WO1998050087A1 - Improved medical device having desirable combination of properties and method of making same - Google Patents

Improved medical device having desirable combination of properties and method of making same Download PDF

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Publication number
WO1998050087A1
WO1998050087A1 PCT/US1998/009495 US9809495W WO9850087A1 WO 1998050087 A1 WO1998050087 A1 WO 1998050087A1 US 9809495 W US9809495 W US 9809495W WO 9850087 A1 WO9850087 A1 WO 9850087A1
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WIPO (PCT)
Prior art keywords
coating
medical device
balloon
durability
catheter
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Application number
PCT/US1998/009495
Other languages
French (fr)
Inventor
Eugene Tedeschi
John Hudson
Laurel Wolfgang
Original Assignee
Medtronic Ave,Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Medtronic Ave,Inc. filed Critical Medtronic Ave,Inc.
Priority to AU74774/98A priority Critical patent/AU7477498A/en
Priority to EP98922169A priority patent/EP0983097A1/en
Publication of WO1998050087A1 publication Critical patent/WO1998050087A1/en

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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61LMETHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/08Materials for coatings
    • A61L29/085Macromolecular materials

Definitions

  • This invention relates to medical devices, particularly medical devices adapted to pass through narrow body vessels such as catheters which have an outer surface polymeric substrate having coated thereon a coating of such nature and sufficiently low thickness that the resulting coated medical device has high hoop tensile strength and good puncture resistance (durability).
  • Catheters are placed at various locations within a patient for a wide variety of purposes and medical procedures.
  • a balloon dilatation catheter which is used in the treatment of a vascular stenosis.
  • Such a catheter has a balloon at its distal end which is intended to be placed, in a deflated condition, within the stenosis, and then inflated while in the stenosis to expand radially the stenosed lumen of the blood vessel.
  • the placement of such catheters involves the use of a guidewire which may be advanced through the patient's vasculature to the location which is to be treated.
  • the catheter which has a guidewire lumen adapted to receive the guidewire, then is advanced over the wire to the stenosis, or, alternatively, the wire and catheter may be advanced in unison to the stenosis with the wire protruding from the distal end of the catheter.
  • a medical device e.g. , a catheter having a coating of such nature on its outer surface substrate is provided whereby the medical device has a puncture resistance greater than its uncoated form without affecting hoop tensile strength which results in an improved catheter of improved durability.
  • a medical device e.g. , a medical catheter, and in particular, the inflatable balloon portion of the catheter, a polymeric coating of such nature and of sufficient thickness to obtain an improved puncture resistance over that of the uncoated parent substrate so as to impart greater durability to the coated medical device over the parent uncoated medical device.
  • Suitable methods for applying the polymeric coating to the substrate surface of the catheter include dipping, painting, spraying or wiping the coating on the catheter outer surface substrate. Dipping is a preferred method as it allows for more control over the coating process.
  • the thickness of the coatings is typically less than about 1 mil. A thickness range of about 0.02 to about 0.5 mils is more preferred. Thickness ranges of about 0.05 to about .25 mils and about 0.1 to about 0.25 mils are also preferred.
  • suitable coating compositions are solutions or dispersions of polyurethane, acrylic polymers and epoxy resin materials in a suitable solvent or liquid carrier.
  • suitable coating compositions are solutions or dispersions of polyurethane, acrylic polymers and epoxy resin materials in a suitable solvent or liquid carrier.
  • commercial polyurethane coatings such as Helmsman Urethane Coating or Carver Tripp Clear Polyurethane
  • commercial acrylic polymers such as Thompson's Minwax Polyacrylic
  • the basic building blocks of polyurethanes are isocyanates containing two or more isocyanate groups and polyols containing two or more hydroxyl functions. Toluenediisocyanate, polymeric diphenylmethanediisocyanate, monomeric 4,4'-diphenylmethanediisocyanate, 1 ,6- hexamethylene diisocyanate and isophorone diisocyanate are common isocyanates that can be used either individually or as a mixture to produce polyurethanes for use in this invention.
  • Polyurethanes are classified according to the polyol used.
  • the polyols are generally polyethers and polyesters.
  • Polyether-based urethanes are more resistant to hydrolysis and have higher resilience, good energy-absorption characteristics, good hysteresis characteristics, and good all-around chemical resistance.
  • a polyester-based material will generally be stiffer and will have higher compression and tensile moduli, higher tear strength and cut resistance, higher operating temperature, lower compression set, and optimum abrasion resistance.
  • Castor-oil-based potting compounds are also convenient to use.
  • CasChem markets a family of polyurethane systems based on ricinoleate polyols derived from castor oil.
  • Diamines are the best general purpose curing agents for polyurethanes.
  • suitable acrylic polymers are those made up of methyl acrylate, ethyl acrylate or methyl methacrylate acrylic-esters.
  • Other examples include the use of copolymers of methyl methacrylate with other monomers such as methyl and ethyl acrylate, acrylonitrile and styrene.
  • Non-limiting examples of suitable epoxy resin materials are those based on the reaction of bisphenol A and epichlorohydrin in the presence of an alkaline catalyst, novolac epoxies such as cresols, and cycloaliphatics.
  • Epoxy resins can be cured with cross-linking agents or catalysts to develop desirable properties. Additional information on the production and use of polyurethane, acrylic polymer and epoxy resin can be found in the Modem Plastics Encyclopedia, October 1986, Volume 63, Number 10A, published by McGraw Hill, New York, NY and references therein or the Handbook of Plastics, Elastomers, and Composites, Third Ed. , by Charles A. Harper, published 1996 by McGraw Hill,
