CA2236879C - Method of balloon formation by cold drawing/necking - Google Patents

Abstract

A method for forming a balloon for a dilatation catheter involving the steps of extruding a segment of thermoplastic material, maintaining the center portion at a temperature below the glass transition of the thermoplastic material, drawing the segment to a predetermined length, wherein after the drawing the wall thickness of the center portion does not appreciably change, and expanding the segment in a mold to produce the balloon.

Description

' 1 i V l . '~ ' i J ; 1 1 ~ ~ L~ I IU l l~ ' ~A 02236879 1998-0~ 06"~ ~

- -METHOI~ OF BA~LOO~ FOR.~A~IO~ BY C~L~ ~ CKT~G
BAC~G~O~'ND O}i T~ ~ENTION

The present ~n ~e~ti.on rel~tes to a .nethod ~r ma~cing balloon~ ~or 5 catheters used in medicaI dii~tatian procedures.
B~loon catll~ter~ are beL~ used extensive1y n procedures related t~ the tre~ nt of blood vesseIs. For example, arterial s~er~osi~ is commonl~ ~eated ~y angi~pl~stt~ procedur~s which involve inserting b~lloorl catheters into spec~c arteri~s BallQo~ Galhcters h~e 21so ~e~rl found use~ul ~n prc~cedu;es ir:volviIlg dil~tion of bo~y lO cavitie~.
~ The rnost widely used foIm o~ angiopl~sty m2~es use of ~ t~tion ca~eter wkich ;~ inflata~le ba1loo~ at ~s distal er~d. UJin~ f'uoroscopy, & physician g~ndes ~e catheter ~rvugh the.~isscul~ .s~stem ur.ti~ ~he baIloon is positioned ac~oss t~
stenoses. The balloon is then infl~ed b~ suppIy~g licuid under ~ressure through a~
1~ infl~ion l~me~ ~o t~2e ~alloon. The inflation of t~e bz~loo;~ causes stretchir.g of a b'ood vessel ~rld lJ~ of thc lesi~n iiltO the bl~od vesscl u~all to reestablish ~cceptable ~Lood flow t~o~gn th~ ~lood ~essel.
In c~dcr to ~L~ ve,ry t~ight stenoses w ith s.-i:Lall openi~gs, there has been acontir.ui~ .rort ~o red~ce t~l~ pr~file o~ tll~ catLct_r so that thc ca~hcter can rcach an~
20 pass t~rough the s~ l openh~ oî the stenoses. There ha~ ~lso been ar~ efFort to red~ce the prof~le of the cathcter ~ter an initiaL use ar~d defla*on of ~e balloon to pesmit ,~ passage of tile c#~cler througl~ additJon~l lcsionst;latare to be ~cd or to ;~loY.~ try all~ L~ nt of lesions ~t rec~ose after initial ~ nt.
C: ne factor m~ at~ to r~duce the prof~le of the ~ t~ n c~theter is ~5 the wall thickness ofthe balloon m~te~l. Balloons for cli~at~tion balloon cathctc~e ha~e beer. made f~om a w.de va~et~ o~poly~eric m~teri~l~ Ty~ the ~aIloon ~valI
~knPe~,-c havc been csn ~e order o~ 0.0003 to O.OQ3 inches ~7.62xlO 6 to 7 6 xl 0~5 rn) for mos~ m~enaIs. The~e l~ve been contin~tin~ e~forts, howe~rer, to develop evcrthirmer wa~led balloon m~teri31s, whi1~ s,~i 11 retainsng the ncces;xu~ d.stensibilit v a~sd 30 b~-st pressure r~tin~, so as ~o pen~t lower deflated profiles.
The profilc of the defl~ted ~alloon is also li~ted by ~he thickrless of the waist. and corle portions of the b~llooT~ ually, the waist a~d col~e waII

~ ,tC~'~DFD SH~F~
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W O~7/17098 PCTAUS96/159S8 --2--thirlrnPsses are thicker than that of the body of the balloon due to the smallermPter of the waist and cone portions. In order to reduce the overall profile of the deflated balloon, reduction of the wall thicknPcc of the waist and cone portions must be addressed.
It is possible to make balloons from a variety of materials that are generally of the thermoplastic polymeric type. Such materials may include:
polyethylenes, iollolllel~, ethylene-butylene-styrene block copolymers blended with low molecular weight poly~Lyl~nc and, optionally, poly~,~,L,ylene, and similar colllpo~ilions sub~ g bl-t~-lirnP- or isop~ e in place of the ethylene and butylene; poly(vinyl chloride); polyulcLllalles; copolyesters; thermoplastic rL ~s;
silicone-polycarbonate copolymers; polyamides; and ethylene-vinyl acetate copolymers. Orientable polyesters, especially polyethylene terephth~1~te (PET), are among the L~lefe.l~;d materials for forming catheter balloons. Refe~ lces illu~
the materials and mPthofls of making catheter balloons include: US 4,413,989 andUS 4,456,000 to Schjeldahl et al, US 4,490,421, US Re 32,983 and Re 33,561 to Levy, and US 4,906,244, US 5,108,415 and US 5,156,612 to Pinrln~rL- et al.
High tensile ~llcll~ Ills and uniformity of wall thirlrn-o~c are important in angioplasty balloons becduse they allow for the use of high ples~ul~ in a balloon having a relatively thin wall ll~irL~ . High ~ ule is often needed to trea, someforms of stPnoci~. Thin and unirol~ll wall thirL-nPsses enable the deflated b~l~oon to remain narrow, making it easier to advance the balloon through the arterial system.
Prior art balloon forming terhniql~es involve ~Ll~tchil~ and blowing of the balloon from a seglll,l~l of extruded polymer tubing. Balloons produced by stretching and blowing a tubular preform or "parison" typically have much thicker waist and cone walls than the wall thir~n~c~ of their body portios. The thicker cone~walls contribute to the overall thirknPss of the c~th.oter, making tracking, crossing and recrossing of lesions more rliffirlllt Further, thick cones hlLtlrtl~ with refolding of the balloon on deflation so that the deflated balloon can only be further inserted or withdrawn with difficulty, occasionally even ~m:-ging the blood vessel.
There have been several solutions proposed for reducing the cone or waist ll.irL~ s of c~ll-- t~,. balloons in US 4,906,241, US 4,963,313, US 5,304,340, US 5,087,394, EP 318,919l EP 485,903. However, the procedures involved in SUBSTITUTE SHEEr (RULE 26~

