CA2005306A1 - Electrical conductor coated with polybutylene terephthalate - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An Elongate conductor has a layer of insulating or jacketing material comprising an oriented polybutylene terephthalate composition having an initial elongation of at least about 25%, most preferably at least about 75%, and an elongation after heat aging at least about 25%, most pre-ferably at least about 75% of its initial elongation. The conductor is provided with the surrounding layer by extruding the polybutylene terephthalate composition around the conductor as a loose tube and then drawing the loose tube, after cooling, down onto the conductor.

Description

2~ 53~i MP1~87 This inv~ntion relates to an elong~t~ ele~trlcal conduc-tor a l~yer o~ insula~ing or jack~ting m~terial ~ompri ing ori~nted poly4utylene terephthalate and t~ a m~hod of pro-vi~ing a layer of oriented polybuty~ne t~rephthalate insu-l~tin~ or ~acketing ma~erial on an elon~a~e ele~trical conductor.
Pol~mer~ of polybu~ylen~ terephth~ e, are well known and h~ve many use~ul properties. However, their ~ndency to embrittle At elevated tempera~ures, i.~. ~o 108e ~long~tion, :~
renders them unsui~a~le for us~ in general aY ~oating~ ~or ele~trical conductor~ ~nd in p~rticul~r for u~e aY w-ire insulation. ~ solution to this proble~ i~ di~lo~ed in U.S~
Patent No. 4,~32,855, to ~ingheim and Lunk, in which it i~
tau~lt t~a~ th~ a~di~ion o~ ~ ~econd poly~r hav~n~ a fl~x modulu~ of sno to 1~0,000 p~i an~ ~ specL~ied solubility p~rameter ~o poly~utylene terepht~alat~ (also known ~ poly-tetra~ethylene tereph~halate~ improv~s the perorm~n~ of pol~u~ylene ter~p~thalate AS wire or ~able in~ulatlon or ~cketing~ The ~e~ond polymer is pre~er~bly a polyether/polye~ter blo~k copo~ymer. ~he resulting ~om~
po~itlon h~ improve~ retention of ~lon~ation a~ elevate~
temperA~ures .
U.S. ~at~nt ~o~ 4,7~7,~B to Smith and ~hornley rel~tes to a composltion compri~ing poly~u~ylene t~rephthala~e and polyethe~/polye~ter bl~ck copolymer having a relatively high propor~ion of hard blo~k~ The composition i~ un~xpectedly ~up~rior to comparable composi~ion~ cont~inin~ A
polyetherJp~lyest~r 4100k Gopolymer~ having a lower p~opor-. :
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2~3530~i ~on ~ h~.rd blo~ in r~6~6~;a~CI~ tc~ 8~ rtl~o~-crazing when us~d a~ wire or cable insulating~or jack~ting ma~erial, ~he additiorl of ~uch a se~ond polymex ~o poly~u-tylene tereph~hala~e, as tauyht ln th~e patent~ re~lt~ in greatly impro~e~ wire and ca~le ooated th~rewlth ~ut increa~es the cost of the composition ~nd results ~n an in~ulation lay~r having a x~latively low ~ensile ~trength.
Japane~e Pat~t Kokai No. 54-68990 to Nariki and Kawase disclo~e~ the u~e orien~ed polybutylene te~phthalate as a wire coa~in~. The method used in ~hl~ 3apane~e pat~nt to apply the wire coating results in a ~elakively lo~ d~gree orientation of th~ polybutylene terephthalate~ It is reported in the patent that ~he coated wire i~ cApabl~ of being bent ~bout 1~0C witho~t cr~kin~. 5ub~equently, it has been ~ound that the coaked wira be~om~ britt~ ~i.e.
lo~e~ itB elongation) when ~ubjected to eleva~ed kem-peratu~e~ for a ~hort time.
We have now unexpectedly di~covered that an elongate electrical conductor ~uch as a wire or ~a~le can be in~u~
la~ed ox jaoketed with p~lybutyl~n~ terephthalate in ~u~h a m~nner a~ to provi~e an elongAte ele~tric~l ~ondu~tor ha~in~
~ polybutylene terephthalate 12yer whi:h haa surprisingly high ten~ile ~txength and impxoved ratention o~ elongati~n When subjected to heAt a~ing.
On~ aspec~t o~ this inven~lon ~ompri~es a m~thod o~ pro-viding an elongate electrical conductv~ with a l~yer of insulating or ~acketing materi~l, which compri~e~

