Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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APPARATUS POR UTILI~ING POSl~
CON8UMER ( RECYCI.ED ~ POLYESTER RESIN
TAINING CONTAMINEN'rS
Shls lnventlon relatQs ln general to new and
uo~ul l~provoment~ ln an apparatus. ~or ln~ectlon
~oldl~y ~re~or~ from ~ polyest~r re31n, partlcularly
~B~ an~ Eoro y~rtlcularly to an appara~u~ for
~tlll~lng po~t conuumer (recycled) polyester resin
ooAtalnlng cont~mlnent~
Rocyallng and reuse of polyester resin~, such
a~ pEr~ ln ne~ oontalners 18 a growth lndustry.
~onty p~rcent of ~ll PE~ package~ produced annually
a~o now belng recycled. Thls rate exceeds that of
~ ~nd 1~ expected to achleve the SO~ rate o~
alu~lnu~ cont~lne~s by lg95.
Th~ ~cle~nU recycled PET is at best 99.97~
pure. The 0.03~ (or 300 parts per mllllon)
cont~mlnent 1~ typlcally comprlsed of alumlnum from
closuro~ PE ~nd PP from base cup8 and plastic
c;osures, glue from the label adheslve, etc., ana
~l~c~ neous m~terlal lncludlng paper.
It ~hou}d be noted that the average
~oleoular weight o~ PCPET varles from lot to lot as a
fu~ctlon of the type/qua~tlty of the PET bottles
co~prl31ng tho lot. Tho mo}ecular welght of PET
dlr~otly ~n~luenco~ the propertles of the polymer and
~rtlclo- produced from lt.
~ o produce preforms for contalners of
~cc~table quallty lt 1~ noces~ary to pro-process the
~cl~n~ tl~ko~ of rocyclod or po~t-conuumor polya~ter
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ro~ln ~PET) by extruslon through a screen pack to
rcmov~ the solld contaminent particulates. It ls
crltlcal to remove the residual al~minum partlcles as
tho 3rlnd~r scr~n slze u~ed by most recyclers to
granuldte lncoming bottlc3 and the like i5 3/8" whereas
~ typic~l ln~ectlon hot runner valve gate opening has a
dlamet¢r on the order of 1/8". ;~
The extruslon and pelletizing step adds
~pp~ox~m~tely 10 c~nts/pound to the cost of clean
~lA~e. In addltlon, the extrusion fllterlng process
degrades the a~e~age PET molecular weight (intrinsic
v~c081ty ) by 5-10~ thus reducing the physical
propertl~ of thc resulting "clean" polymer.
In ~ccordance with thls invention, the screen
pack, whlch may be an auto change screen pack, is
placud d1rectly on the injectlon machine itself.
Thls ellmlnates th~ co~t of the extruslon filtering
oporation and the correspondinc3 PET molecular weight
109n. ~n addltlon a viscosity feed back loop is
dl~closed whlch elimlnates the influence of varying
post consumer PET IV fluctuation on the final IV of the
ln~ection molded article.
Wlth the above and other objects in vlew that
~lll ht3reinafter appear, the nature of the invention
will be more clearly understood by reference to the
follo~ing detailed description, the appended claims,
and the st3veral views lllustrated in the accompanying
dr~wl nq .
Tho dsawlnq ls ~ ~chematlc vlew ~howing the
dctalls of the apparatus for utLlizing recycled
poly~tt3r rt3~ln (P~T) in accordance wlth thls
lnvuntlon.
~ ofurrlng n~w to thc drawing in detail, it
~lll bo ~un that tht~re l~ lllustrated d conventlonal
ln~tctlon moldinl3 Inachlnu 10 whicl1 has an lnlet 12 and
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dl~chArgo 1~. ~ormally the machlne 10 l~ connected
directly to a manlfold 16 of an lnJectlon mold 18 for
pre~ormJ. Th~ ln~ectlon mold 18, for illustratlon
purpo~er/ ~ lllu~trated to have but a slngle preform
caYlty 20 with a cora 22. It 18 to be under~tood
thnt A ~ultablo valve gate tnot shown~ controls the
tlo~ o~ the ~olton resln through the manlfold lnto the
cnvlty 20. . .
In sccordance wlth this inventlon, there i~
lnt~rpo~ed between the discharg~ 14 and the manifold 16
several element~ lncluding an auto change screen
p~ck ye~o~ally ldentlfled by the numeral 24. The
~crq~n p~ck 2~, however, cannot withstand the resln
pros~u~a requlred to form a preform in the mold cavlty .:
20. Therefore, there ha~ also been added a shootlng
pot ldentl~led by the numeral 26 which is provided wlth
plunger or plston 28. There i~ also incorporated , :
in ~ dl~ch~rge paa sge 30 from the screen pack 24 a
rot~ry v~lvo 32. The valve 32 l~ first positloned to
co~unic~te the shootlng pot 26 wlth the ln~ection
~achlne 10 through the screen pack 24 until the
shootlng pot 26 i8 fllled. The valve 32 is then
rot~ted so as to connect the shootlng pot 26 with the
~anl~old 16. The pl~ton or plunger 28 ls then moved
to forc~ the ~olten thermoplastic resin out of the
~hootln~ pot 26 lnto the mold cavity 20. It is to be
underJtood thAt the molten resin i9 ln~ected lnto the
~old c~vlty 20 at a high pres~ure. The shooting pot
26 ~rovldus ~or thls hlgh preqsure.