CA 02236879 1998-0~-06 W O 97/17098 PCT~US96/15958 . --3--these referenccs arc quite cumbersomc and so il is desirable that simplified methods be developed to provide cone and waist walls with rcduccd, uniform thir~n~sses.
EP 318,919 to Noddin ct al. discloses ;- procedure in which a portion of the tube is crystallized to render it rlimPn.cionally stablc under heated conditions.
S The portion stabilizcd can not be apprcciably innated or clrawn. The tube is heated in a heated bath and as one end is secured in i)lacc thc otl~er is drawn to a desired length and in thc process is necked-down. Thc tubc is drawn down to a constant mrt~r sleeYe. After the initial n~cking-down of the tube, the tube is reversed in thc bath and thc sccond necked-down portion is formcd by the same procedure.
10 After the prcform is complete the tube is submcrgcd horizontally and restrained at both ends. Two conical portions at opposing c~lds are arrangcd to define the shapc of the tapercu sections of the balloon. SimulLaneously the tube is drawn and e~p~n~ l wi~llout constraint until thc molcculcs of tllc wall matcrial in the balloon region bccome stabilized in a biaxially orientcd condition. The portions of the tube 15 having the ~reform tapérs expand until they alc constrained to the shape of the constraining cones.
US 5,087,394 discloses a method of forming a balloon wherein a length of polymer tubing is formed by drawing the tubing material from an extruder using an extnlder die and then irradiated. The stretching method involves 20 positionin~ an in~crnal support mandrcl within the tubing and compressing a portion of Lhe intennP~ tt~ segment onto the mandrel with a body clamp. The end segment is heated and stretched longitudinally to the dcsired length. Thc process of pulling the tube through a restricted hot die or body clamp forms the neckcd portions and thin waist segments. The other end segmcnt is optionally strctched in a similar 25 manner. T}le tubing is then heated, radially sLrctchcd by blow-molding to define the balloon and cooled.
EP 485,903 describes a method whcrein a tubular parison is formed of a draw~ ~le or orientable polymer. It is hcated in a metal mold in the range from the second order transition temperature to thc first-order transition temperature of 30 the polymer used. The parison is stretchcd in the direction of its axis and then infl~t.o~l rariially rcsulting in a biaxially-drawn or biaxially oriented crude balloon.
The pariso~l is thcn cooled below the second-order transition temperature and rlefl~tPcl. The tapcred portions of the crude balloon are redrawn by strctching to ,.uv 11 .J~ .u~ u~u .11 V~ CA 02236879 1998-0~-06 u~ u~v~vu~ r~;J ~

~educe their w~ll thiclmes~es. The bal~oon is infLated aigain alld hemed above ~e second transition t~ e~L~nd ~hen cooled.
~ e ~evy patents, teach first dra~in~ the tubing by ~ua~ly p~ling the tubc in a ~i~o~m mann~ apart and t~en ~r~n~ini ~e tube w~ ~luid in a confin;n~
~; a~iaLu~. The stretcll process occ~s dl u t~nl,w~lu,e aboYc thc gl~ss ~sition L.,.~ dLu.~ below the melting t~~ rc of the t~b}n~ m~ti~
US ~ .31 G~ 16 to A~rns &t ~b di sclos~l int2~ a~ r~tlleter ~
~lloon thereon. The ballnon is fnnr ed by isolating a ~ortion of a Dolv~utylene ~ere~hth~l~t~;polvet~vlene ~Tegh~late gl~YCol (PBT/PETG! tube ~nd a~?lYirsg a tcn~ile l{? force to thc cn~ of the t~:be at room temper~ re. The ~rcc i5 re~noved before th~
isol~t~ ortion is af~eeted. The h~lloon ~re~orm ic then r~Aia51y ex~ I Pn~ n . ~
WO 96~1~5 l ~ de~cribes a rnethod of DrodUCin~ dilatation baTloo~s ;n wbich. i7~ter ~lia. ~LliollS of a t~b~ r rnember a~acent to 1~eDortion of ~e mem~er 1~; ~t w~lJ become the bo~dY o~the ba5lovn ~: heated via the usc of r&diation. Ten~ion i~
then ~r~lred to the rLIbul~r m~m~r sn ~ ~o for~n t~pers in the regic~ o~e t~b~ rrn~mher a~jaçent bo~h sides of the urlheat~d portion s:~f th~ member, 1'h~ tubula~
nlembe~ ix subsec~uentl~ expan~ed to form a ball~n.
There rem2ins, howe~er, a need to c~l h la~e to irnproYe ba~ w~ll ~0 st~engths while s~ t~n~vux~y r; ducirlg thcir w~l t}~ickn~s~ and n~ lint7.;nTn~
unifon~itv. l~he pTesent invent~on addresses these n~ds by rcdu~in~ the wall thiclcn~
o~ eone and waist portions and bv r~linim~ n~ pro~uding bu~ps and distoItions during fol~ng of the balloon and w~ppsng arouIld the catheter S~L. '~e resl~ltin~ ~oalloon is ~naller in size ~or eas~e~ i~sertion into ~he bod~ lumen.
SIJMMARY OF THE~ INVE1!~1T10~
~ he present in~ention i~ on~ aspec~ is a method for f~rtnin~ a balloon for a ~ t-~ti~ he~er inv~lving ~ steps of extruding a sc~nt of ~ermoplasti~
m~teri~ in~ in~ the ~enter portiOn at a ~ e be~ow ~Le g~ass t~n~ition 30 t~np~aLuLe (T~) of the ~hcrmoplastic materi~l so ~at ~ rema~ns ~iim~n~i~nally sta~le and ca~noe bc appr~Tab~y drawn, drawing the se~ ntto a pre~ cd le~g~h, wherein aRer rhe drawing the wall th;t~n~;s of the cc~ po~on does not 5~l~5ts~nti~lly change, and ~n~inp.ths:se~m ~Sin a mold t~ produce ~e laalloan. ~i nt~inin~ the C~ O S~IE~r ., .~

I l V ~ I U ~ V ~ ' --V I I . Y I Lf . l ~.J r l l '. l ~ J I L I l l i~ I I V . V; ~ ~ J .J V ~.i L

ce~ter portion at a t~ O.Lu.e below the T~, o~the th~moplastic rn~teri~l px~ ents it from stretchi~ axi~lly~ thus ~llow~g it to Jn~int~in itst~ick~ Only dur~ the n~inn ph~ do the ccnter portion walls thiIl due to l:he radi~l p.essure. The ~ esultin~, stretched port~o~ n ~i~er sidc of tne cent~r port~on foml ~e wa~st ~nd p~rt o~
5 the cone portions. 3uc to the taI~ct s~retchine, of the prese.~ invent}on, ~he resul~
wais~ ,qnd ~nne portions ha~e reduc~d w~ll thic~cn~s, thus reducin~ thc b~lloon p~ofille.
l'he blowing step of'I~ rrning ~e b~lIoon for a c~thetcr7 comprisec placLng the ~bin,~7 of a therrnoplastic m~terial ~n ~ rnold and 7~10~hn~7 the balloo~ b~ pre~ i7;n~
a~d tert~ nin~ ~e tU~ ~d ~<t(i~t~ t~' dippIn~ ~e mold i~to ~ hea~ed t.~sfer ~di8 SO
10 t to seauen~ y blow the first v~aist, the body a~d ~s s~,-on~ wa~t por~ons of ~Le b~ cn, the bubing be ~g subjected .o arela~vely Lower FEj S~

CA 02236879 1998-0~-06 pressure, and preferably a relatively a lower Lcnsion, while the body portion isblown thall while the first and second waist portions arc blown. The variance in the thirl~n~-5s of balloon concs and waists can be furtller improved during the blowing process by Yarying thc axial tension and blowing pressure at several stages as the 5 mold cont~lining the balloon preform is dippcd into a hcating mrAit~m BRIEF DESCRIPIION OF TI-IE DI~WlNGS
Figure 1 is a perspective view of an angioplasty c~thPter having an example of a balloon fabricated from the invcntive method mounted thereon.
Figures 2a, 2b and 2c illustrate the results of various process steps in forming a catheter balloon, depicting respectivcly, side elevational views of anextruded tube of polymer material used to form the balloon, a strctched polynlertubing preform prepared from the extruded tubc, and a formed balloon prepared from the stretched polymcr tubing preform.
Figure 3 is a schrm~tir view of a stretching device that may be useful in practicing the method of the invention.
Figure 4 is a cross-sectional view of a preferred mold used in the method of thc invention.
Figure 5 is a side elevation view of a molding station that may be useful in practicing the method of the invention.
Figure 6 is a perspective sch~om~tic represent~tinn of relevant portions of thc molding station of Fig. 5.
Figure 7 is a side view of a drawn or stretched segment of tubing within a mold before the molding process.
Figure 8 is a side view of a drawn or stretched segment of tubing within a mold before the molding process according to an alternate embodiment ofthe invention.

