Note: Descriptions are shown in the official language in which they were submitted.
~146~2~;
This invention relates to methods for biaxially orient-
ing thermoplastic materials, e.g., polystyrene and more particu-
larly, to a continuous method and manufacturing means for extruding
webs of such material and form~ng objects therefrom by interfacing
the continuous extrusion process with intermittent orientation and
forming means.
The specifics of the following discussion and specifica-
tion refer to oriented polystyrene material, hereinafter referred
to as OPS but it should be expressly ~nderstood that the process
constituting aspects of the present invention is applicable to a
wide variety of thermoplastic materials, polymers or mixtures of
polymers including such materials as e.g., polymers of ethylene,
polypropylene, styrene~ vinyl chloride, etc.
Whilc in~lividual materials have problems whic]) are oftcn
eeuliar to tllose materials an~ aml~er commercial cxl)loitatioll of
tllem, tllc l)olystyrelle materials exllibit low-cost, lli~]l stiffllcss
all~l c~;cellellt transl-arellcy wllell prol~erly orient~l all(l tllc l)rol)er
molecular orientati.on urther enhanccs tllc l)olystyrellc material by
removin~ its inllerellt brittleness in the abscnce o~ molecul.lr
oricntatioll.
l llcrc al'C various l)rior art a~ roacllcs to n~iti~atill~ tllc
brittlclless factor in l)olystyrcne materials, by tl~e usc Or iml)~ct
molliricrs and tlle like. Ilowever, tllis ~leereases the sti~flless,
clilllill;ltcs transl)alerlcy an(l increases tllc cost si~nific;l3ltly.
Illerefore, I rior art al-proaclles to reme~ly the l)rittleness
roblem all(l increase the ilnl)act rcsistance of l)olystyrelle result in
ccrtnill un~lesiral)le l)rol)erties wllich di~l not cxist pJ-ior to the
n~lditioll of sucll modificrs.
~' ~ .
463~2~
I Accor~ ly, i~ sucl~ m;lteli;lIs coul~l he use~ rel;ltively
u~ o~irie~ st.~te ill m~l~uL3eturill~ sl)eets or stril)s or this In~terial
in a continuous extru~ing process ill wllie~ xial orielltatioll is
¦iml)arted to this material and tllcn, without (Icstloyill~ tllc basic
¦¦continuitY of the proce~s, mol~ articles or otllerwise form ~rticles
¦from it, all of tlle ~esirable pllysical prol)erties of tlle material
eoul~ be realized. At the same ti~ne all of tlle ~esira~ilities,
sl)ee~ all~ efficiellcies of a su~stanti~lly colltinuous extrusion an~
forlnin~ proeess coul~ be realize~ in tlle ultimate plO~UCt cost.
i11is inte~rated al)~roaell whiell combines contilluous extrusion,
~n~ se4uelltially orientatillg an~ formillg irl rapi~ suecession is
the crux of tl-e present inventioll.
lleretoCore, tlle eonventioll.ll al)l)roaches e.g.~ witll foam
slleet materials an~ non-~oame~ or noll-cellulllr sheet In~terials has
been to first produee sheetillg, store it in roIle~ form an~ terlllina t-
the illitial process at that pOillt, 'I'llen, subse~ucntly, the sl-eeting
is ul-rollc~l, relleate-l aJld ultimately forme~l illto pro~lucts or
,articles ill its rel~e~te~ state. As with ail tllerlllol)l;lstic teclll~ ues,
Ijtllere ale tllree basic il~terrelate(l V;ll'i.ll)lCs illVOlvC~I ill l)I'OCCssill~
2~ tl~e~ ol)l;lsti~ Ill.lteli;lIs wllicl~ eet l)otll tlle ll;-tl~l~ or ~lle ol-el~-
¦Itioll al~-l tlle cllalacteristics o~ tlle rillaI l~ro~l~lct. Il~ese v.lrial)les
¦¦;lrc teml-cratllre, tlmc all~l pllysic.ll st.ltc, witl~ tllc l;lttcr vari.ll)le
I~lc;ll i1lL~ w itl~ ~)r css UIC, strc s s, ct c .
!~ As a ~e~leral rule, teml)er.lture ,al~l tilllC shou.l~ l)c Illil~illliZ
Iv.Iri;ll)les lec;luse extel~le~ l~eat l~istory cal~ materi;lIIy arfect tl~e
l!l)ropcrticsoC;IIlcll~ll)ro~luct Illthcctlscof()l~S rOrcx.lllll)le
¦¦tl~e tellll)elatllle ~It wllicll the materi,ll IllUst l)c oriclltc~ rel)rcscllts
¦~ coml)rolllise l-etweel) Ievels whicll are best rrom ;l flow l~oi~t oC
liview ~ l IeveIs whicll ale l)est ~rom a stress (oriel~tatiol~) pOillt
3() llview. ()I~CC a stl'Css is iml)ose~ at a ~iVCI~ tellll)el.lture, ror
¦Iex;~ lo, ~ oloc~ oliol)t.-tioll is a~llievo~. Ilo~over, tl~e 10ll6or
~1 - 2 -
1, . I
11463~4~
tllc illcrclncl~t Or time illvolvc~l l)ct~ccll tl~c ;l~llicvclllcllt; o~ tllat
oricntatiol~ an~l ~ sul)se(~uellt operatioll, thc morc strcss (oricllta-
tiOII) ~ Igaill be relaxe~. /\ccor~lingly, t]lc (Ic~ree of oricntatio n
o~ a l~articular material is not neccssarily a solc runctioll o~ the ¦
S allloullt o~ hc~t stretclling applie~l to that m~teri~l to crcate the
oricntation since relaxation o~ that orielltation may silllultancously
bc takin~ l-lacc.
Ihcreforc, ~ h~ sl~cccl, intc~rate~l a~ ro;lcll is uni(~ue an~l
iml)ort;lnt not ollly from a stall~lpoillt Or cost l~ut also from tlle
10 ¦standl)oillt of results hereto~ore not otherwise attaill~ble.
l Ihese inherent a~lvantages of a high speed integrated al~proac
¦are iml)ortInt in relatively thill l~ro~lucts eg ~ tllose with wall
¦tllicknesscs of 0.005 to 0.010 inclles all~l become illcrcasin~ly si~nifi
¦cant Witll l)ro(lucts h~viJIg wall thicknesses grcater tll~n o.0l0inches
15 ¦lhis is ~lue to tlle fact that conventiollal systen~s as heretofore
~lefille~l, neccssarily involve not only ~re~ter time/teml)erature
cxl)osure ~lurin~ the pro~luction of shectill~ from t~l]liC]I tlle ultimate
ro~lucts are formcl, but also involve tlle rcllcatin~ all~l sul)se(~ucllt
recoolill~ o~ thc sllect ~lurill~ tllc sul)sc(lucllt formill~ ol)cl;ltioll.
2U /~ccor~lill~ly, tlle relicf Or stress occurs ~lurill~ rcllcltin~ ;ll)tl
subsc(lucllt rccoolill~ as well as ~lurin~ a l)ossil)lc rcl; xa~ioll ~luri
tllc l)ro~lllctioll of the slleetill~ l cr sc.
