Thin-walled lubricated polyethylene liner

Abstract

The present disclosure provides tubing comprising a blend of two or more polyethylenes. For example, the blend may comprise at least 80% by weight of one or more of LLDPE, LDPE, MDPE, and HDPE, and up to 20% by weight of UHMWPE. Such tubing may have a low average wall thickness, e.g., 0.1 mm or less, making it suitable for use as a catheter liner. The combination of properties exhibited by the disclosed tubing may make it particularly suitable for use in catheters, including catheters designed for flexibility, and the thin wall thickness and low modulus values ​​of the disclosed tubing result in a remarkably flexible tubing / liner product. Additionally, the polyethylene tubing of the present disclosure is radiation-resistant and sterilizable.

Description

[Technical Field]

[0001] This application relates generally to the field of tubing for use as thin-walled catheter liners and the like, comprising two or more polyethylene resins, and to methods and properties relating to such tubing. [Background technology]

[0002] Vascular treatments utilize minimally invasive catheter-based procedures as well as specialized equipment and techniques. Catheters used in these procedures typically utilize coatings or liners to provide a lubricious inner surface. The lubricious inner diameter (ID) associated with these devices is beneficial in reducing friction caused by various catheter technologies, such as stents, balloons, and atherectomy or thrombectomy devices, as they are pushed through the narrow confines of the catheter lumen. If the catheter ID is not sufficiently lubricious, devices such as stents may cause the liner to collapse like an accordion as they are pushed through the catheter lumen. The effect of improved catheter ID lubricity is reduced catheter device placement forces as they pass through the lumen, increasing the likelihood of a successful procedure. The mechanical properties of catheter liners are also crucial. For example, high tensile and yield strengths are required for certain devices (e.g., flow shunts, embolization coils, aneurysm bridging devices, scaffolding, and thrombectomy devices) to pass through microcatheters in a compressed state. The compressed shape exerts a radially outward force that causes friction with the ID and generally makes delivery of the device through the lumen difficult. On the other hand, a highly flexible liner is often desirable when the catheter must traverse vasculature with sharp kinks and bends (e.g., cerebral vasculature and below-the-knee (BTK) applications).

[0003] For example, among the various materials being pursued as the base liner material for such catheter devices is polytetrafluoroethylene (PTFE) due to its excellent chemical resistance, high-temperature resistance, biocompatibility, and very low coefficient of friction / high lubricity. One of PTFE's major drawbacks is its lack of radiation stability. Radiation sterilization (i.e., gamma radiation or electron beam) is one of the most widely used and safest sterilization processes for medical devices. While radiation sterilization improves catheter manufacturability because it can be performed quickly on the production line, the alternative ethylene oxide (ETO) sterilization procedure typically used with PTFE-lined catheters requires storage for up to 48 hours to allow the gas to diffuse out of the sterilized device. Furthermore, ETO must be handled with care due to its flammability and toxicity. Due to its strict handling requirements and technically complex sterilization process, ETO sterilization techniques are often undesirable. In recent years, medical regulatory agencies around the world have also urged the medical industry to minimize ETO use or replace it with alternative sterilization methods.

[0004] Some radiation-stable alternatives to PTFE utilize polymers such as nylon and Pebax®, but these polymers have not been widely accepted as catheter materials due to their relatively high coefficients of friction. Therefore, the radiation-stable advantage offered by nylon and Pebax® is offset by their lower lubricity compared to PTFE. Polyethylene materials, particularly the higher-density grades, have significantly lower coefficients of friction than other commonly extruded polymers, such as polypropylene. Like nylon and Pebax®, polyethylene is radiation-stable, and catheter liners made from polyethylene materials can be sterilized using radiation.

[0005] Another drawback of PTFE-based lubricious liners is the hydrophobicity of their inner surface. Certain applications, such as infusing saline-based solutions through the catheter, require a highly lubricious, wetted inner surface of the liner. The hydrophobic nature of PTFE tends to prevent sufficient wetting of the surface, reducing the lubricity of the PTFE surface.

[0006] Typically, to improve the wet lubricity of polyethylene liners, hydrophilic lubricious coatings are applied to the inner surface of the substrate. These hydrophilic coatings have been used to reduce the coefficient of friction of medical devices such as catheters, probes, and feeding tubes. Some commonly known lubricious coatings applied to the surface of medical devices include formulations made from polyvinylpyrrolidone, polyurethane, acrylic polyester, vinyl resin, fluorocarbon, silicone rubber, and / or combinations of these materials. For example, Micklus et al. (U.S. Patent Nos. 4,100,309 and 4,119,094) described hydrophilic coatings made from polyvinylpyrrolidone-polyurethane interpolymers formed with polyisocyanates. Ratner et al. (U.S. Patent No. 3,939,049) described a method of lubrication by grafting hydrogels onto polymeric materials using radiation. Hungton et al. (U.S. Patent No. 3,975,350) described hydrophilic polyurethane polymers for use as lubricants. Storey et al. (US Pat. No. 3,987,497) relates to a tendon prosthesis with a lubricant hydrogel coating.