DETAXLED DESCI~IPIION OF THE PRE:EFRRFn El\~BODIIYIENTS
The dilatation balloon fabricated by thc present inventive method illustrated generally at 10 in Figure 1, in~ clcs an infl~t~hle balloon 14 mounted at the distal end of an elongated flexible shaft 11. C~tllet~r 10 is conventional in its construction, proYiding a lumen cornmllnicating with the interior of balloon 14, for CA 02236879 1998-0~-06 W 0.97/17098 rCTAUS96/15958 inflation and deflation of the balloon, and other optional features conventional in the dilatation c:-th~ter art. The balloon 14 is in its inflated configuration. The balloon 14 is formed of a thermoplastic polymer material which provides the balloon with its esse~ l compliancc charactcristics. It may be any thermoplastic polymer suitablefor use as an angioplasty balloon material. Preferred materials includc thermoplastic elastomers, suitably, polyamidc el~tom.ors, such as Pebax~ 7233, 7033, or 6333, polyester/polycther elastomers such as Arnitel EM 740 (DSM Fnginpcring)~ and polyurethane elastomers such as Pcllethanc 2102-80D. Other thermoplastic matcrials such as PET, Surlyn~ (polyethylene ionomer), nylon, ethylene-vinyl acetate or those previously describcd for catheter balloons may bc employed. Most advantageously the balloon material is Pebax 7033 (~Atochrm, Pcnnsylvania) or PE:T.
The mcthod of thc invention is performed by extruding tubing of a thermoplastic polymer. Any conventional cxtrudcr may be employed to perforrn theextrusion process. After the extrusion, the center portion 12b of the polymer tubing, which evcntually becomcs thc balloon, is m~int~inrA at a temperature below tlle tubing's glass transition temperature as described in more detail below. At this point the polymer tubing has thrcc scctions, a proximal end 12a, a distal end 12c and a centcr portion 12b. The polymer tubing is then prcstretched on either side of thc center portion 12b by elongating the proximal 12a and distal 12c ends axially.
Refcrring to Figs. 2a-2c, the prcstretching process compriscs applying an axial stretching force to the extrudcd polymer tubing 12, allowing thc cxtruded polymer tubing to stretch while m~in~ining thc axial stretching force and finally allowing thc stretched polymer tubing 13 to rcach approximately room temperaturc. Once the prestretch is complcte, the strctchcd polymer tubing 13 is radially cxpanded into the form of a balloon 14 by using a molding process. The molding process coll~p~isesplacing the stretched polymcr tubing 13 in a mold, heating the mold and expanding the stretched polymer tubing radially by means of int~rn~l pressure. After sufficient time has passed for the balloon to form, the mold is cooled and thc balloon 14 is removed.
The cold drawing prestretch step stretches the section of a cut length of polymer tubing from the extrusion to a predetermined length at a specific rate.
Dcsirably, the stretching tempcrature is set just prior to stretching. Fig. 3 illustrates one device useful in performin~ the plc;,l~etch. The device 18 of Fig. 3 pocsess~s CA 02236879 1998-0~-06 WO 97/17098 PCT/US96/1595~

two jaws 20 and 22 capable of gripping at least one-cut length of extruded polymer tubing 1?. The appropriate temperature, which is defined by the method and described below, is established. The first gripping jaw 20 may remain st~tionarywhile the seeond gripping jaw 22 moves horizontally at a set rate to a predetermined S final position, thereby achieving the desired final stretch. The stretch ratio is calculated by diYiding the final lengtl of the strctched section of polymer tubing (the portion l tween jaws 20 and 22) by the initial length of that section.
After the proximal and distal ends 12a & 12c of the polymer tubing 12 are stretched to the dcsired stretch ratio and Iength, the ends are allowed to cool.
10 The stretched polymer tubing 13 may then be moved to a water bath (not shown), preferably m~int;lin~d at room temperature. During this process, the stretched polymer tubing portion 13 of polymer tubing 12 is held on both ends in order to apply sufficient tension to ensure that the polymer tubing does not relax and shrink or recover from the strctch.
The methods and conditions of cold drawing are ~ ellsse~l below.
The basic objective is to m~int:lin the center portion 12b as shown in Fig. 2a at a temperature below the Tg, or below the m~imnm Tg if the material has multiple Tg's, of the tubing material and then to draw the polymer tubing. This is to assure that only the ends are drawn and not the center portion. The temperature of the 20 eenter portion 12b may be m:lint~inPd by isolating the center portion 12b so it remains below the Tg, cooling the center portion 12b of the tubing before stretching, cooling the entire segment of tubing or positioning cold clamps on the center portion. During the stretching process, the polymPr tube is drawn through a neck, the undrawn material being transformed gradually into drawn materials with a 25 eonstant reduetion in cross-section as it passes Lhrough the newly formed neck portion prop~g~ting toward the center portion. Cold drawing allows the necks to be formed without die or ciamp restriction as disclosed in the prior art. M~int~ining the desired lemperature of the center portion 12b acts to restrain the center portion 12b and promotes a substantial transition in thicknPss causing molecular alignment 30 and changes in morphology for both crystallinc and amorphous polymers.
The stretching process can occur under a number of conditions as long as the center portion remains below the Tg temperature. In one embodiment the center portion 12b of the extruded polymer tubing is cooled by dipping the center CA 02236879 1998-0~-06 W O~7/17098 PCTAUS96/1595B

portion 12b and thc distal portion 12c of the tubing into a cold watcr bath and drawing the proximal portion 12a to a dcsirable length and then removing the tubing from the water bath and tun1ing the tubing over and dipping thc proximal portion12a and the centcr portion 12b into the cold water bath and drawing the distal S portion 12c to a desirable length. In another embodiment, the same effect is achieved by holding the center portion 12b in place with cold clamps, thereby m~int~ining the center portion 12b at a low temperature during the drawing step.While the center portion of thc polymer tubing is m:lint:linrd at a temperature below the glass transition temperature of the extrudcd polymer tubing 12 it is gradually drawn apart. A suitable temperaturc is the range extc n~ling rrom -178~ C to ~70~
C and is below the Tg of the polymer material or thc maximum Tg if the polymer material comprises block copolymers. However, the preferrcd tcmperature being inthe range of -100~ C to -20~ C (+/- 5~ C). Preferably, but not required, for block copolymers the temperature is below the lowest Tg. The strctch rate may be in the range between 25% - 75% per second. The preferred rate of strctching is 75% per second. The desired amount of axial elongation prior to radial expansion is in the range of 200% to 500%. I'referably, however, thc axial elongation occurring in this phase is 280%. The tubing is then allowed to rcach appro~im~t~ly room temperature. The rf s~1lting tubing has a varied wall thi~Lnr5s as shown in Fig. 7 which shows a drawn segment of tubing insidc a mold 78, whcrein thc center portion 12b subst~nti: lly m:~int~in.c its original thirL-nf c~ and gradually thins out toward tl~e ends 12a and 12c to a subst~nti ~lly constant smallcr thi~L-nr5s. After the polymer tubing assumes a worl;able tenlperdture it is transferrcd to the moldingprocess.
An ~Itrrn~tive method for tubing made from highly orientable material, such as PE:T or nylon, is performed by coolin~ the entire extruded polymer tubing below the glass transition temperature of the tubing matcrial. If the Tg of the material is above room tcmperature cooling may not be n~cess~ry. The targeted temperaturc is ~lic t:3ted by the type of material used. The tubing is then gradually drawn apart. As this is done, the walls of the tubing thin out from thc cnds gradually toward the center, slowly decreasing the lcngth of thc center portion 12b until the desired length is reached. The tubing is thcn allowed to reach approxim~t~ly room temperature.