Theoretically, the ideal process would be biaxially to orient
the thermoplastic material, to form it and to cool it simultaneously.
25 In conventional systems, the time factor is significant and there-
fore detrimental. Accordingly, the shorter the time factor the
less detrimental the effect thereof on the maintenance of a stressed
r oriented condition of the _teria1.
114632~! 1
r tlle collve~ltio~ ctl~o~ls elllplo)~e~l fol tl~e l)ro~ ctioll Or
articles ma~le from material wllicll is biaxially oriente~l perllal7s
tlle most l)opular an~l widely use~ prior art system involves tlle
extrusion of a sllcet from a slot die onto a roll tlle teml~erattlre
S of that roll being eontrolle~l, an~l thell tllrou~ll a series of
a~l~ition ll rolls wllicll first bring the slleet to an al~prol)riate
temperature level for orientation an(l then lon~itu~ ally stretch
tlle sheet betweell t-10 rolls runllirl~ at (liffercnt spcc~ls. lllis
lon~itu~lillal stretehillg or drafting orients tlle matcrial in tlle
10 mael~ine ~lirection. lhe material with tl~e lonFitu~linal orientation
is thell passed OlltO a tenter frame to orient it transversely in a
manller well-known in the art. Since conventiollal tenterillg involve ;
lar~e lleavy e(~uipmellt, it is also llccessary th;lt teml~eratures be
mailltaillc~l in tlle sheetill~ tllrou~ll tlle use Or larL~e exl)ellsive ovenj.
15 IAfter tlle slleeting h lS been oriente(l both lon~itu~ lly an~l trans-
¦versely it is then rolled ali(l store(l ~or subse(lucllt use.
¦ 111e formillg oL OI~S sheetillg is usually carrie~l out on noll-
¦rotltill~ tllerillorormillg e(luipmellt witll special l)rovisiolls for tlle
I()l'S matcri.ll. It is llecossary th;lt tllc relleltill~ of thc slleetill
2(1 ¦.IS i.t is r.~ illtO tlle ~ormin~ e(~uipmcnt l)c m;lillt;lille~l unirorlmly tllrou~llout its wi~ltll afi~l len~tlls. ~s tl~e m;ltcli;ll rca(:lles a
satisfactory fornling temperature, tllc stresses llllicll llavc beell
iml)ose~l ~lurill~ thc biaxial orienthtioll must bc re.sistc~l by a(le~luate
l cl.lml)illg ~levi~:es in or(ler to preclu~le tlle slleet frolll sl~rin};ill~ bac~;
25 to its ori~inal (limensiolls an~l losing the orientation tllereill.
Since m0st non-lotlry formill~ equilllllellt is neccssarily inter-
nittcllt ;n its opel;ltion tlle intermittent fec~ lg Or oriellte~l
~ leet ill ~ CI~ collvcntiollal formill~ e~luil)lllcllt illll)o~ics illllcrellt
~(lifficultie; in the creation ancl mailltell;lllce of unirorm teml)erature
3l) con-litiolls tllrou~llout tl~e forming area o~ tlle sl~cet.
i3Z~ I
'I'l~ere;rc sevcral otl~er al-l7ro~cllc.c ~ ll llavc beell use(l to
Isome e~tent ill tllc pro~luctioll o~ bi.axially oriente~l sl~cetillg. One
joE tl~ese, thc bul)ble T~rocess, is tyl~i.cally t.l~e l~lay mucll tllermo-
jl)lastic ~ilm is l)ro~luce~l. By prol)er control ol' tcml)erature an~l
5 Istretc~ g, it is l~ossible to producc a bill~ially oricnte(l film or
slleet usinL~ this bubble techllique. Ilowever, in l)ractice it is
.I)roven to bc vcry critical because Or teml)erature uniforlllity
rc~luirements. Also this techni((ue is not usal)le wherl it comes to
Ithickcr Illatericll SUCII as tllat usc(l ill tllermoforme~ alti(:les or
10 products on tlle order of meat trays, containers an(l tableware.
¦ ~urtller, there is some e~luillment in use wllicll simultaneously
jstretclles transversely an~l lon~itu(linally. 'I'llis e(~uiplllellt obviates
the usc of longitudinal stretchi~ig rolls e.g., tllose l)reviously
.~lescribc~17 but it llas certain disaclvalltages, naloely, t]-e amoullt of
5 Iselvage WiliCIl must be (liscar~e(l ~lue to the increase~l scallope~l
ff~ect resultill~ from clam~s wllicll are necessarily move(l furtller
al)art in tlle longitu(lillal ~li.rection in order to ac]li.cve such a
simultalleous biaxial stretclling action.
'I'l~c molccular oricnt;ltioll Or tllcrn~ol~las~i.c n~.ltcri.lls, .IS
Z() ~rcvi.ously i.n~licatecl resui.ts in sigl~iric;lnt .i.ml)rovcmel~ts i.ll m;lll~ of
tl~e cll;lracteristics Or ccrtain Or tllesc matcli;lls. 13i.a.~ 1 orienta
tion is cssential in most packagillg allcl (lisl~os.lble l)roLIucts. If
,oricl~tatiol~ is only i.n OllC (lirection, cvcn thouyll l)rol)erties may bc
Isul)stallti;llly iml)rovecl in that ~lirection, tlley arc re~luce~l ill the
25 lotller ~li.mellsiolls. l'yl)ical of l)ro~lucts wllicll are orielltc(l in one lirectiol~ only are monofilamellts an(l fil)crs. I)uril~g orielltation,
tllc molecules in thc matcrial arc slliftecl froln ran~olll coil entall~le
mcnt to a relative aliglllllellt l~arallel to l)rillc.il~al axcs o~ stretcll.
'l'llis rcsults ill sigllificallt im~rovcmellts .in l)l~ysical l~rol)crtics,
30 ol~tical l)rol)crtics all~ iml~rove~l barr.ier l~rol~ertics all(l stress
Icrack resi St.ll)CC .
1 ~146324t
I:ol c~ J)~ loll~ tl~ si~;lL l~lol-~rty illll-lovc~ ts, tll~
iml-~ct strcn~tll in nlaterials e.g., 01'~ .Irc iml~rovc~l on tllc or~er
of tcn timcs Witll two to three timcs the tcnsile strcngtJI of noll-
oricnte~ polystyrel-e an~ as mucl~ as thrcc times t]lC ilnl)rovelllent in
S yiel~ elongation.
lllcre is a definite neccl in tlle art to combiJIe thc a~vantages
of continuous cxtrusion with intermittent oricntill~ all~ forming
systcms ~ue to the wi~e availability of such intern)ittcllt systems
;IIId tlle cal)ital invcstments whicll tlley rcl)rcscnt. I:urtllcrmore, suc
intermittent systems are familiar and basically relia~le e(luipment
which have a market acceptancc and goocl will that kcep them in
~cman~.