[0007] However, a major disadvantage of such hydrophilic lubricious coatings is that the processes developed to apply them to such medical devices involve many steps and are time-consuming, making large-scale production economically unprofitable. Other disadvantages of such lubricious coatings include poor lubricity, the lack of durability characteristic of silicone- or fluorocarbon-based coatings, and the use of hazardous solvents or unstable reactive materials in their manufacture. Lubricants manufactured for medical use from unstable reactive materials require more frequent preparation of the coating solution, thereby increasing waste and costs. Similarly, lubricants made with hazardous solvents used in medical applications are undesirable due to concerns about patient toxicity and OSHA regulations. Furthermore, lubricant coatings on medical devices used during invasive procedures can leave the body susceptible to infection and / or thrombogenic reactions, and have failed to incorporate pharmaceutically acceptable levels of antibacterial and antithrombotic compounds. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 4,100,309 [Patent Document 2] U.S. Patent No. 4,119,094 [Patent Document 3] U.S. Patent No. 3,939,049 [Patent Document 4] U.S. Patent No. 3,975,350 [Patent Document 5] U.S. Patent No. 3,987,497 [Non-patent literature]

[0009] [Non-Patent Document 1] Maleic Anhydride Grafting on EPDM: Qualitative and Quantitative Determination, 1999 Summary of the Invention [Problem to be solved by the invention]

[0010] To address these and other potential disadvantages of lubricant-based hydrophilic coatings, such as those in the above-cited patents, alternative methods are needed to produce thin-walled lubricious polyethylene liners that are sufficiently lubricious when wet to be useful in the medical device field. The lubricious polyethylene liners should be able to adhere to a wide variety of substrates and be resistant to wet abrasion. Furthermore, it would be beneficial if such lubricious hydrophilic polyethylene liners could be produced with fewer processing steps. [Means for solving the problem]

[0011] The present disclosure provides thin-walled, lubricious polyethylene (PE) tubing, products incorporating such tubing, and methods for producing and using such tubing and products. The disclosed PE tubing generally comprises two or more PEs and can be produced by melt extrusion of a polyethylene blend. Exemplary average wall thicknesses of the tubing provided herein may be less than 0.100 mm (preferably less than 0.050 mm), with moderate to high machine direction orientation of the polyethylene polymer. In some embodiments, depending on the polyethylene blend formulation, the tubing may have high flexibility while the inner tubing surface exhibits high lubricity and abrasion resistance. In various embodiments, the thin wall thickness and low modulus values ​​of the disclosed tubing result in highly flexible tubing / liner products, making the combination of properties exhibited by the disclosed tubing particularly suitable for use in catheters, including those designed for flexibility. Furthermore, the currently disclosed polyethylene tubing is also radiation-resistant and sterilizable (unlike PTFE liners). In some embodiments, the tubing may be oriented in the machine and / or cross directions, which may result in improved mechanical, thermal, and barrier properties. Additionally, the polyethylene tubing of the present invention can be used as a liner for metal tubing, such as laser cut hypotubes.

[0012] The present invention includes, but is not limited to, the following embodiments.

[0013] Embodiment 1: A tubing comprising a blend of two or more polyethylenes, the tubing having an average wall thickness of 0.1 mm or less, and comprising a blend of UHMWPE in an amount of 20 weight percent or less and at least 80 weight percent of at least one second polyethylene resin selected from the group consisting of LLDPE, LDPE, MDPE, and HDPE.

[0014] Embodiment 2: The tube of embodiment 1 in the form of a tube on a wire or mandrel.

[0015] Embodiment 3: The tube of any of embodiments 1-2, wherein the average wall thickness is less than 0.075 mm.

[0016] Embodiment 4: The tube of any of embodiments 1-3, wherein the average wall thickness is less than 0.050 mm.

[0017] Embodiment 5: The tubing of any one of embodiments 1-4, comprising 10 weight percent or less UHMWPE.

[0018] Embodiment 6: The tubing of any of embodiments 1-5, comprising 5 weight percent or less UHMWPE.

[0019] Embodiment 7: The tube of any of embodiments 1-6, wherein the at least one second polyethylene resin comprises HDPE.

[0020] Embodiment 8: The tubing of any of embodiments 1-7, wherein the two or more polyethylenes include at least one chemically modified polyethylene.

[0021] Embodiment 9: The tubing of embodiment 8, wherein the chemically modified polyethylene is maleic anhydride grafted polyethylene.

[0022] Embodiment 10: The tube of any of embodiments 1-9, further comprising one or more additives selected from the group consisting of one or more antioxidants, antimicrobials, processing aids, colorants, slip aids, and combinations thereof.

[0023] Embodiment 11: The tubing of any of embodiments 1-10, further comprising a continuous layer on the interior or exterior surface, the continuous layer comprising a second blend, the second blend comprising chemically modified polyethylene.

