U.S. patent application number 13/937856 was filed with the patent office on 2013-11-07 for high performance balloon catheter/component.
The applicant listed for this patent is Boston Scientific Scimed, Inc.. Invention is credited to John J. Chen, Daniel J. Horn, Jeffrey S. Lindquist, David Meister, Irina Nazarova, Scott R. Schewe.
Application Number | 20130292043 13/937856 |
Document ID | / |
Family ID | 34979126 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130292043 |
Kind Code |
A1 |
Schewe; Scott R. ; et
al. |
November 7, 2013 |
HIGH PERFORMANCE BALLOON CATHETER/COMPONENT
Abstract
Composite fiber reinforced balloons for medical devices prepared
by applying a web of fibers to the exterior of a preformed
underlying balloon and encasing the web with a matrix material to
form a composite balloon. The fiber web is applied to at least the
cone portion of the underlying balloon form. Either the cone
portion of the underlying balloon form, or the web fibers applied
to said cone portion, or both, have a friction-enhancing material
coated thereon.
Inventors: |
Schewe; Scott R.; (Eden
Prairie, MN) ; Lindquist; Jeffrey S.; (Maple Grove,
MN) ; Meister; David; (Madison, WI) ; Chen;
John J.; (Plymouth, MN) ; Horn; Daniel J.;
(Shoreview, MN) ; Nazarova; Irina; (Woodbury,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boston Scientific Scimed, Inc. |
Maple Grove |
MN |
US |
|
|
Family ID: |
34979126 |
Appl. No.: |
13/937856 |
Filed: |
July 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12637490 |
Dec 14, 2009 |
8481139 |
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13937856 |
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|
10889574 |
Jul 7, 2004 |
7635510 |
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12637490 |
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Current U.S.
Class: |
156/213 |
Current CPC
Class: |
Y10T 428/1362 20150115;
Y10T 428/1369 20150115; Y10T 428/1359 20150115; Y10T 428/139
20150115; Y10T 156/103 20150115; Y10T 428/1352 20150115; Y10T
428/1303 20150115; A61M 25/1029 20130101; Y10T 428/13 20150115;
A61L 29/126 20130101 |
Class at
Publication: |
156/213 |
International
Class: |
A61M 25/10 20060101
A61M025/10 |
Claims
1. A method for preparing composite fiber reinforced balloons for
medical devices, the method comprising: applying a web of fibers to
the exterior of a preformed underlying balloon layer having a cone
portion having a varying diameter along the length of said cone
portion; and encasing the web with a matrix material to form a
composite balloon, wherein in said applying step, the fiber web is
applied to at least the cone portion of the underlying balloon
form, and prior to the applying step, coating a friction-enhancing
material is coated onto at least a cone portion of the underlying
balloon form, or onto the web fibers to be applied to a cone
portion, or onto both.
2. A method as in claim 1 wherein the friction-enhancing material
is an elastomeric polymer.
3. A method as in claim 1 wherein the friction-enhancing material
is a polymer having a coefficient of friction of about 0.7 or
more.
4. A method as in claim 1 wherein the friction-enhancing material
is an adhesive having at least some surface tack at the time the
fibers are applied to the underlying balloon.
5. A method as in claim 4 wherein the adhesive is set to form a
stronger bond at a time subsequent to applying the fibers to the
underlying balloon.
6. A method as in claim 1 further comprising preparing the
underlying balloon layer by a process comprising radially expanding
a tubular parison of polymeric material comprising a crystallizable
polymer.
7. A method as in claim 1 wherein said web is applied by forming a
roving, mesh, weave, braid, helical winding or knit on the
underlying balloon.
8. A method as in claim 7 wherein the size of the fibers is in the
range of from about 10 to about 100 denier.
9. A method as in claim 1 wherein the fiber material is selected
from the group consisting of aramid, ultrahigh molecular weight
polyolefin, liquid crystal polymer and mixtures thereof.
10. A method as in claim 1 wherein the underlying balloon is
inflated under pressure while the web fibers are applied
thereto.
11. A method as in claim 1 wherein the underlying balloon layer
comprises a polymer selected from the group consisting of
polyurethanes; polyesters and copolyesters; polycarbonates;
polyamide/polyether block copolymers; polyester/polyether segmented
block copolymers; silicone-polycarbonate copolymers; polyamides;
thermoplastic polyimides; polyacetal; liquid crystal polymers,
polyetheretherketone; polyether sulfone; and combinations
thereof
12. A method as in claim 1 wherein the matrix material is an
elastomeric polymer.
13. A method for preparing composite fiber reinforced balloons for
medical devices, the method comprising: applying a web of fibers to
the exterior of a preformed underlying balloon layer; and encasing
the web with a matrix material to form a composite balloon, wherein
prior to said applying step an adhesive is applied to at least a
portion of the underlying balloon layer, or to the web fibers
applied to said portion of the underlying balloon layer, or to
both, so that an adhesive bond is formed at least between the
underlying balloon layer and the web fibers applied to said portion
of the underlying balloon layer.