llVV I 1 VI IVU J I''tU I 11 I CA 02236i'i9 199i'-05-06 -r-iJ ~'J ';j'JJ;~

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- U~clcr conve~uonal cor~itio~s when the specLmen is extended, oceasior~al~y a cnn~;-lerable nse o~ he occurs in the region of ~e nec~c, however, the mcre~se in temperature is srn~ t slow ~ates and therefo-.e call be co~trol~ed to pre~ t o~ d~ f the c~nt~l portion 12b.
~he m~hod ~f ~old drawing at lo~rer tc.~ IlJ~ S described herein gives sha~per ~d more -.~vorable reck transition. Th~ rG~lltin~ tub~n~ has a va~ie~
Ll~ckness ~s shown in Fig. 7, wherein ~e center portion l~b ~P;n~inC its original thickness ~r.d ~rad~ally t~ins ol~t to~arcl the ends to a substarltially constant smaller thic~ness. The neck~d port~o~s fom~ waists ~d p~t of the cones of the b~lloon att~ p~oximal end a~d d~stal end ar.d the ltnn~ekf d por+ion f~ms the b~lloon body. A$
s}lown i~ ~ig. 7, thc cente~ p~rtic~ 12b is ~pp~oxim~+cly thc lc~h of thc ~alloon por~n of the ~qlold ~efo~e tke blowin~,. Alte~tively, i;he cen~er portion I ~b mav ~e d~awn so t~at it is short~r than ~ balloo~ portion of ~he mold and then eve~
~nd~d out to fill out the mold a~.e~ the ~lowing p~ocess.
A~er the pres~etck process the stretched po~ymer tubing 13 is exp~nded rzdi311y using i lt~ al press~Lre. The C~;?tPt~Ci O;LC +O which it is stretehed ~e prefera~ly co~olled by perF3r~ e radial ~ ic~rLg uhile the po!ymc~ tu~ng l~ ~s ~n a mold hav~r.g t~e s~ape ofthe desir~d ba~loen A suita~le mold ~ is snown in Fi~;. 4. l~ tin~
the stretched polymer tubin~, 13 while radi~lIy expa.na~g it r~ay best }:e ac~omp1ished '~0 by dippin~ the mold ~8 into hot water while inter~al ~ess~ Is appl~od. ~aris~
tcr~sions and pressurcs ~re uscd in t~ dist~ od~ proxim,al po;~ions. Pre~era~ly,lo~ tenC;on~ and lowpressur~s 3re used in t~e body portion to rrl~nt~ the ri~ht wall thick;ness and max~mi~ cons~ster.t butst prcssurc.
To ~r~ the ra~ expansion step, one end of ~he stretche~ pol~ner t,lbin~ de of the ~ca where it was .npped ~v j aws 20 aIlcl 22 is ~:u~ f to pro~ide an openi~g to the l~unen ~f the polyme. tubing 13 The s~etched polymer tub~7lg 13 is then fed throu~h the mold 28 w~ch co~sists of three parts: the p~ximai portion (top~ 30, tho body 4~ ~nd t~e distal ~bonnm~ port~on 50. T.he~e three sectior~s fit ~io~htly together and pro~ide ~e polyme. tubin~ 13 a fiG~l to blow to ~efemn~ to Fi~. 4~ ~hc ~i~taS port~on S0 of the ~l~,f~ d ~nold ~8 is generally b~ 0.6 an~l ~.4 inches (0.015 ar~ 036 m~ long, whLchincl~de~ the ~n~s~r~-t end sec~on .r)~t~
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IIV V 1 1 ~ I I UL 'J I ' ~rl 1l~ vlu~ .,~.Jrt~.......................... .
- ~CA 02236879 1998-05-06 ~u~ ~vu. I,U~

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~S l used to hold the mold 28 in ~e molding fixture 62 (Fig 5). The distal cone section 52 is formed ~Ltall ~gle o~l~c,c ~ 15 ~ and ~;a With the axis o~ the mold 28. I~ne cup 54 of ~e dist~l portior~ which interfaces ~ith ~he dist~l insert portio2 42 of bod~ 40.
genr~llly has a leng~ of Q.12G inches ~0.003 m)~ roxirn~l por~on 30 of the 5 P1e~L1ed mold ~8 ;~ gencrally ~-Lryr-c~ nd 2.0 ~nches (0.028 2nd 0.051 m) 1On~.
The proxima~ co~e sectron 3~ is a1~o form~d at an angle of l~ YrV~iLL 15 ~ s~d 45 ~ ~ith t~e axis o~ the mold 28 . The cup 34 of the prox:imaI portion intcrf~es witk the~roxir. ,al insert portion ~$4, symrnet~icaI wi~ ~,e dist~l insert mald portion 42 o~ y 40. Tke le~th for the ba1ll~on body 40 ~s gener~lly betw~en 0.4 atld 7 inches (0.0 l and 1~ 0.0~ m) lor.c,. The ~nner aIld o~t~r diameter of the mold sectio~s 30, 40 aIld 50, ~d the ~ngles o~a~h cone ~2, 52 are ~o~ dependent OIl ~e desi.ed ~a~loon si~e The mols for t~e b~llo<~n will be different when producir~g di~~erent si:zed ba~lo~ns, wE~ich i~
ne essary to mec~ t~e ".~ e or ne~s of thcse who will pC~ Ll.. medical tre~tments with the baIloon.
1~Thc :~oI~ 28 of the prese~t irLv~ntiors r~r~ pref~ra~ly ma~e of ~ Q3 5~;nl~sq steel with a smooth miIror fin~sh to provid~ a SDlOO~ finish on the baIloon surface. The a~r~r.~tc mold 2~ i~ the st:~tched polymer tubing ~ 3 ins~de, may ~e heate~ whi~e ple~ e is appli_d using a device 6~ s~h as the one depicted ~n Figs. S
~nd 6. Wi~ thLS de~ice 60~ ~he mold 28 is placed in a holccr ~i2 The polymer tubing ~0 13 e~t.,~ds out from ~e top of ~e mo~d 2~ an~ is ~ed into a Tau~y claulp ~ t~ougn ~hich a p.~s~ ed fluid, prefcra~Ly ~itrogen g~c, i~ applied ~o the ~nner !umen of ~
. - polyme~ tubing 1 3 l~he tubin~ at the bottom of the rnold 2~ is clamped off such ~at r.o gas can fltJW th~sh it. ~ cs~u,e ~.pplied is suitably ir the range of ~00-700 psi (6.~g~x~o5 - 4.8258x6 pa)~

2~One a~Ya~ltagc of us~ dc~ce 60 is th~t tension may ~e applied to U1e polymer tub~n~ 13 ~ring ~e r!lolding ph;ase. A s~ing ~ ~raineà o~er pu~ley ~6 ~shown ~n ~ig. 6 blrt deleted ~m Fig S fo~ sake of cl~n~y) may bc ~tt~ct~cd to ~ tcn~ion cl~mp 67 ~accnt the Touhy clamp G4. Thc t~nsian clamp 67 holds thc polym_r tubing 13 to apply tension ~o it wIthcl~t c~ ing of ~ e flow patll of ~JL~s>~ uid into polyDler 30 ~ubi~ 13 . We~gh~ ~8 ~tt~ ec~ to the en~ oE st~ g lS~ may thus pro~lde tension to the pol~mer tu~ing 1~ ernatively,. ~e ~ ulc may be applied ~y a co~ tei controlled pneumatic c~ er f~r highly accurate measu2~me~ts Gencr.all~r~ 0-700 ~ ~0 - 6.8~ N) of tension may be ap~lied. Tension m2y ~e NDFE~ SH~E~

