Non-crosslinked heat shrinkable tubing

Abstract

A non-crosslinked polymeric heat shrink tubing comprising poly(ether-block-amide) (PEBA) and a method for making such non-crosslinked polymeric heat shrink tubing are provided. The non-crosslinked PEBA heat shrink tubing disclosed herein finds application, for example, as a processing aid and final component in the manufacture of catheters and other medical devices.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This application relates to heat shrinkable polymer tubing and methods for making said heat shrinkable polymer tubing for inclusion as a component in a catheter assembly. [Background technology]

[0002] Tubing made from poly(ether-block-amide) (PEBA) resin is currently used as the outer sheath of many commercially available catheter shafts. Catheters are used to provide an intravenous pathway for the shaft, which can then deliver medical devices or medications into the body once the shaft is in place during a medical procedure.

[0003] Catheters often include an internal passageway lining made of a lubricious material, such as polytetrafluoroethylene (PTFE), to facilitate insertion and withdrawal of medical devices. A reinforcing member often surrounds the lubricious internal passageway of the catheter shaft, providing strength, pushability, and torque translation. This reinforcing member can be constructed of several different materials, depending on the intended function and specifications of the finished catheter.

[0004] Materials commonly used as reinforcing members in catheter shafts include metal or polymer hypodermic tubing (also referred to herein as "hypotubing"), metal wire braids or coils, liquid crystal polymer (LCP) fiber braids, and other polymer fibers braided or otherwise incorporated into the composite structure of the catheter shaft. The outer sheath, also referred to herein as the catheter jacket, serves several functions as a component of this composite catheter shaft.

[0005] The jacket provides durability by covering and protecting the outer surface of the reinforcement member. The jacket also provides a barrier defining the outer surface of the catheter, preventing leakage of fluids, drugs, devices, and other therapeutic agents along the length of the shaft. It is desirable for catheter jackets to have a glossy outer surface finish to provide smooth, abrasion-free transmission through the vascular system during use during a medical procedure.

[0006] Catheter jackets are typically constructed from polymers such as polyamides, polyurethanes, polyolefins, or poly(ether-block-amide) copolymers (PEBA), which are commercially available as medical-grade extrusion resins. These resins can be converted into a tubular shape by melt extrusion and then used with processing aids (often referred to as "fusion sleeves") to provide an outer sheath for the catheter shaft.

[0007] Catheter shafts are typically manufactured utilizing fluorinated ethylene propylene (FEP) heat shrink tubing as a processing aid to form the outer jacket and bond underlying components to complete the catheter shaft construction. Such heat shrink tubing has been commercially manufactured for decades using a variety of processes, such as vacuum expansion, gas compression molding, and continuous heating / stretching. For known methods of expanding heat shrink tubing, see, for example, U.S. Pat. No. 2,987,767 to Edwards et al., U.S. Pat. No. 3,412,189 to Sullivan, U.S. Pat. No. 7,625,194 to Yoshida et al., U.S. Pat. No. 9,296,165 to Henson, U.S. Pat. No. 9,327,444 to Henson, and U.S. Pat. No. 9,440,044 to Ruf et al.

[0008] The conventional catheter manufacturing process, also known as the "reflow process," is well known to those skilled in the art. During the reflow process, FEP heat shrink tubing or "fused sleeve" is placed over a pre-assembled set of catheter shaft components (i.e., a "catheter shaft pre-assembly" or "pre-assembly") and then heated to complete the construction of the catheter shaft.

[0009] A catheter shaft pre-assembly typically consists of several components: a solid core, a thin-walled, lubricious liner tube, a stiffening member, and an outer sheath tube. Preparing the pre-assembly can include providing a solid core that is inserted into a thin-walled, lubricious liner tube (also referred to herein as a "lubricious liner" or simply "liner"). The lubricious liner typically comprises a thin-walled polytetrafluoroethylene (PTFE) tube with a modified outer surface (e.g., a PTFE tube with an etched outer surface, such as a sodium etch, to enable bonding with other materials).

[0010] A reinforcing member can then be applied onto the exterior surface of the liner (e.g., a braid, wire coil, or hypotube structure can be applied onto the exterior surface of the liner). It is important to note that a reinforcing member is not necessarily utilized in the construction of a catheter shaft, especially for catheter shafts that do not require specific internal pressure resistance (i.e., burst resistance).

[0011] After the reinforcing member is secured to the outside (i.e., on the exterior surface) of the liner, an outer sheath tubing (e.g., medical-grade PEBA tubing) can be applied over the reinforcing member to provide a catheter shaft pre-assembly. The pre-assembly (i.e., solid core, thin-walled liner tubing, reinforcing member, and outer sheath tubing) can then be inserted into FEP heat shrink tubing and heated to form an outer jacket tubing, which can then be bonded to the underlying components to complete the catheter shaft.

[0012] This is an effective method for manufacturing catheter shafts because the recovery (i.e., "shrink") temperature of the FEP heat shrink tubing is higher than the crystalline melting temperature of the outer sheath tubing. When the pre-assembly and fused sleeve are heated, the PEBA outer sheath tubing melts and is forced to flow radially inward by the dimensional recovery of the FEP heat shrink tubing, making intimate contact with the underlying components.

[0013] In this way, the strong recovery force exerted by the FEP heat shrink tubing as it is heated (i.e., as its diameter decreases) causes the molten PEBA tubing to "reflow" within the crevices or gaps in the reinforcement members, and after cooling, forms a strong bond between the inner surface of the outer sheath tubing and the outer surface of the inner liner. Outer sheath tubing comprising polymers other than PEBA can be used in conjunction with the reflow process described.

[0014] Other materials used as the outer sheath in this reflow process can include, for example, polyamide, polyurethane, and polyolefin. After the assembly cools, the FEP heat shrink tubing is removed and discarded. Finally, the solid core that maintained the lumen shape during reflow is removed, leaving the final catheter shaft. A general schematic of a typical conventional reflow process 10 is shown in Figure 1.

[0015] The reflow process employs many different heating methods, including but not limited to forced air ovens, hot boxes, induction heaters, heat guns, traverse laminators, lasers, and glow rings. In the construction of catheter shafts utilizing coiled or braided reinforcing components, the outer jacket tubing is often designated during the reflow process to flow and fill all gaps / gaps between the underlying reinforcing members and bond to the outer surface of the inner liner, forming a continuous composite structure.

[0016] This type of design often requires a certain level of pressure (i.e., burst) resistance. If the gaps in the reinforcing members are not fully filled by the outer jacket tube during the reflow process, air pockets or "bubbles" remain embedded within the composite structure, known as voids. Voids can, in some cases, adversely affect the durability and pressure resistance of the finished catheter shaft.

[0017] It is also important that the reflow process provides a strong bond between the PEBA outer jacket and the liner tube. In certain circumstances, delamination of the bond between the outer sheath tube and the inner liner tube is unacceptable because the thin-walled inner liner tube can kink or wrinkle in tortuous vascular pathways. This can impede or ultimately prevent delivery of the medical device or drug through the lumen.

[0018] Catheter shafts are often designed with varying flexibility along their length to balance functionality and optimize performance at the proximal and distal ends. Generally, the distal end of the catheter is preferably soft and flexible to allow maneuverability through the vascular pathway.

[0019] Conversely, it is desirable for the proximal portion of the catheter shaft to be stiffer (i.e., more rigid) than the distal end to provide pushability (i.e., columnar stiffness to aid advancement and retraction) and predictable torque translation. This balance of functionality is typically achieved by utilizing multiple outer sheath tubes of varying durometer hardness (i.e., PEBA tubing manufactured with different resin grades) along the length of the catheter shaft.

[0020] Medical-grade tubing composed of, consisting essentially of, or including PEBA resin as part of a blend can vary significantly in durometer and flexibility depending on the final composition of the tubing. For example, medical-grade PEBA resin manufactured by Arkema Inc. and sold commercially as PEBAX MED® has a durometer ranging from about 25 Shore D to 74 Shore D and a flexural modulus ranging from about 12 MPa to 700 MPa.

[0021] See Arkema's Pebax® Elastomers Catalog, incorporated by reference. Variable stiffness catheters are currently manufactured using conventional manufacturing techniques that use FEP heat shrink tubing as a processing aid. After the reinforcing member is applied to the top layer of the inner liner (i.e., the outer surface of the inner liner), PEBA tubing spanning a range of durometers can be successively slid over the reinforcing member and subsequently reflowed to impart the desired flexibility to each section of the catheter shaft, forming a multi-durometer catheter shaft. This allows catheter manufacturers to tailor the properties of the finished shaft to specific applications by varying the length and composition of the outer jacket.

[0022] To complete the construction of the multi-durometer catheter, the prepared components are inserted into an FEP fused sleeve, which is subsequently heated to melt and reflow the outer sheath tubing, providing a catheter with sections of varying flexibility (i.e., durometer hardness). It is important to note that the circumferential mechanical forces exerted by the FEP fused sleeve (i.e., as the sleeve "shrinks" above the melting point of the underlying outer sheath tubing) cause coalescence at the outer sheath tubing interfaces, providing a smooth transition between sections.

[0023] Another approach to achieving variable flexibility along the length of a catheter shaft involves varying the stiffness of the reinforcing member. This can be achieved by varying the braid material and pattern along the length, but is more fully customizable using laser-cut hypotubes.

[0024] These hypotubes are constructed from metallic or polymeric materials and typically have a varying or transitional cut pattern along their length. Many commercially available laser-cut hypotubes are helical and contain continuous or interrupted cut patterns along their length.

[0025] The helical laser cut pattern can be continuous or abrupt in cut pitch, cut width, cut spacing, and other characteristics along the length of the shaft. A wide variety of hypotubes are known in the art and can be used in accordance with the present disclosure.

[0026] For catheter shafts that contain laser-cut hypotubes as a reinforcing member, it is undesirable for the outer jacket to flow through the laser-cut gaps, as this would alter the variable flexibility built into the cut pattern design. Using traditional catheter manufacturing techniques, including FEP heat shrink, for these types of catheter shafts presents significant challenges for medical device manufacturers and designers.

[0027] The use of FEP heat shrink tubing adds significant material costs to the catheter manufacturing process. The development and optimization of the dimensional and recovery properties of the FEP fused sleeve must be optimized for specific catheter shaft constructions, often through third-party suppliers, which can be very costly and time-consuming.

[0028] Some of these optimizations include sizing, the required recovery rate, and adjusting recovery conditions to provide void elimination and a good bond between the jacket and inner liner. The labor and tooling required to remove FEP heat shrink tubing also contribute to increased operating costs.

[0029] Additionally, the need to remove the FEP fused sleeve after the reflow process can damage and potentially waste the finished catheter shaft, and the resulting FEP material scrap is at odds with the goals of a circular economy. Summary of the Invention

[0030] The present disclosure relates to heat-shrinkable polymeric tubing comprising one or more polymers that are not cross-linked. In some embodiments, the present disclosure relates to heat-shrinkable ("heat shrink") tubing comprising poly(ether-block-amide) copolymer (PEBA), wherein the PEBA is not cross-linked.

[0031] Typically, such heat shrink tubing is in the form of an extruded and expanded molded tube. Surprisingly, it has been found that certain such extruded tubes can be expanded to form heat shrink tubing without a crosslinking step.

[0032] Such heat shrink tubing can continue to be used as the outer jacket of the catheter shaft during the catheter shaft assembly process, without the need for expensive disposable manufacturing aids such as FEP heat shrink tubing. Due to favorable conditions for expansion, recovery ratio, and time / temperature profile of the recovery process, satisfactory catheter shafts can be manufactured using tubing containing non-crosslinked PEBA, eliminating the need to remove disposable manufacturing aids before use.

[0033] Several catheter shaft configurations, including various components, can be assembled utilizing such heat shrink tubing as an outer jacket, under conditions described in more detail below.

[0034] The present invention includes, but is not limited to, the following embodiments. Embodiment 1: A heat shrink tubing comprising a non-crosslinked PEBA, the heat shrink tubing having a recovery ratio (RR) of greater than about 1.05:1 and / or an inside diameter (ID) shrinkable by about 4.8%.

[0035] Embodiment 2: The heat shrink tubing of embodiment 1, which is based on non-crosslinked PEBA.

[0036] Embodiment 3: The heat shrink tubing of any of embodiments 1-2, wherein the RR is greater than about 1.10:1 and / or the inside diameter (ID) is shrinkable by about 9.1%.