14. A method as in claim 13 wherein the adhesive is applied to
substantially the entire exterior of the underlying balloon
layer.
15. A method as in claim 14 wherein the adhesive is tacky at the
time of applying the fiber web and subsequently sets to form a
stronger bond.
16. A method as in claim 13 further comprising radially expanding a
tubular parison of polymeric material comprising crystallizable
polymer to form said underlying balloon layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of copending U.S. patent
application Ser. No. 12/637,490 filed Dec. 14, 2009, issued as U.S.
Pat. No. 8,481,139 on Jul. 9, 2013, which is a continuation of
copending U.S. patent application Ser. No. 10/889,574 filed Jul. 7,
2004, issued as U.S. Pat. No. 7,635,510 on Dec. 22, 2009, the
entire content of which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] Medical devices comprising catheter shafts and catheter
balloons are used in an increasingly widening variety of
applications including vascular dilatation, stent delivery, drug
delivery, delivery and operation of sensors and surgical devices
such as blades, and the like. The desired physical property profile
for the balloons used in these devices varies according to the
specific application, but for many applications a high strength
robust balloon is necessary and good softness and trackability
properties are highly desirable.
[0003] Commercial high strength balloons having wall strengths in
excess of 20,000 psi have been formed of a wide variety of
polymeric materials, including PET, nylons, polyurethanes and
various block copolymer thermoplastic elastomers. U.S. Pat. No.
4,490,421 Levy, and U.S. Pat. No. 5,264,260, Saab, describe PET
balloons. U.S. Pat. No. 4,906,244, Pinchuk et al, and U.S. Pat. No.
5,328,468, Kaneko, describe polyamide balloons. U.S. Pat. No.
4,950,239, Gahara, and U.S. Pat. No. 5,500,180, Anderson et al
describe balloons made from polyurethane block copolymers. U.S.
Pat. No. 5,556,383, Wang et al, and U.S. Pat. No. 6,146,356, Wang
et al, describe balloons made from polyether-block-amide copolymers
and polyester-block-ether copolymers. U.S. Pat. No. 6,270,522,
Simhambhatla, et al, describes balloons made from
polyester-block-ether copolymers of high flexural modulus. U.S.
Pat. No. 5,344,400, Kaneko, describes balloons made from
polyarylene sulfide. U.S. Pat. No. 5,833,657, Reinhart et al,
describes balloons having a layer of polyetheretherketone. All of
these balloons are produced from extruded tubing of the polymeric
material by a blow-forming radial expansion process. U.S. Pat. No.
5,250,069, Nobuyoshi et al, U.S. Pat. No. 5,797,877, Hamilton et
al, and U.S. Pat. No. 5,270,086, Hamlin, describe still further
materials which may be used to make such balloons.
[0004] A particular application which has a very high pressure
requirement is reopening of stenoses which develop at or in
long-term shunt, ports or grafts employed for repeated blood
access, for instance with dialysis patients. Such stenoses are
often highly calcified and essentially must be subjected to very
high pressure for successful treatment. Moreover, frequently the
vessels into which the access devices are connected are quite
large. Consequently there is a need for balloons whose pressure
profile allows for use of pressures in excess of 20 atm at balloon
diameters which can exceed 5 mm.
[0005] Fiber reinforced balloons have been known for use in
angioplasty and similar applications. U.S. Pat. No. 4,896,669,
Behate, U.S. Pat. No. 4,706,670, Andersen, U.S. Pat. No. 5,647,848,
Jorgensen, all show balloons formed with a fiber web reinforcement,
but the rest condition of the balloon is straight. In some cases
the balloon is a portion of the catheter tube in which a web
pattern such as a braid has been modified to allow for elastic
radial expansion to a diameter determined by the angle of the fiber
reinforcements. The web is encased in an elastomeric polymer
material.
[0006] U.S. Pat. No. 5,201,706, and U.S. Pat. No. 5,330,429,
Noguchi, describe a laminate balloon which uses a release agent
between a web layer and an inner layer of the balloon
structure.
[0007] U.S. Pat. No. 5,827,289, Reiley, shows a mesh 170 "embedded
or laminated and/or winding" used to form a neck on the balloon and
a second mesh 170a used to form a tapered base.
[0008] As understood, the mesh conforms the underlying balloon to
the mesh shape, rather than conforming the mesh to a tapered
section of a balloon.
[0009] U.S. Pat. No. 6,156,254, Andrews, shows a balloon formed by
braiding fiber onto an unoriented tube and encasing the braid in
same material; longitudinally stretching the braided tube onto a
rod of smaller diameter; heating the tube ends, but not the
middle;
[0010] and then releasing the stretch force so the center recovers
to formed diameter but the ends remain at the stretched diameter.