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(a) extrudin~ a polybutylelle tereph~hal~te com~osition at a temperature, ~ ove the meltln~ tem~erature of the compo6ition ~o a~ to form a tu~ whi~h ; surrounds the. electrical c~onducto~ to be lnsulat~
or ja~keted and has an inner dia~ete.r gr~ater thas the outer diameter of s~id ~ondu~tor;
~b) coolin~ the extruded tube to a t~mperaturet T~, below the meltin~ temperature o~ th~ compo~i~ivn:
tc) drawing the ~ube down onto the elec~ical conducto~ with a draw ratio gre~ter thAn ~out 1.1.
~ no~her a~ect of t~is invention c~mpri~e~ an ~longate electrical c~nductor h~ving ~ l~y~r of insulating or ja~k~ting mAteri~l comprising an o~i~nt~d polybutyl~ne ter~phthalat~ aompo~itlon having a te~sil~ ~tr~ng~h o~ at least a~out ~,ao~ p~ n initi~l elony~tion at 25C of at leas~ about ~.5% and an elc.ngation ater hea~ agin~ at laoo~
fo~ ~even d~y~ of ~t least about ~54 ~f it~ initial elon~a-ticn, FI~.. 1 i3 a sc.he~atic view of an appAratu~ and pro~ss ~o~ applyin~ A layer o~ oriented polybutylen.e terephthalate t~ an electrical conductor in acco~dance with this invention.
FIG. 2 i~ a cxo~s sec~ional view o~ ~he ex~rud~d loo~
tube of polybutylene terephthalate around the ~ondu~tor '~ ~rior to drawing.
~ IG~ 3 is a aro~ ~e~ional view o~ the ~du~k~r pro-vided with a laye~ o~ oriented polybutylene tex~ph~hala~

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after the tube has been drawn down onto the conductor.
In accor~ance with this i~ention, the elongate electri-cal ~onductor i~ ~ro~ided with a layer o ln~latlng or ja~etin~ materi~l of oriented polybutylene terep~th~l~t~.
The polybl-tylene terephthalate can be a homopoly~ner of buty-l~ne t~rep~thal~e or a copoly~er th~reof with an ~romatic, aliphatic or alicycli~ dicarboxylic acid andfor A diol or derivations of ~aid ~eid or diol, for ex~mplq i~ophth~lic acid, 2,6-naph~halene dicarboxylic ~cid, 2,7-naphthalene dicar~oxylic ~cld, diphenyl dicarboxylie ~cid, diphenyl sul~one dicar~oxylic ~cid, diphenylethe~ dicarboxylic acid, diphenoxyethane ~icar~ox~lic acid, adip~c acid, sebA~i~
acid, d~Ane ~ica~boxylic acid, ~-hydroxyethoxy b~n~oic ~cid, o-~arboxy¢~proic acid, hexamethylene glycol~ dec~me~hy-lene gly~ol, do~ec~m~th~lene glycol/ bis~-hydr~ethoxy-phenyl~ 8U l~one, ~,2-bis~hydroxy~tboxyphenyl1pro~an~, diethylene gly~ol, cyclohexane dimethylol, cy~lohexane dic~r-boxylic acid ~nd 90 on. A mix~ure of more than one kind nf su~:h com~ound~ may be us~d al~o~
A polyfwnctional compound ~uch ~ trimesic ac~id, tri-meth~rlolpropar~e; or pentaerythritol and s~ on, and/or mono fullc~ional compound such as o-bRnzoyl l~enzoic a~id ox methoxypolyethylene glyol and ~o on m~y be copolymerized to the ext~nt that ~he obt~ined polyester can ~naintain its llnea~ chAracter, E3utylene terephth~late pc~lymer~ can be prepared ~y any o~ ~he oxdinary met~od~ such as by e~ter exch~nge reactic~n or a dire~t polymerigatLon m~t~od.
ïn addi~ion ~o polyb~ltylene te~ephthalate, tlle com-po3i~ion may ~ontain ~tarious additive~ Additives that ~an .~ . . . ~