[0037] Embodiment 4: The heat shrink tubing of any of embodiments 1-3, wherein the RR is greater than about 1.2:1 and / or the inside diameter (ID) is shrinkable by about 16.7%.

[0038] Embodiment 5: The heat shrink tubing of any of embodiments 1-4, wherein the RR is greater than about 1.3:1 and / or the inside diameter (ID) is shrinkable by about 23.1%.

[0039] Embodiment 6: The heat shrink tubing of any of embodiments 1-5, wherein the RR is greater than about 1.4:1 and / or the inside diameter (ID) is shrinkable by about 28.6%.

[0040] Embodiment 7: The heat shrink tubing of any of embodiments 1-6, wherein the RR is greater than about 1.5:1 and / or the inside diameter (ID) is reducible by about 33.3%.

[0041] Embodiment 8: The heat shrink tubing of any of embodiments 1-7, wherein the RR is greater than about 1.6:1 and / or the inside diameter (ID) is reducible by about 37.5%.

[0042] Embodiment 9: The heat shrink tubing of any of embodiments 1-8, wherein a durometer hardness measurement according to ASTM D2240 performed on a flat specimen produced by melt pressing the heat shrink tubing in an expanded form is about 20-80 Shore D.

[0043] Embodiment 10: A heat shrinkable tube according to any one of embodiments 1 to 9, recovered on a PTFE liner, such as a surface-modified PTFE liner.

[0044] Embodiment 11: The heat shrink tubing of any of embodiments 1-9, recovered on a laser cut hypotube.

[0045] Embodiment 12: The heat shrink tubing of either embodiment 10 or 11, wherein the heat shrink tubing exhibits a cohesive failure mode when peeled from the underlying PTFE liner or laser-cut hypotube.

[0046] Embodiment 13: A heat shrinkable tube according to any of embodiments 10 to 12, wherein after recovery, the outer surface is modified, for example by passing the tube through a heated die to modify the surface smoothness (to provide a smooth outer surface or a textured / surface-treated surface), thereby changing or enhancing the sliding properties of the material.

[0047] Embodiment 14: A heat shrink tube according to any one of embodiments 1 to 13, further comprising a liquid or polymer coating on the outer surface of the tube that enhances the lubricity or chemical resistance of the tube.

[0048] Embodiment 15: The heat shrink tubing of embodiment 14, wherein the liquid or polymer coating is hydrophobic.

[0049] Embodiment 16: A catheter comprising the non-crosslinked heat-shrinkable tube according to any one of embodiments 1 to 9.

[0050] Embodiment 17: The catheter of embodiment 16, wherein the catheter is selected from the group consisting of a guide catheter, a microcatheter, a balloon catheter, and a steerable delivery catheter.

[0051] Embodiment 18: A method of making the heat shrink tubing of any of embodiments 1-15, comprising extruding PEBA resin into a tubular shape and expanding the tubular shape.

[0052] Embodiment 19: A method of assembling a catheter, comprising providing a catheter pre-assembly comprising a solid core, a liner comprising PTFE, a reinforcing member, and a heat shrink tube as described in any of embodiments 1 to 9, and heating the catheter pre-assembly, the method not including the step of applying additional heat shrink tube over the heat shrink tube.

[0053] Embodiment 20: A composition comprising: a first tube selected from a liner comprising PTFE and a laser-cut hypotube; and a second tube disposed on the first tube, wherein the second tube is the heat-shrinkable tube of any of embodiments 1 to 15.

[0054] Embodiment 21: A composition comprising: a first tube selected from a liner comprising PTFE and a laser-cut hypotube; and a second tube disposed on the first tube, wherein the second tube comprises non-crosslinked PEBA.

[0055] Embodiment 22: The composition of embodiment 21, wherein the second tube is a heat shrink tube in an expanded form.

[0056] Embodiment 23: The composition of embodiment 21, wherein the second tube is a heat shrink tube in a recovered form.

[0057] Embodiment 24: The composition of any of embodiments 20-23, wherein the second tube consists essentially of non-crosslinked PEBA.

[0058] Embodiment 25: The composition of any of embodiments 20-24, wherein the first tube is a liner comprising PTFE, the liner having an etched outer surface.

[0059] Embodiment 26: The composition of any of embodiments 20-25, wherein the first tube is a liner comprising PTFE, and further comprising a reinforcing member between the first tube and the second tube.

[0060] Embodiment 27: The composition of embodiment 26, wherein the reinforcing member is selected from the group consisting of a braid, a coil, or a hypotube.

[0061] Embodiment 28: The composition of any of embodiments 20 to 27, further comprising a tie layer.

[0062] Embodiment 29: The composition of any of embodiments 20-28, wherein the composition exhibits a cohesive failure mode when the first tube is peeled from the second tube.

[0063] It will be apparent to those skilled in the art that other embodiments of the present invention are possible and that the examples set forth herein are not intended to be exhaustive. These and other features, aspects, and advantages of the present disclosure will become apparent from a reading of the following detailed description in conjunction with the accompanying drawings, which are briefly described below. The present disclosure includes any combination of two, three, four, or more features or elements described in this disclosure or recited in any one or more of the claims, regardless of whether such features or elements are explicitly combined or recited in the description or claims of a particular embodiment. The present disclosure is intended to be read in its entirety such that separable features or elements of the disclosure are deemed combinable in any of its aspects and embodiments, unless the context of the disclosure clearly dictates otherwise.

[0064] To provide an understanding of embodiments of the present invention, reference is made to the accompanying drawings, which are not necessarily drawn to scale and in which reference numerals refer to components of exemplary embodiments of the present invention. The drawings are merely illustrative and should not be construed as limiting the present invention. [Brief explanation of the drawings]

[0065] [Figure 1A] FIG. 1A is a generalized schematic diagram of an exemplary reflow catheter shaft manufacturing method 10 according to one embodiment of the present disclosure. [Figure 1B] FIG. 1B is a general schematic diagram of a catheter shaft manufacturing method 20 with recovery according to one embodiment of the present disclosure. [Figure 2] 2 is a cross-sectional view of a typical reinforced single lumen catheter assembly after heating step 16 of reflow process 10 and prior to removal of FEP heat shrink melt sleeve 40. The layers of the composite structure are solid core / mandrel / lumen 32, thin-walled liner 34, reinforcing member 36, outer jacket 38, and FEP heat shrink manufacturing aid 40. [Figure 3] 3 is a cross-sectional view of an example of a reinforced single lumen catheter assembly after heating step 24 of recovery process 20, which bonds the non-crosslinked PEBA heat shrink to the outer surface of the underlying components. The layers of the composite structure are a solid core / mandrel / lumen 32, a thin-walled liner 34, a reinforcing member 36, and a non-crosslinked PEBA heat shrink outer jacket 44. [Figure 4]Figure 4 illustrates the definition of adhesive failure modes 50 and cohesive failure modes 60 observed in bond tests performed on sections prepared from the unreinforced catheter shaft described herein, according to certain embodiments of the present disclosure. A PEBA outer jacket tube 56 was bonded to a modified outer surface 54 of a PTFE liner tube 52 using a typical reflow catheter shaft manufacturing method 10 for a non-heat-shrinkable outer jacket or a recovery catheter shaft manufacturing method 20 for a heat-shrinkable outer jacket. Prior to bonding, an aluminum foil tab 58 was placed between the PEBA tube 56 and the modified outer surface 54 of the PTFE liner tube 52 to prevent bonding at the end of the sample and to provide a tab for peeling the layers. A single longitudinal slit was cut with a razor blade through one wall of the prepared length of unreinforced catheter shaft and flattened to obtain a roughly rectangular peel specimen. The test specimens were then manually peeled and visually inspected to determine whether adhesive failure mode 50 or cohesive failure mode 60 occurred upon peeling the interface between the modified outer surface 54 of the PTFE liner tube 52 and the PEBA tube 56. [Figure 5A] Figure 5A is a microscopic image captured during the examination of Example 10, i.e., 5 French stainless steel laser cut hypotube covered with the non-crosslinked PEBA heat shrink tubing of Example 9 using recovery method 20. Figure 5A was obtained at 50x magnification. [Figure 5B] Figure 5B is a microscopic image captured during the examination of Example 10, i.e., 5 French stainless steel laser cut hypotube covered with the non-crosslinked PEBA heat shrink tubing of Example 9 using recovery method 20. Figure 5B was obtained at 100x magnification. [Figure 6A] Figure 6A is a microscopic image captured during examination of Comparative Example 6, i.e., a 5 French stainless steel laser-cut hypotube that was covered with the non-crosslinked PEBA heat shrink tubing of Example 9 and an appropriately sized FEP heat shrink fusion sleeve using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. Figure 6A was obtained at 50x magnification. [Figure 6B] Figure 6B is a microscopic image captured during examination of Comparative Example 6, i.e., a 5 French stainless steel laser-cut hypotube that was covered with the non-crosslinked PEBA heat shrink tubing of Example 9 and an appropriately sized FEP heat shrink fusion sleeve using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. Figure 6B was obtained at 100x magnification. [Figure 7A] Figure 7A is a microscopic image captured during the examination of Example 11, i.e., 2.75 French stainless steel laser-cut hypotube covered with the non-crosslinked PEBA heat shrink tubing of Example 8 using recovery method 20. Figure 7A was obtained at 50x magnification. [Figure 7B] Figure 7B is a microscopic image captured during the examination of Example 11, i.e., 2.75 French stainless steel laser-cut hypotube covered with the non-crosslinked PEBA heat shrink tubing of Example 8 using recovery method 20. Figure 7B was obtained at 100x magnification. [Figure 7C] Figure 7C is a microscopic image captured during the examination of Example 11, i.e., 2.75 French stainless steel laser-cut hypotube covered with the non-crosslinked PEBA heat shrink tubing of Example 8 using recovery method 20. Figure 7C was obtained at 200x magnification. [Figure 8A] Figure 8A is a microscopic image captured during examination of Comparative Example 7, i.e., 2.75 French stainless steel laser-cut hypotube that was covered with the non-crosslinked PEBA heat shrink tubing of Example 8 and an appropriately sized FEP heat shrink fusion sleeve using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. Figure 8A was obtained at 50x magnification. [Figure 8B]Figure 8B is a microscopic image captured during examination of Comparative Example 7, i.e., 2.75 French stainless steel laser-cut hypotube that was covered with the non-crosslinked PEBA heat shrink tubing of Example 8 and an appropriately sized FEP heat shrink fusion sleeve using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. Figure 8B was obtained at 100x magnification. [Figure 8C] Figure 8C is a microscopic image captured during examination of Comparative Example 7, i.e., 2.75 French stainless steel laser-cut hypotube that was covered with the non-crosslinked PEBA heat shrink tubing of Example 8 and an appropriately sized FEP heat shrink fusion sleeve using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. Figure 8C was obtained at 200x magnification. [Figure 9] FIG. 9 is a microscopic image at 50x magnification captured during testing of Example 12, i.e., a braided reinforced catheter shaft covered with the non-crosslinked PEBA heat shrink tubing of Example 4 using recovery method 20. [Figure 10] Figure 10 is a microscopic image at 50x magnification captured during testing of Comparative Example 8, i.e., a braided reinforced catheter shaft covered with the non-crosslinked PEBA heat shrink tubing of Example 4 and an appropriately sized FEP heat shrink fusion using a conventional reflow method 10. The FEP heat shrink fusion sleeve was stripped from the construction prior to microscopic examination. DETAILED DESCRIPTION OF THE INVENTION

[0066] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0067] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It will also be understood that the terms "comprises" and / or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0068] The present disclosure provides heat shrink tubing with unique properties and unique combinations of properties, as further outlined herein. Generally, heat shrink tubing is a shrinkable tube prepared by expanding a polymeric ("input") tube (e.g., extruded tubing) to provide the heat shrink tubing (also referred to herein as the "expanded" form). Upon heating, the heat shrink tubing "shrinks" to a size equivalent to (or close to) its original / input size, commonly referred to as the "recovered" size. The composition and overall size of heat shrink tubing according to the present disclosure can vary widely and are not particularly limited. Heat shrink tubing can be defined by measurable properties such as, for example, its inner diameter ("ID") either after expansion (also referred to herein as the "expanded inner diameter" (IDe)) or after recovery (also referred to herein as the "recovered inner diameter" (IDr)), its length (L), the change in length upon recovery (i.e., the rate of change in length upon recovery, ΔL), its average wall thickness, its wall thickness concentricity (also referred to herein as concentricity or simply concentricity), its expansion rate (ER), its recovery rate (RR), and the rate of change in inner diameter upon recovery (ΔID). Such properties can be defined using the following equations:

number

number

number

number

number

[0069] In these equations, Le and Lr are the length of the heat shrink tubing (in its expanded state) and the length of the "recovered" (i.e., heat-shrunk) tubing, respectively. IDo refers to the original inner diameter (ID) of the input tubing (i.e., the tubing before it was expanded and then "shrunk").