The patent states that the fibers should be bonded to the wall
material so that they do not move or slide significantly with
respect to the wall material. Soft wall materials are described as
balloon materials: polyurethane, SBS block copolymer,
butadiene-acrylonitrile block copolymer. As an alternative, the
inner tube layer may be PET or PVC, while the outer encasement
material is polyurethane. In an alternative method of making the
balloon, a polyurethane film is cast from dispersion onto an
inflatable balloon form, the fiber braid is applied to the film
layer and an outer layer of polyurethane is applied. The balloon is
removed from the form by deflating the form.
SUMMARY OF THE INVENTION
[0011] The invention pertains to fiber reinforced laminate
composite balloons and processes for preparing laminate composite
balloons. In one such aspect, the balloon comprises a polymer
material underlayer, an overlying fiber web/matrix material
composite, wherein the fiber web material has a friction-enhancing
material interposed at least between the underlayer and the fibers
immediately adjacent thereto over a portion of the balloon that has
a varying diameter. In another aspect, the balloon has an
underlayer of a biaxially oriented polymer adheringly bonded to an
overlying fiber web/matrix material composite. In yet another
aspect, the balloon has an underlayer of a crosslinked polymer and
an overlying fiber web/matrix material composite.
[0012] In some aspects the invention pertains to manufacturing
processes for preparing composite fiber reinforced balloons by
applying a web of fiber material to the exterior of a preformed
underlayer balloon and encasing the web with a matrix material to
form a composite balloon. In one such aspect, the invention
pertains specifically to the step of applying a fiber web to a cone
portion of an underlying balloon form. Either the underlying
balloon form, or the web fibers applied to the cone portion, or
both, have a friction-enhancing material applied thereto to reduce
fiber slippage as it is applied to the cone portion. The friction
reducing material may be a polymer coating or an adhesive.
[0013] In another such aspect, the invention pertains to a
manufacturing method wherein the material of the polymeric balloon
form, the fiber material and the matrix materials are mutually
bonded to form a laminate composite balloon.
[0014] A still further aspect is a medical balloon comprising a
styrene-isobutylene-styrene (SIBS) block copolymer, especially such
a balloon which further comprises a reinforcing fiber web.
[0015] These and other aspects of the invention are described in
greater detail in the following detailed description, drawings and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic side view of an underlayer balloon
with a partial cutaway.
[0017] FIG. 2 is an enlarged cutaway view taken at line 2 of FIG.
1.
[0018] FIGS. 3-5 are views as in FIG. 2 illustrating steps of an
embodiment of the inventive method.
[0019] FIG. 6 is a view a balloon of the invention illustrating an
alternate embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Balloons of the invention are particularly suited to use in
medical devices, for instance on balloon angioplasty catheters, in
stent delivery systems, perfusion balloon devices, cutting balloon
devices, cryoplasty devices, and the like. Typically they will be
mounted on a catheter or probe device.
[0021] Referring to the drawing FIGS. 1-6, several aspects of the
inventive processes are illustrated.
[0022] FIGS. 1 and 2 show an underlayer balloon 100 comprising
waist regions 102, 104, cone regions 106, 108 and body region 110.
The underlayer balloon is formed of a single layer 122 of a
radially oriented thermoplastic polymer.
[0023] FIG. 3 is a view as in FIG. 2, after a coating layer 124 of
a friction-enhancing coating material has been applied to the
underlayer balloon.
[0024] FIG. 4 is a view as in FIG. 3, after a fiber web 126 has
been applied over the friction-enhancing coating 124.
[0025] FIG. 5 is a view as in FIG. 4, after application of a matrix
material which is the same as the friction-enhancing material. The
web is encased in within the combined friction encasement/matrix
128.
[0026] FIG. 6 is a view as in FIG. 4, after a matrix material 130,
different from the friction-enhancing material, has been
applied.
Underlayer Balloon
[0027] In some aspects the invention pertains to a composite
balloon, or method of forming same, in which a web material is
formed from fibers by application over an underlayer balloon form
that becomes integrated into the composite balloon. The underlayer
balloon has a rest state at ambient pressure (i.e. not pressurized)
that includes cone portions. In the cone portions the diameter of
the balloon varies, typically in a substantially continuous
way.
[0028] The underlayer balloon may be preformed in a manner known
for forming medical device balloons, for instance by radial
expansion of a tubular parison, which is optionally also
longitudinally stretched, of a semi-crystalline polymeric material
to form the underlayer balloon or a preform balloon which is
further processed into the underlayer balloon. The extruded parison
may be radially expanded as is into a mold or by free-blowing.
Alternatively, the parison may be pre-stretched longitudinally
before expansion or reformed in various ways to reduce thickness of
the balloon cone and waist regions prior to radial expansion. The
blowing process may utilize pressurization under tension, followed
by rapid dipping into a heated fluid; a sequential dipping with
differing pressurization; a pulsed pressurization with compressible
or incompressible fluid, after the material has been heated.
Heating may also be accomplished by heating the pressurization
fluid injected into the parison. Examples of these techniques may
be found in the patent documents already mentioned or in U.S. Pat.