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2~ 31)6 be u~ed includ~, for example ~ntioxidants such a~ ~lkyl~ked phenolæ, e.g. those comme~cially avAilable R~ Gooa~it~ 312$, Irg~nox 1010, Irganox 1035, Irganox 1076, rr~anox 1~3 ~
~kanox sKF, organic pho~phite or p~o~pha~e~ e~g. ~ilau~yl pho~phite, bist2,4-dl~t-butylphenyl~ p~n~aerythri~ol dlphosphi~e, M~rk 117~: alkylidene polyphenol~, e.g. Ethanox 330, thio-bis alkylated phenol, e~g. Santono~ Rr or~ho coupled oligomer o~ 4,4'-thio-bis~3-methyl~ bu~yl-phenol~, dileluxyl thio-dipropionater ~,g. ~ar~o~ DI~rrDp~
dimyri~yl thiodipropionate, e.g~ Car~tab ~ P, di~earyl ~hi~dipropion~te~ e.~, Cyano~ ST~P, ainine~, ~.g. Win~st~y 2 eta; UV stabilizer~ ~uch as L~ hio bis~4-~-octyl phenol~to)] n-butylamine nickel, Cya~or~ UV 1084~

3,5-ditertiarybutyl p~hyd~oxybe~zolc acid, W Che~ Am-~40;
thermal stahilizer~, ~UGh AS poly~arbodiimide; ~la~e reta~
d~nt~ ~uch ~ de~bromodiphenyl ~he~, per~hlo~opan-t~cyclodec~ne, 1,2-bi~t~trabromophthalimld~ ethylene~
pigments ~uch a~ ti~anium dioxide, ~ntimony t~ioxide, zin~
oxide, zin~ sulfide, iron oxide, ~tc., and th~ l~ke.
Mixture~ of ~uch additives c~n ~e u8ed.
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~` ~ypically, the composition compri~es at least about 60 by weight, of polybutylene terephthal~te, pre~rably at lea~t a~out B0~ and ~os~ prefe~ably a~ least ~bout ~0~ by : w~ight, ba~d on the weight of the compo~ition.
~ h~ ~omposi~i~n can be preparad by mixiny polybutylene terephthalate and the d~sired addi~i~e~ toge~her in an internal mixer ~uch as a banbury or Brabende~ mixer, a two-roll mill, an extruder or the like~ SuCh mixing ~ypically ~' ~ ' '` ` ' . .' , ~ , ' ' ' ' ,.: ~, ' ` ' : , .
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i~ conduoted ~t a temperature of ab~ut 230C to ~out 2B0C, pre~erably about 240~C to about ~OGC.
The e}on~ate elect~ical conductor coated w~th vri~nted polybutylene ter~phthalate in a~ordance wi~h this invention can be fo~ example ~ wire, oable, ~u~ b~r, or the like.
Pr~erably the ~onductor i8 a wire and pref~r~bly is o a size of from about 4 to ~ou~ 3~ AWG, more pre~rably ~rom about 10 to about 30 AWG. ~he conduo~or ~an be ~ingle~ or multi-~tr~nd. The oondu~tor can be coat~d with one or more inner layers, i~ desired bef~re th~ l~yer o~ oriented p~ly-butyl~ne ~rephthalat~ is a~plied in accord~nce with this in~enti~n. The u~e o~ the term conductor applle~ not only -.
to the electrically conducting mem~r but ~leo ~o sai~
m~m~r and 3ai~ inn~r ~ayer~s), if presen~ Th~ lnner layer may be, for ~xampl~, polymeri~ oomposition~, inolu~in~ in~u- ;
lat.ing compo~lti~ns ~r c~mpo~ition~ containing ~lactri~lly ~ondu~tive or magneti~ particles, metalli~ mat~rials ~uch a~
metal braid~, or the like. The ~erm conduator al~o applles to a cable whiah comprises a plurality of conduc~ing ele-mentsr generally in~ulated frsm aach other and op~ionally ~ur~vunded by ~hielding means. Further, ~h~ polybutylene tereph~halAte may it~el~ be ~urrvun~ed by addi~ional lay2~s, if d~sir~d.
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The polybutylene terephthalate compo~ition i~ ~oatad o~o the ~o~ducko~ by ex~rudin~ a ~1003e ~ube" o~ the com-p~sition a~ound the ~onductor. ~ "loo~ tube" i~ meant th~t a tube having an inner di~meter greater t~an the out~r diam~ter o~ the conductor iq ex~rude~ ~round the conduc~o~.