  • the preparation of the coatings can be a multi-step process.
  • Non-limiting examples of suitable solvents or carriers are water, aliphatic or aromatic hydrocarbons, heterocyclic aromatics, ethers, amines, amides, ketones, esters, halogenated aliphatic or aromatic hydrocarbons, sulfides, sulfoxides and the like. If the coating composition employs a curable material, the curable material is cured after evaporation of the liquid solvent or carrier of the coating composition after the coating solution has been applied to the substrate.
  • the solvent or liquid carrier is preferably allowed to evaporate from the coated substrate often by exposure to ambient conditions for from about 10 to about 180 minutes but can be evaporated at temperatures of from about 35° F to about 400° F for time periods of a few seconds to overnight depending upon the selection of solvent or liquid carrier and the speed with which evaporation is desired.
  • the organic balloon substrate that can be coated with a suitable coating for obtaining a coated catheter with high hoop tensile strength and acceptable puncture resistance in accordance with this invention include nylon, polyether block amide, polyethylene terephthalate (PET), polyetherurethane, polyesterurethane, natural rubber, rubber latex, synthetic rubbers, polyester-polyether copolymers, ethylene methacrylic acid di-and inter polymers containing metal salts, polyethers, polyesters, and other polyurethanes, polycarbonates, polytetramethylene glycol ether urethane, and other organic materials including polyvinylchloride and other vinyl polymers, polyethylene and the like, as well as blends and alloys of the above.
  • PET polyethylene terephthalate
  • polyetherurethane polyesterurethane
  • natural rubber rubber latex
  • synthetic rubbers polyester-polyether copolymers
  • ethylene methacrylic acid di-and inter polymers containing metal salts polyethers, polyesters, and other poly
  • the balloons are preferably made from nylon, PET or blends or alloys thereof. It is desired that the hoop tensile strength or Hoop Stress of the balloons (uncoated and after coating to enhance durability) be about 10,000 psi or greater. It is more preferred that such balloons have a hoop tensile strength of about
  • the size of the balloons typically is in the range of about 0.5 to about 25 mm in diameter. More preferably the balloons range from about 1 to about 18 mm in diameter and most preferably from about 1 to about 4 mm in diameter.
  • the balloons are typically biaxially orientated, but the use of other forms is also useful in the practice of this invention.
  • the uncoated double wall thickness (DWT) of the balloon is typically from about 0.25 to about 3 mils thick. An uncoated DWT of about 0.5 to about 1.2 mils is more preferred.
  • Coating A is a solvent based polyurethane coating.
  • the coating was prepared by dissolving Helmsman Urethane Coating in toluene.
  • the dilution ratio of polyurethane to solvent was from about 1:2 to about 1: 10 depending on the thickness of the coating desired.
  • Coating B is a water soluble polyurethane coating.
  • the coating was prepared by dissolving Carver Tripp Clear Polyurethane in water.
  • the dilution ratio of polyurethane to water was about 1: 1 to about 1 : 10 depending on the thickness of the coating desired.
  • Coating C is a water soluble acrylic polymer coating.
  • the coating was prepared by dissolving Thompson's Minwax Poly acrylic Finish in water.
  • the dilution ratio of polyacrylic to water was about 1: 1 to about 1: 10 depending on the thickness of the coating desired.
  • Coating D is a solvent based polyurethane coating.
  • the coating was prepared as follows. Initially, Cellulose Acetate Butyrate (1.8 g), e.g. , Eastman Cellulose Acetate Butyrate 500-5 available from Eastman Chemical Company, Kingsport, Tennessee was combined with 16.2 g N-Butyl Acetate available from Van Waters & Rogers Incorporated, San Mateo, California. The solution was mixed for approximately 24 hours on a paint roller or until all of the Cellulose Acetate Butyrate was dissolved. When dissolved, polyisocyanate (45.5 g), e.g. , Mondur CB-60 PMA available from Miles Corporation, Pittsburgh, Pennsylvania, castor oil (35.0 g), e.g.
  • Cellulose Acetate Butyrate can be used in the range of about 0.02 to about 2% with a preferred range being about 0.03 to about 0.68%.
  • N-Butyl Acetate can be used in the range of about 0.1 to about 10% with a preferred range being about 0.2 to about 6.5% .
  • the polyisocyanate can be used in the range of about 0.5 to about 22% with a preferred range being about 0.7 to about 18% .
  • the castor oil can be used in the range of about 0.4 to about 14.5% with a preferred range being about 0.5 to about 14%.
  • Additional N-Butyl Acetate can be used in the range of about 24 to about 54% with a preferred range being about 30 to about 45%.
  • iso-Butyl Acetate can be used in the range of about 24 to about 60% with a preferred range being about 30 to about 50%. All percentages are weight/weight.
  • Table 1 shows variations of coating D that were made and applied to balloons.
  • Table 2 shows balloons dipped in the various formulations of coating D shown in Table 1.
  • the burst pressure and hence the hoop tensile strength of the coated balloons was determined and compared to similar balloons that were not coated. The results show that the coatings of this invention do not reduce the hoop tensile strength of balloons.
  • Coating E is a solvent based epoxy resin coating.
  • Hardman Epoxy Part A (2.5 g) and Hardman Epoxy Part B (2.4 g) both available as Hardman Epoweld ® 8173 from Elementis Performance Polymers, Belleville NJ were dissolved in toluene (4.9 g) to produce a 50% solution of solids.
  • Serial dilutions were performed to produce coating solutions of 33%, 25% and 20% solids. Balloons were single dipped immediately after mixing.
  • Balloons were coated with coating E as outlined in Table 3 below.
  • the burst pressure and hence the hoop tensile strength of the balloons coated with coating E was determined.
  • the hoop tensile strength of the coated balloons was then compared to similar, uncoated balloons. The results show that the coatings of this invention do not reduce the hoop tensile strength of balloons.
  • a polyol (170 g), e.g. , Desmophen A 405A, available from Bayer Corp. Pittsburgh, PA, a polyisocyanate (44 g), e.g. , Modur CB-60 PMA, available from Bayer Corp. , and acetone (2014 g) can be mixed to produce a polyurethane coating.