[0024] Embodiment 12: The tube of embodiment 11, comprising a first continuous layer on the interior surface and a second continuous layer on the exterior surface, the first and second continuous layers being the same or different.

[0025] Embodiment 13: The tube of any one of embodiments 1 to 12, which exhibits a coefficient of friction in air at 23° C. of 0.2 or less.

[0026] Embodiment 14: The tube of any one of embodiments 1 to 13, which exhibits a coefficient of friction in saline at 23° C. of 0.2 or less.

[0027] Embodiment 15: The tube of any one of embodiments 1 to 14, which exhibits a coefficient of friction in saline at 23° C. of 0.1 or less.

[0028] Embodiment 16: A medical device comprising the tube of any one of embodiments 1 to 15.

[0029] Embodiment 17: A method of preparing the tube of any of embodiments 1-15, comprising providing two or more polyethylenes; and extruding the two or more polyethylenes through an extruder to form the tube.

[0030] Embodiment 18: The method of embodiment 17, wherein the two or more polyethylenes are in the form of a blended material.

[0031] Embodiment 19: The method of embodiment 18, wherein the blended material has an MFI of 3.0 g / 10 min or less.

[0032] Embodiment 20: The method of any of embodiments 18-19, wherein the blended material has an MFI of 2.5 g / 10 min or less.

[0033] Embodiment 21: The blended material has a viscosity of 0.94 g / cm 3 ~0.96g / cm 3 21. The method of any of embodiments 18-20, having a calculated density of

[0034] Embodiment 22: The method of embodiment 17, wherein the two or more polyethylenes are individual components that are combined immediately prior to extrusion.

[0035] These and other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description, briefly described below, read in conjunction with the accompanying drawings. The present invention includes any combination of two, three, four, or more of the above-described embodiments, as well as any combination of any two, three, four, or more features or elements described in this disclosure, whether or not such features or elements are explicitly combined in the description of a specific embodiment herein. The present disclosure is intended to be read holistically, such that any separable features or elements of the disclosed invention, in any of its various aspects and embodiments, are deemed to be intended to be combined unless the context clearly dictates otherwise.

[0036] 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 designate components of exemplary embodiments of the present invention. The drawings are illustrative only and are not to be construed as limiting the present invention. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a general schematic diagram of a tube of the present disclosure, including relevant parameters, and an enlarged view of one of the cross-sectional end faces of the tube. [Figure 2A] 1 is a general schematic diagram of a cross section of a tube according to various embodiments of the present disclosure. [Figure 2B] 1 is a general schematic diagram of a cross section of a tube according to various embodiments of the present disclosure. [Figure 2C] 1 is a general schematic diagram of a cross section of a tube according to various embodiments of the present disclosure. [Figure 2D] 1 is a general schematic diagram of a cross section of a tube according to various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be described in further detail below. However, the present invention 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 be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As used in this specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0039] A general schematic diagram of a tube is shown in Figure 1. The tube is generally cylindrical in shape. "L" indicates the length of the manufactured tube, which can be processed, e.g., cut, to provide a tube of the desired length "1" (not shown). The enlarged area on the right side of Figure 1 is a cross-sectional view of the interior of the tube. As shown, the "lumen" is the interior region of the tube, i.e., the open passage / cavity (e.g., through which a catheter device can be passed). The inner diameter of the tube, designated "ID," is the average distance from a point on the inner wall of the tube to the opposite / farthest point on the inner wall of the tube. The outer diameter of the tube, designated "OD," is the average distance from a point on the outer wall of the tube through the lumen of the tube to the opposite / farthest point on the outer wall of the tube. Therefore, half of the OD value minus the ID value indicates the average wall thickness of the tube. Representative "wall thickness," "inner wall surface," and "outer wall surface" of a tube are shown in Figure 1. The present disclosure provides thin-walled, lubricious polyethylene tubes. "Polyethylene tubing" means that the tubing is primarily made of one or more polyethylenes, e.g., two or more polyethylenes.

[0040] In some embodiments, the tubing provided herein is substantially uniform in composition throughout the wall and / or length of the tubing (e.g., as shown in FIG. 2A, which shows a cross-section of tubing 10 comprising a polyethylene blend). In some non-limiting embodiments, the tubing provided herein is substantially uniform, except that the interior and / or exterior surfaces of the tubing may include different materials. For example, FIG. 2B is a cross-section of tubing 10 comprising a polyethylene blend in which a different material 12 has been applied as a layer onto the exterior surface of blend 10. FIG. 2C is a cross-section of tubing 10 comprising a polyethylene blend in which a different material 14 has been applied as a layer onto the interior surface of blend 10. FIG. 2D is a cross-section of tubing 10 comprising a polyethylene blend in which a different material 12 has been applied as a layer onto the exterior surface of blend 10 and a different material 14 has been applied as a layer onto the interior surface of blend 10 (where the composition of 14 may be the same as or different from the composition of 12).