[0070] IDe refers to the inside diameter (ID) of the expanded heat shrink tubing, and IDr refers to the inside diameter (ID) of the restored (heat shrunk) tubing. The values ​​needed to determine concentricity are the minimum and maximum wall thicknesses of the tubular wall, wt min and wt max RR, ΔL, and ΔID can be evaluated under any recovery condition (i.e., heating time, temperature, and method), but the time and temperature at which the expanded tube recovers must be determined, as this may affect the degree of recovery observed (i.e., expanded tubes exposed to lower temperatures and / or shorter times may not fully recover their capacity).

[0071] Concentricity can be evaluated in either the expanded or recovered state. Concentricity is a measure of the uniformity of wall thickness, and concentricity values ​​can affect performance in a particular application in both states. The above parameters used here were calculated as follows:

[0072] The percent change in length (ΔL), also referred to herein as longitudinal change, is determined as follows: Before placing the heat shrink tubing in an oven for indefinite recovery, a certified ruler is used to cut the expanded tubing to a length of 2.5 inches. Carefully cut a 2.5 inch long specimen from the heat shrink tubing to ensure it is free of burrs or other deformities and perpendicular to the longitudinal axis of the tubing.

[0073] After the unlimited recovery step at the specified temperature, re-measure the length of the tubing to the nearest 1 / 32 inch using a validated ruler to determine the amount of shrinkage or elongation that occurred during the step. For example, subtract the expanded length from the recovered length, divide by the expanded length, and then multiply this amount by 100 to determine the overall percent change in length due to recovery (ΔL).

[0074] Typically, ΔL is measured within about + / - 10% (i.e., the change in length upon recovery is less than about 10%). In some embodiments, the longitudinal change is measured within about + / - 9%, about + / - 5%, or about + / - 2%. In certain embodiments, the longitudinal change averages 2% or less.

[0075] The percent recovery (RR), percent change in inside diameter (ΔID), and concentricity are determined as follows: Three 2.5 inch long specimens are cut from the expanded tubing and the expanded inside diameter and wall thickness are measured using a validated measurement tool. To accurately determine the concentricity (i.e., uniformity of wall thickness) of the tubular wall, multiple wall thickness measurements must be taken. The minimum wall thickness measurement measured on the expanded tubing is divided by the maximum wall thickness measurement measured on the expanded tubing and multiplied by 100 to determine the percent concentricity of the expanded tubing.

[0076] The specimens are then placed in an oven set to the specified temperature for approximately 10 minutes. Each heat shrink tubing specimen is exposed to the specified recovery temperature for 10 minutes, then removed from the oven and allowed to cool to ambient temperature. This allows the expanded heat shrink tubing to be subjected to an unlimited recovery process. After cooling to ambient temperature, the recovered ID and wall thickness are measured using a validated measurement tool.

[0077] The recovery rate (RR) of the heat shrink tubing at the specified recovery conditions (i.e., recovery temperature and time) is calculated by dividing the expansion tube ID by the recovery tube ID. The rate of change of the heat shrink tubing's inner diameter is then calculated by subtracting the recovery tube ID from the expansion tube ID, dividing by the expansion tube ID, and multiplying this amount by 100 to obtain the overall rate of change of inner diameter (ΔID). The minimum wall thickness measurement taken on the recovery tube is divided by the maximum wall thickness measurement taken on the recovery tube and multiplied by 100 to obtain the concentricity of the recovery tube.

[0078] In some embodiments, the disclosed non-crosslinked heat shrink tubing comprises, consists essentially of, or consists of one or more polymers, such as polyamide, polyether, polyester, poly(ether-block-amide), or copolymer, blend, or derivative of any two or more of the foregoing. Examples of polymers according to the present disclosure include, but are not limited to, poly(ether-block-amide) (PEBA) (i.e., a block copolymer composed of polyamide segments (e.g., polyamide 6 (PA6), or polyamide 11 (PA11), or polyamide 12 (PA12)), polyether segments (e.g., polyoxymethylene (POM), or polyethylene glycol (PEG), or polypropylene glycol (PPG), or polytetramethylene glycol (PTMG))), which may, in some grades (e.g., poly(ethylene adipate) (PEA)), contain polyester segments.

[0079] In certain embodiments, non-crosslinked heat shrink tubing comprising PEBA is provided. When referring to the composition of a particular PEBA resin grade, the polyamide segments are referred to as "hard segments" or "hard phase," the polyether segments are referred to as "soft segments" or "soft phase," and the polyester segments (when present at low composition in a particular grade of PEBA resin) function as chain extenders.

[0080] The ratio of polyamide, polyether, and polyester segments of the PEBA in the heat shrink tubing can vary significantly without departing from the scope of this disclosure. Different composition ratios of polyamide hard segments to polyether soft segments (in addition to polyester chain extenders in some resin grades) affect the physical properties of the resulting resin, and ultimately the final physical properties of the non-crosslinked PEBA heat shrink tubing of the present invention. Different composition ratios allow for the production of non-crosslinked PEBA heat shrink tubing with varying flexibility (i.e., durometer hardness).

[0081] In various embodiments, the heat shrink tubing disclosed herein is prepared from one or more poly(ether-block-amide) (PEBA) resins. As used herein, "resin" refers to a material consisting essentially of a given type of polymer (e.g., copolymer) or two or more polymers / copolymers.

[0082] The resin is typically provided in a solid form (e.g., as a solid pellet), but is not limited to other forms including, but not limited to, powder, paste, granules, dispersion, solution, gel, etc. In some embodiments, the heat shrink tubing disclosed herein can be prepared from a resin that comprises, consists of, or consists essentially of one or more forms of PEBA resin described herein.

[0083] In some cases, a "resin" as used herein may contain one or more additional components as additives and / or have one or more additional components added thereto (e.g., lubricants, colorants, fillers, etc.). In other embodiments, one or more additional components (in the form of granules, powders, or pellets, or in the form of a gel or liquid) may be included with the PEBA resin and extruded therewith. Thus, the heat shrink tubing ultimately produced may, in some embodiments, include one or more such additional components.

[0084] In certain embodiments, the heat shrink tubing of the present disclosure is prepared using a PEBA resin and, therefore, in some embodiments, can consist of, be based on, or include PEBA. Typically, PEBA resins can be provided in a variety of different forms, such as, for example, solid pellets, powders, granules, dispersions, solutions, gels, etc.

[0085] In certain embodiments, PEBA heat shrink tubing can be prepared using medical grade PEBA extruded resin pellets. The type of PEBA resin utilized in certain embodiments can vary and can include PEBA medical grade extruded pellets of different compositions (i.e., different durometers) as a single PEBA copolymer resin grade, or as a blend of two or more PEBA copolymer resin grades, or as a blend including a PEBA copolymer resin grade.

[0086] The PEBA resins used in certain embodiments may be blended or compounded with other polymeric components, such as, for example, polytetrafluoroethylene (PTFE), to tailor the final properties of the resulting non-crosslinked heat shrink tubing to suit a particular application.

[0087] Examples of medical-grade PEBA extrusion resins suitable for use in accordance with the present disclosure include PEBAX® 7433 SA 01 MED, PEBAX® 7233 SA 01 MED, PEBAX® 7033 SA 01 MED, PEBAX® 6333 SA 01 MED, PEBAX® 5533 SA 01 MED, PEBAX® 4533 SA 01 MED, PEBAX® 4033 SA 01 MED, PEBAX® 3533 SA 01 MED, PEBAX® 2533 SA 01 MED, and PEBAX® MV 1074 SA 01 MED, manufactured by Arkema; ​​or VESTAMID® Care ME71, VESTAMID® Care ME62, VESTAMID® Care ME81, VESTAMID® Care ME91, VESTAMID® Care ME102, VESTAMID® Care ME122, VESTAMID® Care ME141, VESTAMID® Care ME162, VESTAMID® Care ME183, VESTAMID® Care ME184, VESTAMID® Care ME185, VESTAMID® Care ME186, VESTAMID® Care ME187, VESTAMID® Care ME188, VESTAMID® Care ME189 ... VESTAMID® Care ME55, VESTAMID® Care ME47, VESTAMID® Care ME40, and VESTAMID® Care ME26. However, it should be understood that the heat shrink tubing provided herein is not limited to PEBA resins and can be prepared using one or more of the polymer resins described herein in addition to or in place of PEBA.

[0088] As described herein, certain embodiments of the disclosed heat shrink tubing can include, consist essentially of, or consist of PEBA, and such heat shrink tubing may be referred to herein as "non-crosslinked PEBA heat shrink tubing" or simply "PEBA heat shrink tubing."

[0089] In some embodiments, one or more additives can be incorporated into a majority of the tube wall and / or coated on the inner and / or outer diameter surfaces. In some such embodiments, the one or more additives can be distributed (e.g., substantially uniformly) throughout the wall thickness and length of the tube. In some embodiments, the one or more additives can include a lubricant, such as, for example, a thermally stable extrusion process lubricant.

[0090] In certain embodiments, the lubricant may be a pentaerythritol ester, such as, for example, GLYCOLUBE® from Azelis America, Inc. In some embodiments, one or more additives may include a radiopaque filler (i.e., an inorganic radiocontrast agent) to assist in medical procedures that use fluoroscopy for navigation of medical devices within the body.

[0091] In certain embodiments, the radiopaque filler may be, for example, barium sulfate (BaSO), bismuth subcarbonate (BiOCO), bismuth oxychloride (BiOCl), bismuth trioxide (BiO), or tungsten (W). In some embodiments, the one or more additives may include a pigment to provide a desired color for the final PEBA heat shrink tubing.

[0092] In some embodiments, other additives such as inert fillers, stabilizers (i.e., radiation stabilizers, antioxidants, etc.), conductive fillers, anti-blocking agents, anti-microbial agents, etc. may be included to produce the desired functionality of the final PEBA heat shrink tubing for a particular application.

[0093] The amount of additives that can be included in the final PEBA heat shrink tubing is not particularly limited. In some embodiments, for example, one or more additives (e.g., lubricants, pigments, fillers, etc.) can be included in an amount ranging from about 0.1% to about 80%, from about 1% to about 30%, or from about 5% to 20% by weight, based on the total weight of the PEBA heat shrink tubing. In other embodiments, the PEBA heat shrink tubing can be free of any additives.

[0094] The size (e.g., length, diameter (i.e., expanded inner diameter, ID), and average wall thickness) of the heat shrink tubing is not particularly limited within the scope of the present disclosure. For example, the lengths of the tubing described herein can vary from discrete sized units (e.g., in some embodiments, on the order of 0.1 inches to 120 inches for the production of catheters or medical device components), to lengths that can be easily shipped and further cut into discrete sized units, to lengths for large-scale production (e.g., on the order of several hundred feet).

[0095] Certain extended IDs of the tubing described herein may range from about 0.005 inches to about 1.5 inches (e.g., from about 0.01 inches to about 0.7 inches or from about 0.015 inches to about 0.5 inches), particularly for catheter and medical device applications, although tubing having extended IDs outside of this range are also encompassed by the present disclosure, particularly in view of applications in different fields.

[0096] Generally, the method for preparing heat shrink tubing can vary. Generally, the desired resin or resins, such as the PEBA resins described herein, are converted into a tubular shape by extrusion and then mechanically expanded. The means for carrying out these steps can vary, as described herein.

[0097] Resins (such as PEBA resins) can be formed into tubing by extruding the resin. Extrusion generally involves placing the desired resin or resins into an extruder (e.g., a single-screw melt extruder). Within the extruder, the resin or resins are heated, compressed, and forced through an annular die set to form the tube.

