Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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READlLY REPLACEABLE ROLL CO~ERS
BACKGROUND OF THE INVENTION
The present invention relates to apparatus for selective çngAg~.ment with an
advancing web. ln particular, the invention relates most specifically to apparatus and
methods for the assembly and ready replacement of covers for rolls used to engage
advancing webs.
It is well known to provide a cylindrical roll with specifically desired frictional
lU characteristics on its exterior surface for use in web advancement and lleal,~lel~L
processes. In the textile industly, tlle use of rolls to convey, pull and hold back fabric is
very common, and these rolls are referred to as pull rolls. For in~t~nt~e, weavin~
machines. inspection machines, finishil1g lines, napping lines, sueding lines and dye lines
all contain numelous pull rolls to aid in pert'orming such operations. Steel or aluminllm
1~ rolls themselv,es do not pro~ide surfaces witll sufficient frictional forces to keep fabric
from slipping in most applications. Such rolls are thus covered or coated with a material
whicll aids in gently guidillg tlle fabric through the textile processing m~f hin-?ry without
distorting its weave, yet keeping the fabric relatively uniform in advancement and
spread.
The cover Oll a pull roll may have a low or high coefflcient of friction, depending
upon the particular tàbric, process cllaMcteristics and desired engagement or traverse of
the pull roll with the fabric. Nul1lel0us materials have been used to define the frictional
interaction betweell tl~e roll sulfàce and the fabric. Typical prior art pull roll cover
materials include cork~ rubber, modified cork, smooth rubber. sandpaper and bristle-
bearing materials. During use of such materials, their frictional characteristics can
change. For installce, CO11~ and mbber-based materials tend to glaze over as they wear
and become smoother, presentill=, a cllall~e in fi-iction level to the fabric web over time.
This can result in a slow deterioration of fabric quality or increased motor power usage
due to slippin~,, whicll are both difFicult to detect. In addition, abrasives such as
3() sandpaper do not wear evenly, because of theil- random surface textures. Further, while
abrasives such as sandpaper presellt higller frictional characteristics for a pull roll cover,
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they are non-unifoml by desi~n and thus are ~Inc \it~ble for some fabric webs because
their non-uniformity results in damage to the fabric. Pull roll covers based on a bristled
stnucture (SUCIl as the BRUSHI,O~TM bnush material of Minnesota Mining and
ManufactLIring Company. St. Paul, Minnesota), are also random in bristle dispersion and
alignment.
A pull roll cover material is typically applied by helically wrapping a 5 to 7.5 cm
~two to three inch) ~vide strip of the material down the length of the roll. Adhesion of
the material to the roll surface has been accomplished by the use of contact cements,
spray adhesives, and nonrepositionable pressure sensitive adhesives. To remove such
1() roll covers from a roll requires removal ofthe roll from the textile processing m~f~.hin~ry,
and in some installces the machining off' of the covering. These types of adhesion
arranoen1ellts typically lead to build-ups of adhesive on the roll surface over time,
contain flamlllable solvents in the adhesive, re~luire long cure times on the roll surface,
and in many cases require the use of flammable solvents for roll clean-up.
Environmental concerns and restrictions no~ prohibit the use of many of these
adhesives in textile plants, thereby requiring the removal and application of roll surfaces
by outside parties and at locations other thall the textile processinO tàcility.One type of pull roll cover folms a cylindrical brush~ as disclosed in Dupre U.S.
Patent 4,627,1'~7. il1 ~upre, a fabric strip containinO bristles on an outer peripheral
surtàce thereof is ~vrapped in a lleli~; about a cylinder. The fabric strip is adhered to the
cylinder by means of an adhesive such as polyurethane. ThrouOh use, the bristles wear
do~n and the r enlailling covering must be replaced. To remove such a covering bonded
to the cylinder by an adhesive requires the use of solvents. This can be messy, relatively
time consumin~ (res~ltin~g in machine dowlltime) and, as mentioned above, the use of
solvents to remove adhesives creates undesirable hazardous waste removal issues.In an e~'olt to address these environlllenta3 concerns. and also to forrn a morereadil!~ replaceable pull roll cover, mecllallical tàstenino schernes (such as hook-and-loop
~stener stmctures) have been used instead of adhesives to bond the cover material to
the roll. One roll cover material curTently available for this purpose has 3mm (1/8") trim
.~) nyloll 6, 12 bristle BRUSHL,ONT"I brusll material (available from Minnesota ~Linin~ and
ManLIfacturillO Compally, St. Paul, l~linnesota) 011 one side of a support substrate, with
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a loop structure material on its other side. A hook structure material (having projecting
hooks or capped stems thereon) is bonded to tlle exterior surface of the cylindrical roll,
typically in strip fornl wrapped thereabout in a helix. The bristle/loop structure assembly
is also wrapped in Stlip form itl a helix about the cylindrical roll, with the loop structure
interengaging with the hook structure to affix the bristle/loop structure assembly to the
pull roll cylinder. While this arranoement allows for ready removal ofthe exterior bristle
bearing fabric, and replacement thereof with an alternative roll exterior material having a
loop stmcture backing, it also is not ideal. The combination of the bristles, support
substrate and hool;-and-loop fastener form a pull roll cover assembly having a relatively
o higll profile. Fulthel, if the pull roll cover material is wrapped in an imperfect helix
along the roll, one or more hooks may be inadvertently exposed from the hook structure
material mounted on the cylindlical roll. These exposed hooks can damage the fabric
web being traversed by the roll by picl;ing or tearing at fabric fibers, creasing the fabric,
scuffing its surface or by causing some other similar surface phenomenon.
A typical textile pull roll ~,vill have a diameter in the ran~e of 10 to 30 cm (4-12
incl1es~, but can be smaller or largel-. A higll profile ~relatively thick) pull roll cover
increases the effective diameter of a pull roll, and this effect is even more significant on a
smaller diameter pull roll e.g., a 2.5 - 7.~ cm (1-3 inch~ diameter pull roll. It is an
undesh-able necessity that drive roll speeds be adjusted if a significant change in roll
diameter results from the application of a roll cover, and thus a pull roll cover should be
as thin as possible.
The pich-up or transfel- of paniculates or fluids by a pull roll cover is also
undesirable. A cover material is aiso unacceptable if it allows lint and fiber build-up
thereoll during use. In addition, in some applications the roll or fabric web will be wet.
2~ For example, a roll cover must not pick up and hold fabric dyes from the m~ f~ctl~ring
process. ~olor cl1anges are commoll and the transfer of dves from one fabric lot to
anotller is ~Inacceptable.
In view of the disadvantages associated with the various pull roll cover schemesof the prior an, it is desirable to pro~,ide a pull roll that has a changeable exterior
3() covering. wllerein the coverin, is relatively inexpensive, reusable or replaceable, easily
and securely attachable to the c~lindrical pull roll and which, in use, does not allow
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undesirable contact or dama;,e to tlle web traversed thereby. Other desirable features in
a replaceable pull roll cover are that tlle cover assembly have a relatively low profile,
that it not collect lint or fibers~ and that it not transfer dyes between webs. In addition,
an exterior material for a pull roll cover is desired that has a long life, and provides the
desired frictional characteristics, or range of frictional characteristics for customer
fle~ibility.
SIJMMARY OF THE INVENTION
In one embodiment, the present invention includes an en~,agement apparatus for
selective enga~emellt with an advancill~ web. The engagement apparatus inc.llldçs a
base having an outer surface with hooli-ellgagin~, structures disposed thereon, and a
surface substrate sheet havin;, first and second major surfaces. The second surface of
the substrate sheet has desired charactelistics for frictional engagement with an
advancing web. A plurality of llool;in~ stems are provided on and project from the first
1~ surface ofthe substlate sheet. The hool;in~ stems include means for hooking the hool~-
engagin~ surfaces on tlle outer surface of the base to releasably affix the surface
substrate to the base.
ln anothel embodilllellt the presellt invention includes a low profile ensga,~Pmtont
apparatus for use 011 a roll ha~ill;, a cylindrical outer surface. The engagement apparatus
2() comprises a surface substl-ate sheet havin~ first and second sides, with the second side
thereof havin~, desired characteristics for fi-ictional enga~ement with an advancing web.
A repositionable press~ll-e sensitive adllesive is disposed between the cylindrical outer
surface of the roll and the first side of tlle surfàce substrate sheet to releasably adhere the
surface substrate slleet to tlle cylindrical outer surface of the roll for re~ cem~nt or
2:. reali,gnment.
In anotller embodiment, the second surface includes means for defining a
frictional enga~en1ent sulface for the advancin~ web. The defining means inclu(lçs a
plurality of surface stems prc jectin~ outwardly from the second surface of the surface
substrate sheet, witll the surface stems collectively definin<J an operative contact surface
.~() for contactin~ the advanci~ web. Preferably, the surface stems are disposed in a
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selected arrangement on and formed integrally with the second surface of the surface
substrate sheet.
The present invention further includes a method of making a textile pull roll,
wllich includes prov;din(J a base having an outer cylindrical surface, and providing a
:, substrate sheet havin~ first and second major sides. The first side of the substrate sheet
is releasably bonded to the outer cylindrical surface of the base. A plurality of surface
stems are provided on and project outwardly from the second side of the substrate sheet,
witll the sulface stems being formed integrally with the surface substrate and having
outer ends which are generally uniform in height. The surface stems collectively defme
o an operative textile contact surface for contacting a textile web. The bonding of the
substrate sheet to the outer cylindrical sulface of the base includes adhering the first side
of the substrate sheet to the outer cylindricai surface by opposed hook-and-loopfasteners, with the ioop fasteners bein;, on the outer cylindrical surface of the textile pull
roll.
s The present inventioll also includes a further method of making a ro~l,
which includes providing a base havin~r an outer cylindrical surface and providing a
substl-ate sileet havillg first and second major sides. The second side of the substrate
sheet has the desired characteristics for frictional engagement with an advancing web.
