Medical device tubing with discrete orientation regions
View Patent ↗Medical device polymeric tubing segments suitable for forming catheter shafts or as balloon parisons are formed with discrete regions having different orientation relative to each other. Wall thickness may also be varied of the length of the segment.
1. A method of making a parison for forming a medical device balloon in which portions of the parison are slated to form cone and waist portions of the balloon and a portion is slated to form the balloon body, the method comprising a step of extruding polymeric material to form a tube, and forming the parison having said slated portions from the tube, wherein the extruding step is controlled to provide the extruded tube with a varying longitudinal orientation, such that the slated parison formed therefrom has variation providing a lower or higher orientation for the cone and waist slated portions of the parison relative to the portion slated to form the balloon body, and said variation provides one of said portions with a elongation at yield which is at least 20% below the elongation at yield of another of said portions.
2. A method as in claim 1 wherein the extruding step is controlled to provide the portion slated to form the body with a higher relative longitudinal orientation, the portions slated to form the waists of the balloon with a lower relative longitudinal orientation and the portions slated to form the cones of the balloon with a varying longitudinal orientation ranging between the higher and the lower relative orientations.
3. A method as in claim 1 wherein the extruding step is controlled to provide the extruded tube with a varying wall thickness, the variation providing a lower wall thickness for the cone and waist slated portions of the parison relative to the portion slated to form the balloon body.
4. A method of forming a polymeric tubing segment for a medical device comprising extruding a tube of polymeric material through a die and cooling the extruded tubing by drawing it through a cooling region spaced at a gap length from the die to the cooling bath, wherein the drawing rate, or the gap length, or the cooling rate of the cooling region, or any combination thereof, is altered along the length of the segment, whereby the segment is formed with at least two regions along the length thereof, a first of said regions and a second of said regions having different elongation at yield properties relative to each other and wherein
said alteration of the drawing rate, or the gap length, or the cooling rate of the cooling region, or combination thereof, is selected on the basis of the elongation at yield properties of said first and second regions and said alteration is selected to provide one of said regions with a elongation at yield which is at least 20% below the elongation at yield of another of said regions.
5. A method of forming a polymeric tubing segment for a medical device comprising extruding a tube of polymeric material through a die and cooling the extruded tubing by drawing it through a cooling region spaced at a gap length from the die to the cooling bath, wherein the drawing rate, or the gap length, or the cooling rate of the cooling region, or any combination thereof, is altered along the length of the segment, whereby the segment is formed with at least two regions along the length thereof, a first of said regions and a second of said regions having different elongation at yield properties relative to each other and wherein
said alteration of the drawing rate, or the gap length, or the cooling rate of the cooling region, or combination thereof, is selected on the basis of the elongation at yield properties of said first and second regions and said alteration is selected to provide one of said regions with a elongation at yield which is 30% below the elongation at yield of another of said regions.