0. ~ U~ t l l 11 ~ ~ U~itJ rl~ il CA 02236879 1998-05-o6 Ulc JU~ ~Uu~ t ~ ,J ~SV _~:J~ tJ.~ J

applied during the mo~ding process to better con~rol the walL ~ickness of cer~n arezs of the balloorl~ ~rimar~l~ the ~aist sec~ions. The te:tlSIOIl decr~ases t~e cros5 secti~
area of the balloon waist~e., thereby incrc~ fl~xibi~ity in those re~ions.
Thc po1yTner tubing 13, subjected to spccific inte~or pressures, is ~en he~ted~ A~ d~picted by d~.hed lines in Fig. ~, the ~nold 2g i~ d~pped into a ~ter b~th 70, ~uita~ly ~ a rate of 4 mm/sec., with the total pr~cess of submer~ the mold 2.3 mches (O.OS~ m~ o the bat~ 70 taking a,o~ a~1y 15 seconds. Prefer~15~, the ~ath 7û is a ho~ ter b~th mni27t~ined at a te~ ture~ eof 85-~8~ C, ~i~ ~ C~
~+~- 0.4 ~ C) being the most lJLG~Llcd temperature. Once the entire mold ''8 has beer 1~ s~me~ged it is held sta~onary for a period O~t.tll'lC, ~suita~Iy 40 seconds, wni~e the ~allcon and w~.st port~ons yield compIete!~ ~d stabili7~. l~e radi~l expan~ion, or hoop r~tio ~caIcuIat~d ~ diYidin~ the in~cr diR~rr.et-r of ~.he balloon ~y ~e inrer diamc-.er of the ext~u~ed ~u~n~, should be in the r~lge of 4-g. However, the ~r~fe~ r~d hoop ratio for pr.~ is ~:~yL~ a~ely 8.~ and fo. Pe~ax is approxhmately 6Ø A lower l~i hoop l~tiO ma~ result i;l conpiiance w hich is ~g~er ~.ha.~ desire~ A L~gher hoop rauo may res~lt in prsfQ~ns which ~11 not blow o~t fu'ly. ~urin, t~is phase of radial ncinn, the po~y~r.ertub~nO 13 is slighlIy elv~
~n accordance ~th a further aspect o~ ~he irl~enlon thc stretched pc~lyrne~
tubing 13 is blo~n du~ing ~ programrned dippin~ cycle, for dippir~ nto ~ot wa.er bath 70~ dunng ~kich the ~ aul~' a~ 2xi~ ~c~sion ~rev~edatse~er~ ~esso ~hat~l~
~lloon is seque~tially blown ~o~ one ~nd tc th~ oth~r (psoximaL, body and di~tal~ or v~ce ~;ersa~. ~y ~s rr~ethod, a fi~r re~uced waist and co~.e thi~.k~cc is ob~;ned Fig. 4 has bccn labeled to show deFth re~ions at ~hic~ tras~sitions of pressu~e and/or tension o~cur in this aspect of the iJlv~ntion ~s mold ~8 is dipped into ~5 batl~ 70. Correspor~din~ Iocations on the balloon 14 ~r~ labeled in Fig. 1. T~e regio~
C co~npris~s t}~c prox:~nal waist por~ol3, thc rcgion C-3 cnmr~i~es ~he ~loxi.~ cone porticn, ~ region D-~. comprises the body portion, the region E-E~ comprises the distal eone p~rtion and the regio~ F-G COnlp~iSeSthe distal ~diSt pOrtiOI~ of ~e mold. 'I*e balloon blowint, process of the invention invol~es the stcps o~
pressu}izing the st~e~ched tubin~ to a fi~ cs~ule in the range of 150-500 psi(l~o34xlo~-3~47xlo6pa)an~appl~ngafi~ttensionLn the ~nge of ~-~0~ g (0.0~-5.Q ~);

D Sf f~

V . 1 u I I u . v ~ ~ ~, ", CA 0 2 2 3 6 8 7 9 1 9 9 8 - 0 5 - 0 6 T l ~ t ' ~ - dippin~ the mold tc~ a f~st depth in the range of f~om the ~;t;on ~C~ from the first v~ist to th~ first co~e t~ the tr~n~ n (D~ i~om the first co~c to the body portion of ~e ~2l100n;
~e~ Le L~lc~ .. G to a second pre~xu~c be~ween 80 and t 70 psi (5.51 Sxl 05 - 1.17~xlO6 pa) a~d settin~ a s~cond tension in t31~ range of the f~st tension, dipp~ng thc mold to a second ~.epth in the ~nge of fiom the tr~nsition ~:' from ~he body portion to the second cone portion to the t~ansitior om the second cone to the ce~o~d waist;
creasing ~e p~c~ to a third press~ h~gher tllan thc seco~d ~ ~ pressure and ~etween 1~ and 500 psi (~ ~034X1~!6 - ~.447xlO6 pa) a:r~d hlc~easi tlle tension to a third te~sio~, hi~hcr than the first ~d second tC~slo~s, and tnen, dipp~ng the mo~d to a thiTd dcpth ~ bevoncl th~ dep~ ~G) of the second waist Although ~e process ma~ be ~ccem~ h~ witk. ~bs~antial1y ccntinuous dippin~, it is pre~e~red that th~ ld be h~ld at eac~ of ~e nrst, seccnd and ~ird dept~
~or pT~et~ine~ t~me inte~als before ~'h~ ng; n~ pressl.~e/tenslotl p~meters and moving to the r.ext dep!:h. Su~ta~le hold time intel~als ~e between 1 2nd 40 se~nnS 2:~
the fi$st c~epth, ~e~een I and 4~ s~con~s at the second depth and beh~een l O an~ 1 OG
ZCi seconds at ~e t~ird dep~l. For example, ~ typioal dippi~g pro~am ror a PE~ polymer b~lloon, be~nn;n~ at an ini~ial de~ ~) before the depth (B) of the L~lrst waist of the balloon, a~d ~ing a 95 ~ C hot wa~er b~th as he~ting media, will take a total ofapp~ox~matel~ 60-~G se~onds.
Ihe ~d ~ension is suitably in ~e r~n~e OÉ 50 .o 700 8 (0.4~ to 5.~
2~ ~nd is hi~her tha~ ~he second tension, suitably hi~hes than both the firs~ ~ld seco~d tensio~ss. . Ft~r balloons of 4 00 mm diameter o~ less, th~ third te~sion will usualIy nGt excecd 700 ~; ~6.86 N~. The second t~nsion rn~ be ~e s2rne or di~erent from the first tension a~d if dif~crcrt wiI1 usnf.~ly ~e less th~ ~e first t~.sion. 1~ general the ~er.sior~
employcd at al1 dea~.s ~ be higher ~s t~e dianeter of thc b~Tloon is increased l~or 30 b~tl l~on~ ha~ing ~ m . n~ qmçt~s of at least ~ mm it ij prefer.red that the thi~d te~ion be ni~e~ than both th~ fi~;t and second tellsions by at le~st 150 grams ( 1.47 ~r) aqd at a~l t}~i~l an~3iopl~ baI~oon ~ m~t~. it is l,~V~..~d ~t ~e difference , A!'.~ nF3 S~icEr :

iV V I 1 v I I U l_ U ~ I 1 1 V I L~ L I I 'CA 0 2 i 3 6 8 i 9 1 9 9 8 - O 5 - O 6 U I ~ ~) U .J J U ~J I r - i ' ) . j: J ' ' ;~ ' J ' ) I I i j: ~: 11 1 "

bet~een ~e sccon~ a~d third ~cs~s be at ~eas~ 100 psi ~.Sg4xlO~ pa) I usual~y atleast 1~0 psi (1.034xlO6 pa).