The metllod furthel includes releasably bonding tlle first side ofthe substrate sheet to the
2() outer cylindrical surface of the base with a repositionable pressure sensitive adhesive to
permit read~ removal or realigllment of the substrate sheet relative to the base.
Preferably~ tlle inventive method furthel includes positioning the repositionable pressure
sensitive adhesive on the first side of the substrate sheet prior to the bonding thereof to
the base.
2:) The invention is further embodied in a method of changing the outer textile
en~,a~in~r surface of a textile pull roll. In this process, a pull roll is provided having a
cylindlical pull roll base, a loop fastener structure secured to the pull roll base, and an
initial suTbstrate sheet releasably affixed to the loop fastener structure. The initial
substrate sheet has first and second majc-r sides, with the second side of the substrate
3() sheet being defined by a te.~tile engagemellt material and the first side thereof being
defined by a hoo~ fastenel- stluctul-e WlliCIl iS releasably engaged witll the loop fastener
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stl~lcture on the pull roll base. Tl~e initial substrate sheet and textile engagement
material thereon are removed from the pull roll base by ~lir~nQg;~ginl7, the hook fastener
structure on the initial substrate sheet from the loop fastener structure on the pull roll
base. A replacement substrate sheet having frst and second major sides is provided,
Witll its second side being defined by a replacement textile engagement material and its
first side beinjg defined by a hoo3~ fastener structure. The replacement substrate sheet is
affixed to the pull roll base by adherillg the hook fastener structure thereon to the loop
fastener structure on the pull r oll base.
In another embodiment of the above process, a pull roll is provided having a
0 cylindrical pull roll base, with an initial substrate sheet releasably affixed to the pull roll
base. The initial substrate sheet has first and second major sides, with the second side of
the initial substrate sheet being defined by a textile enga~ement material and the first side
thereof being bonded to the pull r oll base by a repositiollable pressure sensitive adhesive.
The initial substMte sheet and textile engagemellt material thereon are removed from the
pull roll base by overcoming the adherence force ofthe repositionable pressure sensitive
adhesive. A replacement substrate sheet havillg first and second major sides is provided,
witll its second side being defined by a replacement textile engagement material. The
replacement substrate sheet is affixed to the cylindrical pull roll base by means of a
repositionable pressure sensitive adhesive disposed therebetween to perrnit repl~c.o.m.ont
2n or realio,nmellt thereof on tlle cylindrical pull roll base.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invelltion will be further explained with reference to the drawing
figures refèrenced below, whereill like structure is referred to by like numerals
2~ througllout the several views.
FIG. I is an isometric view of a textile web being advanced over a pull roll cover
of the present invention.
FIG. '~A is a top plan view of one prefèl-red embodiment of the exterior pull roll
cover of the present invention having upwardly projecting surface stems.
3() FIG. 2B is a sectional vie~i as talien along, lines 2B--2B in FIG. 2A.
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FIG. 3 is a scl1en1atic illustration of an apparatus and process for forrning the
pull roll cover of FTGS. 2A and '7B.
FIG. 4 is a schematic view of a strip of loop fastener structure partially woundabout the cylindrical base of a pull roll.
FIG. 5 is a scl1e~l~atic view of a strip of pull roll exterior cover material partially
wound over tl1e f rst strip and cylindrical base of a pull roll.
~IG. 6 is a sectional view as taken along lines 6-6 in FIG. 5.
FIG. 7 is a sectional view of an alternative pull roll cover assembly.
FIG. ~ is a sectional view of an altemative pull roll cover assembly.
() FIG. 9 is a schematic view of a strip of another preferred embodiment of a pull
roll exterior cover matelial paltially woul1d about the cylindrical base of a pull roll.
FIG. 10 is a sectional view as taken along lines 10-10 in FIG. 9.
FIG. ] I is an enlar~ed sectional view of a portion of FIG. 10.
FIG. 12 is a sectional view of an alternate pull roll cover of the present
invention.
While the above-identified dra~ing figures set forth several pl e~l, ~d
embodiments, other embodiments of the present invention are also contemplated, as
noted in the discussiol1. This disclosure presel1ts illustrative embodiments of the present
invel1tiol1 by way of replesel1tatiol1 and not limitation. Numerous other modifications
and embodimel1ts can be devised by those skilled in the art which fall within the scope
and spirit of the principles of this invelltiol1. The drawing figures have not been drawn
to scale as it has been necessary to enlarge celtain portions for clarity.
DETAILED DESCRII'TIOI\' OF THE PREFERRED EMBODlMENTS
~5FIG. I illustrates a te~ctile or fabric web 10 being processed along a web travel
path whicll is defined, at least in palt, by te.~;tile pull rolls such as pull rolls 12, 14 and 16.
Such rolls may be driven or idler rollers, depending UpOIl the processing application.
The sulfaces of the IOIIS are coated or covered with materials having the desired
frictional cllal acteristics t'or the application and for the fabric web being processed. The
3()pull rolls are intended to l;eep the fablic web taut and uniformly disposed as it is
processed. Dependil-~ upon the re(1uirements for a specific pull roll, a high degree of
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friction may be required bet~een the pull roll and fabric web to prevent slippage, or a
lo~v degree of friction may be required to allow a controlled degree of slippage of the
fabric ~eb over the pull roll
FIGS 2A and 2B illustrate the inventive pull roll cover material of the present
invention ~unctionally, the inventive pull roll cover 20 has a substrate 22 with a first
side 2a. adapted to be moul1ted OI1tO a pull roll, and a second side 26 defining a frictional
engagemeIlt surlàce f'or a fabric web which may be traversed or advanced over the pull
roll This engagemel1t surtàce is furtl1er de~lned by a plurality of surface stems 28, which
are disposed in a selected alTangement ~it is preferred that this arr~n~Pment be a
1() predetermined pattern) across the second surface 26, and are formed to have a generally
uniform height projection from the substrate sheet 22 The selected arr~ng~ment for
surlàce sten~ dispersal is prefèrably a unifol m an-ay, althou;,h any arrangement of surface
stems is possible (includil1g even a randomly designed dispersal of surface stems within a
~iven area~ In a prefèrred embodiment, the surface stems 28 are arrayed in staggered
1~ rows across the substMte 22, SUCII as row a, b, c, d in FIG 2 Preferably, each surface
stem 28 projects at a light al~,le relative to the second side 26 of the substrate 22, but
altemati~ely an,,led stem olientations are also contemplated
Preferably, the surface stems 2~ and substrate ~ are formed integrally as a stemweb, and the substrate requil-es no additional support layer or backing material As
~) shown, the surface stems 28 of the pretèrred embodiment are equally spaced apart and
eacll is row1d in lateral cross section, having a generally uniform diameter along its
height, from its outer end 30 to the second side 26 The surface stems 28 collectively
serve to defil1e an operative region or contact surface for the pull rol? cover which
contacts the advancil1~, fabric web
2~ With a pull roll cover material 20 of this design (e g, FIGS 2A and 2B), the
surface sten-s 28 provide a very unifol-m fi-ictional engaging surface for presentation to
the ad~ancil1g fabric web, both initially, and as the surface stems '~8 wear down during
usage The surface stems ~ ~vear unifolmly, and since the diameter of the surfacestems 2~ is ~enerally uniform alon~ their height in the pret'erred embodiment, the surface
area of sten~ ends 30 does not change because of changing stem structure along the
entire heioht of tlle sulface stems 2~ as the sllrface stems 28 wear down The inventive
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pull roll co~er material thus presents a frictional engaCSing surtàce that is resistant to
1azing and maintaills a constallt friction level during its use~l life.
The use of uni~orn~ly disposed and formed surface stems as the ~nCSzl~rin~ surface
of a pull roll cover results in a highly controllable and predictable frictional ~.n~m~nt
s relationship between the pull roll cover and web. In addition to opposed roll and web
material-to-material frictional interenga~ement characteristics, the precisely formed
nature of the pull roll cover surface intl-od~lces a significant mech~nic~l engagement
component into the fi-ictional en~,agement relationship. The upstanding surface stems on
the pull roll cover penetrate interstices on the web surface (e.g., between the crossed
] (~ fibers of its weave for a woven web) to engage the web mechanically. Testing sll~e~t~
that such surface stems disposed on a pull roll cover do not damage many woven
fabrics, as other~vise might be e~cpected. Outer end portions of the surface stems
actually en~ra~re tlle tl-reads of a ~oven fàbric web to mechanically engage with the
wovell web as it is advanced past the pull rol~. While such mechanical interengagement
~5 is a factor in the fi-ictional relafiollship of prior art pull roll cover rnaterials and woven
webs (e.g., bristle based covers or abrasive material covers), those cover materials are
not entirely uniform in the dispersement of their bristles or abrasive particles (as well as
being less than fully uniform in terms of the size, height and diameter of their bristles or
palticles). As a r esult, the web en(~agement surfaces presented by those prior art cover
2~) materials to the web ~vere not as unitorlll t'rictionally as desired. The uniforrnly shaped,
sized and disposed surfàce stems of the present invelltive pull roll cover present a
homogelleous fi-ictional surt'ace f'or contactin~, the web. The surface stems of the
in~entive pull roll cover are particularly useful and effective in this regard when the web
has a relatively ulliform sulface structure (e.g., woven or knitted3, ~Itho~l~h the
2~ mechallical en~,a,,elllellt characteristics are evident in relation to other web structures as
well (e.~r..Spllll bonded. nollwoven~ etc.3.