No. 4,963,313, Noddin et al, U.S. Pat. No. 5,306,246 Sahatjian,
U.S. Pat. No. 4,935,190, Tennerstedt, U.S. Pat. No. 5,714,110, Wang
et al, U.S. Pat. No. 5,304,340, Downey. Various known methods of
altering the properties of a radially expanded balloon such as
heat-setting, heat shrinking, and/or radiation crosslinking may
also be employed in forming the underlayer balloon. See U.S. Pat.
No. 5,403,340, Wang et al; EP 540858, Advanced Cardiovascular
Systems, Inc.; and WO 98/03218, Scimed Life Systems.
[0029] The underlayer balloon may be formed of any material which
may be made by radial expansion of a tubular parison, typically
thermoplastic polymers. Such materials may include low, linear low,
medium and high density polyethylenes; polypropylenes;
poly(ethylene vinyl acetate) (EVA); poly(ethylene vinyl alcohol)
(EVOH) and EVA/EVOH terpolymers; polyolefin-ionomers;
ethylene-butylene-styrene block copolymers blended with low
molecular weight polystyrene and, optionally, polypropylene, and
similar compositions substituting butadiene or isoprene in place of
the ethylene and butylene; poly(vinyl chloride); polyurethanes;
polyesters and copolyesters; polycarbonate; thermoplastic
elastomers; silicone-polycarbonate copolymers; polyamides;
thermoplastic polyimides; liquid crystal polymers; ABS
(acrylonitrile butadiene styrene); ANS (acrylonitrile styrene);
Delrin polyacetal; PEI (polyetherimide); polyetheretherketone
(PEEK) and PES (polyether sulfone). Physical blends and copolymers
of such materials may also be used.
[0030] Orientable polymers are among the preferred materials for
forming the underlayer balloon. Suitable orientable polymers
include aromatic polyesters, especially polyethylene terephthalate
(PET). PET polymers may have an initial intrinsic viscosity about
0.5 or more, for instance, 0.6-1.3. Other high strength polyester
materials, such as poly(ethylene naphthalate) (PEN); and
poly(butylene terephthalate) may also be used. Polyester copolymers
incorporating ethylene terephthalate, ethylene naphthalate,
butylene terephthalate and/or butylene naphthalate repeat units,
may also be employed. Polyester copolymers such as the random
copolymer made from dimethyl terephthalate dimethyl isophthalate
and ethylene glycol described in U.S. Pat. No. 5,330,428 Wang, et
al. may also be employed.
[0031] Examples of polyamides which may be used include nylon 6,
nylon 64, nylon 66, nylon 610, nylon 610, nylon 612, nylon 46,
nylon 9, nylon 10, nylon 11, nylon 12, and mixtures thereof.
[0032] The underlayer balloon may be formed of polyurethanes such
as Tecothane.RTM. from Thermedics. Tecothane.RTM. is a
thermoplastic, aromatic, polyether polyurethane synthesized from
methylene diisocyanate (MDI), polytetramethylene ether glycol
(PTMEG) and 1,4-butanediol chain extender. Tecothane.RTM. 1065D and
1075D are examples. Other polyurethanes that can be used include
Isoplast.RTM. 301, a high strength engineering thermoplastic
polyurethane, and Pellethane.RTM. 2363-75D, both sold by Dow
Chemical Co. References illustrating polyurethane balloon materials
include U.S. Pat. No. 4,950,239, to Gahara, U.S. Pat. No. 5,500,180
to Anderson et al, U.S. Pat. No. 6,146,356 to Wang, et al., and
U.S. Pat. No. 6,572,813, to Zhang, et al.
[0033] Underlayer balloons may be also made of polyamide/polyether
block copolymers. The polyamide/polyether block copolymers are
commonly identified by the acronym PEBA (polyether block amide).
The polyamide and polyether segments of these block copolymers may
be linked through amide linkages, however, most preferred are ester
linked segmented polymers, i.e. polyamide/polyether polyesters.
Such polyamide/polyether/polyester block copolymers are made by a
molten state polycondensation reaction of a dicarboxylic polyamide
and a polyether diol. The result is a short chain polyester made up
of blocks of polyamide and polyether.
[0034] Polyamide/polyether polyesters are sold commercially under
the Pebax.RTM. trademark. Examples of suitable commercially
available polymers are the Pebax.RTM. 33 series polymers with
hardness 60 and above, Shore D scale, especially Pebax.RTM. 6333,
7033 and 7233. These polymers are made up of nylon 12 segments and
poly(tetramethylene ether) segments linked by ester groups.
[0035] It is also possible to utilize polyester/polyether segmented
block copolymers. Such polymers are made up of at least two
polyester and at least two polyether segments. The polyether
segments are the same as previously described for the
polyamide/polyether block copolymers useful in the invention. The
polyester segments are polyesters of an aromatic dicarboxylic acid
and a two to four carbon diol.