  • the polyol can be used in the range of about 2 to about 15%, with the preferred range being about 5 to about 10% .
  • the polyisocyanate can be used in the range of about 0.5 to about 10%, with the preferred range being about 1 to about 5% .
  • Acetone can be used in the range of about 80 to about 99%, with the preferred range being about 85 to about 95 % .
  • An amine (6 g), e.g. , EpiCure 3005 Amidoamine, available from Shell Chemical, and a second amine (16 g), e.g. , Ancamine 1638 Aliphatic Amine is mixed together to produce part B of the epoxy resin.
  • Epoxy resins, e.g., Epon 828 Bis A Epoxy Resin, available from Shell Chemical an acrylate modifier (25 g), e.g., M-Cure 200 Acrylate Modifier, available from Sartomer, and an acrylate modifier (15 g), e.g.
  • Epon 828 Bis A Epoxy Resin can be used in the range of about 45 to about 75% with the preferred range being about 48 to about 72% .
  • Modifiers, e.g. , M-Cure 200 Acrylate Modifier can be used in the range of about 18 to about 32% with the preferred range being about 22.5 to about 27% .
  • Modifiers, e.g. , M-Cure 202 Acrylate Modifier can be used in the range of about 11 to about 19% with the preferred range being about 13 to about 17% .
  • Amidoamine can be used in the range of about 4 to about 8% with the preferred range being about 5 to about 7% .
  • Amines, e.g. , Ancamine 1638 Aliphatic Amine can be used in the range of about 12 to about 20% with the preferred range being about 14 to about 18%.
  • Equal parts of part A and part B can dissolved in two parts toluene. The mixture can then be serially diluted to produce coating mixtures.
  • a high durometer coating can be made as follows. Two epoxy resins, e.g. , AboCast 8-8 (100 g), available from Abatron, Kenosha, WI, AboCure 8-8 (100 g), available from Abatron, can be combined with toluene (100 g) to produce an epoxy coating. Typically the resins can be used in equal portions and toluene can be used in the range of about 10 to about 95%, with a preferred range being about 25 to about 75% .
  • Dipping is the preferred method of coating because the thickness of l i ⁇
  • the coat is more uniform and easier to control compared to other methods.
  • the balloon was first cleaned with acetone, isopropyl alcohol or the like. The balloon was then inflated to from about 2 to about 4 bars pressure and dipped into the coating mixture.
  • Factors that affect the coating thickness and adhesion properties were the speed at which the article was introduced into and withdrawn from the mixture, the dwell time in the mixture and the number of times dipped into the coating mixture.
  • the dwell time was found to influence the extent to which the coating was imbibed into the article surface.
  • the down speed (inches/minute) can be over the range of about 1 to about 200 with a preferred range being about 40 to about 140.
  • the dwell (seconds) time has no limit but typically is about 2 to about 40.
  • the withdrawal rate (inches/minute) can be over the range of about 1 to about 200 with a preferred range being about 40 to about 140.
  • the double wall thickness of each balloon is first measured.
  • the balloon is then cleaned with isopropyl alcohol, acetone or similar solvent and heat sealed at each end with about 2 to about 4 bars pressure inside the balloon.
  • the ballon is dipped, distal end first, into the coating solution. After removal from the coating solution, the balloon is air-dried. For multiple dipping, the balloon was allowed to air-dry for 20 minutes between dips. The balloons were then placed in a drying oven to cure. After curring, the balloons were removed and the double wall thickness measured.
  • Balloons were examined for durability using the following procedures.
  • the device used for testing was specifically designed for balloon catheters and to represent the environment the balloon catheters are typically used in.
  • the device consists of a series of stainless steel sleeves with internal diameters that match the balloon's nominal outer diameter (OD).
  • a balloon's nominal OD is defined as the outer diameter of the balloon after it has been pressurized from the collapsed position to the inflated position that is free of wrinkles (normally pressures are from about 50 to about 125 psi).
  • Each sleeve has one screw ground to a 60° included taper down to a 0.0065 inch diameter flat. The screw can be extended 0.011 inches toward the center of the cylinder.
  • the sleeve was placed in a submersible fixture and the deflated balloon loaded into the sleeve.
  • the screw was adjusted to a length of 0.011 inches and the apparatus submerged into a body temperature water bath.
  • the balloon catheter was attached to an inflation device i.e., burst machine and inflated to either 12 or 16 bars. If the balloon did not burst, it was deflated and reinflated repeatedly until the balloon burst.
  • the table below compares coating thickness, DWT, inflation pressure and durability between similar, coated and uncoated balloons.
  • DWT 'Double wall thickness
  • the uncoated balloons burst during the first inflation.
  • Durability is defined as a coated balloon attaining at least one more cycle in the above-described test than a similar, uncoated balloon.
  • a more preferred durability is greater than about 5 cycles more than an uncoated balloon and a most preferred durability is greater than about 10 cycles.
  • a preferred range of durability 5 is about 5 to about 50 cycles and a more preferred range is about 10 to about 20 cycles.
  • the testing is done from about 12 bar to about 16 bar which is the working pressure of the balloon. The testing can be done at pressures ranging from about the nominal pressure of the balloon to about the busting pressure of the 10 balloon.
  • the coated tube was then formed into a balloon.
  • the resulting product was a balloon catheter with durability (as measured by cyclic penetrations with a pointed probe to measure puncture resistance) greater than a jr . catheter without above coating.
  • Hoop tensile strength also known as Hoop Stress was determined as follows. A balloon at body temperature was attached to a burst machine and inflated to the point at which the balloon ruptures. The Hoop Stress was then calculated by the following equation: 0
  • the Hoop Stress of a balloon of 3 mm diameter with a wall thickness of 5 0.0005 inches that ruptures at 20 bar is calculated as follows:

Abstract

This invention relates to coated medical devices adapted to pass through narrow body openings such as catheters. The coatings provided by this invention impart durability to the catheter without appreciably adding to the thickness of the catheter and without decreasing the hoop tensile strength of the catheter.

Description

IMPROVED MEDICAL DEVICE HAVING DESIRABLE
COMBINATION OF PROPERTIES AND METHOD OF MAKING SAME
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application Serial No. 60/045,953, filed May 8, 1997.
FIELD OF THE INVENTION
This invention relates to medical devices, particularly medical devices adapted to pass through narrow body vessels such as catheters which have an outer surface polymeric substrate having coated thereon a coating of such nature and sufficiently low thickness that the resulting coated medical device has high hoop tensile strength and good puncture resistance (durability).
BACKGROUND OF THE INVENTION
Catheters are placed at various locations within a patient for a wide variety of purposes and medical procedures. For example, one type of catheter is a balloon dilatation catheter which is used in the treatment of a vascular stenosis. Such a catheter has a balloon at its distal end which is intended to be placed, in a deflated condition, within the stenosis, and then inflated while in the stenosis to expand radially the stenosed lumen of the blood vessel. Typically, the placement of such catheters involves the use of a guidewire which may be advanced through the patient's vasculature to the location which is to be treated. The catheter, which has a guidewire lumen adapted to receive the guidewire, then is advanced over the wire to the stenosis, or, alternatively, the wire and catheter may be advanced in unison to the stenosis with the wire protruding from the distal end of the catheter.
It has long been known that hydrophilic coatings with low friction
(coefficient of friction of 0.3 or less) are useful for a variety of medical devices such as catheters, catheter introducers and the like. When low friction coating surfaces are applied to the substrate of such medical devices, such devices when introduced into the body slide easily within arteries, veins and other body orifices and passageways. Examples of prior art catheters which have been provided with a lubricious coating in the manner referred to in the foregoing paragraph are coated catheters disclosed in U.S. Elton Patent No. 5,077,352, U.S. Elton Patent No. 5, 160,790, U.S. Opolski Patent No. 5,272,012 and U.S. Rowland Patent No. 5,041 , 100.
While a number of prior art medical catheters possess high hoop tensile strength they are lacking in a sufficiently high enough puncture resistance. By the present invention, a medical device, e.g. , a catheter having a coating of such nature on its outer surface substrate is provided whereby the medical device has a puncture resistance greater than its uncoated form without affecting hoop tensile strength which results in an improved catheter of improved durability.
DESCRIPTION OF THE INVENTION
It is an object of this invention to provide a medical device, e.g. , a medical catheter made of a polymeric material which has been coated with a coating of such nature and applied in such a manner that the puncture resistance of the medical device (durability) has been increased while not decreasing any desirable physical property like hoop tensile strength nor significantly increasing the diameter of the product. Another object of the invention is to obtain a medical catheter composed of a polymeric material having a coating wherein the resulting coated catheter is composed of materials of such characteristics, morphology and thickness that said coated catheter has a desirable combination of properties, including a high hoop tensile strength and acceptable puncture resistance.
It has been found that the objects of this invention may be realized by applying to the outer polymeric surface of a medical device, e.g. , a medical catheter, and in particular, the inflatable balloon portion of the catheter, a polymeric coating of such nature and of sufficient thickness to obtain an improved puncture resistance over that of the uncoated parent substrate so as to impart greater durability to the coated medical device over the parent uncoated medical device.
Suitable methods for applying the polymeric coating to the substrate surface of the catheter include dipping, painting, spraying or wiping the coating on the catheter outer surface substrate. Dipping is a preferred method as it allows for more control over the coating process. The thickness of the coatings is typically less than about 1 mil. A thickness range of about 0.02 to about 0.5 mils is more preferred. Thickness ranges of about 0.05 to about .25 mils and about 0.1 to about 0.25 mils are also preferred.
Examples of suitable coating compositions are solutions or dispersions of polyurethane, acrylic polymers and epoxy resin materials in a suitable solvent or liquid carrier. For example, it has been surprisingly found that commercial polyurethane coatings such as Helmsman Urethane Coating or Carver Tripp Clear Polyurethane, commercial acrylic polymers such as Thompson's Minwax Polyacrylic
Finish or commercial epoxy resins such as Hardman EpoWeld® can be used. It is noted that these commercial products may contain additives such as coloring which are unnecessary for practicing this invention. The basic building blocks of polyurethanes are are isocyanates containing two or more isocyanate groups and polyols containing two or more hydroxyl functions. Toluenediisocyanate, polymeric diphenylmethanediisocyanate, monomeric 4,4'-diphenylmethanediisocyanate, 1 ,6- hexamethylene diisocyanate and isophorone diisocyanate are common isocyanates that can be used either individually or as a mixture to produce polyurethanes for use in this invention. Polyurethanes are classified according to the polyol used. The polyols are generally polyethers and polyesters. Polyether-based urethanes are more resistant to hydrolysis and have higher resilience, good energy-absorption characteristics, good hysteresis characteristics, and good all-around chemical resistance. A polyester-based material will generally be stiffer and will have higher compression and tensile moduli, higher tear strength and cut resistance, higher operating temperature, lower compression set, and optimum abrasion resistance.