Accor~ingly, the nee~ is establislle(l to interfacc tllc
conti~uous extru~ing systcms ~or thermol)lastics e-g- 7 0l)~ with
intermittcnt orienters an~ formers ~llile mcticulously ~reserving
the intc~rity of dimension and orientation of tlle continuously
ro~uce~ thermol)lastic material. -
Ille thcrlllal sta~i1ity of tllc orientc~ tllcrmo~ stic m.ltcriali~ illso critical i~ tllc llcat o~ cxtrusion ~n~ oricnt.~tioll is to bc
2U I)rcscrvc~l in tl~e contilluou~ly l~ro~l~lcc~l wcl) Or tllcrmol~ tic to a
su~licicllt ~cglee to l)ermit illtcrmittcnt rOll~ n~ cooling in thc
. illtcrmittcnt forming ap~)aratus.
It is therefore an object of one aspect of the present
invention to provide a method for forming thermoplastic products
by continuous extrusion and intermittent orientation and forming
in rapid succession in an integrated in~line system.
An object of yet another aspect of the present invention is
to provide a thermoplastic product forming method which extrudes~
biaxially orients and forms thermoplastic products and minimizes,
3(l to an optimum degree 7 the time lag between the extrusion, orien-
tation and forming stages thereof.
114~
An object of yet another aspect of the present invention is
to provide an integrated method for forming biaxially oriented
thermoplastic products in a continuous extrusion, orientation and
forming process which achieves higher basic linear speeds than has
heretofore been accomplished while interfacing intermitten orienta-
tion and forming means with continuous extrusion means to preserve
the dimensional, orientational and thermal state of the material
through the interface.
An object of yet another object of the present invention is
to provide a method for thermoforming biaxially oriented thermo-
plastic products of enhanced quality.
By one aspect of this invention, a method is provided for
forming products of biaxially oriented thermoplastic material
comprising: continuously extruding and providing a web of thermo-
plastic material; intermittently ingesting the continuously pro-
vided web into intermittently activated biaxial orientation means
and biaxially orienting a predetermined throw of the web for each
intermittent actuation of the biaxial orientation means; inter-
facing the continuously provided web with the the intermittent
means ~ 4accumulatingo said continuously provided web in an open
loop; the open loop oonfiguration and the throw of the web
being compatibly dimensioned such that each throw of web ingested
nto the intermittently actuated orientation means will transform
the said web from the open loop configuration to a taught substan-
tially straight line configuration substantially devoid of stret-
ching forces; the compatible dimensions of the throw of the web
and the open loop configuration constraining any physical and
thermal discontinuities in the web to positions substantially
immediately proximate to the extreme ends of each said loop and
1~6~2~
each said throw; and intermittently and immediately ingesting each
throw of the biaxially oriented web from the biaxial orienting
means into an intermittently actuated thermoformer means synchro-
nized therewith and forming products in that portion of the biaxi-
ally oriented throw of the web intermediate the discontinuities.
By a variant thereof, the method further includes: separating
the formed products from the webj and recycling the remainder of
the web for further extrusion.
By a variation thereof, the remainder of the web is first
granulated during the recycling.
By another variant, the method further includes: separating
and accumulating the formed products from the web; granulating
remainder of the web; and recycling the graunlated remainder of
the web for further extrusion.
By another aspect of this invention, a method is provided
for extruding and orienting a web of thermoplastic material in a
continuous mode and subsequently forming molded products therefrom
in an intermittent mode without interruption of the continuous
mode, comprising: extruding a web of thermoplastic material and
presenting it continuously to an orientation means at an optimum
orientation temperature; intermittently stretch orienting the
web in a biaxial orienting means to a desired degree in the trans-
verse and longitudinal dimensions thereof while the web is in a
continuous longitudinal motion over predtermined intermittent
throw lengths thereof; intermittently extracting the oriented
predetermined throw lengths of the oriented web from the biaxial
orienting means in synchronism with the intermittent actuations
of the latter and ingesting the said throw lengths into a forming
means; and intermittently forming products in the throw length6
~1 46324
of oriented web with the forming means while preserving the in-
tegrity of orientation therein.
By a variant thereof, the method includes the further step
of: stripping the formed products and the remainder of the web
from the forming means.
By a variation thereof, the method includes the further steps
of: separating the formed products from the web; and recycling
the remainder of the web for further extrusion.
By a further variation, the method further includes stacking
the formed products separated from remainder of the web.
By another variant, the method includes the further steps
of: separating the formed products from the web; and recycling
the remainder of the web for further extrusion.
By a variation of any of these aspects of variants, the
thermoplastic material is polystyrene.
By another variation of any of these aspects or variants,
in the biaxial orientation means, 50% of the orientation of the
predetermined throw lengths of the web in the longitudinal direc-
tion is performed both upstream and downstream of the transverse
orientation thereof.
By anothen aspect of this invention, a method is provided
for forming products of biaxially or'ented thermoplastic material
comrpising: continuously extruding a web of thermoplastic material;
biaxially stretching the web in an intermittently actuated biaxial
orientation means in a continuous manner,over a predetermined
throw length of each actuation of the orientation means to effect
biaxial orientation therein and dimension the web for subsequent
forming; interfacing the continuously extruded web with the inter-
mittently actuated orientation means in a dimensionally and
g
~14~3~
thermally stable manner through a graivty formed accumulation
loop sized in accordance with the predetermined throw length;
substantially immediately and in synchronism with the orientation
means transferring a said throw length of oriented web from the
orientation means onto ~ downstream transfer means while maintain-
ing the dimensional integrity of the web; and forming products
in the intermittently advanced lengths of the web on the transfer
means substantially immediately upon the completion of each ad-
vance to enhance thermal stability therein and preserve the
orientation.
By a variant thereof 5 the method further includes: separating
formed products from the remainder of the web; and recycling the
remainder of the web for extrusion back into a said web.
By a variation thereof, the remainder of the web is first
granulated during the recycling.
By yet another variant, the method further includes: separating
and accumulating the formed products from the remainder of the
web; granulating the remainder of the web; and recycling the
granulated remainder of the web for extrusion.
By a further aspect of this invention, a method is provided
for extruding a web of thermoplastic material in a continuous
mode and subsequently orienting and forming molded products there-
from in an intermittent mode without interruption of the conti-
nuous mode, comprising: extruding a web of thermoplastic material
and presenting it continuously to an intermittently actuated
orientation means at an optimum orientation temperature through
a gravity formed accumulator loop accommodating a predetermined
throw length of web; stretch orienting the predetermined throw
length of web to a desired degree in the transverse and longitu-
-- 10 --
~1463;24
dinal dimensions thereof while the web is in continuous longitu-
dinal motion over a given intermittent actuation cycle of the
orientation means; continuously interfacing and juxtaposing the
oriented throw of web during the given actuation cycle with a
downstream transfer means sunchronized with the orientation means
in a dimensionally and thermally stable engagement therewith to
preserve the integrity of the orientation and the temperature
therein and to establish an intermittent feed mode of the web
downstream of the orientation means without disturbing the conti-
nuous mode upstream thereof; the downstream transfer means being
the input of an intermittent thermoforming means; and intermit-
tently forming products in the incremental lengths of oriented
web within the thermoforming means substantially immediately upon
receipt thereof to enhance the thermal stability of the web while
preserving the integrity of orientation therein.
