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Publication numberCA2179744 A1
Publication typeApplication
Application numberCA 2179744
PCT numberPCT/US1994/014970
Publication date13 Jul 1995
Filing date27 Dec 1994
Priority date6 Jan 1994
Also published asDE69433627D1, DE69433627T2, EP0738169A1, EP0738169B1, US6024722, WO1995018647A2, WO1995018647A3
Publication numberCA 2179744, CA 2179744 A1, CA 2179744A1, CA-A1-2179744, CA2179744 A1, CA2179744A1, PCT/1994/14970, PCT/US/1994/014970, PCT/US/1994/14970, PCT/US/94/014970, PCT/US/94/14970, PCT/US1994/014970, PCT/US1994/14970, PCT/US1994014970, PCT/US199414970, PCT/US94/014970, PCT/US94/14970, PCT/US94014970, PCT/US9414970
InventorsBruce H. Rau, Susan M. Shoemaker, Paul J. Buscemi
ApplicantBruce H. Rau, Susan M. Shoemaker, Paul J. Buscemi, Scimed Life Systems, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: CIPO, Espacenet
Thermoplastic polyimide balloon catheter
CA 2179744 A1
Abstract
The present invention discloses the incorporation of thermoplastic polyimide into various parts of balloon catheters such as catheter shafts and balloons. Such catheter construction may be integral or unitary in which the shaft or a portion thereof and balloon are manufactured are a single unit or the construction may be comprised of a separate shaft to which a balloon is attached, as by adhesive or other bonding.
Claims(32)
WHAT IS CLAIMED IS:
1. An improved balloon catheter comprising a shaft portion having a proximal end and a distal end, and a balloon portion located at the distal endof said shaft portion, wherein the improvement comprises one of said portions of the balloon catheter being comprised of thermoplastic polyimide.
2. The balloon catheter of claim 1 in which at least a portion of the shaft is thermoplastic polyimide.
3. The balloon catheter of claim 1 in which the balloon is comprised at least in part of thermoplastic polyimide.
4. An improved balloon catheter comprising a shaft portion having a proximal end and a distal end, and a balloon portion located at the distal endof said shaft portion, wherein the improvement comprises the balloon portion being comprised of an innermost balloon layer and at least one additional layer, and wherein at least two of said layers are comprised of polyimide, and one of said polyimide layers is comprised of thermoplastic polyimide.
5. The balloon catheter of claim 4 in which the inner most balloon layer is thermoplastic polyimide.
6. A balloon portion of a balloon catheter wherein the balloon is comprised at least in part of thermoplastic polyimide.
7. The balloon portion of claim 6 comprised of multiple layers, one of said layers being an innermost layer, wherein at least one of said layers is thermoplastic polyimide.
8. A balloon portion of a balloon catheter, said balloon portion being comprised at least in part of thermoplastic polyimide, and further comprising at least two layers, one of said layers being an innermost layer, wherein one of said layers is a thermoplastic polyimide, and the other said layer a thermoset polyimide.
9. The balloon portion of claim 8 wherein the innermost layer is thermoplastic polyimide.
10. A catheter comprising a shaft, said shaft being comprised, at least in part, of thermoplastic polyimide.
11. A balloon catheter comprised of thermoplastic polyimide, said balloon catheter further comprising a) a shaft having a proximal end and a distal end; and b) a balloon portion projecting from the distal end of said shaft.
12. A catheter comprising:
a) a shaft having a proximal end and a distal end; and b) a balloon portion further comprising:
i) a proximal waist portion, constructed and arranged to be bonded to the distal end of the shaft of the catheter;
ii) an intermediate body portion of larger diameter than the waist portion;
iii) and a distal end portion of a size smaller than the proximal waist portion, said balloon portion being comprised at least in part of thermoplastic polyimide.
13. A catheter comprising:
a) a shaft having a proximal end and a distal end; and b) a balloon portion comprised at least in part of thermoplastic polyimide, said balloon portion further comprising:
i) a proximal waist portion constructed and arranged to be bonded to the distal end of the shaft of the catheter;
ii) an intermediate inflatable body portion of larger diameter than the waist portion;
iii) and a distal end portion of a size smaller than the proximal waist portion, said balloon portion being comprised of multiple layers, at least one of said layers being thermoplastic polyimide.
14. The catheter of claim 12 wherein the balloon portion has a diameter of about 1.5 - 25 mm.
15. The catheter of claim 12 wherein the balloon portion has a wall thickness of about 0.0003 - 0.003 inch.
16. A balloon portion of a balloon catheter, said balloon portion being comprised at least in part of thermoplastic polyimide, and further comprising at least two layers, one of said layers being an innermost layer, wherein one of said layers is a thermoplastic polyimide, and the other said layer is a thermoset polyimide.