[0098] An annular die set (also referred to herein as "tooling") consists of a circular extrusion die and a mandrel that forms the polymer melt into a tubular shape as it exits the extruder. Tubes of various diameters, wall thicknesses, and lengths can be produced using the forming methods described herein. The final dimensions of the extruded tubular body, along with other parameters of the extrusion process such as temperature, pressure, and screw rotation speed, can be adjusted and optimized through the selection of appropriate tooling.

[0099] The tube forming tooling is attached to the extrusion head (i.e., end) of an extruder, which typically consists of a hopper, barrel, screw, breaker plate, and extrusion head. The extruder screw typically consists of several sections (e.g., feed zone, compression zone, and metering zone) that can be optimized to provide an efficient and consistent extrusion process.

[0100] Typically, there are multiple temperature-controlled zones throughout the extruder, each of which can be adjusted and optimized to produce tubular articles of desired dimensions and quality. In some embodiments, tubing having a relatively uniform wall thickness (i.e., high concentricity) is provided.

[0101] The proper sizing of an annular die set used during an extrusion process is generally determined by the specified finished tubular dimensions, the extruder specifications, the desired drawdown ratio (DDR), and the draw ratio balance (DRB). DDR and DRB are dimensionless quantities used by those skilled in the art to describe the relationship between the dimensions of the polymer melt as it exits the annular die set and the dimensions of the final tubular product (i.e., the dimensions of the final extruded tube).

[0102] The drawdown ratio (DDR) is defined as the ratio of the cross-sectional area of ​​the polymer melt as it exits the annular die set to the cross-sectional area of ​​the final tubular product. After exiting the annular die set, the molten tubular product must be "drawn down" (i.e., reduced in diameter and cross-sectional area by drawing) to obtain the desired final tubular dimensions before it can be quenched (i.e., rapidly cooled in air or a cooling liquid).

[0103] Generally, utilizing an annular die set that provides a high DDR relative to the dimensions of the final tubular formed body allows for faster line speeds (i.e., faster production rates. It is also important to note that tubes produced with a higher DDR have a higher degree of longitudinal orientation of the polymer chains than tubes produced with a lower DDR.

[0104] It is well known to those skilled in the art that imparting a particular degree of orientation to a polymeric material can affect the mechanical and physical properties of the final product, and these properties (e.g., mechanical properties) can be optimized for a particular application (i.e., input for the secondary expansion process) by varying the degree of orientation.

[0105] The draw ratio balance (DRB) is defined as the diameter ratio of the extrusion die to the mandrel divided by the diameter ratio of the final tubular body. Generally, DRB characterizes the relationship between the annular shape of the polymer melt exiting the die and the annular shape of the final tubular body. Those skilled in the art are well aware that careful tooling selection is required to achieve a stable tubular extrusion process.

[0106] The dimensional relationship of the tooling used to produce a particular size tube influences the line speed (i.e., production rate) of the DDR-based extrusion process. However, this dimensional relationship must be balanced because it also directly affects the overall stability of the DRB-mediated extrusion process. Tooling selection is a critical aspect of the extrusion process to produce tubular shapes of specified dimensions that also possess the desired mechanical properties.

[0107] The extruded tubular form is then typically radially expanded (e.g., by mechanical means) to provide an expanded tube, i.e., heat-shrinkable tubing (i.e., a tube that decreases in diameter when heated). Expansion of the input tube (i.e., the initial extruded tubular shape) can be performed in-line with extrusion or offline (i.e., independent of and / or secondary to the extrusion process).

[0108] All means for radially expanding the tube are intended to be encompassed by the present invention. Generally, during the expansion process, the tube is radially expanded by pressurizing the inside of the tube, introducing stress into the tube wall. This pressurization can be accomplished by any means capable of creating a pressure differential between the inside and outside of the tube.

[0109] This pressure differential can be created by applying pressure above atmospheric pressure inside the tube, pressure below atmospheric pressure outside the tube, or a combination of the two. The stress induced in the tube wall causes the tube to radially expand, i.e., increase in diameter. The rate of expansion can be controlled by ensuring that the tube remains expanded and does not recover until subjected to further thermal cycling.

[0110] The extent to which the tubing is expanded will depend on the intended use of the final heat shrink tubing. The rate and extent to which the tubing expands will depend on the temperature at which the expansion process occurs. It has been found that the temperature of the expansion chamber must be carefully controlled to optimize the rate and extent of tubing expansion.

[0111] In some embodiments, the tube is expanded in inner diameter from about 1.05 times its original (unexpanded) inner diameter to about 10 times its original (unexpanded) inner diameter.

[0112] In certain embodiments, PEBA heat shrink tubing prepared according to the present disclosure can be radially expanded using, for example, the process described in U.S. Patent No. 9,296,165 to Henson, which is incorporated herein by reference in its entirety. For example, the Henson patent describes a process for making thermoplastic polymer heat shrink tubing that uses a first fluid inside the tube to expand the tube and a second fluid outside the tube to restrain the expansion in an expansion chamber.

[0113] In other embodiments, the tube may be expanded by adjusting, for example, the air flow rate outside the tube, the chamber temperature, the air pressure within the tube, and the speed at which the tube passes through the expansion chamber. In certain embodiments, the heat shrink tubing of the present disclosure is expanded at an elevated temperature through a die using any number of methods known in the art, and then cooled at the exit of the die.

[0114] Cooling can be achieved using fluids such as water, oil, air, etc. Adjustable process parameters include, but are not limited to, die type, die diameter and length, die temperature, fluid pressure inside the tube, fluid pressure outside the tube, cooling method, refrigerant type and temperature, expansion rate, tube material, tube inner diameter (ID), tube outer diameter (OD), and tube wall thickness.

[0115] It should be noted that while certain heat-shrinkable PEBA tubings are known, these tubings primarily comprise cross-linked PEBA, which provides the tubing's heat-shrinkability. Generally, the PEBA heat-shrink tubing provided herein is expanded through an expansion die under carefully controlled conditions of internal pressure, temperature, and throughput, before rapidly cooling the tubing to lock it into an entropically unfavorable expanded state.

[0116] Examples of heat-shrinkable cross-linked PEBA tubing are provided, for example, in the disclosures of Cobalt Polymers, TE Connectivity, and Ross in US Pat. No. 7,306,585 and Pieslak in US Patent Publication No. 2008 / 0317991.

[0117] Crosslinking, either by chemical means or radiation, has long been used in the manufacture of heat-shrinkable tubing and films to obtain greater elastic recovery of the expanded section upon heating (i.e., to increase the rate and / or force of recovery achievable upon heating). Crosslinking a polymeric product such as tubing or film effectively increases the molecular weight of the polymer in addition to improving the polymer's elastic response to forced deformation.

[0118] This effective increase in molecular weight also results in a significant increase in the viscosity of the polymer (due to an increased likelihood of interchain entanglement), hindering the material's ability to flow and fill voids (i.e., gaps or interstices in the underlying reinforcing member pattern). The increase in viscosity due to crosslinking also reduces the polymer's ability to tightly conform and bond to the underlying substrate during recovery. The increased recovery achievable with crosslinked materials can also cause undesirable deformation or damage to sensitive underlying substrates (i.e., delicate laser-cut hypotubes) during recovery.

[0119] Advantageously, as referenced herein, when heat shrink tubing comprising PEBA is provided, the majority (e.g., all) of the PEBA in the tubing is not crosslinked. In some embodiments, the tubing provided herein contains no crosslinked polymer, less than about 2% by weight crosslinked polymer, less than about 1% by weight crosslinked polymer, or less than about 0.5% by weight crosslinked polymer. The disclosed heat shrink tubing can exhibit high recovery rates.

[0120] In some embodiments, the disclosed heat shrink tubing can have a recovery ratio (RR) of greater than about 1.05:1, greater than about 1.10:1, greater than about 1.2:1, greater than about 1.3:1, greater than about 1.4:1, greater than about 1.5:1, or greater than about 1.6:1, such as from about 1.05:1 to about 2:1. In some embodiments, the heat shrink tubing can be described based on the reduction potential of the inside diameter (ID) (at recovery).

[0121] Examples of such values ​​include, but are not limited to, tubing that can reduce in inner diameter (ID) by at least about 4%, at least about 5%, at least about 6%, at least about 7%, at least about 8%, at least about 9%, at least about 10%, at least about 11%, at least about 12%, at least about 13%, at least about 14%, at least about 15%, at least about 20%, at least about 25%, or at least about 30%, such as about 5% to about 40% (e.g., including about 4.8%, about 9.1%, about 16.7%, about 23.1%, about 28.6%, about 33.3%, or about 37.5%).

[0122] In some embodiments, the disclosed heat shrink tubing can be described based on a durometer measurement. For example, in certain embodiments, the durometer measurement of the heat shrink tubing provided herein, performed on a flat sample produced by melt pressing the heat shrink tubing (in its expanded form) in accordance with ASTM D2240, is from about 20 to about 80 Shore D.

[0123] The heat shrink tubing provided herein can be used in a variety of ways: In some embodiments, they are advantageously used in catheter assembly processes, for example, as a replacement for conventional (e.g., FEP) heat shrink tubing used as a manufacturing aid to compress the underlying catheter pre-assembly during heating / reflow.

[0124] Such a process can avoid the need for disposable parts typically required in the manufacture of catheter assemblies, such as, for example, FEP heat shrink tubing. According to the present disclosure, the heat shrink tubing (e.g., PEBA heat shrink tubing) provided can function as both a catheter jacket and a processing aid / heat shrink, providing sufficient compression during heating / reflow.

[0125] Thus, the disclosed heat shrink (i.e., expandable) tubing allows for the fabrication of a catheter shaft by heating the heat shrink tubing as the outer layer ("jacket") of a catheter shaft pre-assembly, inducing dimensional recovery of the heat shrink tubing, allowing reflow through the reinforcing member (if present), and bonding to the underlying liner without the use of a fused sleeve (e.g., FEP).

[0126] Because the polymeric material of the disclosed heat shrink tubing is not crosslinked, its viscosity is such that the polymer flows easily to encapsulate the reinforcing members (if present) and adhere to the outer surface of the inner liner when heated under an appropriate recovery profile.

[0127] Selection of an appropriate heating temperature and heating time (also referred to herein as a "heating profile" or "recovery profile") for a particular non-crosslinked heat-shrinkable outer jacket tubing can vary substantially depending on the underlying catheter assembly components and the composition of the non-crosslinked heat-shrinkable tubing.

[0128] In certain applications, the recovery rate can also be tailored to match the recovery profile, with the outer jacket bonding only to the outer surface of the reinforcing member, leaving the underlying gap open to provide a more flexible catheter shaft. In this way, the expansion conditions, recovery rate, and recovery profile can be tailored to provide a non-crosslinked PEBA heat shrink tubing capable of forming outer sheaths for a variety of different catheter configurations.

[0129] The present disclosure also enables the fabrication of catheter shafts by heating non-crosslinked heat shrink tubing over a laser-cut hypotube, inducing dimensional recovery of the tubing so that it bonds to the outer surface of the laser-cut hypotube without flowing within the interstices of the laser-cut structure.

[0130] The recovery rate and recovery profile can be tailored to provide a well-bonded outer jacket for these types of catheter shafts. The recovery process can also be optimized to maintain the mechanical properties built into the design of the laser-cut hypotube reinforcement structure.

[0131] The conventional catheter manufacturing process 10 utilizing an FEP fused sleeve to reflow the outer jacket tubing provides a relatively high recovery force, which, combined with the high recovery temperature of the FEP heat shrink, allows the molten outer jacket tubing to flow through the interstices of the underlying stiffening member.

[0132] Typically, for applications involving braided or coiled reinforcement structures, this is a desired outcome of the reflow process 10. However, in certain embodiments involving laser-cut hypotubes, it is undesirable for the heat shrink material to flow within the laser-cut gaps during the heating step 16.

[0133] To achieve varying degrees of flexibility along the length of the catheter shaft, medical device engineers can adjust or change the pattern of laser cutting the hypotube wall. In this particular application, if the outer jacket flows into the gaps during heating step 16, the outer jacket material seeping into the gaps will prevent the laser cuts from deforming as designed, permanently reducing the flexibility of the finished shaft.

[0134] In this particular embodiment, it is desirable for the outer jacket to bond to the exterior surface of the laser-cut hypotube without infiltrating or destroying the flexibility of the laser-cut structure, which is possible due to the ability of the PEBA material to bond to metal substrates.