The inve1ltive pull roll cover 20 illustl-Ated in FIGS. 2A and 2B is ,~s;sLallL to the
piCI;Lip of lint and fiber dL!rill;, use. Fulther, it is possible to use materials to fabricate the
inventive pull roll cover 20 so that the cover 20 is resistant to dye pickup and transfer
from the fabric web. In one embodimellt, the inventive pull roll cover 20 is molded ~om
SRD7-:-60 impact copolymer resin available fi-om Sliell Polypropylene Company,
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Houston, Texas. Other possible materia]s for forming the pull roll cover 20 include
PrevailT''' 3050, available from Dow Chemical Company, Midland, Michigan, HimontKSOS4P, Montell-Himont, Atlanta, Georgia, and HytrelT~'~ 5526 or SurlynrM 1702, both
available from E. 1. du Pont de Nemours & Co., Inc., Wilmington, Delaware.
The nature of the inventive cover 20 is described by its co~ Jdlion of stem
height, stem diameter, stem spacing and number of stems per square inch. The frictional
characteristics of the cover 20 presented to the fabric web are altered by changing stem
density, stem diameter. stem height or stem spacing, which in tun1 affect the surface area
presented by the stem ends 30 of the surface stems 28 to the fabric web, and also affect
the mechal1ical engagemellt relationsl1ip between the weave of the fabric web and the
surface stems Z8 (e.;,., a chan3e in stem height may affect stem flexibility). Four
examples of these parameters for the cover 20 are listed in Table T below:
TABLE l
l:~
Stem Density Substrate Stem Height Stem Stem
ltem Thickness Diameter Spacing
0.127 mn1 Approx. 0.4 mm 1.4 mm
Al stemslcm2 0.94 mm
50 stems/cn12 0.1~7 mm Approx. 0.38 mm 1.4 mm
A'~ 0.64 mm
150 stems/cn1~ 0.1 tmn Approx. 0.13 mm to 0.8 mm
A3 0.15mm 0.18mm
355 sten1s/cn1~ 0.076 mm Approx. 0.13 mm to 0.53 mm
A4 0.15 mm 0.18 mm
The stem spacin(J is the distance between centers of two adjacent stems. As shown in
FIG. ~A, in a preferred embodiment the stems are uniformly spaced apart in all
directions across the second sulface '~6 of the substrate ''''.
The paMmeters listed in Table l are not meant to be limitil1g, and numerous
variations in those paralneters are possible ~'or a particular cover. For instance, the stem
density is preferably greater thall ]7 stems/cm~, and more preferably greater than 15
stems/cm~. Table l presents specific stern density examples of 50, 150 and 355
stems/cm~. but stem web slem densities greater than 355 stems/cm2 are also possible.
I ~
_
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Further, the surface stems may have a heigllt gradient across the pull roll (e.g., shorter in
center tltan near its ends~ in order to facilitate web handling, the stems may not be round
in cross-sectioll, and the stem density and/or stem spacin~ may vary across the pull roll.
In some applications, it may even be desirable that adjacent stems have dirre~ heights,
or to have stems which change in profile (i.e., cross-section) along their height (e.g., a
cylindrical stem having an enlarged, tapercd stem base~.
In the pull r oll cover 20 just desclibed, and the methods of mal~ng such pull roll
cover materials described below, the cover material is typically formed by molding a
flo~vable material. The flowable material can be any suitable material, such as a
1() polymer, a metal or a ceramic precursor. It is also within the scope of this invention to
use t~vo or more din'elel-L flou~able materials to make the surface stems. The flowable
material is a foamed or solid polymeric material (such as that described above), such as a
themloplastic material or a thel-lllosettill, malerial. Othel- suitable materials include
thennoplastic polyul-etllalles, polyvinyl clllolides, polyamides, polyimides, polyolefins
1~ (e.g., polyethylelle and polypropylene), polyesters (e.,~., polvethylene terephthalate),
polystyrelles. nylons, acetals, block polymers (e ~, polystyrene materials ~ith
elastomeric segments, availal~le from Shell Chemical Company of Houston, Texas,
under the designation KratollT'''), polycarbonates, thermoplastic elastomers, and
copolymers and blends thereot' The flowable material may also contain additives
2n includill~J but not limited to fillers, t;bers, antistatic agents, lubricallts, wetting agents,
foamin~ agents~ sultàctallts, piglllellts~ dyes, coupling agents, plasticizers, suspending
agrellts and the lil;e.
FIG. 3 illustrates one embodiment of an apparatus and process for forming the
inventive pull roll cover. This process gellerally involves molding surface stems in a
2:, substrate sheet fi-om whicll the surface stems project. Substrate sheet 22 is formed,
bearin;, a plul-ality of projecting surtàce stems 2~ on one majc)r surface thereof. The
moldin(r step may include any suitable moldill~, apparatus~ as kno~vn in the molding art.
For example, tlle surfàce stems and substrate sheet could be injection molded, molded
by compressill;, a heated sheet nlelllbel- agaillst a molding surface, or molded by mol-iing
3() a flowable material over and into the cavities of a mold, which may be stationary or
movin;, (e.g., a belt~ a tape Ol a drum).
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As illustrated schemalically in FIG. 3, the process includes an extruder 35
adapted for e7~truding a flowable material, sL1cll as an impact copolymer resin, into a
mold ~,7. The surface of the mold 37 includes a plurality of arranged cavities 39, which
are adapted to foml a like plurality of surtàce stems from the flowable material. The
cavities 39 may be ananged, sized and shaped as required to form a suitable surface
stem structure t'rom the flowable material. ~ypically, a sufflcient additional quantity of
flowahle material is extruded onto the Inold 37 to form substrate sheet 22 concurrently
witll the formation of surface stems 2~. The mold 37 is rotatable and forms a nip, along
with an opposed roll 41. The nip between the mold 37 and opposed roll 41 assists in
forcing the flowable material into the cavities 39 ofthe mold 37, and provides a uniform
substrate sheet ~'~. The temperature at whicll the foregoing process is carried out
depends on the patticulal- flo-vable matel ial used. For e~ample, the temperature is in the
range of l 40~ to 260~ C. for an impact copolymer resin available from Shell
Polypropyletle C~ompally, Ho~Iston, Te~cas, ullder the designatioll SRD7-560.
s The mold 3 7 may be of the type used t'or either continuous processing (such as a
tape, a c~lindrical drum or a belt), or batch processing (such as an injection mold),
althou~,ll the former is prefen-ed. The cav,ities 39 ofthe mold 37 may be formed in any
suitable mallller, such as by dlilling" machillin~" laser drilling, water jet m~c.hining
casting, etchin~,, die p~lncllill<J, diamond tur~ g and the like. The plac~ nt of the
2() ca~ities 39 detemlilles the spacin~ and orielltatioll of the surface stems 2g on the
substrate sheet _, and tllus on the invelltive pull roll cover. The mold cavities 39 can be
open at the end of the cavity opposite the surtàce from which the flowable material is
applied to tàcilitate injection of the fiowable material into the cavity. If the cavity is
closed, a ~acuunl can be applied to the cavity so that the flowable material fills
2s substalltially the entire ca~ity. Alternatively, closed cavities can be longer than the
lengtlls of tile stems bein~ formed so that the injected material can compress the air in
the cavities. The mold ca~ities should be desi~ned to facilitate release of the surface
stems theret'rolll, and thus may include all~led side walls, or a release coating (such as a
TeflonTI'f material layer) Oll the ca~ity walls. The mold surtàce may also include a
.~() release coatin~, thel-eollto tàcilitate release of Ihe substrate sheet fiom the mold.
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The mold can be made from suitable materials that are rigid or flexible. The
mold componellts can be made of metal, steel, ceramic, polymeric materials (in~lu~1in~
both thertnosetting and themloplastic polymers) or combinations thereof: The materials
forming the mold IllUSt have sufficient inte~rity and durability to withstand the thermal
ener~y associated witll the particular molten metal or thelmoplastic mater.ial used to
fonl- the substrate sheet and surface stems. In addition, the material forrning the mold
preferably allows for the cavities to be formed by various methods, is inexpensive, has a
long service life, consistently produces material of acceptable quality, and allows for
variations in processing parameters.
The flowable nlaterial is flowed into the mold cavity, and over the surface ofthe
moldto forlll the substrate slleet. To facilitate flo~ of tlle material, the material typically
must be heated to an appropriate temperature, and then coated into the cavities. This
coatin~ teclllliclue can be any convelltional tecllllique, such as calendar coating, cast
coating, curtain coating, die coatin~, extrusion, gravure coating, knife coating, spray
coating or the like.
A~[er the thel~lloplastic matel ial has been coated into the mold cavities and over
the mold sulface, the material is cooled to solidif~ and form the surface stems. The
flowable matel ial is solidified itl alld 011 the mold to form the surface stems and substrate
sheet, whicll are then separated t'rom tlle mold. The flowable material will often shrink
2() when it is solidified, which facilitates release ofthe surface stem and substrate sheet from
the mold. Part or all of the mold may be cooled to aid in solidit~ing the sur~ace stems
and substrate sheet. Cooling can be effected by the use of ~vater, forced air, liquid
nitrogell or other cooling processes.