r.;~ C~ S~E~

I UL U ' 't'J I 11 ~ l Url..J ~ ~CA 022368i9 l 998 05 06 ~ -r~/ ~,~, _. ..,~, ., ~ ,., " . ., It should be noted th~t ~is sspect of the invention can also be pra~;ticed by inserting ~e end of mold ~8 ~Jhich form~ the d~l end o~the balloon i~sto the heatIrg ~a~L first.
The balloo~ ~onne~ i~ the mold ~s next coolecl. One ~ ay to cool the 5 balloon is to Temove ~c mold~2g from the hot v~ater bath 70 ar~d pl~ce it in z cooling bath 7~. As shown in ~ig. 5, ~is step may be accomp~shed through use of a rn;~r.l~;n~
~0 ha~ing a pivot arm ~4 c~pa~le of ~ the mold 2X from ~he kot 7~ to ~e co~d ~ater ~ath 7~. The c~oling ba~h 72 ;s prefer~ly m~int~ined at 7-~5 ~C. ln the prefe~ed embodirnent, th~ ballo~n remams ~n t~e cooling ba~ 7~ ~or ~pro~m~tely 10 IO seconds.
,~ Finally~ the ends of the tubin~ 13 e~n~ting ~om the m~ld 78 are cut off and th~ ~a~1oon is rer.loved fr~m t~e r~id 2g by removing either the dist~l e~ld ~0 o.
proxi~r31 cnd 20 firon~ ~e body se~tion 4Q of mol~ 28, tl:~en ger.tly pullinO ~he baIloon from tne relnsTinTn~ r~old sectio~s. lc~ moullt oll a C&lh~_lcr lO, balloon 14 is C~t Qt E~
1~ and G ~ld adk~rcd to the catheter irL con~ren~onal ~anner.
In atlOthOE v~i~tion of ~e me~od using P~T t~h~n~, the t~bing is first stretched lm;f~rrnly ~t 9~C"hen u7~e tub;ng ~s co!d ~trctchcd at room t~ Ct~C ~he ~old strel&hing ~ be ~ ~L~ d ~n onc erld or both cnds. T f it is ~ o~ ed o~ one end (dist~l end~ necked ~ort~on nol stretched (prcxim~l cnd) by cold dr~ g wLlI fosmi~G ir to the dis1aI waist ~d partia~ co~c por~on ~u~ing thc blowin~, ~7roces~ ~s described ~e~ow.
A fu~'-cr vanation of the method of ~e in~rent~orl c311s ~or draw~ng, o~lly one cnd, the prox3ma~ e~d7 of ~o t~bin ~, or i~ o.~er w~ s, 2lIowin~ the ce:nt~r portio~.
12b to remain at a ~reater leDg~ so thatwhe} th~ tu7~ g ~s i~serlcd iIl~o the mold, ~ke ~5 center ~o~ion l 2~ e-~e~ds out ~hrou~-,h the dis~l end of ~c mold a3 s~own irl Fig. 8.
The re n~7;nin~ ~spects of ~7e proccdure are ~7n~h7ln~ed 7~)uri~g the blow~ng process ~g~ pressur~ and high tension i~ mA; l~t;A ;I-cc~ . The 7~strctckcd e~d as ~ resuli is ~orced out longit~dinally talcing the sh~pe of ~e ~istal end o~ the mold and thus fo~n ng a d~stal cone pn~ion.
~he invent~on ~lows the distensiblc portion of a balloo~ to be cor~ee~:ly m -~nuf~ctllred while provid~ng smalI diamet~ers a~ ~he pl ~ d ~s~al ends ther~of and su~ n~ ~tl y ~ J I ~ t1~ickn~ss throughout. Therc is contit~llin ~ ;cd to rc~u~
balloon ~nd sh~ft profiles so that tighter a~ ial lesions may be E~'D~D S~

CA 02236879 1998-0~-06 W O 97/17098 PCTrUS96/15958 crosscd and trcated. This invention allows for thc forrnation of an uniform, thin-wa.llcd balloon having a flexible tapered end. Thc thinncr, uniform walls and reduced diameters also allow tighter protcctor or compression slceves to be installed ovcr the balloon to further reduce its lminfl~ d profile, allowing for easier passa~ge 5 into and across a Sten( si~. In the present invention the polymer tubing is not siml~lt~n~ously drawn and expanded, in fact, the center portion 12b is appr~eiably not drawn at all. Constraint is used in both the stretching and molding ~lUCcs~cs so that the molecules of the wall material in thc balloon region become stabilized. The balloon does cxtend axially slightly in thc molding process, but only due to ~rowth 10 from the radial pressurc and not due to strctching.
The various aspects of the invention are illustratcd by thc following non-limi~in~ examples.

liVV Ll ~' IU~ 'J~ 1 CA 02ii6879 1998-0~-06 mp}e 1 Pe~ax 7033 tube ~nth d~nensio~s ID (i~ner ~;~m~t~r)0.01~8"(0.50 ~n) OD ~outer diametcr) 0.033~" (0.8~ n) is co1d-drawn at aVer'JIOW te~lperatU
ap~o~l~late1y in ffle ra~cs of -100 ~C to -:;20 ~ C. A s~rcw (or air) dn~en s~etchin~
;5 rn~ hinc Wi~ p3ir of p~e~matic ~jLlp~C~ S used to stretch the tub~ng. The center por~io~ is cooled under l~e gl~ss t~S~tiOtl temperat~e of ~.he t~bmg n~t~n~l b~ ~irectly spraying ILquid N2 (Supcr ~reeze m~y ~lso be used) on t:he center portion ~e cooli~g m~y a~so be ~ccomplisked by hold~n~ the centel po~ion wi~ co!d clamps. in which case the l.,lLF~-d~e is pre~t~rminRd). ~en ~tenli~ed b~loor~ (3.0 D~ in diamcter a ld 2C
~O mm in length) ~re m~ with 2aYera~e doul~le wall thic~ess 0.00143" ~0.03~ mm). T'n~
resuLting burst pless~ is ~70-2~0 psi (~.8~2xloG ~ xlû~ pa). Th~ compIi~ce is 8% at bc~ 6 atm (6.0~xl05 p~ and 12 a~n ~1.22xIO~ pa~ and 16% at between 6 zt~n ~6.08x10~ pa) and 16 a~Q (1.62x106 pa~.