17. The balloon portion of claim 16 wherein the innermost layer is thermoplastic polyimide.
18. A balloon portion of a balloon catheter comprised at least in part of thermoplastic polyimide having a melting point between about 340C -410C.
19. The balloon portion of claim 18 comprised of multiple layers, one of said layers being an innermost layer, wherein at least one of said layersis thermoplastic polyimide.
20. A balloon portion of a balloon catheter as in claim 19 wherein one of said layers is thermoplastic polyimide, and the other said layer is thermoset polyimide.
21. The balloon portion of claim 20 wherein the innermost layer is thermoplastic polyimide.
22. A catheter comprising a shaft, said shaft being comprised, at least in part, of thermoplastic polyimide having a melting point between about 340C - 410C.
23. The catheter of claim 1 wherein at least a portion of the shaft is comprised of thermoplastic polyimide coextruded with another material.
24. The balloon catheter of claim 1 wherein the shaft and balloon are integrally formed.
25. A catheter shaft comprised at least in part of thermoplastic polyimide, said shaft further comprising a reinforcement material.
26. The shaft of claim 25 wherein the reinforcement material is a braided reinforcement.
27. The shaft of claim 25 wherein the reinforcement is located near an outer diameter of the shaft.
28. The shaft of claim 25 wherein the reinforcement is located near an inner diameter of the shaft.
29. The shaft of claim 25 wherein the reinforcement material is a fiber.
30. The shaft of claim 25 wherein the reinforcement material is blended with thermoplastic polyimide.
31. The shaft of claim 25 wherein the reinforcement material is in a spherical form.
32. The shaft of claim 25 having an inner diameter covered with a fluoropolymer, and wherein the reinforcement material is located in the polyimide material.
Description  (OCR text may contain errors)

wo g~/186~7 2 ~ 7 ~ 7 4 4 PCTIUS9.~ 970 Termoplastic polyimide Balloon catheter Back~round of the Invention This invention relates to dilation balloon catheters, ~ ullllly 5 those used in ~IllgiU~ iy. More specifically, it relates to the balloons on such catheters and to some extent to the catheter shaft as well. Angioplasty relates to opening of stenoses in the vascular system usually by means of a catheter having a balloon at its distal end. Such catheters may be single or multiple lumen, may be over-the-wire or non-over-the-wire. Very similar catheters 10 may be used for placing stents. All such catheters are referred to herein collectively as "balloon catheters". The invention described herein could also be utilized in the production and I~ lurdu~ of guide catheters or infusion catheters.
It is possible to make balloons from a variety of materials that 15 are generally of the Ih ~ polymeric type. Such materials may include: p~l~,l,yl..l.~ and ionomers, ethylene-butylene-styrene block CUI!OIYIII~L~ blended with low molccular weight pol~ and, optionally, PUI.~ U~ C~ and similar ~ g butadiene or isoprene in place of the ethylene and butylene; poly(vinyl chloride); p~lyul~/l~ll.,i~, 20 ~,u~uul,~ h --~"~ rubbers; ~ U.~IJUI~ P ' UU,UI)I,YI.._I~, and ethylene-vinyl acetate Cu~ul~..l...~.
One rnaterial of choice for such catheters has been thermoset polyimide, primarily because of its high strength and flexibility in small diameter with very thin walls. Being thermoset, the polyimide used heretofore 25 has involved c~ procedures due to the fact that it is insoluble and "il:ltractable" i.e., not meltable. For example, in forming catheter shafts, it has been necessary to build up the shaft with multiple layers of polyimide on a substrate which is - h~ l. .lly dissolved away. This has also been necessary in making the catheter balloon m which multiple layers of WO 95/186-17 2 1 7 9 7 4 4 -2- PC~/US9-111-1970 thermoset polyimide were layered onto a form, of glass for example, which was later etched away leaving a polyimide balloon.
This type of polyimide is a ~..,..~U~IIdill polymer typically made of two base mr)nnmFrC, a diamine and a di4ll1.ydlidF (e.g. para 5 and pyromellitic d;dl~lydlid_). Such polyimide is typically formed by two stepreaction like the following example. First, a polyamide is formed from the monomers. The reactin proceeds at about 25 C. and the product is soluble and stable in very polar solvents. Second, the polyamide is condensed to polyimide at about 120 C. Further description of polyimides and their 0 ,UI~pa~d~iUII can be found in Androva et al. Polyimide, A New Class of Heat-F~esistant Polymers, pp. 4-13 (1969~.
As already indicated other plastics have been used in catheter co.~. . u.,Lio.l for shafts and balloons in which the plastic has been of the type- For exaunple, pol~ i , ' ' (PET) has been 15 used to make the balloons. Tl.. ~ materials lend themselves to simpler _ techniques, such as extrusion in forming shafts and blow molding in forrning the balloons than do the dr~.. ~ .. li~).~F~I thermoset polyimide materials due to the fact that they are soluble and meltable.
lIowever, the art has failed to recognr~e that 1l. "",pl 1;~ polyimide is 20 available for balloon catheter c~
Although many of the procedures employing balloon catheters are still in the ~ 1 stage in the United States, there is a ' ' ' amount of art available on the formation and use of balloon catheters.