By a variant thereof, the method includes the further steps
of: cooling the formed products and the web in the intermittent
forming means; stripping the formed products and the remainder
of the web from the forming means.
By a variation thereof, the method includes the further steps
of; separating the formed products from remainder of the web;
and recycling remainder of the web for further extrusion.
By another variation, the method further includes stacking
the formed products separated from remainder of the web.
By yet another variant, the method includes the further
steps of: cooling the formed products and the web in the inter-
mittent forming means; separating the formed products from the
remainder of the web; and recycling remainder of the web for-
further extrusion.
-- 11 --
~1 463;2~
\
By another aspect of this invention, manufacturing means are
provide~ for extruding and presenting a continuous web of thermo-
plastic material in a continuous mode and transferring incremental
lengths thereof to an orienting and forming device and forming
~roducts in the latter in an intermittent mode downstream of and
with no effect on the continuous mode, comprising: first means
continuously extruding and presenting a web of thermoplastic
material at a temperature suitable for subsequent orientation to
an accumulation position; interface means continuously ingesting
the extruded web from the extruding and presenting means and
intermittently discharging predetermined throw lengths of the
web; orientation means intermittently receiving the pPedetermined
throw lengths of the web and continuously biaxially orienting the
web over each said throw length; each said throw length correspon-
ding to a given actuation cycle of the intermittent orientation
means; and thermoformer means downstream of the orientation means
and synchronized therewith to ingest each throw length of biaxially
oriented web and form products therein.
The method of an aspect of the present invention commences with
the continuous extrusion of a relatively narrow web of thermoplastic
material from a die at a relatively high linear speed and.wXich is
cxtru<lc~ at thc l)rercrre~l oricntatioll tcml)cr.lturc. ~t tllC cxtrusioo
tcml)cr~turc is ~bove tlle desire~ oricntat.~on tcnll)cr.lturc tllc~l it m;ly
be l)assc~l over cooling rolls in or(lcr to brillg it ~owl~ to tllc ~csirc~l
orietlt.ltioll tcml-erature. lllc web lcavcs tllc coolill~ rolls
cntcrs .an acculllulatillg zone whcrc it .is pcrlllittc~ to S.lg ull~cr tlle I
torcc ot ~ravity in thc l~rovision oL a fa~c or ol)cll lool ~imcllsiolle~l
to intcrf.lco thc cyclic throw of tllc intcrmittcnt orielltcr an~
rorn~cr with tlle contilluo-ls~tlow from tlle e.~tru~r. Illc web is
- 12 -
~1 463;~
thcn l)assc(l tIlrou~Il dif$crclltial sI)cc~l rol1s ir dcsir(!d, to i)nl)art
a l)rc-lctcrmillccl maximum or l)arti~l amount o~ longitu~ a.l or n~acI~ine
<lircctiol~ strctcI~ orlentatioll thcrcto and imme-liately suI~sc~Illent to
tI~is ol ientatioll is passe~l illtO a trallsvcr!;c stretcII.illg station
whicll consists basically of a pair of divcrgelltly disl)ose(l rotating
saw bladc-like dcvices whic11 cngago tl~c web aloIlg cach cdge an-l -
~livide it into a series of increments wllicll are tllcn coIltinuously
sel)arated transversely to a distance of al)l)roximately three times
the original dimension of tIlc extru~lc~l web.
Sillce the longitudinal direction is also ~lesirably oriented
by strctchillg on an ordcr of magllitudc of tIlree times t]lC ori~inal
diIneJlsioll iE this Ilas not bccn acllievcd by tIIc strctclIing rolls
ul stream from thc transverse stretchillg mecIlanism, tlle balance of
the longitudinal stretching may be taken care of downstream from
the transverse stretching al)paratus. /~11 of tIIe foregoing
strctchillg steps, Ilowever are ~)erformed on a continuous and
unintcrrulltecl basis by the orientation apparatus OVel tlle extcnt of
tllc cycle throw of the intermittently actuatcd oricntcr and former.
After tlle ~ ror)er degree of orientation has bccn biaxially
iml)artc(l to t]IC extrude~l and now lcngthcIled aIl~l WidCllCd web of
m;ltcri.al, tlle material is imInedi;ltcly trallsfcrrcd tIIrougIl aIl inter-
mittcIlt rccd nIealls timcd coterm:iIl;ltely witll tllc actIl;ltioll o~ thc
oriclItillL~ a~ ratus aIld syncIlrollizcd witII tIlc intclIlli.ttcnt rormcr
to in~est; a givel1 increlIlental lcngtIl of oricntcd wcb Col r csl)oll(lin
to a saicl cyclic throw of web and ~lisl)ose it witllill the intcr-
llli ttCllt [Ol'IIICI' for an in~mediately succccdi.Ilg t]~C~ o rO,,,,i,-g cyclc.
IIlus I)ccausc of coter1Ilill.ltc an(l si.mlllt.lIlcous actuatioIl Or tlle
OriCl~t-ltiOII al)l)ar.ltUs alld tl~c intCrlllittCllt fcc~l IIIC~IIIS, cffcctive
mcalls arc l)rovidc~l to mailltain the cliIllcllsiollal aIld oricllt;ltioIlal
-- 13 --
~1 ~63;~
illtC~t ity a~ )res~lYo the teml)el.lt--re ill tl~e weh fr-)tll tl~c outlet
of tl~c oriclltatlo~ evicc illto tl~e illtcrm:ittollt rorlllor sucll t~ t
sufriciellt lleat oE extrusioll an~l oriclltatioll is l)rcsellt to J)ermit
tlle rllloforlllin~ .
Illerti~]. all~l tllermal (liscontilluitie~;, ir ;IIIy, tY.i.ll exist
only at the ul~strealll and ~lownstrealll extrcmities oE tlle accumulator
fake or loop, the ultimate extellt o~ wllicll is controlle~ b~
relative ~cljustlllellt of tlle extrusioll rate all~l cyclie l)erio~l o~ tl-c
intermittent orienter an~l formill~ al)l)aratus. lllus, if any such
~liscontinuities exist they are at tllc extremes o E tllo cycl ic throw
oE tl~e intcrlllittent former, namely, in tl-e selva~e ratller tl-an in
thc fillishell l)ro(lucts.
In the accompanying drawings,
Figure 1 is a schematic of an in-line continuous extru-
sion, and intermittent biaxial orientation and forming system of
one aspect of the present invention;
Figure 2 is a top plan schematic of the system and
Figure l;
Figure 3 is a schematic of the cutting, stacking and
selvage recycling mechanism used in an aspect of the present in-
vention; and
Figure 4 is a schematic illustrating the common drive
and timing used in an aspect of the present invention.