[0041] Typically, the composition of 10 comprises a blend of two or more polyethylenes. Suitable polyethylenes include, but are not limited to, low-density polyethylene ("LDPE"), linear low-density polyethylene ("LLDPE"), medium-density polyethylene ("MDPE"), high-density polyethylene ("HDPE"), ultra-high molecular weight polyethylene ("UHMWPE"), and chemically modified polyethylenes, such as modified LDPE or LLDPE (or possibly modified HDPE), including grafted polyethylene. Suitable chemically modified polyethylenes include, but are not limited to, anhydride-grafted LDPE, LLDPE, or HDPE, such as maleic anhydride-grafted LDPE, LLDPE, or HDPE. Other chemically modified polyethylenes that may be suitably included in 10 include, but are not limited to, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, ethylene-acrylic acid ester-maleic anhydride terpolymer, and the like. Such chemically modified polyethylenes generally serve as binder resins and may therefore be referred to as such in some places herein. In some embodiments, 10 may further include one or more optional additives, such as one or more antioxidants, antimicrobials, processing aids, slip aids, and colorants, as well as other particulates designed to impart particular properties to the tubing.

[0042] In one embodiment, 10 comprises: a) HDPE, LDPE, or LLDPE; and b) UHMWPE. The amount of HDPE in some such embodiments is about 50 to about 90 weight percent, preferably about 65 to about 85 weight percent, and more preferably about 70 to about 80 weight percent, based on the total weight of the tube. The amount of LDPE in some such embodiments is about 5 to about 40 weight percent, preferably about 10 to about 25 weight percent, and more preferably about 15 to about 25 weight percent, based on the total weight of the tube. The amount of LLDPE in some such embodiments is less than 30 weight percent, preferably less than 20 weight percent, and more preferably less than 15 weight percent, based on the total weight of the tube. In certain embodiments, 10 comprises: a) HDPE and b) UHMWPE (and optionally further comprises one or more of LDPE and LLDPE). All such embodiments may optionally further comprise one or more binder resins.

[0043] In some such embodiments, the amount of UHMWPE is less than 20 weight percent, preferably less than 10 weight percent, and more preferably less than 5 weight percent, based on the total weight of the tubing. For example, a given tubing may contain about 1 to about 20 weight percent UHMWPE, about 1 to about 10 percent, about 1 to about 5 percent, about 2 to about 20 percent, about 2 to about 10 percent, about 5 to about 20 percent, or about 5 to about 10 percent UHMWPE. The inclusion of UHMWPE can impart roughness to the tubing. The roughness can be on the inner and / or outer wall surfaces of the tubing. The roughness can be varied by varying the concentration of UHMWPE in the tubing and by varying the size of the UHMWPE particles used to produce the tubing. In some embodiments, the roughness can affect the physical, mechanical, and / or thermal properties of the tubing, such as lubricity, toughness, and modulus. Roughness, particularly on the outer surface of the tubing, can also affect adhesion between the polyethylene blend liner and the catheter jacket.

[0044] When included, the chemically modified polyethylene is generally present in an amount of about 50% by weight or less, e.g., 0% to about 50% by weight, about 0% to about 25% by weight, about 5% to about 50% by weight, about 5% to about 25% by weight, or about 25% to about 50% by weight.

[0045] The two or more different polyethylenes in 10 may differ in composition, grade, molecular weight, or any combination thereof. The amount and grade(s) of polyethylene in the disclosed tubing may vary, which may result in different thermal, mechanical, and structural properties of the tubing.

[0046] For example, in some embodiments, tubing containing one or more chemically modified polyethylenes (tie layer resins) generally exhibits increased hydrophilicity, including increased hydrophilicity of the inner wall surface of the tubing (compared to comparable tubing without chemically modified polyethylenes), making such tubing more suitable for applications requiring high lubricity of the wetted inner wall surface (e.g., for certain catheter applications). In some embodiments, the polyethylene tubing provided herein has a low coefficient of friction (COF). For example, in some embodiments, the COF of the polyethylene tubing provided herein is about 0.2 or less, or about 0.1 or less in saline at 23°C. The inner surface of the hydrophilic liner may be wetted with water or saline to provide an anti-friction layer that lowers the coefficient of friction (COF) and thereby improves the overall lubricity of the inner surface. In some embodiments, such tubing containing one or more modified and / or grafted polyethylenes includes moieties that chemically bond the outer wall surface to an outer layer, such as nylon, polyether-block-amide (PEBA), etc., which is advantageous for use as a catheter liner.

[0047] In some embodiments, the disclosed tubing has a thin wall, e.g., an average wall thickness of less than about 0.100 mm, preferably less than about 0.075 mm, and more preferably less than 0.050 mm. Some such thin walls have an average thickness of about 0.010 mm to about 0.10 mm, about 0.010 mm to about 0.075 mm, or about 0.010 mm to about 0.050 mm. In some embodiments, the disclosed polyethylene tubing does not require additional surface treatments or tie layers to enhance the bond between the outer surface of the polyethylene tubing and adjacent materials (e.g., including, but not limited to, jacketing materials such as those used in catheters).