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Z~5i3~)6 ~he extrusion ~tep i~ conduct~d a~ a temperature ~1~ above the melting temp~rature of the poly~utyl~ne terephthalate.
This tempe~atuxq i8 preferably in the range of ~etw~en ~bout 235 and about 300C, more pre~erably between about 250 and about ~C.
The loose tube i~ then cooled to a te~pe~tu~ r T2 t bel~w the meltin~ temperatu~e of polybutyl~ne terephthalat2.
Pre~erably T~ is betw~en about 15~C to ~out ~10C and more preferably betwee~ abou~ 30C and about 150C. The loose ~ube may ~e ~oole~ by the surroutlding envi~vnment, pa~ing it through a water bath or the like.
~ e loose ~ube is then drawn down onto the conductor pre~era~ly by pas~1ng it throu~h a drawin~ di~f but ~th~r dr~win~ method~ such as a non-con~rained dr~w initiated by local heati.n~ can be used. The drawing ~tep i~ condu~ted ~t a temperature o~ a~out l~aC to about ~10~r more pre~erably of about 30~ ~o a~ou~ 1$0C. Typically ~he drawln~ ~tep i~
conduc~ed at ambient te~perature~ i.e. the temp~ratur~ o~
the environment ~urxounding the e~ulpment.
To provide th~ desired ~egree o~ orlentation~ ~e draw r~tio 6hould ~e at lea~ ahout 1.1, preferably at lea~t about 1. ~, mc3st ~?referably at leas~c a~out 1. 4 and ln par-~i~ular at leai~'c about 1.5. ~he draw ra~i~ may b~3 a~ high a~ 3.O, ~u~ dr~w ratio~ of below about ~.O are preferrqd.
~he term "draw ratio~ aisi u~ed her~in i~ det.erminsd l~y the :Eollowing e~uation;