Whell therlllosettillg resills are used as the flowable material, the resin is applied
2~ to the mold as a liquid in an uncured or unpolymerized state. A~er the resin has been
coated onto the mold, it is polylllerized or cured until the resin is solid. Generally, the
polymerization process involves either a settin~ time, or exposure to an energy source,
or both, to tàcilitate the polymet ization. The energy source, if provided, can be heat or
radiation ener~ y such as an electron beam, ultraviolet light or visible light. A~er the
~o resin is solidified, it is rellloved fiom the mold. In some instances, it may be desired to
further polymerize or cure the therlllosettillg resin afl:er the surfàce stem if removed
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from the mold. Examples of suitable therrn--setfing resins include m~l~minP,
formaldehyde resins, acrylate resins, epoxy resins, urethane resins and the like. The
formation of a substrate having upstanding stems on one side thereof is further detailed
in U.S. Patent No. 5,505,747 and in WIPO International Patent Application Publication
s No. WO 95/19242.
The frictional characteristics of the inventive pull roll cover 20 have been
eslabli~hed through both static and dynamic testing procedures. The dynamic fiiction
was measured between a cloth and a selected pull roll cover surface by the following
procedure. A pull roll cover was formed by helically wrapping a 5 cm (two-inch) wide
lo strip of the designated cover material on a 12.5 cm (five-inch3 diameter roll or core,
providing a minimum of a 10 cm (four-inch) wide covered surface for evaluation
purposes. The 1~.5 cm (five-inch) core, end flanges and a 2 5 cm (one-inch) shaft were
mounted on a free wheeling supporting sha~. A 5 cm (two-inch) wide strip of untreated
jeans cloth (specifically, 96x64 jeans cloth, 1.943 ydsAb, TencelTM fibers, available from
~s Milliken Company, SpalLanl)urg, South Carolina) was anchored at one end and placed
over the designated pull roll cover material with approximately 180 degrees of wrap. A
spring scale and wire were used to rotate the core and measure the amount of force (in
ounces) nec~cs~ry to move the pull roll cover material against the fixed cloth. The
spring scale was a Chatillol1 scale, gauge R, Catalog No. 719-5 (0-5 lb. force gauge)
(available from Chatillon, New York).
The results are tabulated in Table Il below, and demonstrate the range of friction
values provided by the various pull roll cover test materials. The values are in ounces of
force required to produce smootll travel between the decign~ted pull roll cover material
and the 5 cm (two-illcl-~ wide strip of cloth.
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TABLE 11
Item Pull Roll Co~erTes1 Malerial Measured
Load (oul~ces)
B I Scolel) ~ '~ PTFE (Tcnonl ~) Filn~ Tapc :~91 E:~itmded I ~
Smooll1 B~cl~ ol'S1en1 Web (S~enl Heigl~ ypro~;. ().03()". Stem Dia.
B2 ~).()1: ". Slen1 Sptcin~ n~7 Slcm D~nsil~ 32~ sten1s/ll1~. Substr~te
llliclillcss 0.00~") . O
B3 Sal'eh ~ 'T~pe~2()Fil1eResili~ntTreads
B l Steol Sidc of St~m Wcb (S~llllC p.~ ;l > tS IICIII A2 ~0111 ~able 1) 10
B:~ Gllilfor(l 1~3')()~LoopClolll ~ 17
BG s~lrc~ -W~ '' T!pc 37() Mcdiulll Resilicnt Treads ~ 48
B7 BRUSH LON ' " bmsl1 lll~tetial. No. 331 B ().00~ ; (). 1 X75" Trilll 5G
T~pc L 2()~ Tilt
BX BRUSHLON I ~' brusll IlI;ltCr~al~ No. 331 B ~).003" ~ 5" Trim 64
T~pc L ~()~ Tilt
Notes
s 1. Available as identified fi-om Mimlesota Mining and Manllf~ctllrin~
Compally~ St. Paul, l~linllesota.
2. The bacl; side (no stems) of the inventive pull roll cover material forrned
from impact copolymel resin available from Shell Polypropylene
Company, ~OUStOll~ Te~;as, under the desi~gnatio1l SRD7-560.
3. The front (surfàce stem) side of the inventive pull roll cover material
formed fiom impact copolymel- resin available fiom Shell Polypropylene
Company, Houstoll, Te.~;as, under the desi~,nation SRD7-560.
4. Available as identified fi-om Guilfol-d Mills. Inc., Greensboro, North Carolina.
The majority of these items were secured to the core using hook-and-loop
mechanical attachment stnlctures. The pull roll cover test material was l~min~ted to a
hool; structure backinc~ . ith the hOOl;S projectin~l oppositely from the firictional
enga~ ing surface of the pull roll covel- test material. A corresponding loop structure
was secured about the core tor enga~,elllellt with the loop structure backing on the pull
roll cover test matelials. The llool; structul-e in this e~ample constituted either VelcroTM
I,
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8 11 , VelcroT~ 7 (both a~ailable fi-om Velcro USA, lnc., Manchester, New
Hampshile) or tl1e polyolefin "musl1loom" hook fastener portion of the 3M Me~h~nic~l
~astener D;aper Closure System ~available firom Minnesota Mining and ~nllf~chlling
Compal1y~ St. Paul, Minnesota). Tl1e loop structure was Guilford 18904 loop cloth,
s available fi om Guilfol d Mills, Greensboro, Noltl1 Carolina.
Since a pull roll cover is typically intel1ded to prevent slippage of the fabric web
and pull roll surface. a measurement of the static friction or the force required to create a
slip bet~eel1 a fabric and a variety of pull roll cover test materials was perforrned. This
analysis measured the horizontal force re(luired to cause movement of a two-inch by
four-incl1 sulface of 14 oz. denil11 cloth against a pull roll cover material at two separate
normal forces or weights on the t-~o-inch by four-inch surface. The cloth was tested
with its lighter colored (back~ side fàcil1g tlle pull roll cover surface. The cloth was
ancl1ol-ed to a metal block whicl1 was placed on top of a pull roll surface ~tt~,hed to a
table top. The coefficient of fi iction was then calculated by dividing the horizontal force
l:~ to cause slippage by the weigl1t on the two inch by four-inch surface area. The
horizontAl force was measured with a Chatillon force gau~e Model DPP-50 (available
from Cl1atillol1, Johl1 & Sons. Il1c., Greel1sboro, North Carolina). The measured
hol-izontal forces al1d resultal1t coefficients of fiiction (COF) are presented in Table III
belo~ at botll nc:)rmal t'orces. Theol-etically, tlle coefficient of fi-iction is independent of
surface area of contact and the normal force applied (for friction considered on a
microscopic scale--i.e., a "sl11ootl1" surface a ,ainst a "sn1ootl1" surface). In the present
case, the t'rictional effèct must be considered Ol1 a macroscopic sale (i.e., including the
effèct of the penetratiol1 of the sten1s illtO the weave of the web), so the expected
indepcndel1ce of COF on sult'ace area and norl11al force may not hold true.
I ~,
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WO 97/32805 PCT/TJS97J01704
O c~ t~ r, ~ 3 ~ ,~
C~ i Cj ci 5 j ci Cj O i Cj Cj C'
~ Q~
~~ C ~~
_ Z ~o00 ~ C ~ ~~ C~ ~ t c~
t ~ ~ ~ ~ ~r' ~ c~ ~ c~o O c~
~C ~
O ~ 5 tt ,r, ,t~ 3 ~, tr, oo ~ --t t
~J _ ~ 5 ~ ~ cj cj c_ cj cj o O
~ _ ~
1~ c~ t
oo ~ ~! ~ ~ ~ ~ tt-- c~
t t ~ ~ ~ 1~ rr-- 1~ cJ~
v~
D
7 .;~ 7
, _ , - _
- ~r. é
--. C ~ ~
a ~ ~
~ ~ 'n
~ ~.
5 ~ F
~ ~3 o ~ ~ ~ _ ~, ~ 8 c~o 8
U ~ ) 1~ CL ~ C
~; 1-- y 8~ 0 5 0 ~1~ . 5 ~ ~_
tJ ~ m ~ ~ c, ~
-- -- '-- ~ ~ ~C~ 2;. C~ V ~ ~ ~ 'D
~ _ ~ -- -- _ _ _ _ _ _ _
U ~_JtJ tJ U ~ J V ~J
-17-
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W O 97/32805 PCT~US97/01704
Notes
I . Available as identified fi om Minnesota Mining and Manufacturing Company, St.
Paul, Minllesota.
2. The bacl; (no stems) side of the inventive pull roll cover material, forrned from
impact copolylner resin available from Shell Polypropylene Cornpany, Houston,
Texas, under the desi~nation SRD7-560.
3. Available as identified from Guilford Mills, Inc., Greensboro, North Carolina.
4. The front (sulface stem) side of the inventive pull roll cover materiai, formed
from impact copolymer resin available from Shell Polypropylene Company,
Houston, Texas, ulldel- the designation SRD7-560.
The inventive pull roll cover (such as ltems C7 and C8 in Table III) exhibits a
particular frictional perfomlance, as r eco~nized by the above testing That perforrnance
can be varied, not only by varyill, certail) design parameters of the pull roll cover ~e.g.,
s stem hei~ t, diameter, density or spacing) but also by varying the material itsel '
Alternative materials for t'omlin_~ the pull roll cover have been mentioned above, and the
frictional properties of those materials can be further altered by the use of additives (e.g.,
a filler) or coatin~s (e.~., a lubricious coatin~).