Castor-oil-based potting compounds are also convenient to use. CasChem markets a family of polyurethane systems based on ricinoleate polyols derived from castor oil. Diamines are the best general purpose curing agents for polyurethanes. Non-limiting examples of suitable acrylic polymers are those made up of methyl acrylate, ethyl acrylate or methyl methacrylate acrylic-esters. Other examples include the use of copolymers of methyl methacrylate with other monomers such as methyl and ethyl acrylate, acrylonitrile and styrene. Non-limiting examples of suitable epoxy resin materials are those based on the reaction of bisphenol A and epichlorohydrin in the presence of an alkaline catalyst, novolac epoxies such as cresols, and cycloaliphatics. Epoxy resins can be cured with cross-linking agents or catalysts to develop desirable properties. Additional information on the production and use of polyurethane, acrylic polymer and epoxy resin can be found in the Modem Plastics Encyclopedia, October 1986, Volume 63, Number 10A, published by McGraw Hill, New York, NY and references therein or the Handbook of Plastics, Elastomers, and Composites, Third Ed. , by Charles A. Harper, published 1996 by McGraw Hill,
New York, NY and references therein. The preparation of the coatings can be a multi-step process.
Non-limiting examples of suitable solvents or carriers are water, aliphatic or aromatic hydrocarbons, heterocyclic aromatics, ethers, amines, amides, ketones, esters, halogenated aliphatic or aromatic hydrocarbons, sulfides, sulfoxides and the like. If the coating composition employs a curable material, the curable material is cured after evaporation of the liquid solvent or carrier of the coating composition after the coating solution has been applied to the substrate.
After applying the coating solution or dispersion, the solvent or liquid carrier is preferably allowed to evaporate from the coated substrate often by exposure to ambient conditions for from about 10 to about 180 minutes but can be evaporated at temperatures of from about 35° F to about 400° F for time periods of a few seconds to overnight depending upon the selection of solvent or liquid carrier and the speed with which evaporation is desired.
The organic balloon substrate that can be coated with a suitable coating for obtaining a coated catheter with high hoop tensile strength and acceptable puncture resistance in accordance with this invention include nylon, polyether block amide, polyethylene terephthalate (PET), polyetherurethane, polyesterurethane, natural rubber, rubber latex, synthetic rubbers, polyester-polyether copolymers, ethylene methacrylic acid di-and inter polymers containing metal salts, polyethers, polyesters, and other polyurethanes, polycarbonates, polytetramethylene glycol ether urethane, and other organic materials including polyvinylchloride and other vinyl polymers, polyethylene and the like, as well as blends and alloys of the above. Some of these materials are available under the trademarks such as Pebax available from Atochem, Inc. of Glen Rock, New Jersey, Mylar available from E.I. duPont deNemours and Co. of Wilmington, Delaware, Texin 985A from Mobay Corporation of Pittsburgh, Pennsylvania, Surlyn available from E.I. duPont deNemours and Co. of Wilmington, Delaware, Pellethane available from Dow Chemical of Midland, Michigan, and Lexan available from General Electric Company of Pittsfield, Massachusetts.
The balloons are preferably made from nylon, PET or blends or alloys thereof. It is desired that the hoop tensile strength or Hoop Stress of the balloons (uncoated and after coating to enhance durability) be about 10,000 psi or greater. It is more preferred that such balloons have a hoop tensile strength of about
25,000 psi or greater. The size of the balloons typically is in the range of about 0.5 to about 25 mm in diameter. More preferably the balloons range from about 1 to about 18 mm in diameter and most preferably from about 1 to about 4 mm in diameter. The balloons are typically biaxially orientated, but the use of other forms is also useful in the practice of this invention. The uncoated double wall thickness (DWT) of the balloon is typically from about 0.25 to about 3 mils thick. An uncoated DWT of about 0.5 to about 1.2 mils is more preferred.
All publications, patents and articles referred to herein are expressly incorporated herein in toto by reference thereto. The following examples are presented to illustrate the present invention but are in no way to be construed as limitations on the scope of the invention. It will be recognized by those skilled in the art that numerous changes and substitutions may be made without departing from the spirit and purview of the invention.
EXAMPLE 1
Coatings
Coating A
Coating A is a solvent based polyurethane coating. The coating was prepared by dissolving Helmsman Urethane Coating in toluene. The dilution ratio of polyurethane to solvent was from about 1:2 to about 1: 10 depending on the thickness of the coating desired.
Coating B
Coating B is a water soluble polyurethane coating. The coating was prepared by dissolving Carver Tripp Clear Polyurethane in water. The dilution ratio of polyurethane to water was about 1: 1 to about 1 : 10 depending on the thickness of the coating desired.
Coating C