draw ra~io = _~ ~ectional area__~h~ PB~ tu~ drav .
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cro~ sectional area of the PBT laye~ ater dr~w (where PBT stands for polybu~ylene ter~ph~halate).
An apparatU~ ~or applying a l~yer of orien~ed polybuty~
lene terephthalate in acco~dance with this lnvention is shown ~hematically in Fi~. 1. In Fig. 1, a laye~ of poly-~utylene terephtbalat~ ls ext~uded ag a loo~e tub~ aro~nd conductor 4, thro~h extrruder die h k~t of axtruder not shown). The loose tube/condu~tor assembly pa~es through take-off 8 and drawing die 1~. ~he drawn in~ulated wire pa~e~ over take-o~f 12 and ~an then wound on a conventior spool (not shown)~
The thi~kne~s of ~he polybutylene ter~phthala~e co~ki~g ~n the el~ctri~l. conductor ~fter the drawing ~tep varie~
depending on the particular concluctvr being c~ated~ For ex~mpl~ on 4 to 38 AW~ wire, the p~ly~utyl~ne teraphthalate coating i~ pr~er~bly from a~out 3 to About 40 mll~ thick~ .
mor~ pre~rably from about S to about 20 mil~ th~ick. ~.
Th~ polybutylene terephth~lat~ coating may be cro~slinked, i~ de~ir~d~ It maY be ~xo~linked by m~a~ls of ~hemi~al ~ro~-linking ~gen~s o~ by irr~dia~ion, or exsmpl~
by expo~ure tQ high ener~y i~radiatio~ su~h a~ an electron beam o~ gamma ray~. Radiation do~age~ in the rang Es 2 to ~0 Mrads, preferably 5 to 50 ~r~d~, e.~ 10 to 30 M~ads ~re ~n ~eneral appropriat~.
For the purpose of promo~ing ~ross-linking durin~ ~rra-di~tion pre~erably ~om 0.~ to 5 weight per~ent of a prorad ~uch ~g a polyfunctional vinyl or all~l compound, for !
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~00s3n6 _g_ example, triallyl cyanurate, triallyl iso~yanura~e or pen-taerythritol tetramethacrylate ar~ lncorpor~ted in~o ~he compo~iti~n prior to ir~adiation.
The degree of cro6~-linking o~ the compo~ion~ m~y be expre~e~ in terms of the gel eontent ~ANSI/ASTM ~27~5~
of the cross-linked polymeric compo~ition, i.e~ excluding non-pol~meric additiv~s tha~ may be pre~ent. Pre e~ably the gel ~ontent of the cros~link~d ~ompo~i ion i~ at l~t 10%
more ~referably at lea~t 20~, e,~. at least 30%, more pre-~erably at lea~t 4U~
~ he oriented polybutylene t~rephthala~e laye~ h~s an initial elon~ativn at ~S~ o~ at lea~t abou~ ~5~, ~refer~bly At lea~t ~bout ~0% ~nd most prefe~ably at le~at ~ut 75%.
~e initi~l ~longation i~ the elonga~ion of the po~ybutylan~
ter~ph~h~la~e after it ha~ been h~a~ ~et e.g. by h~a~ing i~ :
~t ~ temp~rature o~ about ~0C to about 20Q~C for 1-30 ~inu-tes, ~emoving the polybutylene ~rephthalate layer and measuring the elongat~on accor~in~ to ASTM D3032. A uni~ue feat~re of the article of this inven-tion is th~t ~fter heat aging a~ 180~C ~or 7 days, the polybutylene terephthal~te ~etains at lea~t a~out 25% of it~ initial ~longativn, pre~
fera~ly at le~t ~bouk $0~ a;~d 11109t pre~e~ably at leas~
abou~ 75~. An~the~ fea~u~e of ~he ~rti~le ~ thi~ invention is that the oriented pol~bu~ylene te~ephth~tlate h;~s a ten-~ile st~ength of at lea~t ~bout 9, ~OID p~i ~3 meAsured by A~TM ~032. Preferably the tensi.le strength i~ at least about 10~000 ~nd mo~t pre~rably ak least about 11,00~ p~i~
The excellent ~ensile strength of the oriented polybuty-lene terephthalate layer and its high elong~tion ~nd it~