The si<~nificance of the mecl1allical interengagemellt component of the frictional
~() charactel-istics of the inventive pull roll cover is illustrated by tlle results of further static
f'riction testin~ in tlle mannel- detailed above. The horizontal force required to cause
movelllent of a two-incll by foul--incll surface of 14 oz. denim cloth or steel against a
pull roll cover matelial at a nonllal force of 8.344 Ibs. on a surf'ace was measured. The
cloth was tested with its li~hter colored ~bacl;) side facing the pull roll cover surface.
2~ The cloth was ancllored to a metal blocl; which was placed on top of a pull roll surface
attached to a table top. Items D 1, D~ and D3 were tested on separate occasions for the
cloth, hellce the additional test data. The coel~;cient of fiiction was then caiculated by
dividin~ tlle hc)rizc)lltal f'orce to cause slippa~e by the wei~Jht on the two-inch by four-
incll sul-f'ace area. The holizolltal t'orce was measured witll a Chatillon force gauge
3() Model DPP-~0 (available trom Chatilioll, John & Sons, Inc., Greensboro, North
Carolina). The measuled holizontal t'orce and calculated coefficients offiiction ~COF)
are presented in Table IV below.
- i8 -
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WO 97/32805 PCT~US97/01704
TABLI~ IV
l~em ~IllRollCo~rTesl Surr.7~ l~ u~llalFor~ COF
Matertal M:l~eri,71 (Ibs).atNorll~tl
Force=8.341
Ibs
Slllooll)B~lckofSlelllWeb Sl~l 1.77 0.2117
Dl ~b.lc~sideoflten~D2)
Clolll-lsl ~.33 (.7.39g4
Clotl~-211d ~.3 0.2756
StelnSideorSIelllWeb St~l l.X 0.21~7
D2 (~mepa~mele~orllem
A2 fi~ Tabl~lhe~in)
CJotl~-ls~ 3 0.7231
~loll~-~nd ~.()7 0.7275
SlelnSide Orslclll Wcb St~l 19 0.2277
D........ ~llncp;lr.llllctc~ofllc
A-rrolllT.lblclllcrc~
Clotl~-lst ().1~ 0.73~1
Clolll-2nd ~.76 0.6903
Slem SideofSlem Web
Dl (~lne~.".,.~ orltcltl Sl~l 1'~ 0.2277
AlfirolllT~Iblel
hcreill)
Clolll (.11.- 0.7231
The pull roll cover test matel-ials in Table IV are either the back side (Item Dl -
no stems) of the invetltiVe pull roll cover material, or its front side (Items D2, D3 or D4
- surface stems), and all were formed fi-om an impact copolymer resin available from
Shell Polypropylene Con7pall!~, Houston, Te,~;as, under the desi~nation SRD7-560. The
coefficient of fi-iction for each of the diftèrent pull roll cover test materials in Table IV is
mucll lower for the steel sultàce than the coefficients of fiiction t'or that same material in
relationsllip to the clotll sulfaces. The diftèrence is believed to be the result of the
1(~ mechanical intelellga;,eltlellt of the surface stems and weave of the cloth. and its
contl-ibutioll to the fiictional interrelatiol1ship between those two materials. As can be
- seen by a comparison of the steel coefficients of fiiction al7d the cloth coefficients of
friction in Table IV, this contribution is significant.
In addition to the invetltive pull roll cover '~0 itself, the present invention relates
1~ to tlle apparatus and metllod for use of a r eadily replaceable and repositionable pull roll
1 9
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cover The inventioll allows relatively quick challgeover t'rom one cover to another on a
pull roll by a simple and efflcient arran;,emellt that results in low maci~ine downtime Ln
addition, the present invelltiotl does not require special handling or expertise (eg,
hazardous waste disposal) in the pull roll cover replacement process
Previously, opposed hook-and-loop fastener structures have been used to secure
pull roll covers to pull rolls In all sucll instances, l-owever, the hook structure material
was mounted onto the pull roll The pull roll cover then had loop structure material on
its back side, and was helically wrapped about the pull roll with llook stmcture material
mounted thereoll Occasionally, one or more hooks protruded (because of an imperfect
helical wrap of the plJIl roll cover) fiom the pull roll exterior to contact the fabric web in
use~ piCi';ill~ and tearing at the tàbric web as it traversed the pull roll cover Any change
to the surface of the cloth or its weave produced by the pull roll is considered to be
dama~e to the cloth and is thlls to be avoided
The puil roll cover altachmellt of the present inventiol- involves securing the
loop material on the pull roll instead of the hool; material The loop material is bonded
around the cylindrical outer surface of tl-e pull roll The loop material is pl~;rel~ly
secured to the pull roll by a non-repositionable adhesive, since the loop material would
rarely be removed or need replacement once secured onto the pull roll The loop
material, even if e~posed by an impeltèct spiral wrap of the pull roll cover over it, does
not picl; at the fabric traversin=, the pull roll~ and thus si~nificantly ~ S the
possibilitv of damage to the làbric weave The hool; material used to secure the pull roll
cover to the pull roll now projects away fron- the textile web, thereby preventing the
possibility of picl~ing or tearil-~ the te~;tile as it traverses the pull roll
FIG 4 iilustrates the pret'erred method for the appiication of a strip of loop
2~ stmcture material 45 about the cylindrical outer surface of a pull roll 47 The loop
structure n-aterial 4~s is applied in a l~arro~ strip e g, '~ 5 to 10 cm (one to four inches)
wide wl-apped l~elicallv about a cylindrical outer surfàce 49 of the pull roll 47 The
entire cvlindlical outer SUI fàce 49 of the pull roll 47 (or at least that portion of the pull
roll that contacts the te~;tile ~A~eb) is covered in this mal~l-er with the loop stnucture
n~ateriai 45 An adhesive (such as a pressure sensitive adhesive) is used to secure the
loop material 45 to the pull roll 47
~()
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W ~ 97/32805 PC~AUS97~01704
The extelior pull roll cover material is bonded to a hook structure fastener
material such that one majol side of the pull roll cover (itS inner side) has ~t~nin~
hool;s projectin~r thel-efrolll while the otller side (its outer side) has the desired ~ictional
engagin~ sulface projectilt~ thel efrom (for engagin~, and traversing a fabric web),
tl~ereby definin~, a pull roll cover assembly for application to the pull roll. The pull roll
cover assembly is also preferably applied as a long narrow strip (e.g., one to four inches
w;de) which is helically wrapped around tlle pull roll. FIG 5 illustrates the application
of a strip of a pull roll cover assembly 50 about the pull roll 47. The pul~ roll cover
assembly 50 is llelically wrapped about the loop fastener structure 45, and can be
I () oppositely wound relative to the windillg of tl-e loop fastener structure 45 (as illustrated
in FIG. S) if desired. The use of hool~-and-loop fastening structures allows some slight
axial or side to side play of the pull roll cover assembly 50 as it is being helically
wrapped. This allo~s for the efficient achievemellt of fairly precise edge-to-edge
wrapping, witllout the necessity for continued removal and repositioning of the pull roll
1:~ cover assembly 50 to properly and completely cover the pull roll 47.
While a pretèrl-ed embodimellt includes the application of narrow strips of loopstructure material 45 and pull roll cover assembly 50 in a helical wrap about the pull roll,
otller application configuratiolls are possible. For installce, one or more lnngitll-lin~lly
aligned strips may be adhered to tlle pull roll.
2() F~G. 6 illustlates, in more detail, the nature of the pull roll cover assembly 50
and its n~oulltillg tO the p~lll roll 47 [wllicll has a backing substrate sheet 51 of the loop
structul-e material 45 adheled to itS cylilldrical outer sultàce 52). The pull roll cover
assembly 50 has its extel-ior side defined by the invelltive pull roll cover 20. As such, the
swface stems 28 ofthe cover 20 project outwardly from the substrate 22, with the outer
2~ ends 30 of the sur~ace stems 28 definillcg the cylindrical textile engaging surface of the
pull roll 47.
On its opposite side. the co~er assembly 50 has means for hooking the loop
stmcture material 45. 1n FIG. 6, the hooking means is illustrated as a sheet of hook
stmcture material 53 havillg a supportive substrate 54 ~'ith an array of projecting hook
3() stems 55 Oll one sicle thel-eot, with each stem having at least one head 56 thereon for
- 21 -
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W O 97/32805 PCT~US97/01704
interen .a~ement with the looped and intel-l11in(Jled hook-enga~ filaments of the loop
structure material 45.
Ti1e opposed substrates ''~ and 54 are bonded together to define the cover
assembl~ 50 as a surface substrate sheet, with sutface stems 28 projecting from one side
and hool~ stems S~S projectil1~ tiom its other side. A suitable adl1esive for IA~ the
invel1ti~e pull roll cover 20 to the hook stmcture material 53 is ScotchTM 985 Ilaminatin~r adhesive, available from Minnesota Minil1g and ~nufac.t~lring Company, St.
Paul, l~innesota. An alternative adhesive is Scotch~M 919 laminating adhesive, also
available from Minnesota Minil1~ and Manufacturil1g Company, St. Paul, Mi~ esuLiL.
Tlle particular laminatil1g adhesive used depends upon the characteristics of the
compositions used to t'orm tlle pull roll cover ~0 and hooli structure material 53. Ir~ any
event, the lamil1atioll is intellded to be pennallel1t and no separation of the facing
substrates of the two materials. once bonded together, is desired. Webs of the pull roll
cover ')O and hool; stl~lctul-e material 53 (wllicl1 may or may not be fo~ned ~om the
1~ same material) are laminated by fèedin2 those webs from rolls, removing and winding up
any necessary adhesive liners, and bril1~ , the laminatin~ surfaces together in a rolling
nip ul1del controlled tension and pl-esslll-e. The joined materials are then slit with a
rollin(r };nife and wc)ul1d on cores to produce strip rolls of the pull roll cover assembly
S0. Tlle widtl1 of each pull roll cover assembly strip roll preferably ranges from 2.5 to
2() 10 cm (one to tour incl1es) and, more preferably, fiom S to 7.5 Cltl (two to three inches).