Coating C is a water soluble acrylic polymer coating. The coating was prepared by dissolving Thompson's Minwax Poly acrylic Finish in water. The dilution ratio of polyacrylic to water was about 1: 1 to about 1: 10 depending on the thickness of the coating desired.
Coating D
Coating D is a solvent based polyurethane coating. The coating was prepared as follows. Initially, Cellulose Acetate Butyrate (1.8 g), e.g. , Eastman Cellulose Acetate Butyrate 500-5 available from Eastman Chemical Company, Kingsport, Tennessee was combined with 16.2 g N-Butyl Acetate available from Van Waters & Rogers Incorporated, San Mateo, California. The solution was mixed for approximately 24 hours on a paint roller or until all of the Cellulose Acetate Butyrate was dissolved. When dissolved, polyisocyanate (45.5 g), e.g. , Mondur CB-60 PMA available from Miles Corporation, Pittsburgh, Pennsylvania, castor oil (35.0 g), e.g. , DB Castor Oil available from CasChem, Incorporated, Bayonne, New Jersey, an additional 116.9 g N-Butyl Acetate available from Van Waters & Rogers Incorporated, San Mateo, California, 122.4 g of iso-Butyl Acetate available from Van Waters & Rogers Incorporated, San Mateo, California and 5.5 g Mineral Spirits available from Van Waters & Rogers Incorporated, San Mateo, California were added.
In addition, the components listed above can be varied to achieve different coating characteristics. Cellulose Acetate Butyrate can be used in the range of about 0.02 to about 2% with a preferred range being about 0.03 to about 0.68%. N-Butyl Acetate can be used in the range of about 0.1 to about 10% with a preferred range being about 0.2 to about 6.5% . The polyisocyanate can be used in the range of about 0.5 to about 22% with a preferred range being about 0.7 to about 18% . The castor oil can be used in the range of about 0.4 to about 14.5% with a preferred range being about 0.5 to about 14%. Additional N-Butyl Acetate can be used in the range of about 24 to about 54% with a preferred range being about 30 to about 45%. iso-Butyl Acetate can be used in the range of about 24 to about 60% with a preferred range being about 30 to about 50%. All percentages are weight/weight.
Table 1 shows variations of coating D that were made and applied to balloons.
Table 1. Various Compositions of Coating D.
Figure imgf000009_0001
'Stock Butyl/Iso-Butyl Acetate solution was made by mixing Butyl Acetate (363.27 g), Iso- Butyl Acetate (381.58 g) and mineral spirits (19.32 g) in a clear bottle and rolling until homogeneous.
2Stock CAB solution was made by mixing Cellulose Ester (28.21 g) and Butyl Acetate (253.65 g) in a clear bottle and rolling for 24 hours.
Table 2 shows balloons dipped in the various formulations of coating D shown in Table 1. The burst pressure and hence the hoop tensile strength of the coated balloons was determined and compared to similar balloons that were not coated. The results show that the coatings of this invention do not reduce the hoop tensile strength of balloons.
Table 2 Hoop tensile Strength of Catheters with Coating D
Figure imgf000010_0001
Coating E
Coating E is a solvent based epoxy resin coating. Hardman Epoxy Part A (2.5 g) and Hardman Epoxy Part B (2.4 g) both available as Hardman Epoweld® 8173 from Elementis Performance Polymers, Belleville NJ were dissolved in toluene (4.9 g) to produce a 50% solution of solids. Serial dilutions were performed to produce coating solutions of 33%, 25% and 20% solids. Balloons were single dipped immediately after mixing.
Balloons were coated with coating E as outlined in Table 3 below. The burst pressure and hence the hoop tensile strength of the balloons coated with coating E was determined. The hoop tensile strength of the coated balloons was then compared to similar, uncoated balloons. The results show that the coatings of this invention do not reduce the hoop tensile strength of balloons.
Table 3. Hoop Tensile Strength of Balloons with Coating E
Figure imgf000011_0001
Polyurethane Coatings
A polyol (170 g), e.g. , Desmophen A 405A, available from Bayer Corp. Pittsburgh, PA, a polyisocyanate (44 g), e.g. , Modur CB-60 PMA, available from Bayer Corp. , and acetone (2014 g) can be mixed to produce a polyurethane coating. The polyol can be used in the range of about 2 to about 15%, with the preferred range being about 5 to about 10% . The polyisocyanate can be used in the range of about 0.5 to about 10%, with the preferred range being about 1 to about 5% . Acetone can be used in the range of about 80 to about 99%, with the preferred range being about 85 to about 95 % .
Acrylic Polymer Coatings
An acrylic polymer (4 g), e.g. , PMMA HI 835S, available from LG Chemical, is dissolved in tetrahydrofuran (96 g) available from Aldrich. Acrylic polymers like PMMA HI 835S can be used in the range of about 0.1 to about 25% with the preferred range being about 0.5 to about 10% . Epoxy Resin Coatings
An epoxy resin (60 g), e.g., Epon 828 Bis A Epoxy Resin, available from Shell Chemical, an acrylate modifier (25 g), e.g., M-Cure 200 Acrylate Modifier, available from Sartomer, and an acrylate modifier (15 g), e.g. , M-Cure 202 Acrylate Modifier, available from Sartomer, is mixed to produce part A of the epoxy resin. An amine (6 g), e.g. , EpiCure 3005 Amidoamine, available from Shell Chemical, and a second amine (16 g), e.g. , Ancamine 1638 Aliphatic Amine is mixed together to produce part B of the epoxy resin. Epoxy resins, e.g. , Epon 828 Bis A Epoxy Resin can be used in the range of about 45 to about 75% with the preferred range being about 48 to about 72% . Modifiers, e.g. , M-Cure 200 Acrylate Modifier can be used in the range of about 18 to about 32% with the preferred range being about 22.5 to about 27% . Modifiers, e.g. , M-Cure 202 Acrylate Modifier can be used in the range of about 11 to about 19% with the preferred range being about 13 to about 17% . Amines, e.g. , EpiCure 3005