[0135] In certain embodiments, the disclosed heat shrink tubing can be utilized in a semi-automated process for manufacturing coated laser-cut hypotube catheter shafts. For example, after laser cutting of the hypotube is completed, individual lengths of the disclosed heat shrink tubing can be fed directly from the cutting operation.

[0136] After insertion, the laser-cut hypotube and heat shrink tubing can be exposed to a heat source to restore the dimensions of the heat shrink tubing and bond it to the outer surface of the laser-cut hypotube (i.e., forming a covered laser-cut hypotube).

[0137] This heating step can be done in-line in a continuous process, or in a semi-automated process where the laser cut hypotube is fed into the disclosed heat shrink tubing and manually transferred to a heat source to complete the build. It is also envisioned that lengths of hypotube can be laser cut and continuously inserted into lengths, coils, or spools of the disclosed heat shrink tubing.

[0138] This pre-assembly can then be fed into an oven or other heat source to recover the heat shrink tubing and bond it to the outer surface of the laser-cut hypotube. After heat exposure, the covered laser-cut hypotube can be cut to individual lengths to complete the build. Alternatively, the pre-assembly can be cut to individual lengths before exposure to a heat source to recover the disclosed heat shrink tubing and bond it to the outer surface of the laser-cut hypotube.

[0139] After fabrication of the desired construct with the disclosed heat shrink tubing, and during or after the heat shrink tubing has recovered, the outer surface of the construct (including the heat shrink material) can optionally be further modified or smoothed by a secondary process, if desired. For example, in some embodiments, the construct, during or after the heat shrink material has recovered, can be passed through a heated metal die or a heated polymer-coated die to produce a catheter assembly with a modified (e.g., smooth) outer surface.

[0140] The heated die can be coated, for example, with polytetrafluoroethylene (PTFE). In some embodiments, the construct is passed through a heated or polymer-coated die during or after recovery of the heat shrink material to provide a textured or processed outer surface to modify or enhance the sliding properties of the finished construct.

[0141] The present disclosure can replace the conventional double layer outer jacket assembly 30 comprising the FEP fusion sleeve 40 and non-heat shrinkable PEBA outer jacket tube 38 used in the conventional reflow method 10.

[0142] See Figures 1A and 2. These traditional components and processing techniques can be replaced with the single layer outer jacket assembly 42 provided herein, consisting of a single piece of non-crosslinked PEBA heat shrink tubing, which functions as a heat shrink outer jacket tube 44. See Figure 3.

[0143] Non-crosslinked PEBA heat shrink tubing can be used in the recovery process 20 (see FIG. 1B). The use of the disclosed heat shrink tubing as the outer jacket of the catheter shaft eliminates the need for manufacturing aids such as FEP heat shrink tubing commonly used in the manufacture of catheter shafts.

[0144] This is advantageous in a number of ways. First, a costly component is removed from the manufacturing process. Second, scrap is reduced in the process, as the FEP heat shrink tubing must be removed and discarded after the reflow process is complete. Third, by virtually eliminating the insulating layer (i.e., the FEP heat shrink tubing), heat transfer during the recovery process is greatly improved, improving cycle time.

[0145] Finally, not having to score, scrape, or trim the FEP heat shrink tubing to remove it greatly reduces the chance of damaging the finished catheter shaft during manufacturing.

[0146] Additionally, this replacement significantly improves the efficiency and cost-effectiveness of the catheter shaft manufacturing process by reducing heating cycle times, reducing labor costs by eliminating process steps, and reducing part costs.

[0147] The efficiency improvements in heating cycle time enabled by the PEBA-based heat shrink tubing disclosed herein can be visualized by comparing the heat transfer rate achieved during heating step 16 of a conventional reflow process 20, which includes a dual-layer outer jacket assembly 30 (see FIGS. 1A and 2), with the heat transfer rate during heating step 24 of a recovery process 20, which includes a single-layer outer jacket assembly 42 (see FIGS. 1B and 3).

[0148] Heat transfer rate is a quantity that indicates the amount of heat transferred through a material per unit time under given conditions. In the example calculations shown below, a tubular outer jacket assembly has a heat source located outside the outer surface of the assembly such that heat flows radially inward from the heat source, through the wall layers of the assembly, and toward the inner surface of the assembly.

[0149] This analysis was performed through an idealized application of Fourier's law of heat conduction using a cylindrical coordinate system. See, e.g., "DOE Fundamentals Handbook: Thermodynamics, Heat Transfer, and Fluid Flow" (DOE-HDBK-1012 / 2-92, U.S. Department of Energy, June 1992).

[0150] In order to apply the following equations, several assumptions are made, including that in both cases considered, the heat source is in intimate contact with the entire periphery of the outermost surface, all surfaces are in intimate contact with adjacent surfaces, the thermal conductivity of each layer is assumed to be constant as a function of temperature, and heat loss to the ambient environment and to catheter components underlying the outer jacket assembly is considered negligible.

[0151] Given the above assumptions, the heat transfer rate can be calculated using a form of Fourier's law, Equation 1, which allows the rate of heat transfer through a tubular wall of known thermal conductivity and dimensions to be determined.

number

[0152] Extending Equation 1, the heat transfer coefficient through the composite wall of the dual-wall tube can be determined as shown in Equation 2:

number

[0153] Equation 1 describes the aforementioned assumptions and parameters in more detail and can be used to determine the heat transfer rate through a single, non-crosslinked PEBA heat shrink layer 44 during the heating step 24 of the recovery process 20. The dimensional parameters and heat transfer rate for this single layer outer jacket assembly are shown as Case 1 in Table 1.

[0154] Equation 2 can similarly be used to determine the heat transfer rate through a dual-layer outer jacket assembly 30 including a FEP fused sleeve 40 and a non-heat-shrinkable PEBA outer jacket tube 38 during heating step 16 of a conventional reflow process 10. The heat transfer rate for this dual-layer outer jacket assembly is shown as Case 2 in Table 1.

[0155] These cases were considered to compare the difference in heat transfer rate between heating step 16 of the conventional "reflow" catheter manufacturing process 10 and heating step 24 of the "recovery" method 20 enabled by the present invention. In this analysis, a heat source length (i.e., longitudinal area of ​​heat transfer) of 10 mm was assumed.

[0156] The temperature difference between the heat source and the interior of the tubular structure was assumed to be 187 K (i.e., the temperature difference when the heat source temperature is assumed to be 210 °C (483.15 K), a typical FEP HS recovery temperature, and the interior of the catheter assembly is assumed to be approximately room temperature, 23 °C (276.15 K). The thermal conductivity of PEBA was assumed to be 0.180 W / m K, and the thermal conductivity of FEP was assumed to be 0.180 W / m K.

[0157] See, for example, https: / / www.matweb.com / search / datasheet.aspx?matguid=5a22f9b853e64148b0ffab9d3d1daa5a&n=1&ckck=1, DM Price, M. Jarratt, Thermochimica Acta, 392,231, 2002 and LK Olifirov, AA Stepashkin, G. Sherif, VV Tcherdyntsev, Polymers, 13,781, 2021.

[0158] The dimensional attributes used to determine the heat transfer rate for both considered cases are shown in Table 1. Under the parameters considered, the heating step 24 of the recovery process 20 enabled by the non-crosslinked PEBA heat shrink tubing of the present invention increases the heat transfer rate by approximately 82% compared to the heating step 16 of the conventional "reflow" manufacturing process 10.

[0159] This is an advantageous aspect of the presently disclosed tubing and method that translates into overall energy and resource savings for catheter shaft manufacturers, as well as throughput efficiency. Additionally, process efficiency is improved by reducing labor costs by eliminating steps 14 and 18 of the conventional reflow process 10. In addition to process efficiency, eliminating the need for disposable, expensive FEP heat shrink manufacturing aids helps reduce the environmental impact of these manufacturing processes through reduced scrap.

[0160] [Table 1]

[0161] The heat shrink tubing provided herein can be used in a variety of applications. In certain applications, the heat shrink tubing provided herein can be applied to an underlying material (e.g., a device, a device component, a joint, a fitting, a wire, etc.) and heated (i.e., cured) to form a coating thereon. Thus, the present disclosure encompasses materials or objects to which the tubing disclosed herein is applied.

[0162] For example, in some embodiments, a coated device (e.g., a medical device) is provided that includes the heat shrink tubing disclosed herein (e.g., in a recovered configuration). Exemplary coated devices include, but are not limited to, medical devices (e.g., catheters, catheter shafts, and catheter shaft components) having any of the tubing disclosed herein applied thereto (in expanded / non-recovered and recovered configurations). In some embodiments, a coated hypotube (e.g., a laser-cut hypotube) is provided.

[0163] Constructs using the disclosed heat shrink tubing can exhibit properties suitable for a variety of applications. In some embodiments, the constructs provided herein that include heat shrink tubing as an outer jacket can exhibit good bonding between the heat shrink material and the underlying component of the construct.

[0164] For example, in the context of a catheter assembly, heat shrink materials can provide good bonding through a reinforcing member (e.g., a braid or wire / coil structure) to an underlying liner (which may optionally be surface-modified). Heat shrink materials can provide good bonding to non-reinforced, surface-modified PTFE liners.

[0165] The surface-modified liner (e.g., a surface-modified PTFE liner) can include, for example, an etched outer surface (e.g., at least a portion of the surface is sodium etched) and / or can include a liner having a tie layer thereon (e.g., a PTFE liner having a tie layer thereon). In some embodiments, the construct exhibits a cohesive failure mode when peeled.

[0166] The compositions may include additional components than those explicitly disclosed herein. For example, in some embodiments, the compositions provided herein may further include an outer thin-walled tube disposed over the heat shrink tubing provided herein, the outer thin-walled tube including a heat shrinkable material different from the disclosed heat shrink tubing.

[0167] The two tubes can be brought together over the underlying catheter components to form the outer jacket of the catheter shaft. In this way, for example, thin-walled PET heat shrink tubing can be used as the outer layer to give the catheter shaft a smooth, glossy surface.

[0168] In some embodiments, an outer thin-walled tube comprising a heat-shrinkable material different from the disclosed heat-shrink tubing and having low adhesion to the material of the disclosed heat-shrink tubing can be placed over the disclosed heat-shrink tubing, and the two tubes can be restored together.

[0169] In some embodiments, for example, the disclosed heat shrink tubing can be inserted into FEP heat shrink tubing and expanded by applying temperature and / or pressure to form a two-layer heat shrink tubing.

[0170] In other embodiments, for example, the disclosed heat shrink tubing can be inserted into FEP heat shrink tubing and heated to partially heal the outer FEP heat shrink and contact the outer surface of the inner disclosed heat shrink tubing while applying pressure to prevent the inner layer from appreciably healing.

[0171] After recovery, the outer tube can be removed to reveal a gloss-coated catheter shaft (gloss coating comprising the disclosed heat shrink tubing material). Other examples of dual heat shrink structures are provided, for example, in the disclosure of Hunter et al., U.S. Patent Application Publication No. 2021 / 0370581.

[0172] Additionally, in some embodiments, one or more surfaces of the disclosed compositions can be modified. For example, in some embodiments, the heat shrink material can exhibit increased lubricity on its exterior surface compared to the provided composition (e.g., by chemical treatment or an additional coating, such as a liquid or polymer coating, applied thereto to enhance the surface lubricity).

[0173] As such, in some embodiments, compositions are provided that include the disclosed heat shrink materials (in their recovered form) that exhibit a hydrophobic surface coating. In some embodiments, the disclosed compositions can include one or more additional components, such as one or more tie layers between adjacent layers.

[0174] In certain embodiments, a catheter pre-assembly is provided that includes the heat shrink tubing of the present disclosure, where the heat shrink tubing is an outer sheath (including other components as described elsewhere herein). The present disclosure encompasses both the pre-assembly and the final catheter assembly (provided after heating and shrinking the heat shrink tubing). A wide range of such catheter assemblies can be provided in accordance with the principles provided herein, including, but not limited to, guide catheters, microcatheters, balloon catheters, and steerable delivery catheters.

[0175] In some embodiments, multiple pieces of heat shrink tubing provided herein having different durometer hardness (i.e., flexibility) can be joined together (e.g., using tape or adhesive, heat or solvent welding, interference fit, etc.) and placed onto a catheter before healing to form a catheter shaft with varying degrees of flexibility and smooth transitions.