[0036] The polyether segments of the polyester/polyether segmented
block copolymers are aliphatic polyethers having at least 2 and no
more than 10 linear saturated aliphatic carbon atoms between ether
linkages. More preferably the ether segments have 4-6 carbons
between ether linkages, and most preferably they are
poly(tetramethylene ether) segments. Examples of other polyethers
which may be employed in place of the preferred tetramethylene
ether segments include polyethylene glycol, polypropylene glycol,
poly(pentamethylene ether) and poly(hexamethylene ether). The
hydrocarbon portions of the polyether may be optionally branched.
An example is the polyether of 2-ethylhexane diol. Generally such
branches will contain no more than two carbon atoms. The molecular
weight of the polyether segments is suitably between about 400 and
2,500, preferably between 650 and 1000.
[0037] The polyester segments of the polyester/polyether segmented
block copolymers are polyesters of an aromatic dicarboxylic acid
and a two to four carbon diol. Suitable dicarboxylic acids used to
prepare the polyester segments of the polyester/polyether block
copolymers are ortho-, meta- or para-phthalic acid,
napthalenedicarboxylic acid or meta-terphenyl-4,4'-dicarboxylic
acids. Preferred polyester/polyether block copolymers are
poly(butylene terephthalate)-block-poly(tetramethylene oxide)
polymers such as Arnitel.RTM. EM 740, sold by DSM Engineering
Plastics, and Hytrel.RTM. polymers, sold by DuPont, such as
Hytrel.RTM. 8230.
[0038] A suitable thermoplastic polyimide is described in U.S. Pat.
No. 5,096,848 and is available commercially under the tradename
Aurum.RTM. from Mitsui Toatsu Chemicals, Inc., of Tokyo, Japan.
[0039] Examples of liquid crystal polymers include the products
Vectra.RTM. from Hoechst Celanese; Rodrun.RTM. from Unitika; LX and
HX series polymers and Zenite.TM. polymers from DuPont;
Sumikosuper.TM. and Ekonol.TM. from Sumitomo Chemical; Granlar.TM.
from Grandmont; and Xydar.RTM. from Amoco. Suitably the liquid
crystal polymer materials when employed in the underlayer balloon
are blended with another thermoplastic polymer such as PET, nylon
12, or a block copolymer such as Pebax.RTM. 7033 or 7233 or
Arintel.RTM. EM 740 or Hytrel 8230. The liquid crystal polymer may
be present as filaments in a matrix of the blend polymer.
[0040] Alternatively, the underlayer balloon may be obtained by
polymerization of a curable composition on a mold form, for
instance as described in commonly owned copending application Ser.
No. 10/662,621, filed Jul. 18, 2003.
[0041] The underlayer balloon is formed at a thickness which will
provide a sufficiently rigid profile upon inflation to a low
pressure, suitably 2-3 atm, to permit direct application of fibers
thereto in a manner which forms a fiber web overlying the balloon.
Preferably the underlayer balloon is substantially radially
oriented or biaxially (radially and longitudinally) oriented. The
underlayer balloon may have a wall thickness, single wall basis, of
from about 5 .mu.m to about 50 .mu.m (0.0002-0.002 inches),
preferably 10 to 30 .mu.m (0.0004-0.0012 inches).
Fiber Web
[0042] Various techniques for forming webs are known. Suitable webs
may be braids, weaves, mesh, helical windings, knits or random
rovings. The web may be formed of different materials, for instance
if anisotropic longitudinal lengthening and diameter expansion
properties are desired.
[0043] The fiber selection and the web pattern can influence the
distension properties of the composite balloon. Fiber tension
during application to the underlayer balloon can also affect
distension of the composite balloon, especially if elastomeric
fibers are employed in whole or in part. In some preferred
embodiments, however, the composite balloon is substantially
non-distensible in both the longitudinal and radial directions, in
which case the fibers have very low elongation, and the pattern is
selected to provide minimal expansion. Weaves or braids are
particularly desirable web-forms in these embodiments. A circular
braider may be employed to apply the fibers to the underlayer
balloon.
[0044] The web pattern may provide crossing fibers at any angle.
Typically at least one set of the fibers will wind helically around
the circumference of the underlayer balloon. In at least some
embodiments a set of longitudinal fibers is provided, running
parallel to the longitudinal axis over at least a portion of the
underlayer balloon. The longitudinal fibers may be inelastic. In
some embodiments the longitudinal fibers are interwoven or braided
into the web pattern with fibers that wind helically around the
balloon, for instance, the helical fibers may cross over and under
the longitudinal fibers in an individually or grouped alternating
fashion to provide the weave or braid. Crossing fibers that run at
several different angles may be used. For instance, longtudinal
fibers may be crossed both by fibers running at 45.degree. and at
135.degree. thereto. Particularly with fiber webs produced using
mechanical braiders, crossing angles that produce optimal
reinforcement may not occur with optimal gap spacing between fiber
crossings. Groupings of individual fibers may be employed to reduce
gap spacings at any desired crossing angle. For instance, crossing
groupings of 2-6 fibers by 2-6 fibers may give better results than
1.times.1 crossings. The groupings may have different sizes, for
instance 2 (longitudinal) by 4 (45.degree. helical) by 4
(135.degree. helical).