IS
Example 2 PET tubing with dimensions ID 0.018~ 0.48 mm~ x OD ~?.0~27" ~1.08 ~n~ is cold-~un in a ~ter b~t~ at 58 ~C ~elow ~1ass ~n~it~n~t~l~p~aL~usl~
the machi ~e in Exampie 1 ~til unstret~hed leng~h is ~ O~ s~-nli7~ b~r1oons , O meas~ mrr~ in di~n~er and 20 mm in l-ngth and having an a~Y-e~ge double w ~Lthic~ess of ~.001~8" (0.0~ mm) ~e tested. l'he rcsul~ng burst ~ ~e is 400-~10 psi - ~2.75~ 6 - 2 8~7x1G~ pa~ and the com~ nce is ~.0% ~ bcL~ 6 at~ ~6.08~10~ ~a?
a~d 12 ~m (1 .2'~-x1 Os pa~ a~d 3."~/~ 7.t b~.w~ 6 n~ar. (~i.08x 105 pP~ d 16 ~l (1.62xlOfi pa).
ExampIe 3 P~T ~ing w~t.h dimensions II:s 0.0189" (0.48 mm~ x OD 0.Q4'77" (l.08 s ~le~Ll~ik;hed ~t g~~C in a water bath ~or a 1~% ~lon~;~t;or~ then is cold-drawn at room t~ c usin~; the m~ch;n~ In ~xample I un~1 10 mm uT~s~etched len~tn ~(~ 1eflc. ~our ~ s~1i7?d b~1io<~n~ measuring 3.5 m.m in diarneter and 20 mm in k11gth and h~ing an ~verage dc~uble w~ll thir.l~c of O.CIO l 1 1 " (() .0~ 8 3~) are tes~.e~. 'rhe res~ltinO bu~st p~ is 350 psi ~2.~13X106 p2L) and the compliance is 2.3% at Ar ~ n~D SHE~
' ' ~iVY 11 vl lu~ u~ tv 1., CA oii36879 1998 05- 06U~ JU~ JUVI ~'' ' ~ J

~ -lSa-between 6 atr~ (6.0g~105 pa) and 12 atrn (1.22x106 pa) ~nd 3.5~o at ~ n 6 atm(6.~8x105 pa) :~d 16 atm (1 62xl06 pa~

~}r~ f ~ ~iL~

.~',ivv ~ 'v~ Iv~ ' CA 02236879 1998-05-06 ul~ J U ~ ~ UU ~ U ' 'r l ' Esample 4 Polyester el~tom~r tubing with ~1im~ ;on ~ ) 0. 0179" (0.45 mm) x OI:~
O.G270" (0.69 mm~ iS cold stretched at room t~~ ture usi~g ~he rn~chine I~ Exam~le 1 un~il unstretched leng~ is 8 mun. Ten sterili7r~1 ba~loons meas~lnng 1.~ mm indi~n~ete r and 20 mm in 1eng~ ~nd haY~ng ~ average double wall thic~ness of 0.00 l9"
.048 mm) .~e tested. The resulting b~rst ~J~Cs:: Ul~ is 250-~50 psi (I .724x106 -1 .793xl o6 pa) ~ld lh~ ~p~iarlce is 33.6~,~o at ~ ,ecn 6 a~n (6.08x105 pa) ~d l ~ atm x106 pa) a~d 9g.3% at b~i~eel- o 2~ (6.08x1C~ pa) ~nd 16 a~ (1.62x1~6 pa).

F.~mrle ~;
Nylo~ ubin~ wi~ t1;me~nsi~ns II ~ U.Ol 82" ~0.~ x O~ 0.0254"
{O.v5 mm~ is cold st~otc~ed at room temperature using the m~rki~ cample I untiL
unstletchGd i~ng~ iQ 11) ~n. ~ot:r tmCt~1;~çd b~lloons rneaSIlrin~ 2 0 ~ in ~i~rt~r ~n~ 20 mm in length and havin an avera~e donbl_ wall S~ n~e~ of O.OOOg8" (0.~)2'~
zre tcs~ed. The resultir~g burst E~ sule is 270-280 ps~ (i.862x106 - l.931xlOD pa) .d ~he compEi~ce is 9.~% at oetwoen 6 aml ~6.$~xIO~ pa~ ~Ld I7 atm (l.~xlG6 pa) and }~ 7D~o atl~ c~ 6 atm (~ 08x105 pa) and 16 ~ (1.67xlO~ pa~.

Ex~mple Ç
PE~tubiD~ lim~n~ions r~ 0.0~26" ~0.~7 Ir~n) x OD 0.0470" (l .l~
n~m) is s~etched at 90~C to a st~et~h ratio of ~. 5 at a speed of 0~3 inchlsec (O.Q14 mJs). The tubing is tllen nec~ced by colc~-dra~; the dist~l end at room temperature using t~ met~od in Ex~mple 3 aild at ~ speed of 0.4 inc}~lsec ~0.01 m/s~ to a draw rano of l.18 lo fo.-m ~e resultin~ un'~ dist21 w~st ~;d wnc p~rcion. Four b~lloon3 ~cmade and tested. I~e b~loon si~e is 3.5 mm ~ meter and, O mm in length. The bal}oor~ doubl~ wall 1hic:knesc is a~ ~.0~148" ~.038 mm). As a result afcold-dTaw~ng, the walt f~ .kn~sc of the cone po~on ~s m~sura~ly rcduced a~d the wall tl}ickne.ss o~e walst portion is ~ cd by abo~:t 50% col~p~,d t~ ballc~ns manufacture~ hou~ oold-drawin~: The r~SllltinE bu~ k~le,is~llc is 338 psi ~2.~30xl~6 pa)-A~ NDED SttEr' llVV ~ 1 ~iL l~J-- U-t'-tV I 11 Y ~ . I CA 02236879 1998-0~-06 ;J~ u~

- 1 6;1-E~ample 7 PET tubi~g wi~ ~liml~ nr!s ~ 0.0~26" (~ 7 Ir~n~ x OD 0.04'.70" (I.lg }nm~ is stretchcd at ~0~C to a stre~ch ~atio o~ ; a~ a spe~d of 0.~3 mc~L~sec (0.014 S m/ci). 1 he ~b~ng is t~ ncc~-ed b~ cold-drawin~ t~e dist.~ nd F~rOXirtl al er~c~ at roQ~n temperatu~e ~sin~ the metho~ i~ F,xampie 3 a:~d at a speed of 0.4 inch~sec ~0.01 ~i~'s) to a dra~ uo of 1.18 tc~ form A~E,t,~ CV~

V i 1 ~ U ' U ~2 ~ ~r V ; ~ v ~ . 'CA 0 2 2 3 6 8 i 9 l 9 9 8 - 0 5 - 0 6 ~ u U J U U ~ J ~ t ~ t ~ . ' ~ I ~ i ~ ~he resultinc b~loon's d ~tal ~d proxlmal ~ra~st ar.d corle portio~s~ Fou~ balloons are rnade and testc~ The ba!loan s ~ is 3.5 sr~rn in ~ mPpr and ,0 mm in le~gth. 'rhe ~alloon do~ble walI ~ k-~ss is about 0.~0148" (0.038 mm). As a ~esult o~cold-drawi~, thc ~vall ~hic:kness vf ~e cone port~ons a~e measurably redueed and thc ~.11 5 thiclmes~ of t~e waiat portio~s ~re reduccd by ~bout 5¢% coIrpared to ~Tloons ur~;~.Le~ wi~ul colci~ ing. The resul,i~ burst pless~e is 338 psi ~!.33UxlC~
pa).

Ex~p{e 8 Balloor.~ 50 mm in di~metcr and ''O mm in le~3;th are rn~dc by the m~hod d~-scribec in exarr ple ~ are assemble~ on c~thet~rs. T~ de~latecl dis~l ~alloon p~ of ile. is 0.033 ineh (~.~xlO--m~ ~co~ ecL to a cath-ter ~ade fro~--l balloo;ls w~hout the ~ecking p.~cess Gf~e F~esent inYell~on P.~ h ~Las a defl;~ted d~st,~ ~lo~n ~rc~le of 0.04G i~lch (l.QxlO-~ m~.
~Yample 3 Balloons are rnade b~ ethcd in E~ample 6 ha~ing a L~.O mm m~ r~r ~ isem~led ~n c~leterS. ~e r~sul.lin~. defl~led d~sT~L baIloon pro~lie i~~.0~ inch (~.~gx~0~ m) as compared ;o a profitc of ~.04 5 inCb. tl .1 lxlO; m~ OI
20 ~alloon ~ ters r~.~de f~c- conventional m~ cls.