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~10--~bility to re~ain its elongation at high ~mperature3 make~
it highly des~rable a8 an in9ula~in~ or j~ketin~ m~rial fo~ wire or ~able ~uhjecte~ to me~h~nic~l str~ nd ale-vated t~p~xat~lre.s. F~r ex~mple i~ iB con~empl~t~d th~t wir~ insulated with oriented polybutylene terephthalate in accordance with ~hi~ inven~ion is p~t~cularly useful ~
automotive wire, in~ludin~ wire for ~under the hoo~" u~e.
~ he following examples illustrate the ~oatin~ o~ an el~ctr~ ondu~tor with oriented polybutyl~ne ~x~phtha-late in ac~ordanoe with this invention.
ExamPle a A comm~cially av~ 41e grade of polybutyl~ne t~rephthala~ ~inh~ren~ vi~osity ~ ) was co~npounded with ~l~me r~tardant~ and sta~llizer~ a~ de~i~n~ted b~low Oll ~ 20 ~m counter-rotating t~in screw ZDSK m.ixer at 250C and pelletized. ~e form~lation wa~ as ~ollowa~
~olyhu~ylene terephthalate B4%
(C~lanex 1~00~ fr~m Celanese CO~P.
1,2-bis~tetr~bromopht~alimido)etl~e ; Antim~ny trioxldQ ~
Stab.ilizers and pi~men~s 4%
A flexible condu~tor m~de up of 19 ~rand~ o~ r~nd .008 inches diamater, tin-plated ~op~er wires w~th a bundle diam~ter o~ .039 inch~ w~s u~ed~ A 1~" Davl~ Standard ~xtrud~r ~ith a b~rr~l length to diamet~r rati~ o~ ~4.1 ~itt~d with general puxpose scr~w ~compres~i~n ratio - 3:1) .
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w~s u~ed for ex~ruding a lvose tu~e ~ver the above de~Gri~d conduc~or~ ~he ex~uder harrel, ~ro~3head, die holder and the di~ was m~intained at ~5 ~C and th~ tamper~ture of melt colning out o the dia wa~ 270 C a~; meelsured l~y a f ine AWG
thermocouple~ ~are was exerci~ed to ~n~ure that the conduc-~or did not ~ome in contact with ~h~ molten polymer ¢c~n~.
Th~ molten pc)lymer cone was quen~he~ with ~old wate~ ( ~3 C
at 1~" away from the die exit~ Length of the cold water bath was about 9 feet so that the tub~ wa~ e~ential~y c~ld :~
to touch wh~n it reached b~l~ dr~ven t~action d~vic!e set at 130 ~t/min ~labele~ as Hzlu}-of~ I in Figure I~. The belt ~pacing ~n the tr~ction device waR adjus~d su~h that it would ~irmly grip thq p~lymer ~u4e whil~ ~he ~onductor could ~lide freely. ~hi~ ~olymer t:ube ~with the condu~tor in~ide) w~ pa~ed through a two pl.ece 5plit die m~de o ~ung~ten Carbi~ imila.r in de~i~n and 8~3t-Up to the one~ u~ed in mçtal wire drAwin~ op~ration~, wi~h ad~ustmen~ ~ailable ~or opening and clvsing tl?e die. The die opening ~i~e wa~ . Ofi4 inches3 when ully clo~ed. Initially the ~;plit die wa~ k~pt op~n ~o that the polymer tube could e~sily pass through.
Further ~own st~am a two roll capstan ~ labeled a~i ~aul-of~
~I in Fi~ure I ) ~et ~t a line sp~e~ of 130 ft/min was u~ed for continuoualy hauling away the polymer tube ~nd wa~
t~ken-up on A reel using a mo~.orized sh~lfto ~be polymer tube dimensions Were chosen ~o be at oOSl~l ~n6ide diarneter and .~4" ou~3ide diam~ter~
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The polymar tube (wi~h ~onductor inside) wa~ n~xt cold ~ra~rn by closing the split die ~o itS ~ii813 and a~oelerating the ~pstan ~peed to ~27 t,/min at the s~me time~ Th~ 'eold :

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tion wall th1cknes~ was .Q125 inche~.
Thi~ orien~ed wirs ~as subsequently heat set at 1~5~C
~or 10 m~nutes in an air ciLculating o~n, wi.th ~oth ends of the ~amPle tied ~o~n to a~oid any ~h~lnk b~ck. ~his was ..
labeled a.~ Sample A.
A control ~unoriented) sample wa6 prepared by simply extrudin~ the sa~e material but with ~he melt cone (at 270C~ converginq di~ec~ly on~o th~ ~me con~ucto~. The molten poly~er on the conductor was ~uenched 2" away from the die exi~ ~nd the haul-off speed wa~ ~e ~t l~S ~tfmin.
T~e in~ulation wa~ ~ain .0125" and this ~ampls wa~ als~
h~t ~et ~t 1~5~ Eo~ 10 ~inut~ tli~ the ~ampl~ A). Thi~
unorien~d ~ample WaS labeled as B.
The i~ul~tibns ~re ~emoved from both ~mplq~ and su~pe.~ded in an air ~ir~ul~tin~ oven ~t 180C ~or heat aging. Elongatlons we~e mea~ured ~n an In~tron with a ~w se~ara~io~ $peed ~f ~ inches/min~ ~sults are ~hown in Ta~l~ I below~