[0045] The fibers may be monofilament or multifilament fibers.
Monofilament fibers are generally preferred. The fibers may range
in size from 1 to 50 .mu.m or in denier from 10-100, preferably
25-50. Moreover deviations from this size range can be achieved in
some cases without departing from the invention.
[0046] Individual filaments in a multifilament fiber may have
denier size less than 10 for instance from 1-5 denier. Larger
filaments may also be employed in multifilament fibers.
Multifilament fibers may be a blend of fibers of different
materials.
[0047] The fiber material may be polyester, polyolefin, polyamide,
polyurethane, liquid crystal polymer, polyimide, carbon, glass,
mineral fiber or a combination thereof. Polyesters include
polyethyleneterephthalate (PET), polybutylene terephthalate (PBT),
and polytrimethylene terephthalate (PTT). Polyamides include nylons
and aramids such as Kevlar.RTM.. Liquid crystal polymers include
Vectran.RTM.. Polyolefins include ultrahigh molecular weight
polyethylene, such as Dyneema,.RTM. sold by DSM Dyneema BVm
Heerlen, Netherlands, Spectra.RTM. fibers, sold by Honeywell, and
very high density polyethylene, and polypropylene fibers.
Elastomeric fibers can be used in some cases. In some specific
embodiments of the invention, the fibers are high strength
materials which have a very low elongation and creep, such as
aramid, liquid crystal polymer, or ultrahigh molecular weight
polyethylene described in U.S. Pat. No. 5,578,374, U.S. Pat. No.
5,958,582 and/or U.S. Pat. No. 6,723,267. Fibers comprising carbon
nanotubes or carbon nano-fibers may be suitable. Other carbon
materials may also be suitable in some applications.
Friction Enhancement
[0048] To facilitate integrity of the web applied to the cone
portion of the underlayer balloon, a friction-enhancing material
may be provided at the interface between the underlayer balloon and
the web, at least over the cone portion. The web fibers may be
coated with a friction-enhancing material, or a layer of
friction-enhancing material may be applied to at least the cone
portion of the underlayer balloon before application of the web
fibers, or both. The friction enhancing material may also be
provided at the interface between the underlayer balloon and the
web over other portions of the balloon, for instance over the waist
and/or body portions.
[0049] The friction-enhancing material may be a polymer that has a
higher coefficient of friction than either or the underlayer
balloon and the fiber and which is high enough that the fibers do
not substantially slip off or around on the cone during web
formation. Coefficient of friction is suitably determined per ASTM
D3702 against a polished steel surface and values of about 0.7 or
higher are recommended, especially about 0.8 and higher. Exemplary
materials may be rubbery elastomeric thermoplastic polymers for
instance, styrene-olefin block copolymers and acrylonitrile block
copolymers. In some cases urethane-based thermoplastic elastomers,
ester-based thermoplastic elastomers, olefin-based thermoplastic
elastomers, and amide-based thermoplastic elastomers may be
suitable. Linear low density polyethylene, very low density
polyethylene, polyethylene-.alpha.-olefin copolymers or
polycarbonate-urethane copolymers may be suitable in some
cases.
[0050] One group of friction enhancers includes styrene-olefin
thermoplastic elastomers. The styrene-olefin thermoplastic
elastomer is a block copolymer having a soft segment and a hard
segment within a molecule. The soft segment is a unit that is
obtained from polymerization of an olefin, e.g., a polyisobutylene
block, a polybutadiene block or a polyisoprene block. The component
constituting the hard segment is a unit of styrene block, for
example, that is obtained from a compound having one or at least
two types selected from styrene and its derivatives, e.g.,
a.-methyl styrene, vinyl toluene, p-tertiary butyl styrene,
1,1-diphenyl ethylene and others.
[0051] Specific examples of the styrene-olefin thermoplastic
elastomers include: styrene-isobutylene-styrene block copolymer
(SIBS); styrene-butadiene-styrene block copolymer (SBS);
styrene-ethylene-butylene-styrene block copolymer (SEBS);
styrene-isoprene-styrene block copolymer (SIS);
styrene-ethylene-propylene-styrene block copolymer (SEPS);
styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS
structure); and modified block copolymers thereof. The content of
styrene (or its derivatives) in each of the SIBS, SBS, SEBS, SIS,
SEPS and SEEPS structures is preferably in a range of 10-50 wt. %,
and more preferably in a range of 15-45 wt. % within the copolymer.
A particular example is SIBS with about 17 wt % styrene.
[0052] The friction-enhancing coating material may also be an
adhesive that is biocompatible when set. For instance, the adhesive
may be one that provides at least some tack during application of
the fibers. The adhesive may be a pressure sensitive, hot melt,
solution, dispersion or curable material. In some embodiments of
the invention, the adhesive will set up further after application
of the fiber to provide a biocompatible adhering bond between the
fibers and the balloon which is stronger than the initial tack
adhesion. Partially cured radiation curable acrylate coating
materials are exemplary.