I~CrCrrillg iJ~ ~Ietail to the ~Irawings ;~ l witll l-;lrtiLul;lr
rofcrellce to l:i~ures 1 all~l 2, an extru~ler 11) is ilJustl;ltc(l ;IS
1I,1ViIIg an outl)ut to a ~lie 12 whicll forms ;I llallo~Y wcb 14 ol I)oly-
styrcllc or otllcr thcrnlol)lastic cxtru~l;ltc ;ll~(l rc~ls tl~c S;li~CXtrU~I;ltC 14 i.lltO a ballk oE coolillg rolls (~
As illlJstr(lte~l, the extru~ler 1() ~ l tl~c (li~ 12 Eec~
oxtru~;lte web 1~ tO a b;lllk o~ coolill~ rolls (:l~ IYl~ich arc l~rovi(le~3,
-- 14 ~
~ 463~
as is well klIowl~ in tlle art, win~lI a sIlit;lbIe IIc;-t e~cllall~e mCtiiUIII
aIld control tllerefor, or wl~ich siml-ly I)rovi~Ie tlIC I)rol)er reaeI~ o~
web m;Iterial 14 ror a ~iVCII temI~erature Or e,xtrIisioll to I)elnlit it
to cool sufficiel)tly in tI~e allIbiellt con~Iitiolls of tIIe I)rocess
e(Iuil)mel~t sucII tI)at wllen it reaclles aIl inI)Ilt roll a~sell~ it i~
at tlIC I)roI)er teml)er.ltllre ~or orientatioIl.
I1IC illl)ut roller assellIbly l~ is illustr.Ite~ ~is iIlclu~ g a
first roller 16A and a second roller 1613 wIIich receives the web 14
in a serI)entine I)atIl therebetweell and whicIl rolls 16A an~ 16L are
drivelI at ~ifferential rotational velocities to imI)alt a longi-
tu~in.Il or machille ~irection orientatioIl or stretch to the web 14
I)rior to the en~agement o~ the said web 14 with the tCCt]l 18r oE
a transverse ~tretcher blade assembly 18.
Interme~iate the downstream cooling roll ~I~A in tlle cooling
roll assembly CI~ and tlle upstream roll 16A Or tlIe inI)Ilt roll
assembly 16 is an accumulation area AA ill Wl~iCll the web l~i is
permitted to form an accumulation looI) AL as shown in ~ antom
es. lIIis acculIlulatioll loop AL is ~orme~ un~er tlle actioll of
~ravity an~ iil resI-onse to the timin~ differelItial c;luse~ by the
interfacing Or the continuous emissioIl and cooling Or tIIe web 14
upstrealIl of the accumulatioll area AA an~ tlIe interllIittent orienting
aIld ~ormin~ of tllc said web 14 dowIlstrealll of the ~iccumulation
area AA.
'I'IIe acculiIul.ltioIl lool) AL becomes taugIIt, witllout stretchi
i'-orces l~eing ;I~ ie~l~ as in~lic.lte~l by tllc soli.l ~ e mo~le /~Ls ill
I:igure 1. II~e accumIllation lool) AI, I)ul~atcs or altelllatcs betwee
tlle sa~gill~ ~otte~ e con~IitioIl an-I the tau~IIt soIi~l linc Illo~le
ALS Or tlle web 14 in eoncert witlI tl~e interlllittellt .ICtiOII Or the
web ree~ a~I~I transI~ort aI-I)aratus I~ in tlle tl~erlllorormcr ~ oh~n-
strealn Or the orielltatioll al)l)aratus as Will be more rully aI)I)arent
llcrcinaiStcr.
_ 15 -
~1 46;~2~ !
As sIIow~ ures 1 (In~ 2 assembly 2() is ~)rovi~Ie(I ~ow~ tre.
of tIIe traIlsve2se stretcIIer b1a~e asseIllbly 1~3 coInl)risill~ first,
secoI~d ;In~l thir-I outl)ut rolls 20A, 2(1I3 aIl~ 2()G exten(Iin~ ~ownstreIlll~in tIIat order, rrom tlle transverse b1a~e asseml)ly 1~3. TIIese ro11erIs
20A, 20I3 and 2t)G may be driveIl at selectively ~irferential rota- I ¦
tioI~al velocities to impart ~urtI~er lon~itlIdilla1 strctcll if ~esired
to tlle we~ 14 dowIlstream ol aI~d subse(~ueIlt to tIle in~I)artatioI~ of
transverse orientation thereto. Ihe ~ownstreaIn output roller 20C
is en~aged witII tlle surfaces of web a~vaIlce fce~ belts I:B of an
intermittent feed device F by I~hicll tlle now oriente~ web matcrial
14 will be carrie~ Into position in the iIltermittent thcrmoforJner
TF.
IIle output rollers 20A, 20B and 2UC are mounte~ on a common
fran~e 20~ on -~IlicIl the inI~ut rollers 16A and 16~ are also lI~ounte~.
TlIe tr.Insverse stretcll saw bla~es l~ and tIIe nearest rollers
thereto naIncly~ the uI)stream input rollers 16A an~ l~B an~ the
downstream output rollers 20A, 20B an~ 20C are all ~riven
preferably froln a common drive mDtor G~I tllrougII suita~le ~rive
belt means an~ the rollers 16B an~ 2()A .Ire illustr.Ited in Iigure 4
as being ~rivell by a common ~rive belt I)C wIIicIl en~a~es drive
pulle`ys or sprockets Sl and S2 moullte~ on the sll.lfts of tlle rollers
20A all~ 1613 respeetively.
Iurt.ler tIIe roller 1613 includes a ~rivelI output ueariII~ Gl
.IIicIl is Cll~ Cd witII compatiblc ~eariIl~ (or a I)re(Ietcr~ lc~ ratio
G2 mouIlte~ on tIlc sIla~t o~ tlle i~litia1 iIl])Ut ro1ler 16A SUCII that
tlle ~i~fcrcntia1 spee~ between tlle rolleIs l(-A aIl~ 16~ caIl ~e
e~fectu;Ited from tlle same commoII drive me;Ills I)G tIIa~ ~rives botl
tllC rol1ers 1613 .Ind 20A.
IIlus tIIe ratio Or tlle ~ears Gl aI1~ G2 C;lll I~C Cll;lll~c~ to var~
tlle amOUllt Or lOn~itUdillal strCt(:ll .lClliCVC(I bCtWCCIl tll(.` initial
inI)ut rollers 16A and 1~13.
16;~
Ille last two rolls 2UI3 an~ 2~ on tlle ~lo~nstle;lnl si~e Or tl~e
trallsvelse stretc1ler l)lu~les 1~ are also ~Irivell flolll tl)e rirst ~ea~
Gl Or tlle stretcher al)paratus in like mallller by ~C-II'S (;.~, (;4 all~ ¦
G5. Il~e last outl)ut (interface) roll 2~C is ~riven at tl-e
surrace sl~ee~l of the ~ee~ belts l:B Or tl~e il~termittellt web a~vance
~ all~ tllis is ~riven in turn by tlle u~strelm sprocket l;l~l. lhese
upstrealll sl)rockets ~Rl are ~riven by suital)le ~earill~ ~6 in syn-
chrorlisl~ itll tlle intermittent orientatioll mecllallislll 16-18-20.
ln or~er to maintain a constal~t din~ellsiollal relatiollsllip
between the transverse stretch saw bla(les 18 an~ tlle initial
output roller 20A, the blades 18 are l)ivote~ at t]leir most ~own-
stream e~es on tlle respective llivots 1', ratller thall at the centerl
of tlle sai~ bla~le.s 18. lherefore, tlle relationsllil) between these ¦
blades 18 an~ tlle output roller 20A renlains constallt ~urin~ adjust
mellt of the blacles between a direction l)arallel to the machille
~irectioll oriented at 45 witll resl)ect to the mac}lille ~irection.