Tll~-c~r~inn~ of such art are: U.S. Patent Nos. 4,952,357 to Euteneuer;
25 4,413,989 and 4,456,000 to Scyeldahl et al. and 4,490,421 as well as Reissue Patent Nos. 32,983 and 33,561 to Levy.
The Euteneuer patent relates to the prior art polyimide aLII.. l/l,dlloon Cu~.lu~,Lill. The Schjeldahl patents, illCol~l ~ herein by reference, pertam to catheter assemblies or ' These patents

2 1 79744

-3-disclose expanders (balloons) formed from a thin, flexible, inelastic, high tensile strength, biaxially oriented, synthetic plastic material. The Levy patents, which issued several years after the Schjeldahl patents, sought to provide balloons exhibiting physical properties superior to those exhibited by 5 prior art balloons. The specific qualities Levy ~ ."~ were toughness, flexibility and tensile strength. Levy teaches that a high tensile strength balloon can only be formed from a high intrinsic viscosity polymer, specifically, high molecular weight ~ul~ yl~
High tensile strengths are important in ~u~ iu~ Ly balloons lO because they allow for the use of high pressure in a balloon having a relatively small wall thickness. High pressure is often needed to treat some forms of stenosis. Small wall Ll~iuhl~ enable the deflated balloon to remain narrow, making it easier to advance the balloon through the arterial system.
15 ~llmm~ry of the Invention It is the primary purpose of this invention to apply Ih.. ,1,~
polyimide to the art of balloon catheter l,ullDLlu~,Liull, i.e., to catheter shafts and balloons. It is another purpose of this invention to apply ~
polyimide to the art of guide catheter Cu~.lu~,LiOI~ and infusion catheter 20 uul~LIul,~il~. Such catheter ~ ;-- may be either integral or unitary in which the shaft or a portion thereof and balloon are, --...r~ ;d as a single unit or the ~ , may be comprised of a separate shaft to which a balloon is attached, as by adhesive or other bonding.
25 Brief Descril~tion of the Drawin~s A detailed ti,.crrir~inn of the inventlon is hereafter described with specific reference being made to the drawings in which:
FIG. 1 is a schematic; somewhat idealized view of a balloon catheter using ~h- """~,l _lj, polyimide according to the invention in both shaft WO 95/18(i.17 2 ~ 7 9 7 ~ 4 PCTIUS9.J/1~970

4-and balloon portions.
FIG. 2 is a partial sectional view of the distal portion of the catheter shown comprising a lonoi~ lin~ll cross-sectional view of the balloon ofFIG. 1.
FIGS. 3 and 4 are enlarged cross-sectional views of portions of a wall of a balloon having a plurality of layers forming the wall i.e., a composite of thermoset and ~ polyimide.
FIG. 5 is a front view, with portions broken away, showing a shaft of the catheter of FIG. 1 which is a polyimide shaft with braided 10 ~ rOl~
FIG. 6 is a cross-sectional view of the shaft of FIG. 5 taken on line 6-6 of FIG. 5;
FIG. 7A is a cross-sectional view of a shaft according to the present invention, wherein the shaft has a l~ Ivl~-,ul~llL at its innermost 15 diameter and a polyimide coating over the .rvl~ ... structure;
FIG. 7B is a cross-sectional view of a shaft according to the present invention comprising a ll- "",l,~ polyimide material ~UllUUll.IUlg a reinforcement material;
FIG. 8 is a cross-sectional view of a shaft according to the 20 present invention, wherein the shaft has a ll r ' material embedded in the outermost diameter of the polyimide substrate;
FIG. 9 is a cross-sectional view of a shaft accordmg to the present invention, wherein the shaft has a l-;.~vl~ material at its innermost diameter with polyimide coating the l~,.. fvll structure;
FIG. 10 is a cross-sectional view of a shaft according to the present invention, wherein the shaft is formed from a blend of polyimide and a l~;~Vl~UI~ material;
FIG. 11 is a cross-sectional view of a shaft accordmg to the present invention, wherem the shaft is formed of a lluulu~olyul.. at the inner ~1 7q7 44 WO 951186~7 PCT/IJS9-1114970 -_5 _ diameter, a layer of polyimide ~UIIUUIIdill~ the lluolu~olylll~l layer and a ulru~ ll material bonded to or embedded in the polyimide layer;
FIG 12 is a cross-sectional view of a shaft accordmg to the present invention, wherein said shaft is formed of a polyimide inner layer, an S i..~llll ' lc;llfulciulg material and an outer polyimide layer;
FIG 13 is a cross-sectional view of a shaft according to the present invention, wherein said shaft is formed from a coextruded shaft having a polyimide/liquid crystal polymer blend ~Ull~ , its inner diameter and polyimide ~UIIUUII~ !, its outer diarneter;
FIG. 14 is a cross-sectional view of a shaft according to the present invention, wherein said shaft is forrned from a coextruded shaft having a polyimide/liquid crystal polymer blend bulluull~il.g its outer diameter and polyimide ~ulluu.lliul~ its inner diameter;
FIG. 15 is a cross-sectional view of a shaft accordmg to the 15 present invention having an inner layer of pol~ uc,lu~.Li.jlc.l., ~UII~ ' ' by an outer layer cr~mrnci~ Ih~ polyimide or a ll .