[0053] The friction-enhancing coating may be applied from a
solution or dispersion. In the case of a hot melt or curable
adhesive, the coating may be applied neat. Suitable coating
thicknesses are from about 1 to about 25 .mu.m, for instance from
about 2 .mu.m to about 20 .mu.m or from about 5 to about 10
.mu.m.
Matrix
[0054] A polymeric matrix material is then applied over the web and
over any exposed portions of the underlayer balloon to form the
composite balloon. The matrix material should bind to the material
that that is at least partially exposed to the matrix material
under the particular technique employed. The exposed material may
be one or more of the web fiber material, the friction-enhancing
coating material, and the underlayer balloon. The matrix material
may be the same or similar to the friction-enhancing material. The
matrix material may also be the same or similar to the bulk
material of the underlayer balloon, or it may be a wholly different
material from both the friction-enhancing material and the
underlayer balloon material. The matrix material may be one which
provides a relatively low coefficient of friction, for instance
about 0.6 or lower, especially about 0.5 and lower. Desirably the
matrix material provides the composite balloon with an exterior
which has good trackability, softness and low self adhesion
("non-blocking") after application.
[0055] The matrix material may be applied from solvent or
dispersion. In some cases a curable liquid which sets up after
application may be employed as matrix material. The matrix material
may also be applied from the melt, for instance by spraying or
extruding over the web.
[0056] Examples of matrix materials which may be employed include
the styrene-olefin thermoplastic elastomers already described.
Polyurethanes, for instance silicone modified polyurethanes may be
employed. UV curable compositions as described in more detail below
may also be employed.
[0057] In preferred embodiments the matrix material and the
friction-enhancing material, in combination, also bind the
filaments of the fibrous material to the underlayer balloon to a
degree which is effective to substantially prevent loss of filament
material into the body when the balloon is burst during use.
Composite Balloon
[0058] In addition to the components already described, the
composite balloon may have a coating of a lubricous material or
which comprises drug, as is generally known. See, for instance U.S.
Pat. No. 5,135,516, Sahatjian, et al; U.S. Pat. No. 5,026,607,
Kiezulas; U.S. Pat. No. 5,304,121, Sahatjian; U.S. Pat. No.
5,576,072, Hostettler, et al; U.S. Pat. No. 5,503,631, Onishi et
al; U.S. Pat. No. 5,509,899, Fan et al; U.S. Pat. No. 5,693,034,
Buscemi et al; U.S. Pat. No. 6,110,483, Whitbourne, et al; U.S.
Pat. No. 5,702,756, Thong; U.S. Pat. No. 6,528,150, Nazarova et al;
and U.S. Pat. No. 6,673,053, Wang, et al. An anti-blocking coating
material may also be employed to reduce self adhesion of the matrix
material. In at least some cases anti-blocking and lubricity
properties can be obtained with a single material, for instance a
silicone fluid.
[0059] The composite balloon may have a single wall thickness of
less than 115 .mu.m (0.0045 inches), preferably less than 77 .mu.m
(0.003 inches). Suitably the single wall thickness is about 38
.mu.m (0.0015 inches) or less, for instance about 25-35 .mu.m
(0.001-0.0014 inches).
[0060] Wall strengths for such balloons may be in excess of 15,000
psi (103,421 kPa), typically at least 18,000 psi (124,106 kPa), and
in most cases in the range of about 20,000 (132,895 kPa) to 32,000
psi (220,632 kPa). Balloon diameters may range from about 1.5 to
about 14 mm.
[0061] In use, it is often desirable to place a coating comprising
a lubricious material, a medicament, or both, on the exterior
surface of a medical device balloon. Such practice is also
contemplated within the invention. However, if employed, such a
coating is not considered to be part of the composite balloon
structure for purposes of the claims presented herein.
[0062] The following examples illustrate the invention in
preliminary, non-optimized trials.
EXAMPLE
[0063] Underlayer balloons were prepared by radial expansion of
extruded tubes of Pebax.RTM. 7233 polymer. The underlayer balloons
had an average double wall thickness in the body region of
approximately 0.00252 inches (0.64 mm), a molded diameter of
approximately 6 mm and a molded body length of approximately 2 cm.
The underlayer balloons were sterilized with ethylene oxide
according to a conventional protocol. At this stage, three balloons
were retained, unbraided, as controls for comparison purposes.
[0064] The underlayer balloons were heat-sealed at their distal
end. The proximal end was connected to a pneumatic syringe and
pressurized balloon component to a firm stiffness (1-2 atm internal
pressure).
[0065] A coating of SIBS polymer (17% isobutylene) was applied to
the exterior surface of the underlayer balloon by hand dipping the
pressurized balloon component into a 1% solution of the SIBS
polymer in toluene, drawing the balloon component out of solution
and allowing it to dry.