As met1tiol1cd above~ in a preferred embodiment, the pull roll cover used w.ith a
pallicular pull roll should not be so tllick as to si~3nificantiy modi~'y the effective diameter
ofthe pull roll. Thus, in a pretèrl-ed embodimel1t, a low profile hook-and-loop fastener
structure assembly is desired so that the attachn1el1t means for the exterior pull roll cover
'~ sulface is as thil1 as possible. The hook structure material 5~ and the loop structure
matelial 45 are tllus mated in terms of tlleir cllaracteristics and structure to provide
sufficient bondin~ stren~Jtl1 but maintain a relatively low profile.
The loop structul-e material 45 can be either l;nitted loop, warp knitted loop
fabric, stitched loop tàbric, wovell Ol nol1wovel1 loop fabric. The loop structure material
3~) 45 l~resel1ts intelmill~led fibers f'or en~a~,ell1el1t by the hoolis 55 of the hook structure
n1atelial S~,. Pretèrably, the loop structure n1aterial 45 includes a plurality of loops 60
CA 0224701~ 1998-08-20
W ~ 97/32805 PCT~US97/017M
comprising filaments anchored tOt11elOOp structure substrate 54 at each end. The hook
stems 55 thus become entangled in the loops 60 to attach the cover assembly 50 to the
pull roll 47.
Tlle loop stl~lcture nlaterial 45 should be such tllatitis easy, i.e., without much
s effort Oll the operatol~s part~ to en~age the l~ook stems 55 into the loop structure
material 4~;. Lil;ewise, wllen the cover assembly Sû is to be replaced, the operator
should be able to easily remove the cover assembly 50 from the pull roll 47 by
disengagement ofthe opposed l1ook-and-loop structure materials.
If the loop height is too high, it can lead to shifting of the cover assembly 50,
() W}l;Ch could lead to notl-ut1iforl11 contact with the advancing fabric web and scuffing or
marrin2 tllereof. Tf the loop heigl1t is toO lo~, thel-e may be insufficiellt interengagement
and attachlllellt ofthe hool; stems 5j and loops 60. In ~eneral, the height ofthe loops
sllould be of the same order ot'magl1itude as the height of the hook stems. Additionally,
the loop dimensions and oriel1tations may depend upon the shape and height of hook
]S stems pro~ided.
Tlle loop density may also be selected to provide suitable p~ l"ance
charactetistics. For e~ample, tlle density of the loops can be the same as or di~erelll
fi-om the density of the l1001';S. If the loop density is too hi~h, this increases the cost of
tlle loop str ICtUre material~ alld it may be difficult to disen_age the opposed hook
stl~lcture material. If the loop density is too low, there may be insufficient peel and
shear strength to maintain the cover assembly 50 in place during use.
The loop structure matelial 45 includes a plurality of loops 60 comprising
filaments ~hicll are intermingled to~ethel; as illustrated in FTG. 6. The filaments may
either be individual filamellts, or yams complisillg a group of twisted filaments. The
2s filametlts should be r elatively strong to eff'ectively hold the hook stem and not
prematurely release the l-ooi; stem. E~iamples of such materials include inorgarlic fiber
filaments, such as metal ~includitl~ alulllillum or steel), ceramic (including glass and
fibe.rglass~ and the like The filamellt may also be a combination of dirre~l" materials.
Tlle filament may be straigllt, curved or twisted, and may contaill a surface LI~L~llc;llL of
.() some type, sucll as an antistatic coating, I~lbricious coatino. etc. Examples of organic
based filaments inclllde both tllerllloplastic and themlosettillg materials like polyamides,
CA 022470l5 l998-08-20
W O 97/32805 PCT~US97/01704
polyolefins, pol~urethanes, aramides, polyester, cellulosic materials and the like. In
general, it is pretèrred that the filamel1t diameter be one-half the distance that the head
56 overhangs from the stem of tl1e hook stem 55.
The loop structure material 45 can be bonded directly to the exterior sur~ace ofthe cylindrical pull roll 47 (i.e., thermoplastic loops can be melt bonded thereto).
Alternatively, a la",;natin~ adhesive can be used to secure the loop structure material to
the palll roll. Examp1es of laminatillg adhesives include polyolefins, polyesters,
polyurethanes, polyamides, hide glue, rubber based adhesives, urea-formaldehyde
adhesi~es, epoxy adhesives, acrylate adhesives and the like.
n A preferred loop material is Guilford 18904 loop cloth, available from Guilford
Mills, l11C., Greensboro, Nortl1 Carolina. This knitted loop cloth has a low profile
(approximately 0.3 mm (0.01'' inch) tl1icl;). A scrim l1as loop fibers on one side thereof,
and is provided witl1 an aclylic pressul-e-sensitive adhesive Oll its other side, which
allows easy bondin~ ot'the loop cloth to the exterior cylindrical surface of the pull roll.
Is A suitable adhesive for this purpose is A210 pressure sensitive adhesive film, avai]able
from illbruck, inc.~ IVinneapolis, Minnesota.
The hool; structure material 53 for the pull roll cover assembly 50 also has a
relatively low profile, and preaèrably is formed from hool; stem materials such as those
disclosed in Melbye et al. IJ.S. Patent 5,077,870; Chesley et al. U.S. Patent 5,505,747,
2(1 and WIPO Interl1atiol1al Patent Applicatiol1 Publication No. WO 95/19242. One
version of sucll malel-ial is the 3M Mechanical Fastener Diaper Closure System
(available t'rOIll Mhlllesota Mjnjl1~J and Manufacturing Company, St. Paul, Mir~esota~.
111 a preferred embodiment, the l1ool; structure mate~ial 53 is foamed with the following
characteristics: stem heigllt = approxilalately 0.5 mm (0.0'~0 inches), stem c~i~met~r=
2~ 0.4 mm (0.016 inclles), head diametel- = 0.76 mlll (0.030 inches), stem spacing =
1.4 mm (0.055 hlches), and stem density = 50 stems/cm~ (3''5 stems per inch2). The
hool; stems 55 are formed intega-ally with substrate 54 (whicl1 is 4.5 to 5 mil thick),
preferably of SRD7-560 impact cola~olymel- resill, available from Shell Polypropylene
Compal1y. Houston. Texas.
3() Alten1ative hook struct-lre matelial t'oamations are also contemplated. As used
herein, hooli steln means a stem havit1~ a free end that is spaced fi-om the surface to
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which the stem is attached and a structure that enables the hook stem to releasably hook
the features of the enga~ing sulface ~loop sh-ucture material). In FIG. 6, each hook
stem 55 is illustrated as having a head 56 shaped in the form of a nail head. Alternative
hooi; stem and head configuratiolls ~vill iùnction to suitably en ,age the loop structure
material. For instance, the head may have any suitable three-dimensional shape, such as
a hemisphere, sphere, IllUSIll'OOlll cap, cube, pyramid, etc. Preferably, the head has at
least one undercut portion that e~tends radially away from tlle stem at a right angle, such
as the heads ~6 shown in FIG. 6, to hook loop filaments of the loop structure materiai
45. Also. while the arran~ement and formation of hook stems on the hoolc structure
n material ~3 are illwsts-ated as <renerally uniforlll, alternative stem patterns, such as non-
ullifol m stems and stem array arran~emel1ts, will suff;ce.
A pull roll co~er assembh~, such as described above and illustrated in FIG. 6,
combil1ed witl1 the prefèlred loop ancl hooii materials desclibed above, plere,~bly has a
thici~ness of less thal1 0.~0 inch, more prefèrably less than 0 '~ inch, and most preferably
1:~ less thal1 0.09 inc.h, th~ls definil1g a relati~ely IQW profile coverinC1 for the pull roll. The
lovv Ioft of the Guilt'ol-d 18904 loop cloth ~as significant in its selection as a pler~ d
loop structul e matelial for this purpose.
The embodil11el1t illustlated in FIG. 6 uses both the low profile pull roll cover 20
having upstandil1~ sulface stems ~g, and the disclosed low profile pull roll cover
2() attachmellt means. The pull roll cover assembly ~0 is readily replaceable relative to the
pull roll ~7 bearin,g the loop stlucture matel ial 45 on its extelior cylindrical surface 52.
Whell a challge in pull roll covers is dcsired, the pull roll cover assembly 50 can be
removed by disengagil1g the hooii slen1s ~ on the hook structure material 53 from the
loops 60 of the loop stmcture material 4:n A replacel~1el1t pull roll cover assembly,
~5 havis1g one side defined by a replacemellt textile en~agillg~ material and the other side
defined by a suitable hooi~ tàstener stmctule, is then aftixed to the pull roll by adhering
the hooi~ fastener structule thel-eon to the loop fastener Stl~ctul e on the pull roll. The
replacement pull roll cover assembly is also typically applied as A thil1 strip, helically
wrapped about the pull roll, as illusn-ated in FIG 5. Replacement can be performed
~,() simply to replace a worn pull roll cover witl1 anotl1er having the same filctional and
mechanical engagel11ellt properties, or to replace a pull roll cover with another pull roll
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cover llavillg diffèrellt fiictional and mecllallical en~agement properties. For instance,
with respect to the invelltive pull roll cover 20 illustrated in FIGS. 2A, 2B and 6,
different i'rictional and mecllallical engAaement characteristics may be achieved by
substitutill(~ a different pull roll cover of the same general structure, but having di~
surface stem densities, spacin; ,s, hei<~llts or diameters, or being formed i'rom a dil~
(i.e., less lubricious) material.