[0048] The present disclosure also provides articles of manufacture, such as medical catheters, that include the polyethylene tubing described herein. For example, in some embodiments, medical catheters are provided in the form of tri-layer catheters, including the polyethylene tubing provided herein as the innermost layer. In such applications, the polyethylene tubing generally has an average wall thickness of about 0.025 mm to about 0.070 mm and an inner diameter (ID) of about 0.380 mm to about 4.300 mm. The polyethylene tubing is covered by a braided layer, and an outer jacket surrounds the braided layer. In some embodiments, such structures include an additional tie layer to enhance the bond between the polyethylene tubing and the jacket, further increasing the size and thickness of the catheter. In some embodiments, as referenced above, a tie layer is not required, and in some embodiments, surface treatment of the polyethylene tubing is not required to produce a suitable jacketed structure useful for medical catheters.

[0049] The methods for producing the polyethylene tubing described herein can vary. According to certain embodiments, a melt-processable blend of two or more polyethylenes as described herein above is first prepared.

[0050] In such embodiments, two or more polyethylene resins described above are selected and processed into a blend using conventional melt processing equipment under melt processing conditions. Preferably, an intimate blend of two or more polyethylene resins is formed in the molten state in an extruder (e.g., an intermeshing co-rotating twin-screw extruder, although other types of twin-screw extruders may be used). The twin-screw extruder preferably has a length to diameter ratio of at least about 20:1, more preferably at least about 30:1, and most preferably at least about 40:1. The mixture of polyethylene resins is passed through the extruder to form an extrudate. Upon exiting the twin-screw extruder, the extrudate is generally in the form of a mono-fiber blend and can be chopped, for example, into pellets. The pellets can then be fed into the throat of a single-screw extruder and extruded from the single-screw melt extruder into a tubular structure. In some such embodiments, the melt flow index (MFI) of the blend is 3.0 g / 10 min or less, or 2.5 g / 10 min or less. The blend can also be defined, in some embodiments, by its calculated density. For example, in some embodiments, the blend has a viscosity of 0.94 g / cm 3 ~0.96g / cm 3 has a calculated density of

[0051] In an alternative embodiment, the components of the polyethylene blend can be fed individually in precise proportions directly into the feed throat of a single screw extruder equipped with a mixing screw and extruded into a tubular structure.

[0052] In the embodiments described herein above, the hot tubular extrudate emerging from the single screw extruder is pulled as it exits the extruder and stretched to the desired size 10. Typically, upon exiting the extruder, the extrudate is passed into a cooling chamber which is preferably at a temperature between 5°C and 25°C.

[0053] In some embodiments, the tube is obtained by extruding a material onto a wire or mandrel (which may be metal or nonmetallic, e.g., a polymer such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK)). The mandrel may be smooth or textured. For example, in some embodiments, a textured mandrel is used that includes PTFE and one or more fillers, such as glass beads, glass bubbles, clay, silica, silicates, metal oxides, metal hydroxides, and combinations thereof. Non-limiting textured mandrels encompassed by the present disclosure (e.g., as referenced in the Examples herein) may have a surface roughness characterized by a minimum average surface roughness, Ra, of 0.50 μm; and / or a minimum root mean square (RMS) surface roughness, Rq, of 0.75 μm (e.g., including embodiments in which the surface roughness is characterized by both a minimum average surface roughness, Ra, of 0.50 μm; and a minimum RMS surface roughness, Rq, of 0.75 μm). Extrusion onto a mandrel (metal or non-metal) can affect some physical, mechanical, or thermal properties of the resulting tubing, such as lubricity, toughness, modulus, etc. Extrusion onto a mandrel can also affect the adhesion between the outer surface of the tubing and the catheter jacket.

[0054] During extrusion, molecular / chain orientation can be imparted to the extrudate (e.g., the final part) based on the drawdown of the material. This drawdown and other parameters of the extrusion can be adjusted / modified as known in the art to achieve a desired result (e.g., a desired orientation). The orientation imparted to the material is known to affect tensile properties—particularly modulus, tensile strength, and elongation. The observed change in modulus may also modify the COF. Generally, increasing the drawdown increases the axial orientation of the polymer, thereby increasing the modulus and tensile strength and decreasing the elongation and COF. Again, one skilled in the art can modify the drawdown to modify the modulus, tensile strength, elongation, and / or COF to produce a tube with physical properties appropriate for the intended end use.

[0055] In polyethylene blends containing binder resins, the amount of functional groups, such as maleic anhydride, present on the inner and outer walls of the tubing can potentially be varied by changing the mandrel material (e.g., using a PTFE-coated mandrel). Migration of functionalized polymers to the inner and outer walls will also depend on the overall concentration of these groups in the extruded formulation. Variations in the amount of binder resin on the inner and outer walls of the tubing can affect the physical, mechanical, or thermal properties of each wall, particularly surface tension and lubricity. This can also affect the adhesion between the polyethylene blend liner and the catheter jacket.