[0176] For example, the plurality of heat shrink tubes can include, for example, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or ten or more heat shrink tubes having different durometer hardness values.

[0177] In some embodiments, heat shrink tubing provided herein having different durometer hardness (i.e., flexibility) can be sequentially placed over the catheter assembly and allowed to recover.

[0178] In some embodiments, the transition between adjacent heat shrink tubing can be smoothed by passing the construct through a heated metal or polymer coated die during or after the forming (i.e., recovery) process to form catheter shafts with varying degrees of flexibility and smooth transitions.

[0179] In certain embodiments, heat shrink tubing provided herein having different durometer hardness (i.e., flexibility) can be sequentially placed onto a catheter assembly and restored, and the tubing can be further processed, if necessary, to smooth the transition between sections of the outer jacket using FEP fused sleeves to form catheter shafts with varying degrees of flexibility and smooth transitions.

[0180] <Experimental Example> Aspects of the present invention are more fully described by the following examples, which are provided to illustrate particular aspects of the invention and should not be construed as limiting the invention. Although the examples provided relate specifically to non-crosslinked PEBA heat shrink tubing, it is understood that heat shrink tubing made from other biocompatible or medical grade polymeric materials will also be useful in accordance with the present invention.

[0181] Bonding Test A method based on physical examination of the specimen after performing a "bond test" was utilized to determine whether an adequate bond had been formed between the outer surface of the inner liner tube and the inner surface of the outer jacket tube. The various elements of this method are shown in Figure 4, with numbers corresponding to the various elements as described in more detail below.

[0182] The method involves fabricating a short section of unreinforced catheter shaft, e.g., approximately 4-6 inches in length. Several examples were fabricated using heat-shrinkable and non-heat-shrinkable PEBA tubing as the outer jacket 56. This allows for a comparison of the bond formed between the outer surface 54 of the PTFE liner tubing 52 and the inner surface of the PEBA outer jacket tubing 56 when using an FEP fused sleeve, versus the non-crosslinked PEBA heat-shrinkable tubing of the present invention.

[0183] Preparation of the bond test specimens began with fabricating an unreinforced catheter shaft subassembly for each example tested by hand drawing a PTFE liner tube 52 having a modified (i.e., sodium-etched) outer surface 54 with an inner diameter of about 0.078 inches and an average wall thickness of about 0.0015 inches onto a stainless steel mandrel with an outer diameter of about 0.075 inches.

[0184] This stretching step forces the PTFE liner tube 52 to "pull down" and fit snugly over the metal mandrel, resulting in an unreinforced catheter shaft subassembly.

[0185] A thin strip 58 of thin aluminum foil, 1 inch long, was wrapped around one end of the subassembly (i.e., over the outer surface 54 of the PTFE liner tube 52) to prevent bonding between the outer surface 54 of the PTFE liner tube 52 and the inner surface of the PEBA outer jacket tube 56 to which the foil 58 was applied.

[0186] The inclusion of a 1 inch long aluminum foil strip 58 serves to provide a "tab" for peeling the inner PTFE liner tube 52 and PEBA outer jacket tube 56 after construction is complete.

[0187] For bond test specimens fabricated using heat-shrinkable PEBA tubing as the outer jacket 56, the PEBA heat-shrink outer jacket tubing 56 was applied over the subassembly and aluminum foil strip 58, suspended vertically from an oven rack using clips, and heated in a standard laboratory gravity convection oven to complete the construction.

[0188] For bonded test specimens fabricated using non-heat shrinkable PEBA tubing as the outer jacket 56, FEP heat shrink tubing having an expanded inner diameter of approximately 0.119 inches, a wall thickness of approximately 0.008 inches, and a recovered inner diameter of 0.072 inches was applied over the PEBA outer jacket tubing 56, suspended vertically from an oven rack using clips, and heated in a standard laboratory gravity convection oven to complete the construction. After heating for the times and temperatures listed in Table 3, the specimens were allowed to cool to room temperature and then removed from the metal mandrel.

[0189] For adhesion test specimens fabricated using a non-heat-shrinkable PEBA outer jacket, the FEP heat-shrink tubing was scraped off the construction. After removal, one side of the unreinforced catheter shaft specimen was cut longitudinally using a razor blade and flattened to a "rectangular" shape. It is important to note that the aluminum foil tab 58 typically bonds to the PEBA outer tube 56 after heating, but not to the modified outer surface 54 of the PTFE liner tube 52.

[0190] The bond test was performed by grasping the tab end of the PTFE liner tube 52 (i.e., the portion that was under the aluminum foil 58) with one hand and the aluminum foil tab 58 attached to the PEBA tube 56 with the other hand and slowly pulling approximately 2 inches in opposite directions.

[0191] After peeling, careful inspection of the cross section of the PTFE liner tube 52 peeled from the PEBA outer jacket tube 56 will help determine whether a proper bond has been formed between the modified outer surface 54 of the PTFE liner tube 52 and the inner surface of the PEBA outer jacket tube 56. Methods well known to those skilled in the art involve modifying the outer surface of thin-walled PTFE tubing to allow bonding with other materials.

[0192] Although the surface modification method employed for the PTFE liner tube used herein did not involve the application of a tie resin, it is understood that by combining such a technique with the non-crosslinked PEBA heat shrink tubing of the present invention, the bond strength between the liner tube and the outer jacket is substantially increased.

[0193] Typically, this surface modification (i.e., etching) changes the color of the outer surface 54 of the PTFE liner tube 52 from its natural transparent white / blue color to a translucent brown / amber color. If the PEBA outer jacket tube 56 does not properly bond to the outer surface 54 of the PTFE liner 52 during the heating step, none of the modified outer surface 54 of the PTFE liner 52 will transfer to the PEBA outer jacket tube 56 when peeled in the manner described above (i.e., a "bonded" peel mode 50 will occur, as shown in FIG. 4).

[0194] Through this test, if the PTFE liner 52 can be easily peeled away from the PEBA outer jacket tube 56 (i.e., there is little or no resistance to peeling the layers away), it can be inferred that an inadequate bond was formed during the heating step. Furthermore, if there is little or no color difference between the portion of the PTFE liner 52 covered by the aluminum foil tab 58 and the portion of the PTFE liner 52 that has peeled away from the PEBA outer jacket tube 56 (i.e., both portions of the PTFE liner 52 remain a translucent brown / amber color), it can be inferred that an inadequate bond was formed.

[0195] However, if the PEBA outer jacket tube 56 is sufficiently bonded to the outer surface 54 of the PTFE liner 52 during the heating process, a portion of the modified outer surface 54 of the PTFE liner 52 will be transferred to the PEBA outer jacket tube 56 when peeled in the manner described above (i.e., a "cohesive" peel mode 60 occurs as shown in FIG. 4).

[0196] Through this test, it can be inferred that an adequate bond was formed during the heating process if it is difficult to peel the PTFE liner 52 from the PEBA outer jacket tube 56 (i.e., if there is some resistance or substantial resistance to peeling the layers apart).

[0197] Furthermore, it can be inferred that a sufficient bond has been formed if there is a noticeable color difference between the portion of the PTFE liner 52 covered by the aluminum foil tab 58 and the portion of the PTFE liner 52 that has peeled away from the PEBA outer jacket tube 56 (i.e., the "tab" portion of the PTFE liner 52 remains a translucent brown / amber color, while the portion of the PTFE liner 52 that has peeled away from the PEBA outer jacket tube 56 becomes a clear / translucent white / blue color). A summary of the results of the bond tests performed on the various examples is summarized in Table 3.

[0198] Durometer hardness (Shore D hardness) Durometer hardness is a useful quantity often measured for polymeric materials because it generally relates to the flexibility of the material being tested. For example, a sample with a low durometer value indicates that it is made of a more flexible, less rigid material than a sample with a high durometer value. Samples suitable for durometer hardness testing (i.e., of sufficient thickness) were prepared by compression molding the example tubes using a manual benchtop hydraulic press manufactured by Carver, Inc.

[0199] The example tubes were cut into short pieces and thoroughly dried in a standard laboratory gravity convection oven before molding. The dried tubes were placed into 4" x 4" x 0.04" stainless steel molds and melt pressed between heated cowl plates at a clamping force of approximately 15,000 pounds to produce flat plaque samples of relatively uniform thickness.

[0200] The pressed samples were cut into six equal pieces and stacked to provide durometer hardness test samples approximately 0.24 inches thick. The durometer hardness of the stacked samples was then measured using a Type D indenter in accordance with ASTM D2240-15: Standard Test Method for Rubber Property - Durometer Hardness, 2015. The average of five measurements for the tested examples is shown in Table 4.

[0201] Comparative Example 1 Commercially available poly(ether-block-amide) (PEBA) resin (Arkema PEBAX® 7233 SA 01 MED) was obtained in pellet form and dried overnight in an oven at 167° F. to ensure a resin moisture content of less than about 0.15% by weight. The dried resin was placed in a heated resin hopper under a nitrogen blanket to prevent reabsorption of moisture prior to extrusion.

[0202] The dried pellets were extruded into a tubular shape using a single-screw extruder with an annular die set providing a barrel diameter of 18 mm, a screw speed of approximately 10 rpm, a die temperature of approximately 350°F, and a drawdown ratio (DDR) of approximately 14. After the tube exited the annular die set, it was passed through a cold water bath to sufficiently quench the tube and set its final tubular dimensions. The measured dimensional properties of the produced uncrosslinked PEBA tube are shown in Table 2.

[0203] These tubes do not expand (and therefore do not recover when heated). Comparative Examples 1 (and 2) were prepared and evaluated, for example, to demonstrate that the secondary expansion step of the example tubes leads to product differentiation and that the example tubes are not crosslinked.

[0204] The tubing of Comparative Example 1 was used with an FEP heat shrink fusion sleeve to prepare bond test specimens. The prepared unreinforced catheter shaft assemblies were heated for the times and temperatures shown in Table 3. After cooling, the prepared unreinforced catheter shaft sections were slit longitudinally and flattened to provide specimens suitable for bond testing. The results of the bond tests are summarized in Table 3.

[0205] Bonding tests demonstrate that the example tubing, as shown herein, can produce catheter shafts with good bonding to liners without the need for FEP heat shrinking, for example, comparable in some embodiments to conventional constructions (having non-recovery, non-crosslinked outer sheath tubing and FEP heat shrink).

[0206] Samples suitable for durometer testing were prepared by compression molding dried pieces of Comparative Example 1 using a set temperature of 380°F and a clamping force of 15,000 pounds to obtain plaque samples of relatively uniform thickness. Durometer hardness was measured using a Type D indenter, and the results are summarized in Table 4. A minimum thickness is required for this test; therefore, a tube had to be melted and pressed into the plaque.

[0207] Comparative Examples 1 (and 2) show that the example tubing forms plaque and is therefore uncrosslinked (as are Comparative Examples 1 and 2). Crosslinked materials cannot be melted and reformed, as demonstrated by the inability of Comparative Example 3 (which is crosslinked) to form plaque.

[0208] Comparative Example 2 Commercially available poly(ether-block-amide) (PEBA) resin (Arkema PEBAX® 5533 SA 01 MED) was obtained in pellet form and dried overnight in an oven at 158°F to ensure a resin moisture content of less than about 0.15% by weight. The dried resin was extruded into a tubular shape using the same method and conditions as described in Comparative Example 1, except that a die temperature of about 340°F was used. The dimensional properties of the produced non-crosslinked PEBA tube are shown in Table 2.

[0209] A bonding test sample was prepared using the tube of Comparative Example 2 in the same manner as the bonding test sample prepared using the tube of Comparative Example 1. The results of the bonding test are summarized in Table 3.

[0210] A sample suitable for durometer hardness testing was prepared using the tube of Comparative Example 2, and measurements were made in the same manner as in Comparative Example 1. The results of the durometer hardness testing are summarized in Table 4.

[0211] Comparative Example 3 Commercially available PEBA heat shrink tubing (part number P2-140-006-CLR) from Cobalt Polymers, sold as crosslinked 72 durometer Shore D PEBA heat shrink tubing, was purchased from Chamfr. The measured dimensional properties of the crosslinked PEBA heat shrink tubing before heating (i.e., as received), after heating (i.e., after 10 minutes of exposure to the recovery temperature), and calculated recovery properties are summarized in Table 2.