Ttle use of the inventive hook-and-loop fastener arrangement of the present
invention thus provides i'or a wide range of pull roll cover options for the same pull roll.
The different pull roll cover materials can be readily replaced because of the ease and
l(~ effectivelless ofthe inventive attachlllellt an-allgement wllele the loop structure material
is essentially pellltallelltly attached to the pull roll, while the hook structure material is
adllered or formed on the bacl; of the pull roll cover. This is iliustrated, for example, by
FIG. 7, w hereill a pull roll cover assembly 150 has a pull roll cover 120 formed from an
alternative material. This could include any of the types of pull roll cover materials
:~ mentioned hereill, such as cork, lubber, sandpaper, bristle brushes, films, cloths,
TeflonT~ substrates, polymeric coatings, pol~mel-ic coatings containillg additives, coated
abrasives, nonwoven abrasives, slllootll or textured polymeric films, glass co~tin~
paper, foam, noltwoven materials, metal foils, and otller materials, such as those listed in
Tables ll and 111. Anotllel- pull roll cover matelial is a microreplicated surface, such as a
structural abrasive article, available under the trade desi~mation 207~A structured
abrasive article. i~ Olll Minllesota 1\1inin~, and Manutàcturill~, Company, St. Paul,
Mhlllesota. The possible pull roll cover nlatel-ials are limited only by the desired
frictional chal-actel-istics of sucll materials, and their suitability for use in a particular
te~tile pull roll applicatioll. The altemative pull roll cover assembly l S0 has a cover 120
2: with an e:;terior textile enga~in~ surface on one side, and on its opposite side, it bears a
hool; structule maIel-ial or structule such as hook stlucture material 153. This hook
structure matelial 1S3 hl tUIIl is releasably engageable with loop structure material 145,
wllicll is bollded to cylindrical outel sulfàce 152 of pull roll T47. The cover assembly
IS0 can thus be rellloved i'or replacenlent or change with another pull roll assembly
.~) havin~ the same or dii~'erellt fi ictional engag~elllellt characteristics. as desired.
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FIG. 8 illustrates yet another emboditnent of a pull roll cover assembly 250. Inthis embodiment, no separate or discrete exterior pull roll cover is provided. The
exterior (pull roll) surface of the pull roJl assembly 250 is defined by the side or surface
1251 of llOOIi structure material ?53 opposite its hook stems ?~5 The hook structure
material '~53 is again releasably en~,a~,eable with loop structure material 24~ adhesively
bonded to cylindrical outer surface ?~S2 of puli roll 247. The exterior surface 251 of
hool; structure material ?53 itself serves as the textile en;,a;,emellt surface of the pull roll
cover. The frictional characteristics for two versions of this type of pull roll cover
assembly are listed in Table ll (ltem B2)~ Table III (Item C?), and Table IV (Item Dl).
The invetltive pull rolt cover ?O of the ;nventive embodiments described above
overcomes many of the disadvanta~Jes of the prior art. It provides a pull roll cover
ha~'ill;, illitiall~,' UllifOI-Ill and extremely consistent fi~ictional engagement characteristics,
which includes contrc)lled and noll-ablasive mecltanical en~a~ement with a textile web
traversed thereby. The inventive pull roll cover 20 has a low profile and ll~i.;"l~in~ its
engagement properties unifomlly dutin~ wear of its surface stems. The pull roll cover
surface stems do not picl; or tear at a textile web, it is resistant to the transference of dye
from one textile web lot to al1othel-, and il does not e:;hibit a buildup of lint and fibers
durin~ use. The invelltive pull roll cover ?(), wllell combined with the inventive hook-
and-loop fàstenel mealls tor attachill~S a pull roll cover to a pull roll (with the loop
~0 structure material bonded to the pull roll)l results in a superior, low profile, inexpensive
and easy to use pull roll cover replacemel1t arran~el1lellt. The unique and inventive
attachmetlt arrallgelllel1t eliminates the possibility of dama~,e or picl;ing of the web by
the attachment components themselves
The present invetltiol1 filrther relates to an apparatus and method for use of a~5 readily replaceable ~or repositionable), low profile pull roll cover. The invention allows
relatively cluicl; chan~reover fi-om one cover ~o another on a pull roll by a simple and
efficient arral]~el11ellt that results in low macl1il1e downtil11e. In addition, the present
invel1tiotl does not require special halldlitl~, or expertise (e.~., hazardous waste disposal)
in the pull roll cover replacemellt process~ and it provides for an extremely low profile
pull roll cover attachlllellt. The present invelltioll simplifies the cover application and
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replacement process~ since it does not necessarily require the application of a fastener
matelial onto the pull roll prior to application of the pull roll cover itself.
Wllile the invel1ti~e en1bodinlents described above with respect to FIGS. 4-8
provide man~ advanta~es and are pai-ticularly well suited for many applications, such
two-part fastenin~ arrangemellts re~uire additional material and add depth to the pull
roll cover.
The pull rol] cover attachment of the embodiment described with respect to
FIGS. 9-1'~ involves securing the pull roll cover directly onto the pull roll by means of a
repositionable pressure sensitive adhesive (PSA). A repositionable pressure sensitive
I () adhesive is a low tacl~ adhesive. havill~, sufficiellt adhesive qualities to maintain an article
in place once applied to a sult~ce, but allowin(J tlle adhesive to be overcome if it is
desired to reposition or rell1ove the article. The repositionable adhesive leaves no
appreciable resid~le once rellloved, alld retains sufficient tacl; to be re-adhered once
repositioned on a mountin, surface. Repositionable pressure sensitive adhesives are
1~ filrther described in U.S. Patent Nos. 3,691,140 and 4,166, 15. . This ~tt~-.hm~nt
arrall~,elllellt for a ~I)ull r oll covel- does not appreciably add to the radius of the pull roll
covel-, thus creatillg a ver~ lo~t pl-ofile pull roll cover assembly. Fulther, no undesirable
residue is le~ on the pull roll whell covel-s are changed.
FIG 9 illustrates the l.~retèn-ed metllod for the application of a strip of pull roll
2() cover 320 about the cylindrical outer sul1àce of a pull roll 47. Tlle pull roll cover 320 is
prefel-abl~ applied in a nalrow strip~ e.g,., '~.~ to 10 Clll (one to four inches) wide
wrapl)ed helicall~ about a c\~lindlical outer surface 49 of the pull roll 47. The entire
cylindl ical outer sultàce 49 of the pull roll 47 (or at least that poltion of the pull roll that
contacts the textile web~ is covered in tllis manller with the pull r oll cover 320. While a
2~ helical application is shown, other alignmellts are also possible.
FIG. 10 illustrates, in more detail, the nature of the pull roll cover 320 and its
moulltil1g to the pllll roll 47. When mounled as shown, the surtace stems 328 of the pull
roll cover 3'?0 projcct outwal-dly ti-OIll the second side 3'~G of {lle substrate 322. The
sultàce stems 328 thils detine the c! lindl-ical operative textile contact surtàce of the pull
3(~ loll 47.
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On its opposite side (first side 3?4),the substrate 3'~2 of the pull roll cover 320
is bonded to the cylindrical outer surface 49 ofthe pull roll 47 This bond is ~)le~ bly
achieved by a laminatillg adl~esive assembly, as more speci~ically illustrated in FIG 11
(as meîltioned above, the drawillg f~ules are not to scale, pOltiOllS being enlarged for
s clarity) A slleet or scrim 69 ilas its first side 71 bonded by a nonrepositionable pressure
sensitive adhesive layer 73 to tlle second side 3'~4 of the substrate 322 The particular
nonrepositionable adhesive selected depends UpOIl the characteristics of the
compositions used to form the substrate 322 of tlle pull roll cover In any event, the
lamination of slleet 69 to substrate 3 _ is intended to be permanent
1() On its second side 7~, the sheet 69 is bonded to the cylindrical outer surface 49
ofthe pull roll 47 by a low tacl; pressule sensitive adllesive layer 77 This lamination is
intended to be repositiollable in nature, so that the pull roll cover 320 may berepositioned (or renloved) relative to tlle pull roll 47 by release of the low tack
repositionable pressure sensitive adllesive from the cylindrical outer surface 49
:. In a preferred embodimellt. these low tacl; adllesive properties are provided by
Scotcllmarl;r~' 9870 High-Low lacli Lamillatillg Adhesive, available from Minnesota
Minill~ and Mallufact~llill~g C~ompall~, St Paul, Minlleso~a Tlle Scotchmark~M 9870
laminatill~, adhesive llas a polyester scrim or carlier (sheet 69~ This prevents any bleed
thl OUy,ll of nolll epositionable adllesive toward the cylindrical outer surface 49 of the pull
2() roll 47~ and th-ls lessens the likelihood of ally nonrepositionable adhesive residue being
le~ on the sul1àce 49 Webs of the pull roll cover and lamillatin~r adhesive are laminated
by fèedin~r those webs fi-om rolls~ renlovill(r and willdilt, up any necessary adhesive
liners, and blin;,ill~J the layer 7~. of nolll-epositiollable adllesive together against the
second side 3'74 of the pull roll co~er substrate 3~'~ in a rollillg nip under controlled
2s tension and pressllre The joined materials are thell slit wit11 a rollin~ knife and wound
on cores to produce Stl ip rolls of the pull roll cover The widtl~ of each pull roll cover
assembly strip roll ran~,es fionl '~ ~ to 10 Clll ~one to four inches). and preferably from S
to 7 5 Clll (tWO to thl-ee inclles) A linel- relllaills over tlle laver 77 of low tack pressure
sensiti\!e adilesive, to be relnoved LlpOIl application of the pull roll cover to the
cylindrical outer sultàce 49 of a pull roll 47
~9
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As mel1tioned above, in a prefèrred embodiment, the pull roll cover used with a
particulal pull roll should not be so thicli as to significal1tly modify the effective rii~m~ter
of the pull roll. The thicl;l7ess of the Scotcl-mate'~ 9~70 larninating adhesive is
approxil11ately ".5 mil, and th-ls provides an attachment means for the exterior pull roll
cover which adds no appreciable increase to the pull roll diameter. Any change in
diameter behveell pull roll covers on a single pull roll tl-us depends on the thjr~n~cc of
the pull roll covers then~selves, and not on theil- repositionable pressure sensitive
adhesive attachment nieans. Tl1e pull roll cover, such as described above and illustrated
in FIG. 5, preferably has a thickl1ess of less thal1 1."7 cm (0.500 incl1es), more p~e~el~bly
less thal1 6.4 mm (0."~0 incl1es), and n1ost pretèrably less than 1.3 mm (0.050 inches),
tl-us definil1g an extremely lo~ profile covering f'or the pull roll.
