Medical device balloons with improved strength properties and processes for producing same

Abstract

A tubular parison for forming a medical device balloon. The parison is formed of a polymeric material, for instance a thermoplastic elastomer. The parison has an elongation at break which is not more than 80% of the elongation of the bulk polymeric material. The elongation of the parison is controlled by altering extrusion conditions. Balloons prepared from the parisons provide higher wall strength and/or higher inflation durability than balloons prepared from conventional parisons of the same material.

1 . A method of making a parison for forming a medical device balloon, the method comprising extruding a tube of polymeric material from an extruder having a barrel where the mixture is kept in a molten state at a barrel temperature and a die zone where the molten material is pushed through a die to form the tube, wherein the die zone is kept at a temperature at least about 5° F. below the barrel temperature, to form an extruded tubular balloon parison. 
     
     
         2 . A method as in  claim 1 , wherein said die zone temperature is about 10-40° F. below the barrel temperature. 
     
     
         3 . A method as in  claim 1 , wherein said die zone temperature is about 20-30° F. below the barrel temperature. 
     
     
         4 . A method as in  claim 1 , wherein the barrel temperature is about 395° F. 
     
     
         5 . A method as in  claim 1 , further comprising extruding the tube of polymeric material at a drawn down ratio of about 5 or higher. 
     
     
         6 . A method as in  claim 1 , further comprising extruding the tube of polymeric material at a draw down ratio of about 8 or higher. 
     
     
         7 . A method as in  claim 1 , further comprising extruding the tube of polymeric material at a drawn down ratio of about 17 or higher. 
     
     
         8 . A method as in  claim 1 , further comprising longitudinally pre-stretching the extruded tubular balloon parison at a ratio of about 1.5 times or higher. 
     
     
         9 . A method as in  claim 1 , further comprising longitudinally pre-stretching the extruded tubular balloon parison at a ratio of about 3 times or higher. 
     
     
         10 . A method as in  claim 1 , wherein the tube of polymeric material has an elongation at break which is not more than 80% of the elongation at break of the bulk polymeric material. 
     
     
         11 . A method as in  claim 1 , wherein the elongation at break of the polymeric material is not more than about 70% of the elongation at break of the bulk polymeric material. 
     
     
         12 . A method as in  claim 1  wherein the tube of polymeric material comprises a thermoplastic elastomer polymeric material. 
     
     
         13 . A method as in  claim 1  wherein the tube of polymeric material comprises a polyamide/polyether/polyester, a polyester/polyether block copolymer, a polyamide/polyether block copolymer, a polyurethane block copolymer or a mixture thereof. 
     
     
         14 . A method as in  claim 1 , wherein the tube of polymeric material comprises a polyamide/polyether block copolymer. 
     
     
         15 . A method as in  claim 1 , wherein the tube of polymeric material is formed with a single layer of said polymeric material. 
     
     
         16 . A method as in  claim 1 , wherein the tube of polymeric material comprises two or more layers of a polymeric material. 
     
     
         17 . A method as in  claim 1 , further comprising radially expanding the extruded tubular balloon parison in a balloon mold to form the medical device balloon. 
     
     
         18 . A method as in  claim 17 , wherein the medical device balloon is formed of at least one thermoplastic elastomer polymeric material and has a tensile wall strength of about 34,000 psi or more in a pre-sterilized condition. 
     
     
         19 . A method as in  claim 17 , wherein the medical device balloon is formed of at least one thermoplastic elastomer polymeric material and has a tensile wall strength of about 32,000 psi or more, in a post-sterilized condition. 
     
     
         20 . A method of making a parison for forming a medical device balloon, the method comprising extruding a tube of polymeric material from an extruder having a barrel where the mixture is kept in molten state at a barrel temperature and a die zone where the molten material is pushed through a die to form the tube, wherein the die zone is kept at a temperature at least about 5° F. below the barrel temperature, to form an extruded tubular balloon parison, wherein the tube of polymeric material is extruded at a drawn down ratio of about 5 or higher.