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53~i T~1e I
SamP1e Init~ nikia1~ E1Qn~ti5n ~ Elong~tl~n T~n~ 5tren~ El~n~ation A~ ~ Aæ ~
~p~ ) E~t A~ing ~at Aginy 2 ~y~ 7s~a~

A 11,100 ~~ 40% ~Q~ ~-E~ ~COntrO1~ 7,500 36U~ 404 5 :
Example ~ :
Ano~her set o~ orien~ed ~amples wa~ mada with differ~nt dra~ r~tios a~ ~ho~n in th~ following ~able. ~fter dr~win~, the sample~ were ~e~ed for tensile ~rengt~ an~ ~on5a~iOfl ~e speciied abo~e ~nd w~re then heated at a te~p~r~tu~e of ~ 1~0~ for 7 day~. ~h~ elongation wa~ then m3~ Pd and the : % retention of elongation wa~ cal~lats3d. The re5~ults-~ are shown in the Eollo~inq table.
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2~(~5306 . i Table II
9dElonga'cion~ntlorl o~
Cold Draw Ten~ile ~ ElongationAft~:r 1 w~k ~nitial 5~?1e Ra~io_trength ~p.si) Irltial a~ 180C
i . C 1 . 0~457 275 ~ 3 880 16n ~0 25 E 1. 20g433 137 llû 80 F 1.32llOS~ 117 115 ~4~
~; l.S~12S30 11~ 112 100%
1~7E~73 ~5 72 g~
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Ex~mple 3 (~omparati~
Thi~ example illu~r~tes ~h~ applic:a~ion o~ ~ layer o~
polybutylene terephthalat~ to a con~u~tor iD ~c~or~an~ wi~h prior ar~ proc Colsuner~i~lly available vi~in ~nv oth~ ingredient~
a~ided ) polybutylene terephthalate l~elanex 1600A; colluner ~ially ~v~ilable ~rom C~lans~se Poly~ner Corp. ) dried at aooc for 12 hours wa~ u~ed in thi~ runl The ~me reel of conduc- :
tor ~s d~c!r~ed in exalnple 1 was u~ed i~ thi~ trial . A ~ " :
Davils S~andard extruder ~itte~ wit~ a general pu3:po~ s~r~3 tcolnpxe~ion ratio 4:1) wa~i emplvyed. The extrusion tip ~gui~e ~or ~he ~onduc:tor) h~d an op~nln~ o~ .039~ incbe1 while the ext~us~n dle ~or ~h~pin~ and sizing of mol~3n polymer arour d the c~onductor ~ ~ad an opening o~ ~ 064 in~he~ ~
The die was f itted wi~h ~ m~niature thermocoupl~ b~r drilling a .0~ inches diam~ter hole, .25 in~he~ deep, 0.1~ inches ;' ~. .
- .

Llr:l L 1~ LII I ~ l; c ~ IL~ 1 I tl I I I tL I IU ~ c~ S Pi8 S3~6 away from clie ope~nin~ ~t the melt eXit fa~e. MRlt p~e~ re wa~ monitored at a ~ able location in th~ cro~sliead using a commercial pr~su~e tran~ducer. A 15 ~oot long ~old wat~r ~ath placed 3 inche~ aw~y from the die exi~ wa~ uZ~ed fo~
quenchin~ the co~ted wil~e a~ it came out of the d~e.
An ~x~ruE~lon run was con~ucted unde~ the :~ollowing ~:on ditions and the insulated wir~e thus obtainPd wa~ labeled sample I.
Line speed ~ 1,000 ~t/min Die Tenlp ~ 313 C
Head Pre~ure ~ 5, 000 p3ig In~ul~tion Thicknes~ = . 011 inches Next the die WaB f itted with .1~5 " diameter c~opper tllbin~ tco.iled around the die) with p~ovision for running cold w~ter through 1:he tube~ Another ex~ru~lon run was m~Ae with this ~et-up usin~ ~ame conduc~or ~, p~lym~
b~rrel/cros . head/die holcler ~elnperaltures exc:ept that th~
extru~ion die was ~ol~d ~o a temperature o~ ~t)~C. ~he crosshsad pressuYe wa~ 7, 500 p~ig un~er theAe ~ondition~.
~he in~ulated wixe made in this run wa~ l~beled ~ mple ~.
~ o~h sample~ I and J we~te lle~t ~e'c at l~SDC for la ~ninu-~e~ and t~ted :for perc~nt elo~ga~ion as ~t ~orth in Example 1 and f lex dur~bilil:y hy wrappi/lg it ~round ~
mandrel to ~ m a 180 benA. The re~ult~ ~re ~ummarized ~ n ~e.ble III below~