Tlle second inl)ut roller 16~ an~ its coml)allioll illl)ut roller
16A in tlle illpUt stretch roll set 16 may be move~ in an(l out to
a~just to tlle losition of the transverse stretch saw bla~es 18
~ellen~in~ )on the a~justed positioll o~ tlle latter. Suitable
stol) mealls or l)osses (not sllowll) are l)rovi~le~l on tlle saw bla~le
a~ljustlllellt ~;-ckets to illtelact witll tlle mollutill~ ol the various
inl)llt rollers 16A all~ 1613 to l-reclll(le ell~a~elllel)t Or tlle rolls wit~
tllo saw bla~e l~ut mailltaillill~ tlle ~Iesire~l imlne~lilte l)roxilllity
tllereof.
~ uitable melns (not sllown) are also l)rovi~e~l witllill tlle
moLIlltill~l)l;lckot20l)0ftllcoutlutrollst2()tol)lovi~cfor
movill~ tll~ tl)ree output rollers 20A, 2~l3 all~l 2()~ al)lrt an~ back
to~etller a~;lill to l)rovi~le for tlle tllrea~ of m;ltel-i;ll tllerethrou~l~
;It the be~inllill~ of an extrusioll an~l orielltatioll all~ mol~ cyele !
- 17 -
~1 4~
ell l)laci~lg tlle rollers ul--ler a surriciel)t l)i.~s to l-rovi~le ~
I)re~leter~ e~l IllillilllUIIl Sll.lCillg ;IIUl l)I'CS!;lll-C tll-reoll sllcll as by ~Illal I
air cylill(lers or tlle like, all Or wl~icll is witllin tlle l)ul view Or
01~C oII or-lilla2 y skill in tlle art.
Il~e ell~lless fee~l belts 1:13 of tlle illtermittellt ree~ler 1: are
~lispose~l about input sproekets I~Kl alld outl~ut sl)rocliets F1~2 such
th~t 0l7l)0site selvage e~lges of tlle oriellte-l weh 14 will be gripped
by tl~e fee~l belts F13. lhus, the wel) 14, witll its ~limellsiorl;ll
integrity preserved, will be in~lexe~l tllrough a reci~rocatillg or
interJnittellt thermoformer Tl:.
ll~e fee~l belts I-B may be e(~uil)l~e~l t~lith rows Or ul)stan~liJlg
teetl~ r:l3r such tllat tllese teeth l~ierce tlle selvage e~lges of the
web 14 to l)reserve its ~limerlsional integrity an~l llellce, its orien-
tation. Ihe tllermoformer 11; ingests a pre~leterloille~ tllrow lengtl
of biaxially oriented web 14 for eacll intermittellt enablelllellt of
the web fee~l mecllanism F an(l biaxial orientation mecllanism 1~-18-ZU .
Ille interlnittellt thermoformer 1-1~ is in syllchrollislll witll tllese
intermittent fee~l meellanisms tllrouL~h suitable translllissiolls all(l the
like SUCII tllat tlle common drive motor Cl)hl (or otller e(luivalent powe~
mealls not sllowll) eontrols the interaction o~ all of tllese mechan~ ¦
isms. lherefore, ~lhen the ~ee~l belts 1:13 are stol~l)e~l the tllermo-
~ormer 11~ i11 close its mol~ls 1~1 to l~ro~luce a mol~le~ rocluct 24 ¦
in tlle a~lvallce(l biaYially oriellte~l web 1-1 . I IICII tlle mol~ls 1:~1 willbc OpClIC~] agaill l~rior to tlle COmlllCllCClllCnt of tl~e lle.~t a~lv;ll~ce
cycle o tlle wel) 14 from the accumul;ltor lool~ AL l~y tllC illtermi ttCIl jt
~ee~l mecllanislll 1 al~l the associate~l all~l syllcllrollize-l bi;lxi;~l
OriCllt;lt.iOII IIIC;IIIS 16-18-2().
llle a~lvallce of tlle weh 14 cle;lrs tlle Lorme~ ro~lucts 24 rrO
the moll~s 11:1~1 all~l carries tllem towar~l tlle CUttillg ;111~1 stacl;illg
statioll 23 of l:igure 3.
IJaCII a~lv~llce of the web 14 by tlle ree~l belts 1:13 causcs tlle
acculllul;ltor lool~ to shift ~rom tl~e S~ggill~ ]~II;llltOlll line l)ositioll tol
tlle soli~l line pOsitiOIl in the m;lllller best illustrate~l in l:i~ure 1.¦
-- 1 8 _
1l ~1 463~ 1
en, ~uring tlle therllloforl~ g cyc1e of tlle tllermororlller Il: tlle
¦accumulator lool~ ~L resumes tl~e sa~ging ~ alltolll line l)osition
lawaitillg tl~e next intermittent advallcc of tlle web 14 througll the
jorienter 16-18-20 and web advallce mecllallism l~ 1el1~ ICI1 t]le
5 ! tllerllloformer r~ is opelled to discharge the forlned l-ro~ucts Z4, the
!¦next intermittent orientation and fee~ cycle occur ~l~d the accumu-
¦¦lator loop AL once more assumes the soli~ line taugllt position of
¦lligure 1.
!~ ln ol~cration, in the biaxial orientation mechanism 1~-18-20
;the eircular saw bla~es 18 are a~justable about the l)ivot means P
¦between a maximum divergence of 45 to the nlacllille direction or
ro~uct center lille and a direction l)arallel to that center line
and are driven about their respective central bla~e axes by means
¦~Or ~rive l~ulleys ~P wllich are also positioned for movcment with tlle
~ lades 18 abollt the said resl)ectlve l)ivot means P.
'Ihe teeth 18T about the periphery of eacll bla~e 18 engage tlle
¦~outermost edges of the web 14 and callse it to challge flolll its
jillitial extru~e~l dimellsioll at the inl)ut si~le Or the l)la~es to a
jn~ucll wi~ler (limellsioll comlllellsurate witl~ the ~ivcrgcll~c at WlliCll the2n ~ a~lc5 arc set at the outl)ut side thereor. In tllis m;lllller, a
l,transverse orielitation is iml)arted to tlle wel) 14 ill a colltillnous
l~m~llller ,IS it ~ravcrses the transversc oricnt;ltioll l)L;Idcs 18 frolll
the inl)llt roll asseml)ly 16 to the outl~tlt rO11 aSSCIIII~IY 2~. 1
ractice, the longitudillal stretchillg or m;lcllille ~irection,
25 llstl ctchillg or orientatioll can l)e carrie(l out imlllc~li;ltcl y l~cl orc or
¦!immediately after the transverse stretclling or half l)efore all~ halfj
aftcr tllc sai~l trallsversc stretching. l urtllelmore, ;Illy othcr ratio
0~ illiti.li IlI;lChillC (lireCtiOIl strCtCll alld filla1 lil;lChillC direction
Istrctch is also fcasil~le. Thc de~rec of transvcrsc or l.ollgitu~lill;ll¦
11 1
11 .