polyimide blend;
FIG 16 is a cross-sectional view of a shaft according to the present invention ( . ~ inner and outer layers of polyimide ~u~u~
20 an Iayer comprismg a blend; and FIG. 17 is a partial sectional view of the shaft of a catheter according to the present invention.
Description of the Preferred F..,.l.o.l;"....~
The invention lies m a high strength, thin walled, balloon, and irl some instances the catheter shaft or portions thereof, formed from a l,. ."...~ ;. polyimide. The invention also ~ the process for . - ,.. . r., I ."; "~ such a balloon and/or catheter shaft, and could also be utilized m the production and r C of g~ude catheters or infusion catheters.

WO 951186~7 PCTIUS9-1/1 1970 ' ~ 7~44 A balloon of this invention is preferably obtained by extruding polyimide tubing and then expanding the extluded tubing axially and radially. Any ~oll..,-..iullal extruder may be employed to perform the extrusion process.
S Figure 1 shows a schematic view of a balloon catheter, shown generally at 10. Catheter 10 has an elongated flexible shaft 12 which according to the invention, may at least in parL, be comprised of Ih. . ,~ ic polyimide. That is, the entire length thereof may consist of ll,. """~
polyimide or a l~ l;l-AI section or sections thereof may consist of lO ~ polyimide or it may be entirely of another material with only the balloon bemg of Ih ""~ polyimide. Since it is ~ at least in part, shaft 12 may be formed by tubular extrusion as is the case of the techniques known in this art for extruding other Ih- ~ `l;c materials such as the PET arul.-.-- ;-~... ~i and as already described k.,l~,kl~u.~,. In a preferred 15 ~lllbo~ . of the present invention, !h- ~ polyimide is present in both shaft and balloon portions.
Mounted at the distal end of catheter 10, shown in the lower portion of Figure 1, which is enlarged to show detail, shaft 12 is fltted with an inflatable thin wall balloon generally designated at 14 (shown rnflated).
2 Depending on the particular Cu-l~llu~Liuu of the catheter, the distal tip 16 may be the distal end of a guide wire as shown or it may be the distal end of the catheter per se.
Shaft 12 has at least one lumen (not shown) extendulg from its proximal to its distal erld. Dependmg on its ~U~.I,,-,Liull, multiple lumens may25 be provided. In any case, at least an rnflation lumen extends through shaft 12 for selective rnflation and deflation of balloon 14. Any or all of the lumens may be made from ~l.. . ~-- ,l,l ~l;, polyimide.
Balloon 14 is a thin wall ~ ;, polyimide balloon formed in the art known malmer by blow moldirlg as described above. This technique 21 7q7~4 WO95fl8617 PCTIUS9S114970 is also discussed in the ~rO~ United States Patent 4,490,421 for forming PET balloons. As seen in Figure 1, a balloon in one ~ l comprises a proximal waist portion 18 bonded to the distal end of shaft 12, an il.'~Ll~ " ' inflatable body portion 20 of a larger diameter than waist 18, and

5 a smaller distal end portion 22.
Tl,. ~ polyimide is a linear aromatic polyimide frrst developed by NASA and described in NASA Con~ Pub. #2334 (1984) at pp.
337-355, entitled THERMOPLASTIC/MELT-PROCESSABLE POLYIMIDES, authored by T.L. St. Clair and H.D. Burks.

WO 9!i/186.17 PCT/US9~/14970 ~ 1 797~

The st~uctural formula is shown as follows:
--N~O,,~N~
-m Also shown in that reference is a polyimide sulfone:
1l and is a poly~,ll~...yl,.llc rlh. .~..lrj~ ,;.lr N~of~
Any of the above examples of polyimides may be used according to this invention.
One such ~ polyimide is available commercially under the tradename AURUMD from Mitsui Toatsu Chemicals, Inc., of Tokyo, SU~STlTLlrE SHEET ~RULE 26~

6-17 PCTfUS94fl4970 2 1 ~9744 g Japan. It is the ~ ""L'~ ;' polyimide resin which is described in detail in United States Patent 5,069,848 issued December 3, 1991 and European Patent Application 0,391,633 and is shown as having the following structural formula:
o \, ~ ~LX~
o o wherein X is a single bond or a ll~,AdnUuluisu~.u~lid~.lc group, the foregoing references being ill~UllJU ' ' herein in their entirety by reference.