Othel suitable pressure sel1sitive adhesive arrangemel1ts are contemplated. For
instal1ce, a noniepositiol1able pressule sensitive adhesive can be laminated on the second
side 324 of the substrate ~ , with a lo~ tack pressure sensitive adhesive larrlinated over
the hi~l1 tacl; adhesive. Suitable pressllre sensitive adhesives for this purpose are
Scotcl1 ' '1 919 Lan~il1atil1;, Adhesive and Scotch ' 'l 9449 Laminating Adhesive,
respectivel), both available fi-om Minl1esota Minil1g and Manufàcturil~ ompany, St.
PauL I\ linnesotct. A<~ain, this adhesive an-al1gel11el1t is extremely thin, preferably
accul11ulatil1~ to less thal1 0.0~0 mil. For tlliS specific arran;,emel1t, over time (e.g., 30
days), the nonrepositionable adhesive will bleed througl1 to the low tack adhesive, and
the repositionable characteristics of tlle low tacl; adhesive will deteriorate.
The embc)dimel1t illustlated ill FIG. lO uses botl1 the lo~v profile pull roll cover
3'~0 havil1~ upstandin~ sultàce sten-s 3'~8~ and the disclosed vely low profile pull roll
cover attachn~el1t meal1s. Wl~en a chan~e in pull roll covers is desired, the pull roll cover
3'~0 is sin-ply peeled away fi-om the cylindl-ical outer surtàce 49 of the pull roll 47 to
separate the repositiol1able ~ - tacl;) pl-esslll-e sensitive adhesive layer 77 from the
cylindl-ical outer sultàce 49 of the pull roll 47. A replacen1ent p~lll roll cover, having one
side defined by a replacen~el1t textile en,a_ing material and the other side bearing
repositionable press~lre sensiti\ e adl-esive~ is thel1 applied to Ihe pull roll 47 by wrapping
it about tl~e pull rc)ll 47 and pressin~ it tllereto. The replacel11ent pull roll cover is also
typically applied as a thil- Stlip~ helically ~vrapped about t'he pull roll as illustrated in FIG.
, ~ )
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9. Replacement can be pertolmed simply to replace a wom pull roll cover with another
havillg the same fiictional and mechallical enga(rement properties, or to replace a pull
roli cover with anotller pull roll cover havillg different desired fi ictional and mechanical
en~agement properties. For instal1ce, with respect to the inventive pull roll cover 20,
320 illustrated in FIGS. 2A, 2B and 10, diffèrent desired frictional and mer,h~n~
enj~,a ,ement characteristics may be achieved by sub.stitllting a different pull }oll c~ver of
the same general structure, but having dillè~ enl surface stem densities, ~racing~, heights
or diameters, or bein~ formed from a diffèrent (i.e., less lubricious) material. There is no
appreciable adhesive residue buildup from one cover to the ne~t on a pull roll, so that
1() the initial diametel- of tllat pllll roll is mailltailled over time and various pull roll cover
applicat ions.
Tlle use of the inventi~e repositionable pressure sensitive adhesive pull roll
fastenil1~ all-al1;,ement of the presellt invelltion tllus provides for a wide range of pull roll
cover options for tlle same pull roll. The different pull roll co~,er materials can be readily
s replaced (or repc)sitioned if initially misali~rlled during application) because of the ease
and eftèctiveness of tlle in~entive attachlllent arranrelllellt. This is illustrated, for
e,~;ample. by ~IG. 12~ llereill a pull roll cover 4'~0 is t'ormed from an alternative
matelial or structure. The cover 420 could include anv of the types of pull roll cover
materials mentioned hereill, such as corl;, rubber, sandpaper. bristle brushes~ ~ilms,
cloths, Teflonr~ substlates, polymeric coatin~rs, polymeric coatings conti~inin~r additives,
coated abrasives, nonwovell abrasives, polymeric filnls, ~lass coatin~,s, paper, foam,
nonwovell materials, metal foils, te~;turized pol~mers and other materials, such as those
listed in Tables 11 and 111. Anolllel pull roll cover material is a microreplicated surface,
such as a structul-ed abrasive alticle, available undel- tl~e trade designation 207EA
2:- stmctuled abrasive alticle. available t'rom Minnesota Minin~r and M~n-lfactllring
Compally. St. Paul~ Minnesota. The possible materials are limited only by the desired
frictional cl-arac.teristics of sucll materials~ and their suitability for use in a particular
te:;tile pull roll applicatioll. Tlle alternati~e pull roll cover ~''0 has an exterior textile
en~ra~,in~, sult'ace 421 on one side. and on its opposite side ~22, it bears a layer of
.~1) rel70sitionable pressure sensitive adl-esive ~ihich is brou~llt illtO adhering contact with
the cylindlical outel- sult'ace 49 of pull roll 47. The pull roll cover 420 can thus be easily
- 31 -
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and e'r'ficiently removed for replacement with another pull roll cover having the sarne or
linè,enL f'rictional and mechallical engagement characteristics, as desired.
The pull roll cover of the inventive embodimellts of FIGS. 9-12 overcomes
many of tl-e disadvantages of the prior art. It provides a pull roll cover having initially
unifornl alld e~;tremel~ consistellt frictional engagelnellt characteristics, as well as the
possibility for contlolled and noll-abrasive mechallical en~a~r,emellt with a textile web
traversed thereb)~. The invelltive pLlll roll cover has a low profile and maintains its
enga~r,ement properties ullif'omlly durin_, wear of its surface stems. The pull roll cover
surface stems do not pick or tear the textile web, it is resistant to the transference of dye
from one textile web lot to anothel-, and it does not e~hibit a buildup of lint and fibers
dUrill~r LISC. l~he pull roll cover, wllell combilled witll the inventive repositionable
pressure sensitive adhesive f'or attachin~ a pull roll cover to a pull roll, results in a
superiol. e ;trelllei~ low profile, ine.~;pellsive and easS~ to use pull roll cover replacement
arrangemellt The ullique and in~ellti\~e attachment arran~,ement elii-ninates the
possibilit~ of dama~,e or piCl;ill(J, of the te~;tile web by the pull roll cover ~ttachm~n~
arrangement.
Althougll tlle present in~!elltioll llas been described with reference to preferred
embodinlellts, woli;ers sl;illed in the all will reco~,llize tllat cllall,es may be made in
forlll and detail ~itllout departhlc fiom tlle spirit and scope of the invention. For
2() installce~ t11e base stnict~lre f'or applicatioll of tlle invelltioll has only been described with
respect to c~,~lhldrical pull rolls. The hlvelltive cover and the novel cover attachment
method disclosed heleill can be applied to othel base structures. such as an endless belt
or other s~lrf;ace wllicll may come into contact witll an advancill~, te~tile web in a textile
processill rr ol mall~lfàct~lrill~ iacility Fultller, the hlventioll is also applicable in
applicatic)lls otl1er thall te.~;tile pull rolls. Any surfàce whicll contacts a web or sheet or
otllel- substl-ate worl;piece is a candidate 'r'or tlle hlventive co~er and inventive cover
attacillllellt arran;,elllellt of the present invelltioll. For installce. the roll cover can be
applied to a one-illcll diameter trallsfèr rc ll in a photocop~,~ machine In this regard,
possible web materials ma~ include, but are not Ihtlited tO, wovell, nonwoven, knitted,
.~() needle tacl;ed, wet laid. stitch bonded and SpUIl bonded matelials, as well as papers,
films~ t'oils~ and lnetal sheets or strip~ F~llthermole, the orielltation of the lan~inating
- 3~ -
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W 0 97132805 PCT~US97J~7W
adhesives described ~vitll respect to FIG. I l may be reversed such that the
nonrepositiotlAble adllesive tàces the puli roll surface and tlle repositionable adhesive is
exposed on tlle pull roll (so tllat the ret)ostiollable adhesive is on tl)e pull roll rather than
the on the replaceable cover). Alterllatively, a discrete sheet havillg repositionable
pressure sensitive adhesive 011 both its sides may be disposed between the roll and roll
cover.