11 .
11
I' r~ .._
' ~14632~ !
orientltioll call l~e v~rie~ ~o suit a l);lrticul.ll l)rodllct wllich nlay
Ihave de})tll or sllal~e re~luirillg less initial orient~tion of tJIe
¦sheetill~ in one or another dircction. 'Ihercrore, tllc prescllt
I inventioll provi~lcs a system wllicll is VCly r.~cilc allcl variable with
S ¦ re~ar~ to unique and unusual molded shal-es.
In an aspect of the present invention ? the amount of selvage
¦¦which falls outside of the transverse streteher blades 18 is the
¦ same as that amount of selvage whieh falls outside of the upstand_
ling teeth FBT on the feed belts FB of the intermittent feed
meehanism F. -
I A wide variety of longitu~inal an~ trallsverse stretch-mo~es
can be effectuated with the present invention. In ~11 c~ses, of
course tlle transverse stretchill~ is achieveLI wit]~ the zone 1l
an~ llot witllin tl~e upstream and ~ownstream zones ~ n~
Iresl)cctively.
¦ l~eferrillg furtller to l~igures 1, ~ and 4, the dialneter of the
! rolls 16A, 16B, 2U~, 20~ all~ 2~C are kept as slllall ~s is collsistent
jwitll miniloiZill~ tlle ~leflectioll of tllese rolls ullder lo~d. lhis
jlell~s later~l st:iEflless to the web 14 al)d reduces sllrill~bac~ an~
I,atten~nt loss o~ orient;ltion. Also, tl~e distlllce between tlle
20 1 ro.l.ls ill tlle rcsl)cctivc roll sets 1~ alld 2() is l)rcfcr.lblyl~o
~re~ter tll.lll to allow for sli~llt clcarallcc oE tllc wcl) or extrudate ¦
! 14 wl~icll furtller minilllizes tlle sllrin~back wllicll otllerwi.se occurs
.ls tllo In-lteri:ll is trallsferred rrom olle roll to Illotller.
¦ Ihe surE;Ice sl~ee~ of tlle second roll 1(~l~ is usu~11y ~ster
Ith.lll tlle surr.lce sl)eed of tlle first roll 1~ so ~ to acllieve
~lon~itudill.l1 5trctch ul)stream of the saw b1.ldcs 1~. lf tlle said
¦surf;lcc sl)co~l oE tlle roller 16B is twice th~t oE tlle roller l~A,
thell 5~)~ o~ tlle lon~itu~inal or macllille ~irection orient~tio
l~occurs in tlle tr~nsrer of m~terial between tl~o tall~ent l)oints of
Ithe web 14 oll tl-C rollers 16A all~ 1(13 resl~ectively.
- 20 -
I
~, 1146~1Z~ ~
¦i Also as ShOWII ill l:i~urc 1, tlle teetll 1~'l on ~llC trallsverse
¦Istretcller bla~es 18 are very close to tllc sur~ace o~ tlle second
¦jroller ].6B. 'Ille perimeter speed o~ tlle bl;~-les 18 is pre~erubly
l!slightly ~aster but substantially e(~ual to the surL;lce spee~ of
Ithe roller 16B thereby making the transfer of material rrom one to
!the other more effective. 'rhe teetll 181' actu;llly l)cnetrate the
¦¦edge of the ~eb or striy 14 so as to hol~ the material securely as
transverse stretchillg takes place d~lC to the ~ngular orientation
l of the blacles 18, t]le latter bein~ best showli witll reference to
1 Figures 2 and 4.
j lhe initial output roller 20A is also positiolle~ very close
to tlle teetll 18'1' of the bl~des 18 so as to minimize sllrillkback at
tllis l~articular transfer ~oint coml~rise~ by the illterrace bctween
'¦ tllc sai~ roll 20A and thc blades 18. 'llle sur~ace sl)eed of tlle
roller 20A is usually an~ preferably sli.glltly faster but substan-
¦ tially e(~u~l to tlle perimeter sl-eed of the trallsverse stretching
bla~es 18, tlle secolld output roller 2()B is IlI;lillt;li.llCd close to tllel
!ifirst outl)ut roller 2()A, alld tlle tl~.ird outl-ut ro.ller 2UC close to !
¦jtlle secolld outl)ut roller 20B, ill order to millillliLc sllrillkback
2() ¦1 durill~ the tr.lllsrer ~rom one roller to allotllel. Usu~lly, the
secolld outl)ut roller 20B and the third outl)ut roller 2()~ ~re run
¦twice the periplleral speed of tlle first outl)ut roller 20A witll thc
rererre~ sl~ee(l being sucll .IS to accollll)lisll tllC l'CllI;lillillg 5()o ofI the longitudillal or m~chille directioll orient;ltioll il~ tlle web 14
ias illustr.lte(l. 'Ille web 14, as it Icavcs tllc third outl)ut ro~ler ¦
ZOC Ol~tO tlle rcel belts ll3 is ~ lly l~ xially ori~llto3.
11
11 11 ~6324
¦~ A11 O~ tIIe 1On~itU~ a1 StrCtC~ rO11CI ~; 1(.1\, 1(~13, 2()/~ 3,,~,1
1I 20~ an(l tlle tllir(l output roller 2()C are l)reEcrabl~ coatc(l witll
¦.Eluorocarboll sucll as leflon to avoi~l sticking of tllc wel) 14 thereto.
¦ Also, such rollers arc usually ma~lc ~litll thill-wal1c~l stcc1 tubes in
5 I order to mininlizc tlle lleat retentioll cal~acity an(l lleat trallsfer to
the en(ls of the rollers. lllerefore, in tlle arca Or contact with
¦ tl~e wel) 14, the rolls reac]l about tlle salnc tcml)eratllre as that of
O the web itself an~l thus maintain thcrlllal stal)ility all(l uniformity
1~ in tlle web 14. Ileat-may also be apl)lic~l to tllc rolls ancl drum by
10 ¦¦ any suitable nleans known in the art.