Tl~ polyimide, as used herein, refers to any polyimide polymer which is Ic,ulu~c,aabl~, i.e., the polymer can be heated to a J.ldLu.c at which it is soft enough to be Ic,UlU~ac~ or extruded but at which ~ r. it will not decompose to any d,u~Jlc~ibl~ degree.
Thermoset polyimide, by contrast cammot be lc,ulu~"a~,d or reextruded after it has been formed due to the fact that the material crosslinks or forms chemical bonds as the material is being formed.
Applicants have found that the Ih ~ l;r polyimide, when formed into a balloon by stretching and blowing, exhibits amorphous or only slightly crystallized (up to 10%~ behavior.
The extruded ~ l; polyimide tubing for use in making balloons according to this invention can be formed with wall 11. ~ as low as on the order of .001 to .015 inches which can readily be used for forming balloons by blow molding with wall thicknesses on the order of .0003" to .003" inches.
The present invention has several important ad~ ~ First, ll....",l,l l;, polyimide balloons offer thin walls but have a high burst pressure, up to 16 dLIllua~ ca and even higher, up to 20 dLIllua~h~lca.
Tl.. l.~-~li. polyimide shafts are readily extrudable. Tl .
S~IBSTITWE SHEET (RULE 26) Wo 95/186~7 PcTmss~ s70 polyirnide dccull.pu..~ at a L~ p~.~Lulc range above about 400410C. The softening L~lllp.,laLulc of ~ polyimide is about 320-380C, and the melting Lclll~ Lulc is about 340410C. The physical properLies of ;, polyimide offer the U~pUl~Ulliiy of secondary forming operations.
5 For example, the material as exhuded tubing can be reheated and a balloon can be blown out of it. Tl.- ,-1-~ ;, can be remelted. Scrap can be ground up and run through an exh~uder again. Thermoset polyimide cross links upon curmg, which precludes the possibility of remelting for reuse or recycling.
There is a tendency for the frachure mode upon failure of prior 10 art thermoset polyimide balloons to be more of a c.lL~Llu~ frachlre rather than the preferred Inngih~lin~l burst mode of ~ li, polyimide balloons of the invention. For this reason, an alternate, ' ' of the invention with respect to balloon uu..~..lu.liull may comprise a multiple layer balloon ofthe type shown in Figures 2 - 4. This balloon generally designated 30 is 15 comprised of a blow molded balloon of ~1. ..nr.~ polyimide having a deposited outer layer 34 of prior art thermoset polyimide, polyamide, or any other material laid down in tbe known manner on the inflated Ih- ""~
polyimide 32 of tbe ballon. Such ,, provides a balloon having ~/ICdUlLlil.al.;ly ll~n~ihl~lin~l burst .1,~ This ~,1"~.1; : also offers 20 one the UIJpUllUlliLy of tailoring the ~ of tbe balloon by selectively altering the number, -- "~ and tbickness of these layers in a variety of ....r;~,. ,~;....~ Moreover, the ll. "",~ l;, polyimide balloons of the invention may have no outer layer at all or they may carry a single outer layer or multiple outer layers (full or partial) of exhuded Ih. . .", .1.1 -~I ;.
25 polyimide or other polymer materials for layer 34.
Irl "- .r,.. i-";,~ tbe balloons of the invention, techniques and tools utilized in the prior art for 11, ~ balloons are readily adaptable.
CnnciAl~rinF all of the foregoing, Ih "....I,I-~Ii. polyimide balloons may be readily r ~d which have, for example, diameters of WO 95/186~7 2 ~ 7 9 7 4 4 PCT/VS9 1/14970 about 1.5 - 25mm, lengths of about 5 - 200mm, wall Lll;.hl.Dacb of about 0.0003 - 0.003 inches and to any of tbe typical ranges for balloon rljm~onci~nc and strengths as typically utilized in the medical industry heretofore. The minimum length is from about Smm to about 10mm, and the most preferred 5 length is about 20mm in length.
