may be used to
dt;lelll-ine the noted p&l~ul.t;lers.
ru~ u~,.ler ASTM Test Method
Ball burst impact strength D-3420 (Method A;
pen~ um capacity 50 joules;
12.7 millim.o,t~r radius
- h~mi~pherical impact head)
Tensile s~-, n~ D-882 (Method A)
Flong~tion at break D-882 (Method A)
Modulus of elasticity D-882 (Method A)
Tear prop~tion D-1938
Unlt;~ illed shrink D-2732 (at 200~F)