[0212] Bonding test specimens were prepared using the tubing of Comparative Example 3 without the use of an FEP heat-shrinkable fusion sleeve. The resulting unreinforced catheter shaft assemblies were heated for the times and temperatures shown in Table 3. After cooling, the resulting unreinforced catheter shaft sections were longitudinally slit and flattened to prepare specimens suitable for bonding testing. The results of the bonding tests are summarized in Table 3.

[0213] An attempt was made to prepare specimens suitable for durometer testing using the tubing of Comparative Example 3 in a manner similar to that of Comparative Example 1. However, the specimen obtained by compressing the tubing of Comparative Example 3 under these conditions was very brittle after cooling and did not fuse into a solid test specimen. Durometer testing was not performed on the specimen obtained by compression molding of Comparative Example 3 because a solid test specimen could not be obtained. Because the PEBA heat shrink tubing of Comparative Example 3 is composed of a cross-linked PEBA material, it cannot be melted and remolded into a compression-molded plaque.

[0214] Comparative Example 4 Commercially available PEBA heat shrink tubing (part number P2-100-0025-CLR) manufactured by Cobalt Polymers, sold as crosslinked 72 durometer Shore D PEBA heat shrink tubing, was purchased from Chamfr.

[0215] The measured dimensional properties and calculated recovery properties of the cross-linked PEBA heat shrink tubing before heating (i.e., as received) and after heating (i.e., after 10 minutes of exposure to the recovery temperature) are summarized in Table 2. Because the PEBA heat shrink tubing of Comparative Example 4 is composed of cross-linked PEBA material, it cannot be melted and remolded into compression molded plaques.

[0216] Comparative Example 5 Commercially available PEBA heat shrink tubing (part number P2-060-003-40-CLR) from Cobalt Polymers, sold as crosslinked 40 durometer Shore D PEBA heat shrink tubing, was purchased from Chamfr. The measured dimensional properties of the crosslinked PEBA heat shrink tubing before heating (i.e., as received) and after heating (i.e., after 10 minutes of exposure to the recovery temperature), as well as the calculated recovery properties, are summarized in Table 2. Because the PEBA heat shrink tubing of Comparative Example 5 is composed of crosslinked PEBA material, it cannot be melted and remolded into compression-molded plaques.

[0217] Example 1 A non-crosslinked PEBA input tube was prepared using the commercially available resin PEBAX® 7233 SA 01 MED (Arkema) using the same method and conditions as in Comparative Example 1, except using a screw rotation of about 6 rpm and a DDR of about 10. The result was an input tube with an inner diameter of about 0.048 inches, an average wall thickness of about 0.0145 inches, and a concentricity of about 93%.

[0218] The prepared input tube was then expanded by pressurizing the inner diameter of the tube with compressed air as it passed through a heated expansion die. The heated expansion die had openings along its inner surface that allowed pressurized air to circulate between the outer surface of the non-crosslinked PEBA input tube and the inner surface of the expansion die to maintain a specific expanded diameter. The processing parameters of expansion air pressure applied to the input tube inner diameter (ID), temperature of the pressurized expansion air applied to the input tube inner diameter (ID), expansion die air pressure, expansion die air temperature, expansion die air flow rate, linear tube throughput, cooling air temperature, and cooling air flow rate were all adjusted to obtain non-crosslinked PEBA heat shrink tubing according to the present disclosure.

[0219] Specifically, the uncrosslinked PEBA heat shrink tubing of Example 1 was expanded using an expansion die temperature of about 305°F to about 310°F, an expansion air pressure of about 180 psi, a die air flow rate of about 2.3 cubic feet per minute (cfm), and a linear tubing throughput of about 1.5 feet per minute (fpm).

[0220] The dimensional properties of the inside diameter and wall thickness of the expanded configuration of Example 1 were measured, and the wall thickness concentricity was calculated. Three 2.5 inch long sections were cut from the stretched non-crosslinked PEBA heat shrink tubing of Example 1 and exposed to the recovery temperature in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and the calculated recovery properties are summarized in Table 2.

[0221] Bonding test specimens were prepared using the uncrosslinked PEBA heat shrink tubing of Example 1, without the FEP heat shrink fusion sleeve. The prepared unreinforced catheter shaft assemblies were heated for the times and temperatures shown in Table 3. After cooling, the prepared unreinforced catheter shaft sections were slit longitudinally and flattened to provide specimens suitable for bonding testing. The results of the bonding tests are summarized in Table 3.

[0222] Example 2 A PEBA input tube was prepared using the same materials, methods, and conditions as provided in Example 1 to produce an input tube having the same dimensions as the input tube used in Example 1.

[0223] The prepared input tube was then expanded using the same method and conditions as in Example 1, except that an expansion die temperature of about 310°F to about 315°F, an expansion air pressure of about 187 psi, and a die air flow rate of about 2.1 cfm were used. The dimensional properties of the inside diameter and wall thickness of the expanded shape of Example 2 were measured, and the wall thickness concentricity was calculated.

[0224] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 2 and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0225] Samples suitable for durometer testing were prepared using the expansion tube of Example 2 and measured in the same manner as in Comparative Example 1. The durometer hardness results are summarized in Table 4.

[0226] Example 3 A non-crosslinked PEBA input tube was prepared using the commercially available resin PEBAX® 5533 SA 01 MED (Arkema) using the same method and conditions as in Comparative Example 2, except that a screw rotation of about 6 rpm and a DDR of about 10 were used. The result was an input tube having an inside diameter of about 0.051 inches, an average wall thickness of about 0.0160 inches, and a concentricity of about 97%.

[0227] The prepared input tube was then expanded using the same method and conditions as in Example 1, except that an expansion die temperature of about 265°F to about 275°F, an expansion air pressure of about 120 psi, and a die air flow rate of about 2.0 cfm were used. The dimensional properties of the inside diameter and wall thickness of the expanded shape of Example 3 were measured, and the wall thickness concentricity was calculated.

[0228] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 3 and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0229] Bonding test specimens were prepared using the uncrosslinked PEBA heat shrink tubing of Example 3, without the FEP heat shrink fusion sleeve. The prepared unreinforced catheter shaft assemblies were heated for the times and temperatures shown in Table 3. After cooling, the prepared unreinforced catheter shaft sections were slit longitudinally and flattened to provide specimens suitable for bonding testing. The results of the bonding tests are summarized in Table 3.

[0230] Samples suitable for durometer testing were prepared using the expansion tube of Example 3 and measured in the same manner as in Comparative Example 1. The durometer hardness results are summarized in Table 4.

[0231] Example 4 A non-crosslinked PEBA input tube was prepared using commercially available resin PEBAX® 4533 SA 01 MED (Arkema), obtained in pellet form and dried overnight in a 145°F oven to a resin moisture content of less than about 0.15% by weight. The dried resin was extruded into a tubular shape using the same method and conditions described for preparing the input tube in Example 2, except that a die temperature of about 330°F was used. An input tube was obtained having an inner diameter of about 0.048 inches, an average wall thickness of about 0.0156 inches, and a concentricity of about 96%.

[0232] The prepared input tube was then expanded using the same method and conditions as in Example 1, except that an expansion die temperature of about 220°F to about 235°F, an expansion air pressure of about 100 psi, and a die air flow rate of about 1.8 cfm were used. The dimensional properties of the inside diameter and wall thickness of the expanded shape of Example 4 were measured, and the wall thickness concentricity was calculated.

[0233] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 4 and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and length after heating were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0234] Bonding test specimens were prepared using the uncrosslinked PEBA heat shrink tubing of Example 4, without the FEP heat shrink fusion sleeve. The prepared unreinforced catheter shaft assemblies were heated for the times and temperatures shown in Table 3. After cooling, sections of the prepared unreinforced catheter shafts were slit longitudinally and flattened to provide specimens suitable for bonding testing. The results of the bonding tests are summarized in Table 3.

[0235] Specimens suitable for durometer testing using the expansion tube of Example 4 were prepared and measured in the same manner as Comparative Example 1, except that a set temperature of approximately 350° F. was used. The durometer results are summarized in Table 4.

[0236] Example 5 A non-crosslinked PEBA input tube was prepared using commercially available resin PEBAX® 3533 SA 01 MED (Arkema), obtained in pellet form and dried overnight in a 140°F oven to a resin moisture content of less than about 0.15% by weight.

[0237] The dried resin was extruded into a tubular shape in a manner and under conditions similar to those described for the preparation of the input tube in Example 4, except that a screw rotation of about 8 rpm was used. An input tube was obtained having an inner diameter of about 0.048 inches, an average wall thickness of about 0.0155 inches, and a concentricity of about 96%.

[0238] The prepared input tube was then expanded using the same method and conditions as in Example 1, except that an expansion die temperature of about 180°F to about 205°F, an expansion air pressure of about 55 psi, and a die air flow rate of about 1.9 cfm were used. The dimensional properties of the inside diameter and wall thickness of the expanded shape of Example 5 were measured, and the wall thickness concentricity was calculated.

[0239] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 5 and exposed to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and length after heating were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0240] Example 6 An uncrosslinked PEBA input tube was prepared using the same materials, methods, and conditions as provided in Example 5, except that a DDR of about 9 and a screw rotation of about 7 rpm were used. An input tube having an inner diameter of about 0.062 inches, an average wall thickness of about 0.0150 inches, and a concentricity of about 85% was obtained.

[0241] The prepared input tube was then expanded using the same method and conditions as in Example 5, except that an expansion die temperature of about 180°F to about 210°F, an expansion air pressure of about 40 psi, and a die air flow rate of about 1.7 cfm were used. The dimensional properties of the inside diameter and wall thickness of the expanded shape of Example 6 were measured, and the wall thickness concentricity was calculated.

[0242] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 6 and exposed to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0243] Samples suitable for durometer testing were prepared using the expansion tube of Example 6 and measured in the same manner as in Example 4. The durometer results are summarized in Table 4.

[0244] Example 7 A non-crosslinked PEBA input tube was prepared using commercially available resin PEBAX® 2533 SA 01 MED (Arkema), obtained in pellet form and dried overnight in a 125°F oven to a resin moisture content of less than about 0.15% by weight.

[0245] The dried resin was extruded into a tubular shape in a manner and under conditions similar to those described for the preparation of the input tube in Example 5, except that a screw rotation of about 5 rpm and a die temperature of about 280° F. were used. An input tube was obtained having an inner diameter of about 0.048 inches, an average wall thickness of about 0.0154 inches, and a concentricity of about 89%.

[0246] The prepared input tube was then expanded using the same method and conditions as in Example 6, except that an expansion die temperature of about 165°F to about 190°F and an expansion air pressure of about 48 psi were used. The dimensional properties of the inner diameter and wall thickness of the expanded shape of Example 7 were measured, and the wall thickness concentricity was calculated.

[0247] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 7 and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and length after heating were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0248] Samples suitable for durometer testing were prepared using the expansion tube of Example 6 and measured in the same manner as in Example 4. The durometer results are summarized in Table 4.

[0249] Example 8 An uncrosslinked PEBA input tube was prepared using the same materials, methods, and conditions as provided in Example 3, except that a screw rotation of about 2 rpm and a DDR of about 4 were used. An input tube was obtained having an inner diameter of about 0.024 inches, an average wall thickness of about 0.0077 inches, and a concentricity of about 85%.

[0250] The prepared input tube was then expanded using the same method and conditions as in Example 3, except that an expansion air pressure of about 105 psi was used. The dimensional properties of the inner diameter and wall thickness of the expanded configuration of Example 8 were measured, and the wall thickness concentricity was calculated.

[0251] Three 2.5 inch long sections were cut from the expanded non-crosslinked PEBA heat shrink tubing of Example 8 and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0252] The expanded, non-crosslinked PEBA heat shrink tubing of Example 8 was subsequently used to prepare Example 11 and Comparative Example 7, as described below.

[0253] Example 9 A PEBA input tube was prepared using the same materials, methods, and conditions as provided in Example 3 to produce an input tube having the same dimensions as the input tube used in Example 3.

[0254] The prepared input tube was then expanded using the same method and conditions as in Example 3, except that an expansion air pressure of about 110 psi was used. The dimensional properties of the inner diameter and wall thickness of the expanded configuration of Example 9 were measured, and the wall thickness concentricity was calculated.