[0056] The extrudate may optionally be further processed, for example, by cutting long tubes into shorter lengths as desired for specific applications. The extruded tube may also be exposed to radiation (e.g., at a dose of 50 kGy to 15 MGy), such as electron beam or gamma radiation. Radiation treatment may modify the polymer chain structure of the tube and affect some of the tube's physical, mechanical, or thermal properties, such as lubricity, toughness, modulus, etc. Typically, radiation treatment can impart crosslinks to polyethylene chains, thereby increasing modulus and tensile strength. Those skilled in the art are aware of such radiation treatments and can select appropriate methods and parameters to modify the tube as desired.

[0057] In some embodiments, the modified / grafted polyethylene tie layer resin is incorporated into the blend referenced herein above (and thus incorporated into 10). In some embodiments, other additives are also incorporated into the blend referenced herein above (and thus incorporated into 10). As such, the method may further comprise blending one or more tie layer resins and / or one or more additives with two or more polyethylene resins, or may further comprise adding such components individually directly to the feed throat of a single screw extruder equipped with a mixing screw and extruding them together with one or more polyethylene resins into tubular structure 10.

[0058] Alternatively (or in addition), the optional incorporation of modified and / or grafted polyethylene tie-layer resins into the final tube can be achieved by coextrusion. In such embodiments, the modified and / or grafted polyethylene tie-layer resins are coextruded with one or more of the polyethylenes referenced above, with or without a mandrel (metallic / non-metallic), to form the inner (14) and / or outer (12) wall surfaces of the tube (see Figures 2B, 2C, and 2D). In such embodiments, these optional resins may also be blended with other grades of polyethylene, such as LDPE, LLDPE, MDPE, HDPE, and / or UHMWPE, and coextruded with one or more polyethylenes, with or without a mandrel (metallic / non-metallic), to form the inner (14) and / or outer (12) wall surfaces of the tube (see Figures 2B, 2C, and 2D). The coextrusion process can affect some physical, mechanical, or thermal properties of the polyethylene blend tubing material, such as lubricity, toughness, and modulus. Coextrusion can also affect the adhesion of the polyethylene tubing to the catheter jacket applied over it.

[0059] In further embodiments, catheter jacket materials such as nylon, PEBA, and the like, can also be co-extruded with one or more polyethylenes provided herein.

[0060] Equipment such as a Beahm 810A vertical laminator may be used to manufacture catheters using the disclosed polyethylene tubing. The polyethylene tubing provided herein can be bonded to catheter jackets made from materials such as PEBA, nylon, and polyurethane. The polyethylene tubing provided herein can be stretched to reduce the wall thickness of the tubing without reducing surface adhesion and then used to manufacture catheters. The degree of stretching of the tubing can affect several physical, mechanical, or thermal properties of the tubing, such as lubricity, toughness, and modulus. Typically, increasing the degree of stretching increases the axial orientation of the tubing, thereby increasing modulus and tensile strength and decreasing elongation.

[0061] Manufactured catheters and catheter components, such as liners and jackets, can be tested using interventional device testing equipment such as the IDTE3000 from MSI, which can measure and record device performance characteristics such as pushability, flexibility, and torqueability.

[0062] [Example] experiment Embodiments of the present disclosure are more fully illustrated by the following examples, which are provided to illustrate aspects of the disclosure, but are not to be construed as limiting the invention. Unless otherwise indicated, all parts and percentages are by weight.

[0063] Test Method Tensile properties of polyethylene tubing were determined using an Instron 5965 dual-column mechanical testing machine running Bluehill 3 v3.73.4823 operating software. Testing was performed at room temperature (23 °C) at a strain rate of 508 mm / min using a 1 kN load cell set at a 50.8 mm gauge length. An environmental chamber was used to measure tensile properties at an elevated temperature of 120 °C using a 1 kN load cell. The crosshead travel limit in the environmental chamber was 26.7 mm; therefore, the gauge length was shortened to 2.54 mm and the crosshead speed was reduced to 25.4 mm / min to match the nominal strain rate of 508 mm / min for the 50.8 mm gauge length tested at room temperature. At least three specimens were tested for each blend and temperature, and the average results are reported in Table 2.

[0064] The thermomechanical properties of polyethylene blend tubing materials were determined using a TA Instruments Q800 DMA equipped with a film tension fixture. The primary property of interest was the storage modulus (E'). A temperature scan from -100 °C to 130 °C was performed with a 5-minute isothermal hold at -100 °C. The samples were heated at a constant rate of 3 °C / min and displaced at a constant amplitude of 15 µm with a fixed frequency tensile oscillation of 1 Hz. The resulting DMA data was imported into TA Instruments TRIOS software v4.3. The average storage modulus values ​​at 23 °C and 40 °C are listed in Table 2.