Exar- plc 10 ~ e balloons irl E~mple 1 ~re .~s~n~h!eci on c~:heters. I~e df~ f~i distal b~lloon profile is 0.031 inch (7.~7~;10~ m). ~e pro~lle of b~lloons ~nadc wi'~out 2~ cold ~tretc~:ng or neckin~ ~es~l~ed ill ~ d~;l~ed distal ~lloon profile in ~e ra3~ge of 0.03~i ~o 0.û41 inch {9.14.~ to 1.0~10-3 m~.

The r~sulti!lg baIloons or the ~boYe Examples dispL~v not o~y reduced -bal~oon .~ickness, but redn~ed con~ ~d w~t t~i~k~ ~ssP~ th~.~s prcducin~ a balloon 30 having a redlL~,d profile ~nd ~reatly s~mpli~L g ~he ins~rtion i.~to th~ bociy.

A~lE~ ED SffEET
-

Claims (22)

1. A method of making a balloon for a catheter device, the catheter device having a distal portion to be inserted into a body and the balloon being situated on the distal portion of the catheter device, comprising the steps:
extruding a segment of thermoplastic material having a predetermined wall thickness and length, the segment having a proximal end, a distal end and a center portion, the center portion having a temperature;
drawing the segment to a predetermined length while maintaining the temperature of the center portion below the glass transition temperature of the thermoplastic material, or below the highest glass transition temperature if the material is a block copolymer, wherein, during the drawing, the wall thickness of the center portion does not substantially change, and the proximal and distal ends form a first and second waist, respectively; and expanding the segment in a mold to produce the balloon, the balloon having a body portion, wherein the center portion of said segment becomes the balloon body portion.

2. The method as in claim 1, wherein the thermoplastic material is chosen from the group consisting of polyamide elastomers, polyester elastomers, polyamides, polyesters, polyethylenes, polyurethanes, polyethylene ionomers, and ethylene vinyl acetates.

3. The method as in claim 2, wherein the thermoplastic material is polyethylene terephthalate.

4. The method as in claim 2, wherein during the drawing step the center portion is maintained at a temperature of no more than approximately room temperature.

5. The method as in claim 4, wherein the center portion is cooled just prior to drawing, such that the center portion remains cool during the drawing step.

6. The method as in claim 4, wherein the segment is cooled just prior to drawing.

7. The method as in claim 5, wherein the stretch rate is between 25 % to 75 %
per second.

8. The method as in claim 5, wherein the stretch rate is approximately 75 %
per second.

9. The method as in claim 5, wherein the cooling is accomplished by clamping the center portion with cold clamps, such that the center portion remains cool during the drawing step.

10. The method as in claim 7, wherein the segment is allowed to reach approximate room temperature before the expanding step.

11. The method as in claim 10, the expanding step comprising placing the segment of a thermoplastic material in the mold and blowing the balloon by pressurizing and tensioning the segment and gradually dipping the mold into a heated heat transfer media so as to sequentially blow the proximal end, the center portion and the distal end of the balloon, the segment being subjected to a relatively lower pressure than while the first waist and second waist portions are blown.

12. The method as in claim 11, wherein the segment is also subjected to a relatively a lower tension while the body portion is blown than while the first waist and second waist portions are blown.

13. The method as in claim 10, wherein the expanding step comprises the steps of placing the stretched segment in a mold having an internal form corresponding to the desired outer configuration of the balloon, and blowing the balloon by applying axial tension and internal pressure to the preform upon dipping of the mold into a heated heat transfer media, the expanding step further comprising:
pressurizing the stretched segment to a first pressure in the range of 150-320 psi and applying a first tension in the range of 5-150 g;
dipping the mold to a first depth in the range of from the transition (C) from the first waist to the first cone to the transition (D) from the first cone to the body portion of the balloon;
reducing the pressure to a second pressure between 80 and 170 psi and setting a second tension in the range of the first tension;
dipping the mold to a second depth in the range of from the transition (E) from the body portion to the second cone portion to the transition (F) from the second cone to the second waist;
increasing the pressure to a third pressure higher than the second pressure and between 150 and 320 psi and increasing the tension to a third tension, higher than the first tension, and then, dipping the mold to a third depth (H) beyond the depth of the second waist.

14. The method as in claim 13 wherein the third tension is in the range of 50 to 700 g.

15. The method as in claim 13 wherein:
the mold is held at the first depth for a predetermined first time interval while maintaining said first tension and first pressure before said pressure reducing step;
the mold is held at the second depth while maintaining the second tension and the second pressure for a predetermined second time interval before said pressure increasing step; and, the mold is held at the third depth for a predetermined third time interval while maintaining said third tension and third pressure.

I6. The method of claim 15, wherein said heat transfer media is heated to a temperature of 90° C to 100° C.

17. The method of claim 13, wherein the second tension is the same as the first tension.

18. The method of claim 13, wherein the second tension is less than the first tension.

19. A method of making a balloon for a catheter device, the catheter device having a distal portion to be inserted into a body and the balloon being situated on the distal portion of the catheter device, comprising the steps:
extruding a segment of thermoplastic material having a predetermined wall thickness and length, the segment having a proximal end, a distal end and a center portion;
immobilizing the center portion so that it becomes dimensionally stable and cannot be appreciably drawn;
drawing the proximal end to a predetermined length while maintaining the immobilization of the center portion, wherein, during the drawing, the wall thickness of the center portion does not appreciably change, and the proximal end forms a first waist;
and expanding the segment in a mold to produce the balloon, the balloon having a body portion, wherein the center portion of said segment becomes the balloon body portion, and the distal end, due to expansion in the mold, stretching longitudinally to form a second waist.

20. A method of making a balloon for a catheter device, the catheter device having a distal portion to be inserted into a body and the balloon being situated on the distal portion of the catheter device, comprising the steps:
extruding a segment of thermoplastic material having a predetermined wall thickness and length, the segment having a proximal end, a distal end and a center portion;
cooling the center portion to a temperature below the glass transition temperature of the material;
drawing the segment to a predetermined length while maintaining the temperature of the center portion below the glass transition temperature of the material, wherein, during the drawing, the wall thickness of the center portion does not appreciably change, and the proximal and distal ends form a first and second waist, respectively;
and expanding the segment in a mold to produce the balloon, the balloon having a body portion, wherein the center portion of said segment becomes the balloon body portion.

21. A method of making a balloon for a catheter device, the catheter device having a distal portion to be inserted into a body and the balloon being situated on the distal portion of the catheter device, comprising the steps:
extruding a segment of thermoplastic material having a predetermined wall thickness and length, the segment having a proximal end, a distal end and a center portion;
cooling the center portion to a temperature below the glass transition temperature of the material;
drawing the proximal end to a predetermined length while maintaining the temperature of the center portion below the glass transition temperature of the material, wherein, during the drawing, the wall thickness of the center portion does not appreciably change, and the proximal end forms a first waist; and expanding the segment in a mold to produce the balloon, the balloon having a body portion, wherein the center portion of said segment becomes the balloon body portion, and the distal end, due to expansion in the mold, stretching longitudinally to form a second waist.

22. A method of making a tubular parison for use in manufacturing catheter balloons comprising the steps:
extruding a segment of thermoplastic material having a predetermined wall thickness and length, the segment having a first end, a second end and a center portion, the center portion having a temperature; and drawing the segment to a predetermined length while maintaining the temperature of the center portion below the glass transition temperature of the thermoplastic material, or below the highest glass transition temperature if the material is a block copolymer, wherein, during the drawing, the wall thickness of the center portion does not substantially change, and the first and second ends form a first and second waist, respectively.