,,, ' -- ! ' ' , '' ' ,' ` ',, , ' '~ ,: ' ' "
'" '' ' ' L'l~ L.L.__1 IL.'.1J~ i11 ILL I~U~ ,bl--~lb~:J ~ 1'1'3 2~ 306 ~`
~ble III
Flex Dur~bility After 24 ~rs.
S~mple _ __Elonqat ion ~ 96 S _ _ Init ial _ at 18 0 ~'C_ 5 to 10~ crac:ks J 10 to ~ no crack~ c~ack~

Crack ~ nq of the ~amples indicaLte~ that ~ polyhu~ylene tQr=phthal8t~3 wa8 embrittl6~d and had low e10nglition.

' ' , ~

, :

.

, .
.,

Claims (20)

1. A method of providing an elongate electrical conductor with a layer of insulating or jacketing material, which comprises: .
(a) extruding a polybutylene terephthalate composition at a temperature, T1, above the melting temperature of the composition so as to form a tube which surrounds the electrical conductor to be insulated or jacketed and has an inner diameter greater than the outer diameter of said conductor;
(b) cooling the extruded tube to a temperature, T2, below the melting temperature of the composition;
and (c) thereafter drawing the tube down onto the electri-cal conductor with a draw ratio greater than about 1.1.

2. A method in accordance with claim 1 wherein T1 is bet-ween about 235°C and about 300°C.

3. A method in accordance with claim 1 wherein T1 is bet-ween about l5°C and about 210°C.

4. A method in accordance with claim 1 wherein T2 is ambient temperature.

5. A method in accordance with claim 1 wherein the tube is drawn down onto the conductor by passing the tube and conductor through a drawing die.

6. A method in accordance with claim 1 wherein the draw ratio is greater than 1.2.

7. A method in accordance with claim 1 wherein the draw ratio is greater than 1.4 .

8. A method in accordance with claim 1 wherein the draw ratio is greater than 1.5 .

9. An article of manufacture comprising an elongate electrical conductor having a layer of insulating or jacketing material comprising an oriented polybutylene terephthalate composition having a tensile strength of at least about 9,000 psi, an initial elongation at 25°C
of at least about 25% and an elongation after heat aging at 180°C for several days of ate least about 25% of its initial elongation.

10. An article in accordance with claim 9 wherein said composition comprises at least about 60% polybutylene terephthalate .

11. An article in accordance with claim 9 wherein said com-position comprises at least about 80% polybutylene terephthalate.

12. An article in accordance with claim 9 having a tensile strength of at least about 10,000 psi.

13. An article in accordance with claim 9 having a tensile strength of at least about 11,000 psi.

14. An article in accordance with claim 9 having an initial elongation of at least about 50%.

15. An article in accordance with claim 9 having an initial elongation of at least about 75%.

16. An article in accordance with claim 9 having an elonga-tion after heat aging of at least 50% of its initial elongation.

17. An article in accordance with claim 9 having an elonga-tion after heat aging of at least about 75% of its ini-tial elongation.

18. An article in accordance with claim 9 having an initial elongation of at least about 75% and an elongation after beat aging of at least about 75% of its initial elongation.

19. An article in accordance with claim 9 wherein the poly-butylene terephthalate is from about 5 to about 40 mils thick.

20. An article in accordance with claim 9 wherein the poly-butylene terephthalate is from about 5 to about 20 mils thick.