[0255] Three 2.5 inch long sections of the expanded non-crosslinked PEBA heat shrink tubing of Example 9 were cut and subjected to recovery temperatures in a standard laboratory gravity convection oven for 10 minutes. After the lengths were cooled to ambient temperature, the inside diameter, wall thickness, and post-heat length were measured. The measured dimensional properties of the non-crosslinked PEBA heat shrink tubing before heating (i.e., expanded), after heating, and calculated recovery properties are summarized in Table 2.

[0256] The expanded, non-crosslinked PEBA heat shrink tubing of Example 9 was subsequently used to prepare Example 10 and Comparative Example 6, as described below.

[0257] Example 10 Commercially available 5 French (0.065 inch OD) laser-cut flexible hypotubing (part number AD_043750, Resonetics, Inc.) was purchased from Chamfr to assemble the coated laser-cut hypotube. The 5 Fr laser-cut hypotube was used as received without any modifications. The 5 Fr laser-cut hypotube was inserted into a length of expanded, non-crosslinked PEBA heat shrink tubing from Example 9.

[0258] This assembly (i.e., the laser-cut hypotube of Example 9 and the uncrosslinked PEBA heat shrink tubing) was suspended vertically and heated at a traverse speed of 2.2 mm / s in a Beahm 815A vertical laminator equipped with a sealed circular thermal nozzle with a 0.5 inch opening set at 300°F.

[0259] After cooling, the completed construct was inspected using a Keyence VHX-5000 digital microscope to determine whether the uncrosslinked PEBA heat shrink tubing flowed through the laser-cut gaps in the hypotube during the healing process. The center section of the coated laser-cut hypotube was bent into a U-shape and fixed on the microscope stage during inspection. Images acquired during this inspection are shown in Figure 5, and the results are summarized in Table 6.

[0260] Comparative Example 6 Coated laser-cut hypotubes were prepared using 5 French laser-cut hypotubes purchased from Chamfr (the same hypotubes used in the manufacture of Example 10). Comparative Example 6 was prepared by sliding the laser-cut hypotube over a length of expanded, non-crosslinked PEBA heat shrink tubing of Example 9 in a manner similar to Example 10, except that an FEP heat shrink fusion sleeve having an expanded diameter of about 0.100 inches, a wall thickness of about 0.0090 inches, and a recovered inner diameter of about 0.063 inches was placed over the assembly (i.e., over the non-crosslinked PEBA heat shrink tubing of Example 9) before heating.

[0261] The recovery rate and dimensional properties of the FEP heat shrink sleeve used were selected based on dimensional considerations typical of a conventional catheter reflow process 10. The assembly was then suspended in a vertical laminator and heated in a manner similar to Example 9, except the nozzle temperature and traverse speed were set to conditions typical of a reflow process 10 involving an FEP fused sleeve.

[0262] The nozzle temperature was set at 480°F and a traverse speed of 1.2 mm / s was used. After cooling, the completed build was inspected using a Keyence VHX-5000 digital microscope in the same manner as the inspection performed in Example 10. Images acquired during this inspection are shown in Figure 6 and the results are summarized in Table 6.

[0263] Example 11 Commercially available 2.75 French (0.036 inch OD) laser-cut flexible hypotube (part number KTSS0004, manufactured by Lumenous Device Technologies) was purchased from Chamfr to assemble the coated laser-cut hypotube. The 2.75 French laser-cut hypotube was used as received without any modifications. The 2.75 French laser-cut hypotube was inserted into a length of expanded, non-crosslinked PEBA heat shrink tubing from Example 8.

[0264] This assembly (i.e., the laser-cut hypotube of Example 8 and the non-crosslinked PEBA heat shrink tubing) was suspended in a vertical laminator and heated using conditions similar to those in Example 10, except a traverse speed of 6.2 mm / s was used. After cooling, the completed construct was inspected using a Keyence VHX-5000 digital microscope in the same manner as the inspection performed in Example 10. Images acquired during this inspection are shown in Figure 7, and the results are summarized in Table 6.

[0265] Comparative Example 7 Coated laser-cut hypotubes were prepared using 2.75 French laser-cut hypotubes purchased from Chamfr (the same hypotubes used in the manufacture of Example 11). Comparative Example 7 was prepared by sliding the laser-cut hypotube over a length of expanded, non-crosslinked PEBA heat shrink tubing of Example 8 in a manner similar to that of Example 11, except that an FEP heat shrink fusion sleeve having an expanded diameter of about 0.056 inches, a wall thickness of about 0.0080 inches, and a recovered inner diameter of about 0.035 inches was placed over the assembly (i.e., over the non-crosslinked PEBA heat shrink tubing of Example 8) before heating.

[0266] The recovery rate and dimensional properties of the FEP heat shrink sleeve used were selected based on dimensional considerations typical of a conventional catheter reflow process 10. The assembly was then suspended in a vertical laminator and heated in a manner similar to Example 11, except the nozzle temperature and traverse speed were set to conditions typical of a reflow process 10 involving an FEP fused sleeve. The nozzle temperature was set at 480°F, and a traverse speed of 1.2 mm / s was used. After cooling, the completed construct was inspected using a Keyence VHX-5000 digital microscope in the same manner as the inspection performed in Example 10. Images acquired during this inspection are shown in Figure 8, and the results are summarized in Table 6.

[0267] Example 12 A braided reinforced PTFE liner was fabricated by placing an externally modified PTFE liner tube with an inner diameter of 0.067 inches and a wall thickness of 0.0025 inches onto a 0.065 inch stainless steel mandrel. The PTFE liner tube was hand stretched at room temperature to fit snugly onto the stainless steel mandrel.

[0268] A 16-carrier braided reinforcement member was then formed onto the PTFE liner using a Steeger USA K80 series horizontal braiding machine with a full load pattern of 45 PPI (picks per inch) using stainless steel wire with an outer diameter (OD) of 0.002 inches obtained from Fort Wayne Metals Research Products, LLC.

[0269] The stainless steel braided reinforced liner was then inserted into a length of expanded, non-crosslinked PEBA heat shrink tubing from Example 4. This assembly (i.e., the braided reinforced liner from Example 4 and the non-crosslinked PEBA heat shrink tubing) was suspended vertically and heated at a traverse rate of 1.2 mm / s in a Beahm 815A vertical laminator equipped with a closed circular thermal nozzle with a 0.5 inch opening set at 400°F, resulting in a braided reinforced catheter shaft with an outer jacket comprising non-crosslinked PEBA heat shrink tubing.

[0270] After cooling, the completed construct was inspected using a Keyence VHX-5000 digital microscope to determine whether the non-crosslinked PEBA heat shrink tubing had flowed within the interstices of the braided reinforcement member and made adequate contact with the outer surface of the inner liner during the heating process. Images captured during this inspection are shown in Figure 9.

[0271] Comparative Example 8 A braided reinforced PTFE liner was fabricated using the same materials and conditions as described in Example 12. Comparative Example 8 was prepared by sliding a stainless steel braided reinforced liner onto a length of expanded, non-crosslinked PEBA heat shrink tubing of Example 4 in a manner similar to Example 12, except that an FEP heat shrink fusion sleeve having an expanded diameter of about 0.100 inches, a wall thickness of about 0.0090 inches, and a recovered inner diameter of about 0.063 inches was placed over the assembly (i.e., over the non-crosslinked PEBA heat shrink tubing of Example 4) before heating.

[0272] The recovery rate and dimensional properties of the FEP heat shrink sleeve used were selected based on dimensional considerations typical of a conventional catheter reflow process 10. The assembly was then suspended in a vertical laminator and heated in a manner similar to Example 12, except the nozzle temperature and traverse speed were set to conditions typical of a reflow process 10 involving an FEP fused sleeve.

[0273] The nozzle temperature was set at 480° F. and a traverse speed of 1.2 mm / s was used. After cooling, the completed build was inspected using a Keyence VHX-5000 digital microscope in the same manner as the inspection performed in Example 12. Images acquired during this inspection are shown in FIG.

[0274] Cumulative results Table 2 summarizes the measured tubular dimensions of the PEBA tubing of Comparative Examples 1-5 and Examples 1-8. Dimensional properties measured "before heating" include the as-prepared inside diameter (i.e., the as-extruded inside diameter (ID) of the non-heat-shrinkable tubing of Comparative Examples 1-2, the as-received expanded inside diameter (ID) of the heat-shrinkable tubing of Comparative Examples 3-5, or the expanded inside diameter (ID) of the non-crosslinked PEBA heat-shrinkable tubing of Examples 1-9), the average wall thickness (denoted by "wt"), and the wall thickness concentricity.

[0275] A total of four measurements of the inner diameter and wall thickness were taken optically on cross sections cut from the examples using a Keyence VHX-5000 digital microscope for each sample. Both the inner diameter and wall thickness were measured in inches. Concentricity, expressed as a percentage, was calculated by dividing the smallest (i.e., thinnest) wall thickness measurement observed by the largest (i.e., thickest) wall thickness measurement observed and multiplying the resulting value by 100. The values ​​shown in Table 2 are the average of three replicates.

[0276] [Table 2]

[0277] [Table 3] + Cohesive peel mode at the interface between the PTFE liner and the PEBA outer jacket during peeling - Adhesive peel mode at the interface between the PTFE liner and the PEBA outer jacket during peeling *In Comparative Example 3, both peeling modes were observed intermittently.

[0278] [Table 4]

[0279] [Table 5]

Claims

1. A heat shrink tubing comprising a non-crosslinked poly(ether-block-amide) (PEBA), the heat shrink tubing having a recovery rate (RR) greater than about 1.05:1 and / or an inside diameter (ID) shrinkability of about 4.8%.

2. 2. The heat shrinkable tube of claim 1, which is primarily composed of non-crosslinked PEBA.

3. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.10:1 and / or the inside diameter (ID) is shrinkable by about 9.1%.

4. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.2:1 and / or the inside diameter (ID) is reducible by about 16.7%.

5. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.3:1 and / or the inside diameter (ID) is reducible by about 23.1%.

6. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.4:1 and / or the inside diameter (ID) is reducible by about 28.6%.

7. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.5:1 and / or the inside diameter (ID) is reducible by about 33.3%.

8. 10. The heat shrink tubing of claim 1, wherein the RR is greater than about 1.6:1 and / or the inside diameter (ID) is reducible by about 37.5%.

9. 9. The heat shrink tubing of any one of claims 1 to 8, wherein a durometer hardness measurement according to ASTM D2240 performed on a flat specimen processed by melt pressing the heat shrink tubing in an expanded shape is about 20 to 80 Shore D.

10. The heat shrink tubing of any one of claims 1 to 9, further comprising a liquid or polymer coating on the outer surface of the tubing to enhance the lubricity or chemical resistance of the tubing.

11. 11. The heat shrink tubing of claim 10, wherein the liquid or polymer coating is hydrophobic.

12. A catheter comprising the heat-shrinkable tube according to any one of claims 1 to 11.

13. 13. The catheter of claim 12, selected from the group consisting of a guide catheter, a microcatheter, a balloon catheter, and a steerable delivery catheter.

14. providing a catheter preassembly comprising a solid core, a liner comprising polytetrafluoroethylene (PTFE), a reinforcing member, and the heat shrink tubing of claim 1; heating the catheter pre-assembly; A method of assembling a catheter that does not include applying additional heat shrink tubing over the heat shrink tubing.

15. a first tube selected from a liner comprising PTFE and a laser cut hypotube; A second tube comprising uncrosslinked PEBA disposed over the first tube. A composition consisting of:

16. 16. The arrangement of claim 15, wherein the second tube is heat shrink tubing in an expanded configuration.

17. 16. The arrangement of claim 15, wherein the second tube is a shape-recovered heat shrink tube.

18. The composition of any one of claims 15 to 17, wherein the second tube consists primarily of non-crosslinked PEBA.

19. 19. The arrangement of any one of claims 15 to 18, wherein the first tube is a liner comprising PTFE, the liner having an etched outer surface.

20. 20. The composition of any one of claims 15 to 19, wherein the first tube is a liner comprising PTFE, and the composition further comprises a reinforcing member between the first tube and the second tube.

21. 21. The composition of claim 20, wherein the reinforcing member is selected from the group consisting of a braid, a coil, or a hypotube.

22. 22. The composition of any one of claims 15 to 21, wherein the composition exhibits a cohesive failure mode when the first tube is peeled from the second tube.

Images