[0065] The tribological properties of polyethylene blend tubing materials were measured using a TA Instruments Discovery Hybrid Rheometer (DHR-3) equipped with a tribo-rheometer attachment. The primary property of interest during this test was the coefficient of friction (COF). For use with a ring-on-plate tribo-rheometry fixture, samples were prepared by attaching three 5 mm x 16.5 mm tube sections to the teeth of three half rings. The rings with the samples attached were then mounted in a ring-on-plate upper placement holder, and the samples were lowered into contact with a mirror-polished stainless steel plate at a predetermined axial force. Tribological tests were conducted at room temperature (23 °C) and 40 °C with sliding speeds of 750 μm / s to 7650 μm / s under an axial load of 1 N. Additional tribological tests were conducted in a saline bath at room temperature (23 °C) and 40 °C with sliding speeds of 750 μm / s to 7650 μm / s under an axial load of 1 N. The minimum COF for the specified sliding speed range was calculated using TRIOS software v4.3 from TA instruments. Three samples were tested for each blend and temperature, and the averages are listed in Table 2.

[0066] Infrared spectra of polyethylene blend tubing and polyethylene melt plaques per ASTM E1252 were obtained using a ThermoScientific Nicolet iS50 FTIR equipped with a diamond crystal ATR. FTIR testing was performed on the outer and inner surfaces of the tubing samples and on both sides of the plaques. The amount of maleic anhydride present in the polyethylene tubing and plaques prepared from blends with different concentrations of binder resin was quantified using peak height ratios (Maleic Anhydride Grafting on EPDM: Qualitative and Quantitative Determination, 1999). The 1460 cm peak, present in all polyethylene resins, was also measured. -1 The CH2 band and the 1780 cm -1 The C=O stretching band was used for quantification. The peak height ratio of the two bands (h1780 / h 1460 ) can be used to quantitatively compare the amount of maleic anhydride present in the samples. These ratios are listed in Tables 3 and 4.

[0067] The polyethylene tubing and plaques were evaluated for contact angle with a Tantec Inc. CAM-PLUS contact angle meter using the half-angle method per ASTM D7334. At least three readings were taken for each sample on the outer and inner surfaces of the tubing and on both sides of the plaque. The results are listed in Tables 2 and 4.

[0068] The melt flow index (MFI) of the resin blends was measured using a Dynisco LMI4003 melt index measuring device. Standard ASTM test method D1238 was used with test conditions of 190°C and 2.16 kg.

[0069] The surface roughness of the outer surface of polyethylene tubing samples was measured at λ = 2.54 mm using a Mitutoyo Surftest SJ-410 profilometer. Five readings were taken for each sample. These average values ​​are listed in Table 2.

[0070] The density of the polyethylene blend was calculated using the following equation, where: m a = mass of resin A m b = Mass of Resin B ρ a = Density of Resin A ρ b = Density of Resin B ρ c = calculated density of the blend of resins A and B

[0071]

number

[0072] Catheters were fabricated using a Thermo Scientific Heratherm oven, using polyethylene blend tubing as the liner and PEBA tubing as the outer jacket. The tubing sample was slid over a PTFE mandrel, followed by a PEBA tube whose ID was slightly larger than the OD of the polyethylene blend tubing. Finally, to produce a uniformly bonded catheter, the catheter assembly was covered with FEP heat shrink tubing. The heat shrink-coated catheter assembly was placed in an oven at a temperature of 210–220°C for 5 minutes. After removing the sample from the oven, it was allowed to cool at room temperature. Both the heat shrink cover and the PTFE mandrel were removed from the catheter assembly, and the bonded catheter was tested for peel resistance and adhesion.

[0073] The peel resistance of polyethylene tubing bonded to PEBA catheter jackets was determined using an Instron 5965 dual-column mechanical testing machine running Bluehill 3 v3.73.4823 operating software. The test method used was a modified version of ASTM D1876 (T-peel test), and the ASTM standard layered test specimen was a bonded catheter tubing split in half. The polyethylene liner was clamped on one side, and the PEBA jacket was clamped on the other side. Tests were conducted at room temperature (23°C) at a speed of 1 in / s using a 1 kN load cell set to a 25.4 mm gauge length. At least three specimens per catheter type were tested, and the average results are reported in Table 3.

[0074] Examples of polyethylene blend tubing materials [Example]

[0075] Polyethylene blend tubing containing 89 wt% HDPE, 1 / 9 wt% binder resin, and 1 / 2 wt% UHMWPE was melt extruded to an OD of 1.880 mm and a wall thickness of 0.030 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2. [Example]

[0076] Polyethylene blend tubing containing 89 wt% HDPE 1 / 9.9 wt% HDPE 2 / 1.1 wt% UHMWPE was melt extruded to an OD of 1.850 mm and a wall thickness of 0.035 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2. [Example]

[0077] Polyethylene blend tubing containing 71.2 wt% HDPE 1 / 20 wt% HDPE 2 / 7.2 wt% binder resin 1 / 1.6 wt% UHMWPE was melt extruded to an OD of 1.830 mm and a wall thickness of 0.036 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2. [Example]

[0078] Polyethylene blend tubing containing 48.75 wt% HDPE 1 / 48.75 wt% HDPE 3 / 2.5 wt% UHMWPE was melt extruded to an OD of 1.800 mm and a wall thickness of 0.036 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2. [Example]

[0079] The polyethylene blend tubing material from Example 4 was irradiated with an electron beam to a total dose of 10 MGy. Testing of the tubing was performed using the method described above. The average values ​​are reported in Table 2. [Example]

[0080] Polyethylene blend tubing containing 68 wt% HDPE 1 / 12 wt% HDPE 2 / 8.5 wt% binder resin 2 / 8.5 wt% LDPE / 3 wt% UHMWPE was melt extruded to an OD of 1.900 mm and a wall thickness of 0.030 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2.