EXTRUSION OF THERMOPLASTIC POLYIMIDE
The drying and extrusion equipment must be thoroughly clean and dry to reduce possibility of material It is important to ~ufr~, ;..lLIy pre-dry the resin prior to extrusion to prevent creation of surface 10 defects caused by moisture. The resin can be dried by a desiccant type hot air dryer using 40F dew point air in a plenum style hopper. The moisture content of the polyimide is controlled to less than 100ppm by varying both drying ~...~ dlUlC and time. Polyimide resin dried at a b,ll")~a~ulc of 180C
m excess of 10 hours proYides desired moisture levels. An extruder with a 15 length to diameter ratio of about 25:1 and a minimum of three barrel t~ lLulc control zones with additional heater control zones for adapter, head and die is adequate. T~ , c controllers are ~IIU~)UIi' ' ,, type in order to maintain tight L.,..A,.l~Lulc control and a l~ ,. v--- melt. Both barrel and screw of the extruder are made of ~uu~, " ' bimetallic material 20 that is surface hardened and chrome plated. Cul~ iu.~l nitride metals tend to degrade by oxidation which causes the generation of black rust at high ,,,. A preferred screw fr the extruder is a Barrior design having a length to diameter ratio of from 18 to 28:1 and a UUIIIAJI~ ' ratio of 2.7:1 with a zone ~ - ';.. of about 25% feed, 46% . A CDDiUU, and 30%
25 metering. GeneMI purpose screw with 2.5 to 3.5:1 UU..I~lCDD;Ull ratios and a relatively constant transition from feed to metering zone have also worked effectively. 8reaker plate, adapter, head, and tooling are hard chrome plated and bLIc ' 1, i.e., gradual transitions, rounded edges and minimal ,l~ l ;- . .~ Screen packs with a micron rating of 40 to 80 mesh having wo 951186~7 Pcr~ss-s/l~97(~ --stainless steel gauge .Vl~LIu.~i.~ are generally sufficient to generate adequate back pressure. Die and tip cross-sectional area drawdown ratios (which is the area defined by the die and mandrel divided by the cross-sectional area of the extruded tubing) can range from 3 to 30:1~ and die land lengths range from 10 5 to 60 times the desired product wall thickness. Sizmg can be ~. ~-. l,l,` h ~i by free extrusion methods, ~ constdnt nivrogen pressure inside the tubing while being quenched in a ~u~ iu~l~d water bath at ambient t~ u....
The pre-dried Ih- .111111.l --l;l polyimide pellets are preferably 10 delivered to the feed throat of an exv~uder from a plenum style/hopper, and conveyed forward through several heating zones by rotating the extruder screw. Melt ~,III,U.,I...~...C of the polyimide is maintained from 340C to 410C
by vhe various zone l~,llI,U~ldiUlC convrollers, and by shear generated from theaction of a 3/4 or 1 1/4 inch diameter screw rotating at speeds rangitlg from 2 15 to 50 RPM. The material vhen passes through a screen pack, breaker plate, adapter, tooling head, and extrusion tooling where it is shaped to form the desired product. Oplimally, the residence time in the extruder is kept to a minimum. Once the material exits the tooling in its desired form, it needs to be cooled. One way to perform the cooling process is to pass the extruded 20 tubing from the extruder, through an air gap between tooling and quench tank ranging from 0.25 to 25 inches, and into a water bath maintained at a t.lll~ ,.C ranging from 40F to 120F. A haul-off may be used to pull the tube from the cooled end through the quench tank. Thereafter, the product is spooled or cut to length as desired.
BALLOON FORMING WITH THERMOPLASTIC POLYIMIDE
Some minimal initial orientation of polyimide material is a..u uvli ,l,~ as the material is drawn down during extrusion. This orientation process is typically known as machine orientation and is formed in the WO 95/186~7 2 1 7 9 7 4 ~ PCTlUS9~i/l i970 - direction of extrusion operation. A small amount of additional l.. ,~il.. ,l;.,~l orientation occurs durimg balloon formation. This additional orientation is the result of the material elongation at blow molding t lul~,lalulcD, and is caused by the weight of the balloon mold shretching the hubing downward at a ratio of 5 1.1 to 3:1 at molding ~ .~ Lulc~ ranging from 230C to 330C. The preferred ll~n~ih~linsil stretch time at molding L~ ulc, is from 8 to 10 minutes.
Method iUll,UlU._lll~.lli~ to optimize stretching and heating will probably reduce stretch times. Once the optimum l..~ stretch is achieved, the tubing is expanded radially using mternal pressures ranging from 3 to 100 psig.