Amidoamine can be used in the range of about 4 to about 8% with the preferred range being about 5 to about 7% . Amines, e.g. , Ancamine 1638 Aliphatic Amine can be used in the range of about 12 to about 20% with the preferred range being about 14 to about 18%. Equal parts of part A and part B can dissolved in two parts toluene. The mixture can then be serially diluted to produce coating mixtures.
A high durometer coating can be made as follows. Two epoxy resins, e.g. , AboCast 8-8 (100 g), available from Abatron, Kenosha, WI, AboCure 8-8 (100 g), available from Abatron, can be combined with toluene (100 g) to produce an epoxy coating. Typically the resins can be used in equal portions and toluene can be used in the range of about 10 to about 95%, with a preferred range being about 25 to about 75% .
EXAMPLE 2
Dipping Procedure
Dipping is the preferred method of coating because the thickness of l i ¬
the coat is more uniform and easier to control compared to other methods. For example, when coating a PET balloon, the balloon was first cleaned with acetone, isopropyl alcohol or the like. The balloon was then inflated to from about 2 to about 4 bars pressure and dipped into the coating mixture. Factors that affect the coating thickness and adhesion properties were the speed at which the article was introduced into and withdrawn from the mixture, the dwell time in the mixture and the number of times dipped into the coating mixture. The dwell time was found to influence the extent to which the coating was imbibed into the article surface. The down speed (inches/minute) can be over the range of about 1 to about 200 with a preferred range being about 40 to about 140. The dwell (seconds) time has no limit but typically is about 2 to about 40. The withdrawal rate (inches/minute) can be over the range of about 1 to about 200 with a preferred range being about 40 to about 140.
Typically, the double wall thickness of each balloon is first measured. The balloon is then cleaned with isopropyl alcohol, acetone or similar solvent and heat sealed at each end with about 2 to about 4 bars pressure inside the balloon. The ballon is dipped, distal end first, into the coating solution. After removal from the coating solution, the balloon is air-dried. For multiple dipping, the balloon was allowed to air-dry for 20 minutes between dips. The balloons were then placed in a drying oven to cure. After curring, the balloons were removed and the double wall thickness measured.
EXAMPLE 3
Durability Testing
Balloons were examined for durability using the following procedures. The device used for testing was specifically designed for balloon catheters and to represent the environment the balloon catheters are typically used in. The device consists of a series of stainless steel sleeves with internal diameters that match the balloon's nominal outer diameter (OD). A balloon's nominal OD is defined as the outer diameter of the balloon after it has been pressurized from the collapsed position to the inflated position that is free of wrinkles (normally pressures are from about 50 to about 125 psi). Each sleeve has one screw ground to a 60° included taper down to a 0.0065 inch diameter flat. The screw can be extended 0.011 inches toward the center of the cylinder. The sleeve was placed in a submersible fixture and the deflated balloon loaded into the sleeve. The screw was adjusted to a length of 0.011 inches and the apparatus submerged into a body temperature water bath. The balloon catheter was attached to an inflation device i.e., burst machine and inflated to either 12 or 16 bars. If the balloon did not burst, it was deflated and reinflated repeatedly until the balloon burst. The table below compares coating thickness, DWT, inflation pressure and durability between similar, coated and uncoated balloons.
Table 4. Durability of Coatings A, B, C, D and E.
Figure imgf000015_0001
'Double wall thickness (DWT) is a measure of the thickness of the coating plus the wall thickness of the balloon catheter when the balloon is laid flat and both walls and the coating is measured. durability is measured by cyclically inflating the balloon catheter to a certain pressure in a 3.0 mm sleeve against a 0.011" pin.
3The uncoated balloons burst during the first inflation. Durability is defined as a coated balloon attaining at least one more cycle in the above-described test than a similar, uncoated balloon. A more preferred durability is greater than about 5 cycles more than an uncoated balloon and a most preferred durability is greater than about 10 cycles. A preferred range of durability 5 is about 5 to about 50 cycles and a more preferred range is about 10 to about 20 cycles. Typically the testing is done from about 12 bar to about 16 bar which is the working pressure of the balloon. The testing can be done at pressures ranging from about the nominal pressure of the balloon to about the busting pressure of the 10 balloon.
EXAMPLE 4
A length of PET balloon tubing was dipped into polyurethane solution
15 D. It was then allowed to air dry approximately 20 minutes, followed by baking at
120° F for 480 minutes. The coated tube was then formed into a balloon. The resulting product was a balloon catheter with durability (as measured by cyclic penetrations with a pointed probe to measure puncture resistance) greater than a jr. catheter without above coating.
EXAMPLE 5
Hoop Tensile Strength Testing
25 Hoop tensile strength also known as Hoop Stress was determined as follows. A balloon at body temperature was attached to a burst machine and inflated to the point at which the balloon ruptures. The Hoop Stress was then calculated by the following equation: 0
HS = (Force @ Break (psi)) (Balloon Diameter)
2(Wall Thickness)
For example, the Hoop Stress of a balloon of 3 mm diameter with a wall thickness of 5 0.0005 inches that ruptures at 20 bar is calculated as follows:
HS = (20 bar) (14.7 psi/bar) (3.0 mm/25.4 mm/in)
2(0.0005 in)
which calculates as a Hoop Stress of 34,720 psi.