[0066] A braiding machine was utilized to weave a web of fibers of
55 denier Kevlar.RTM. aramid around the inflated balloon
components. Speeds were adjusted as braiding progressed in a manner
directed to achieve a single layer light braiding (5 balloons)
(estimated about 30-50% surface coverage) or a single layer heavy
braiding as tightly as possible (5 balloons) (estimated 91% fiber
coverage).
[0067] Close attention was paid to braiding in the region of the
balloon cones. These were positions where the fibers had a tendency
to slip. When an attempt to lightly weave fibers on an underlayer
balloon that had not been coated with the SIBS layer was made, the
fibers slipped and bunched up over the waist region of the balloon
when application to the cone was attempted. By contrast, an
excellent result obtained when a SIBS coated underlayer balloon was
used.
[0068] After the Kevlar.RTM. fiber web had been applied, a
secondary SIBS coating (matrix) was produced by again dipping the
pressurized balloon component into a 1% solution of the SIBS
polymer in toluene, drawing the balloon component out of solution
and letting it thoroughly dry.
[0069] Uncoated balloon components were retained as controls. The
controls were inflated but received neither the SIBS coatings nor
braiding.
[0070] The balloons were deflated, by cutting one sealed end, and
the double wall thickness was measured. Double wall thicknesses of
the final braided balloons were: approximately 0.0042 inches (107
.mu.m) for the light braid--and approximately 0.0068 inches (173
.mu.m) for the heavy braid. The balloons were then attached to
burst machines, and inflated in a 37.degree. C. water bath. The
balloon was pressurized at 1 atm increments until burst. Measured
burst pressures were 22-25 atm for the unbraided controls, 30 atm
for the light braid and 34-35 atm for the heavy braid.
[0071] Longitudinal growth over the range 4-15 atm was 15.5% for
the control versus only 3% for the heavy braid balloon.
Curable Material
[0072] As previously described, the invention may use a liquid
composition which is curable to a solid polymer. Such a material
may be employed to form the underlayer balloon, the friction
enhanced interface, the matrix or any combination thereof.
Radiation curing compositions of (meth)acrylate esters (i.e.
acrylates, methacrylates and mixtures thereof) are well known and
may be used in the invention. A wide variety of cured properties
are available from such compositions. Unless e-beam sources are
used, such compositions typically employ a photoinitiator.
[0073] The radiation curable compounds, such as those which are
initiated with UV or visible light radiation, may be monomeric,
oligomeric, prepolymeric, or polymeric in nature. Mixtures of such
compounds are typically used. Typically the compositions are
liquids prior to curing in order facilitate application of the
composition, and then cure to a crosslinked solid after being
exposed to radiation such as UV or visible light radiation.
[0074] Examples of (meth)acrylate terminated radiation curable
compounds include, but are not limited to, epoxy (meth)acrylates,
urethane (meth)acrylates (aliphatic and aromatic), polyester
(meth)acrylates, acrylic (meth)acrylates, polycarbonate
(meth)acrylates and so forth and mixtures thereof. Other suitable
UV curable compositions include cationically polymerizable
compounds, most notably epoxies.
[0075] Examples of commercially available suitable UV curable
epoxies include, but are not limited to, UVACURE.RTM. 1500, 1530
and 1534 available from UCB Radcure, SARCAT.RTM. K126 available
from Sartomer, and so forth. Vinyl ethers and styryloxy ethers are
other cationically polymerizable compounds which can be used.
[0076] Another type of formulation which may be utilized in the
invention is a photo-activated Diels-Alder addition reaction of an
aromatic 2,5-dialkyl-1,4-diketone and a compound having two or more
(meth)acrylate or maleimide groups thereon, optionally with a chain
terminating mono-maleimide, or (meth)acrylate.
[0077] As an alternative to radiation curing, a composition which
is curable upon mixing of two or more components may be employed,
the individual components being stable until mixed. The individual
components may be blended on-the-fly, so that the resulting
composition cures promptly as it is applied, but does not cure in
the application apparatus.
[0078] The above examples and disclosure are intended to be
illustrative and not exhaustive. These examples and description
will suggest many variations and alternatives to one of ordinary
skill in this art. All these alternatives and variations are
intended to be included within the scope of the claims, where the
term "comprising" means "including, but not limited to." Those
familiar with the art may recognize other equivalents to the
specific embodiments described herein which equivalents are also
intended to be encompassed by the claims. Further, the particular
features presented in the dependent claims can be combined with
each other in other manners within the scope of the invention such
that the invention should be recognized as also specifically
directed to other embodiments having any other possible combination
of the features of the dependent claims. For instance, for purposes
of claim publication, any dependent claim which follows should be
taken as alternatively written in a multiple dependent form from
all claims which possess all antecedents referenced in such
dependent claim, if such multiple dependent format is an accepted
format within the jurisdiction. In jurisdictions where multiple
dependent claim formats are restricted, the following dependent
claims should each be also taken as alternatively written in each
singly dependent claim format which creates a dependency from a
antecedent-possessing claim other than the specific claim listed in
such dependent claim below.
* * * * *