10 ~owever, the preferred pressure is 20 to 50 psig. This is dCCulll~ by providing a ~Ic~uli~ fluid or gas, preferably nihrogen gas, to the inner lumen of hubing. Tubing extends outside both ends of the mold, one end is clamped off such that no gas can flow through it, and the opposite end is ~/IC~IlliL.~.d to form the balloon. An i~J~IU. ' ' mold with the tubing inside, 15 may be heated while pressure is applied. The preferred molding ~cll.~ Lulc ranges from 260C to 300C. The ~iinm ncirmc to which it is stretched are preferably controlled by ~ the radial shretching while the tubing is in a mold having the shape of the desired balloon. Suitdble molds are known in the art. The tubing subjected to specific interior pressures and exterior heat is 20 held sLationary for a period of time, preferably 4 to 6 minutes, while the balloon and waist portions yield completely and stabilize. Method ~..,JIU._III.,IIL~ to optimize balloon mold heating will probably result in reduced heat soak cycles. The radial expansion, or hoop ratio (calculated by dividing the inner diameter of the balloon by the inner diameter of the exhuded tubing), 25 should be in the range of 3 to 8:1. The preferred hoop ratio is ~-~U~II. 1~, 5:1. The hubing, now comprising the balloon, is next cooled. One way to cool the balloon is to remove the mold from the heat chamber and place it in a coolmg bath. The cooling bath is preferably maintained at ambient tClllp~ UlC. The balloon may for example, remain m the cooling bath for WO9S/186.17 2 1 ~9j~4 PCT/US9~ 970 d~Upll ' ' '~/ 10 seconds. However, a chilled bath can be used to reduce the quench cycle times. Finally, the ends of the tubing extending from the mold are cut off (unless integral catheter shaft/balloon ~UIL~LLU-,LiUII is intended~ and the balloon is removed from the mold by removing either the distal or 5 p}oximal end from the body section of the mold, then gently pulling the balloon from the remaining mold sections.
As already indicated, for any given catheter .,..,~;.,.. lil"., the entire shaft 12 could be polyester, poly.,LIIyl~ , thermoset polyimide or anything else known in the art. The Ih ~ polyimide balloon would be 10 bonded to such a shaft. On the other hand, the balloon may be integral with the shaft or a portion thereof to provide an all LLI~ IIULJI~L;~ polyimide ~UILIILLU~LiUII.
The shaft may be composed of a blend of materials. The entire shaft or a portion thereof may be coextLuded. For example, a shaft may 15 include a layer of ~ul.~t~, L~Lnuulu~Lll~lu~l~ (PTFE) surrounded by ' , ' polyimide or a blend of ~ IJ~ polyimide and other polymeric and/or fulw~lL~ r ' Such a blend may comprise PTFE or carbon and Il,. "",1,l ~l;, polyimide. Examples of such blends includes up to about 10%
PTFE or about 15 % carbon and a balance of 11.. .,,,,,1,l l;, polyimide.
Another blend may include liquid crystal polymer, radiopaque materials such as bismuth salts, tungsten or titanium, silver or gold (which would impalt ~ull~iviLy to the blend). A shaft according to the present invention may imclude immer and outer layers of Ih- - ~ polyimide ~ULII ' ~ an - - ' Iayer comprising a blend as described above.
The shaft and/or balloon may be reinforced. The 1~ - r ~llI~,llL
material may comprise various types of continuous or .,.,~ .; reinforcing used in tbe composites of this invention. Among such suitable materials are continuous fiber or filament forms such as polyester, polyamide or carbon fiber, and further may be sphere and particulate forms such as glass.

WO95/186~7 2 1 79744 PCT/US9-1~14970 - Reinforcing material may comprise glass, carbon, ceramic, fluoropolymer, graphite, liquid crystal polymers, polyester, polyamide, stainless steel, titanium and other metals such as nitinol, or radiopaque materials (such as Bismuth or Tungsten) and the like.
S The continuous ".. lru~ may be used in filamentary form or it may be employed in the form of a yarn or as a fabric of plain weave, satin weave, twill weave, basket weave, braid, winding or the like. The composite structure may comprise parallel aligned contmuous filaments extending within or along the inner or outermost dimension of the structure, l the fibers being bonded together with the above-described ~
polyimide which intimately contacts substantially the whole of the surfaces of the filaments.
Figures 5 - 6 illustrate an alternative .. I.o,li.. 1 of the shaft, shown generally at 12 of Figure 5. Shah 12 has a continuous 1l :.. r.. 1 in 15 the form of a tubular braid 52 formed of individual strands 5. Polyimide material 54 encases tubular braid 52 on both the inner and outer surfaces of braid 52. Braid 52 is shown centered in polyimide material 54.
Figure 7A illustrates an alternative ' of the shaft of the present imvention, wherein shaft 12 has a ICi. ~UL~ at its innermost 20 diameter and a polyiinide coating over the .c;~ structure. Although a braided l~ `UI~.,Il~.l~ is shown, any continuous or .. :..r...~
as described herein may be employed. For example, Figure 7B shows a Ih. ~ polyimide material 54 , _ IC material 56 a rnaterial such as polyester, polyamide malleable metal or plastic.
Figure 8 illustrates a further alternative of the shaft of the present invention, wherein shaft 12 has a l~h.ful~ ~uL material 5
embedded near the outermost diameter of 1l~ polyimide substrate 54.
Again, although a braided 1. r ~ material is shown, any .~:....,.........
as described herein may be employed.