Claims

We claim:
1. A coated medical device having a hoop tensile strength of about 10,000 psi or greater, wherein the coating has a thickness of between about 0.02 and about 0.5 mils and wherein the coated medical device has a greater durability than a similar uncoated medical device.
2. The coated medical device according to claim 1, wherein the coating comprises polyurethane.
3. The coated medical device according to claim 1, wherein the coating comprises acrylic polymer.
4. The coated medical device according to claim 1, wherein the coating comprises epoxy resin.
5. A coating for a polymeric medical device having a hoop tensile strength of about 10,000 psi or greater that imparts durability to the medical device, wherein the coating does not reduce the hoop tensile strength and has a thickness of between about 0.02 and about 0.5 mils.
6. The coating of claim 6, wherein the coating comprises polyurethane.
7. The coating of claim 6, wherein the coating comprises acrylic polymer.
8. The coating of claim 6, wherein the coating comprises an epoxy resin.
9. A method of increasing durability of a polymeric medical device, wherein a coating of between about 0.02 and about 0.5 mils is applied to the medical device. o
10. The method according to claim 11, wherein the coating comprises polyurethane.
11. The method according to claim 11, wherein the coating comprises polyacrylic.
12. The method according to claim 11, wherein the coating comprises epoxy resin.
13. A coated medical device having a substrate, wherein the coating has a thickness of about 0.02 to about 0.45 mils, and wherein the substrate has a double wall thickness of about 0.5 to about 0.9 mils and wherein the coating provides the coated medical device with a durability of at least 1 cycle at at least 12 bars pressure.
14. The coating of claim 13, wherein the durability is at least 1 to about 76 cycles.
PCT/US1998/009495 1997-05-08 1998-05-08 Improved medical device having desirable combination of properties and method of making same WO1998050087A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009048759A1 (en) 2007-10-09 2009-04-16 Ethicon, Inc. Antimicrobial polymer compositions and the use thereof
EP3409302A1 (en) 2009-09-29 2018-12-05 Ethicon, Inc. Antimicrobial/antibacterial medical devices coated with traditional chinese medicines

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0274411A2 (en) * 1987-01-09 1988-07-13 C.R. Bard, Inc. Thin wall high strength balloon and method of manufacture
US5041100A (en) * 1989-04-28 1991-08-20 Cordis Corporation Catheter and hydrophilic, friction-reducing coating thereon
EP0592870A1 (en) * 1992-09-30 1994-04-20 C.R. Bard, Inc. Process for preparing functionally coated expanded products from expandable tubing and the expanded products produced thereby

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0274411A2 (en) * 1987-01-09 1988-07-13 C.R. Bard, Inc. Thin wall high strength balloon and method of manufacture
US5041100A (en) * 1989-04-28 1991-08-20 Cordis Corporation Catheter and hydrophilic, friction-reducing coating thereon
EP0592870A1 (en) * 1992-09-30 1994-04-20 C.R. Bard, Inc. Process for preparing functionally coated expanded products from expandable tubing and the expanded products produced thereby

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009048759A1 (en) 2007-10-09 2009-04-16 Ethicon, Inc. Antimicrobial polymer compositions and the use thereof
US8691899B2 (en) 2007-10-09 2014-04-08 Ethicon, Inc. Antimicrobial polymer compositions and the use thereof
EP3409302A1 (en) 2009-09-29 2018-12-05 Ethicon, Inc. Antimicrobial/antibacterial medical devices coated with traditional chinese medicines

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