Refcrellcc is now ma(le to l:igures 1 and 3 in wllich thc molded
pro~ucts 24 traveling in the (lirection 26 are delivcre~l to a
1I recil~roc~ting CUttillg an~l stacking n~cans 32 whicll scvcrs tl~c nlO
I I)rO~IUCtS 24 from the selvage of t]lC web 14 an~l causcs tlle sai(l
¦¦ severed l)ro(lucts 24 to be stacl;e~l in a suital31e l~ro~luct stack 24S 1,
1I wllicll is scllematically sllowll. I
While tlle severed pro~lucts travel to a stac}; 2~S, thc selvabc
1.14S travcls to a selvagc gril~ling an~l rccycl.ill~ mc.ll-s ~4 wllicll l~lows
Ij tllC L~roullLI sclvaue tllrougll a convc~or tul)c 34A to a rccyclillg
2() !! llol)l)er 34l3 a(ljaccnt a hol)l-cr 36 fe~ rrolll a tul)c 3lA Eroln a source
¦¦ oE llCW l)laStiC grallUlCS 01' I)e11ets to l)lacc both rc~roull~l sclv.lue
¦lan-l tl~e l)cllcts into a mixcr assembly 38 of a tyl)c ~cll-kllowll in
1I tilC lI't to re~ cct botll ~resll raw nl.ltcri;ll all~l rcc)~-:lc-l sclv;l~e
11 illtO thc CXtl u~lcr 10.
In all of tlle cmbo~lilllents of l:igurcs 1, 2 a~l~l 3, tllc various
le(luil)mcllt mo-lulcs e.g., tlle cooling roll al)l);lratus, tlle oriellt-
linu al)l~;lratus, tllc rormer an~l tlle CUttillg l~ress an~l ~rallulatill&
~al)l)aratus Cor reclai~ the selvagc arc moul~tc(l on a gui~lc tracl;
~il oll a sul)l)orting floor or tllc likc sucll tllat tllesc various Ullits
-22-
11 ~
!! I
1 i
~1463Z~
can be placed together in a dimensionally desirable relative
orientation to define the final in-line system of the present in-
vention. Suitable rollers or wheels W on each of the various
components are illustrated schematically as riding along the guide
tracks ST.
In any of the foregoing embodiments of aspects of the present
invention, an important concept is always positively to restrict
shrinkback of the oriented sheet by holding the dimen~ional in-
tegrit~ and the thermal stability of the sheet 14 to as close a
tolerance as possible.
The thermal integrity of the web 14 subsequent to its orien-
tation is also of importance since the temperature of the oriented
web 14 in the system of an aspect of the present invention is pre-
ferably sufficient for the thermoforming operation to be performed
by the downstream theroformer TF. The temperature of the web 14
is controlled, as previously disclosed by the roll or drum struc-
ture and/or auxiliary heating means of any suitable type known in
the art.
I! Ihe ~imcllsio~ inteF,rity of t:ilc biaxi;lll~ oricntcl anl
2(1 Ijtllerlllally m;l.intaille~l web 14 wl~icl~ cxits r.Om tl~c outl)ut rollcr 20C ¦
!If tl~c intclmittellt orientation mealls 16~ Z~ is m;lintaillc~ by
¦Itl-e tecth l:J~'I on tl~c feed belts lU of the intcrmittcnt [cc~
;mccl-;lll i.sl~ sucl~ tl-at a l)rol)erly oricntc(l all(l st;lb i I izc~l sl~cct Or
¦tl~crlllol)lastic m;lteria.l 14 is incrclllcntc(l within tllc tl~crmQ~orlllcr ll:
¦at a l~rol7cr tcml)craturc for tllcrmoformin~ tl~c l~ro(lucts Z4 thercin.
Illc coolin~ o.[ thc incremclltal scctioll Or ~cb 14 fc-l to tl~e tl~erlno-
forlllcr Il: is accol~ lislle~l by tllc thclllloforlllcr Il; wllilc tllc l~ro(luct
24 is in tl)c mol(l an~l thus, whcn tllC wcb 14 bcarill~ tllc l~ro(luct 24
an~ inclu~in~ the sclva~e scral) 14S leavcs tllc thcrlllororlllcr 11:, tllc
3~) Il)ro(lu~t Z~ vc I~OCII fixc(l in tlleir ori~ntc(l .~ fOlnlC(I con(lition~
_ 23 -
~1~6.~
Aspects of the present invention combine relatively short
cycles (20 to 30 cycles per minute) and correspondingly rapid ex-
trusion rates with relatively thick polystyr~ne sheeting on the
order of 0.030 inches and up in a preferred operating mode. Ori-
entation temperatures on the ~rder of 2600F are considered optimum
for retained orientation in OPS material. Slightly higher tem-
peratures such as 275F have been found to be less desirable for
retention of orientation. The preferred longitudinal orientation
mode is 50% elongation upstream of transverse orientation and 50%
downstream thereof in the input and output roller assemblies 16
and 20.
In an alternate embodiment of an aspect of the present inven-
tion, referring to Figure 5, the three output rollers 20A, 20B and
20C of the orientation means 16~18-20 of Figures 1, 2 and 4 are
replaced by two output rollers 20E and 20~, the upstream output
¦¦rollcr 20l. bcin~ much larger in di~metcr tllall tllc ~ownstrc.lm
I¦OUtl)ut rollcr 2~F. 'l'he larger upstrcam outl~ut rollcr 2t)~ is so
l,lsizc~ ;Is to ingest substanti.~lly a com~)lcte tl~row Or ;It le.lst
,l)arti.l.lly bricl~tccl wcb 14 corr~sl)olldillu to D c)'ClC of tllc illtCF-
~ ittcllt ~ CC~I mc;llls 1. Ille l)ortioll l~ Or tllc oricllt~l w~l) 14
2~ !Icn~ thc slllaller dowllstrc~lll olltl)ut rollcr 2~i: is COllS~l';lillCd to,ll~ss tllrou~ll the therllloformer Tl into a dowllstrc~lll sclvil~c l)ortion
¦I'W~ rcl-ltive to tlle moldcd l)ro~luct 24 sucll tl~t ;Illy l)llySiC~Il or
Itllc~lll;ll (li~colltilluiti.cs occ~siollc~l I) y tllC ~ llcl lollcl 2()l:
¦¦not ;Il)l)c.lr in tllc moldc~ l)roduct 24.
~ crcrorc, tlle moldcd l)roduct 24 will bc tllcrlllorollllc~ in th.lt
ort.ion o~ tlle wcb 14 on thc fccd beLts ll3 whicll w~lS Lormclly on
tllC SLll'l'.lCC O[ tllc l~rgcr outl)ut rollcr 2~l,.
11 - 24 - ,
11 1
~4632g
In this embodiment it should be noted that the feed of the
web 14 is inverted on the transverse blades 18 and that a third
upstream input roller 16C is required. Also, a third downstream
roller 20G is now provided at the downstream end of the feed belts
FB adjacent the downstream sprockets FR2 to stabilize the oriented
web 14 on the feed means F. Suitable drive gearing interconnects
all the rollers 16A, 16B~ 16C, 20E, 20F, 20G, drive sprocket RFl
and transverse stretcher blades 18 in a similar manner to that
described in connection with Figure4.
Therefore, it can be seen th~t aspects of the present inven-
tion provides a means for interacing between a continuous extru-
sion mode and an intermittent orienting and forming mode without
either mode adversely affecting the integrity of the other or the
quality and integrity of the biaxially oriented thermoplastic
material in the system.
- 25 _