WO 951186~7 2 1 7 9 7 4 4 -16- PCTIIIS9~/1.1970 Figure 9-15 illustrate still further ~,.,1.~1;",. .,1~ of the shaft of the present invention. Figure 9 shows shaft 12 having l.,hlru~ .llL material 5 at the ilmermost diameter of 1~ ;( polyimide material 54.
lUI~ ... structure S is coated by polyimide material 54, but is almost 5 exposed.
Figure 10 shows a shaft formed from a blend of polyimide and a ICilll'UI~ material. The l.,.. li`Ul~,.. l~.. i material as shown is in .1;~.. ,.1;.. , form, i.e. dispersed parliculate such as glass spheres 60 embedded throughout polyimide material 54. Blends as described 11.,l~ ',uve may be 10 employed, as may carbon fibers as also described above.
Figure 11 shows shaft 12 formed of an ilmer layer 62 of a l1UUIU~JOI~ a layer of polyimide material 54 ~UII~ " ,, inner layer 62 and a l~hlrul~ .,IlL material 50 as described ll~ dbu..~ bonded to or embedded in polyimide material 54. Figure 11 is also an example of a cross 15 section of a guide catheter accordmg to the present invention. By vaqing diameter, length and flexibility of the shafts described herein, various medicaldevices including infusion catheters and guide catheters can be produced.
Figure 12 shows shaft 12 formed of polyimide inner layer 68, '- ' IC;.lfUI~ material 70 as described h~.,~bu.~" and an outer 20 polyimide layer 72. Fig;ure 13 shows shaft 12 having layer 74 comprising a polyimide/liquid crystal polymer blend layer, surrounded by a layer of polyimide 76. An alternative ~....r;~"...";,,.. wherein polyimide/liquid crystalpolymer blend layer 74' surrounds polyimide layer 76' is shown at Figure 14.
Liquid crystal polymers are known to the art. Liquid crystal 25 polymers are rigid, rod-like III~I~IUII101~ ,. which typically contain a substantial number of polyvalent aromatic groups such as phenylene. After alignment or orientation by shear or ~ d forces, the steric hindrance of molecular rotation provided by the polyvalent or other groups causes the liquid crystal polymers to retain their orientation to effect hardening. Examples of WO 95/186.S7 2 1 7~ 7 4 4 PCT/US9~ 970 - liquid crystal polymers are VECTRA sold by Hoechst-Celanese, or HX
materials sold by DuPont, XYDAR and Econol (t~ olylll.l of llydlu~.yl/~ iu acid, biphenol and terephthalic acid) from Dartco and Sumitomo Chemical, Ica~ ,ly, Vecrora from Polyplastic, and Ueno (terpolymer of 2-oxy-6-5 naphthoic acid, biphenol, and t~lc~ alic acid) from Ueno Seiyaku, and any other polymer material having a rod like molecule which imparts a tendency to align more readily during melt flow than flexible chain polymers The ~ .I.o.l;,., -l of shaft 12 shown at Figure 15 includes an inner layer 80 of polyleLlallu~ lly~ (PTFE) aUII~ ' ~ by an outer layer 10 82 of LII~IIIIuL,l~aLi., polyimide. Outer layer 82 may alternatively be comprised of a blend of ~ ;, polyimide and other ~ as described ll~,l~,u~bove. A still further ~ l ' of shaft 12 according to the present invention as shown at Figure 16 may include inner and outer layers 86,88 of Il....",.I,!-~;;, polyimide aUII~ ~' ,, an illi'~,l ' layer 90, . ~ a 15 blend as described above.
A still further ~...,1.~.1' -,. .: of shaft 12 is shown at Figure 17, where a wire winding type reinforcmg material 92 is used within the polyimide to reinforce polyimide material 54.
While this invention may be embodied m many different forms, 20 there are shown in the drawings and described in detail herein specific preferred .. ,1"),1;,.. 1~ of the invention. The present disclosure is an . "~ of the principles of the invention and is not intended to limit the mvention to the particular . ' ' illustrated.
This invention has been carefully described herein in order to 25 provide those skilled in the art with the j"c~"", ;"" necessary to perform the requisite process and obtain the desired product. However, it is to be understood that the invention can be carried out by different techniques and a variety of equipment. Therefore, various known ,..-,I;r,. -~;"i-~ both as to equipment details and operating procedures, may be illUUI~ without 2~ 79744 departing from the scope of the invention itself.
This completes the description of the preferred and alternate . ..,I.o ~ of the invention. Those skilled in the art may recogni~e other equivalents to the specific rll.l,.~l; . ..: described herein which equivalents are S intended to be ~ d by the claims attached hereto.

Classifications
International ClassificationA61M25/00, A61L29/00, A61M29/02
Cooperative ClassificationA61M2025/1075, A61M25/104, A61M25/1036, A61M25/0009, A61M25/005, A61M25/0045, A61M25/1029
European ClassificationA61M25/10G1, A61M25/10G3, A61M25/00S1
Legal Events
DateCodeEventDescription
27 Dec 2002FZDEDead