It l~ to be understood that the proper blend
of tho thermopla~tlc resln must be dellvered to thQ
~lller 12.
Po~t consumer PET ( PCPET) flake is comprlsed
o~ buver~e ~nd custom PET bottles and contalners of
Y~rylng lntrlnslc v13coslty ~IV). Accordlngly, PCPET
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~l~ko IV will Yary ~rom lot to lot dependlng on the
type o~ bottlo~ and cont~ln~rs whlch are recycled.
Th~ XY ~molecular welght) of PET has a
siqnlf~cant e~gcct on the straln hardening ~stretchlng
lnduaod cry~t~lllz~tlon) of Lniectlon molded ~reforms
~h~ch ~ s~ted ~nd stretch blown lnto a contaln~r
geo~try. ~lg~r IV'n straln harden during ~tretch
~t low~ ~t~etch ratlo~ vs lower IV's. As a result,
~roform8 produced from a lower IV PCPET lot would
rorult 1~ ~tesl~l flow to the bottom of a contalner
~urlng str~tch blow moldln~ whereao a high IY batch
~ould do the reYerue. .. ~.
In order to mlnlmlze materlal consumptlon lt
1~ e~sentl~l to balance the preform IY over time.
PA11Ur~ to do ~o would yleld the need to contlnuously
~d~uJt the blow procesn and lncrease the preform wQlght
to ~cco~modate process varlablllty.
To thl~ end, there is provided a blend of
vlrgln P~T (VP~T) ~nd PCPET. In accordance wlth thls
lnventlon, thor~ 18 provldcd n ir~t feed ln the form
o~ qu~ntlty o~ PCPET ~rom a PCPET supp}y 40 and a
rupply o~ VPEI~ ~rom a VPET supply ~ 2 . The PCPET and
VPE~ ~ro dlr0cted lnto ~ blender 44 ~t a preselacted
ratlo ~hlch ~ay .include between 10 and 80~ PCPET. The
blended ~olyeuter re~ln (PET) blend lo directed lnto a
V~CuU~ dryer w~lch lo provlded with agltatlon, the
v~cuu~ dryer belng ldentlfled by the numeral 4~. The
blqnd ls then dellvered into a flow passage 48
lncorpor~tlng an augor 50.
Sultable moan~ are provlded to determlne the
IY o~ the blend ~hlch 1~ fed through the flow passage
~8 by thD ~uger 50. T~ this blend there wlll be
~dded ~or0 VPET ln order to control the lntrlnsic
~l~cooLty. VPXT lfl dlrected from a VPET ~upply 52
~lrst lnto ~ vacuu~ dry~r 54 and thcn from the dryer 54
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lnto a flo~ pas~go 56 lncorporatlng an auger 58.
~hlle both augers 50, 58 may be o~ a varlable speed
drlv~, lf only one of the au~Jers ls of a variable speed
typ~, lt ~hould be the auc~er 58 so that selected
~o~nt~ of the V~T Inay be directed into the blend.
T~e flo~ pa~sag~s 48, 56 ~oln into a flov passage 60
~hlch dlrects the modlfled blend into the in)ection
~chlne 10.
The ~econd VPET qupply 52 preferably supplles
VP~ h~lng ~ hlgh IV, pr~ferably on the order of 0.76
to 0.~4.
If de~lr~d, sultable auger controls may be
provld~d so that as the melted resln IV varles, the rpm
ol the ~uger 58 wlll be varled to elther increa$e or
decreaao the proportlon of the second VPET. A target
r~nge of X 2 0.02 wlth X being b~tween 0.70 and 0.76 IV
la ~nvi3loned ~or the flnal preform IV.
It ls known that wlth a known hydraulic fluid
supply Sor drlvlng the ln~ectlon Inachlne 10, the lower
the IV oÇ the resln beln~ lnjected the faster the speed
of the screw of the injectlon machine. In a like
manner, as the IV of the resln increases, the speed of
rotat~on of th~ scre~ decreases. In view of this
kno~lcdge, a ~p~ed ~onltor 62 may be mounted on the
ln~ctlon machlne 10 and a speed controller 64 Inay be
mounted on the au~er 58 so as to vary the speed o~ the
augur $8 ln accorddnce wlth the speed of the screw of
tho in~ectlon machlne 10. The monltor 62 will be
elo~trlcàlly connected by wirlng 66 to the speed
controll~r 64.
Although only a preferred embodi~ent of the
~ppdratus and method of utlllzin~ the saI~e have been
~p~clflc~lly lllu~trat~ ~nd d~scrlb~d hereln, lt is to
b~ und~rstood thdt mln~r varl~tlons may be Inade in the
a~)ar~tuu without ~ ar~lng froln th~ spirit and scope
of the lnv~ntlon as d~flned by the appended claims.