[0081] Example of a polyethylene blend catheter [Example]

[0082] Polyethylene blend tubing containing 72 wt% HDPE, 1 / 18 wt% HDPE, 3 / 8 wt% binder resin, and 2 / 2 wt% UHMWPE was melt extruded to an OD of 1.850 mm and a wall thickness of 0.038 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3. [Example]

[0083] Polyethylene blend tubing containing 64 wt% HDPE, 1 / 18 wt% HDPE, 3 / 16 wt% binder resin, and 2 / 2 wt% UHMWPE was melt extruded to an OD of 1.830 mm and a wall thickness of 0.038 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. The inner and outer surfaces of the polyethylene tubing samples were also examined by FTIR. Average values ​​are reported in Table 3. [Example]

[0084] The polyethylene blend tubing from Example 8 was stretched 23% on a PTFE mandrel by heating the tubing sample to 115-120°C. The stretched polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. The average values ​​are reported in Table 3. [Example]

[0085] The polyethylene blend tubing from Example 8 was stretched 45% on a PTFE mandrel by heating the tubing sample to 115-120°C. The stretched polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3. [Example]

[0086] Polyethylene blend tubing containing 64 wt% HDPE, 1 / 18 wt% HDPE, 3 / 16 wt% binder resin, and 2 / 2 wt% UHMWPE was melt extruded onto a PTFE mandrel to an OD of 1.750 mm and a wall thickness of 0.036 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. The inner and outer surfaces of the polyethylene tubing samples were also examined by FTIR. Average values ​​are reported in Table 3. [Example]

[0087] Polyethylene blend tubing containing 74 wt% HDPE, 1 / 24 wt% binder resin, and 2 / 2 wt% UHMWPE was melt extruded to an OD of 1.830 mm and a wall thickness of 0.038 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3. [Example]

[0088] Polyethylene blend tubing containing 52.5 wt% HDPE 1 / 15.75 wt% HDPE 3 / 30 wt% binder resin 2 / 1.75 wt% UHMWPE was melt extruded to an OD of 1.800 mm and a wall thickness of 0.041 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. The inner and outer surfaces of the polyethylene tubing samples were also examined by FTIR. Average values ​​are reported in Table 3. [Example]

[0089] Polyethylene blend tubing containing 52.5 wt% HDPE 1 / 15.75 wt% HDPE 3 / 30 wt% binder resin 2 / 1.75 wt% UHMWPE was melt extruded onto a PTFE mandrel to an OD of 1.780 mm and a wall thickness of 0.038 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. The inner and outer surfaces of the polyethylene tubing samples were also examined by FTIR. Average values ​​are reported in Table 3. [Example]

[0090] Polyethylene blend tubing containing 18 wt% HDPE, 1 / 80 wt% binder resin, and 2 / 2 wt% UHMWPE was melt extruded to an OD of 1.830 mm and a wall thickness of 0.041 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3.

[0091] Comparative Example of Polyethylene Blend Comparative Example 1: Polyethylene blend tubing containing 89 wt% HDPE 1 / 9 wt% LDPE / 2 wt% UHMWPE was melt extruded to an OD of 1.830 mm and a wall thickness of 0.025 mm. Testing of the tubing was performed using the method described above. Average values ​​are reported in Table 2. Polyethylene tubing was also used to fabricate catheters and tested for adhesion using the method described above. The inner and outer surfaces of the polyethylene tubing samples were also examined by FTIR. Average values ​​are reported in Table 3.

[0092] Comparative Example 2: Polyethylene blend tubing containing 70 wt% HDPE 1 / 20 wt% HDPE 2 / 10 wt% binder resin was melt extruded to an OD of 1.850 mm and a wall thickness of 0.025 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2.

[0093] Comparative Example 3: Polyethylene blend tubing containing 50 wt% HDPE 1 / 50 wt% HDPE 3 was melt extruded to an OD of 1.850 mm and a wall thickness of 0.036 mm. Testing of the tubing was performed using the methods described above. Average values ​​are reported in Table 2.

[0094] Comparative Example 4: The polyethylene blend tubing material from Comparative Example 3 was irradiated with an electron beam to a total dose of 10 MGy. Testing of the tubing was performed using the method described above. The average values ​​are reported in Table 2.

[0095] Comparative Example 5: Polyethylene blend tubing containing 70 wt% HDPE 1 / 30 wt% binder resin 2 was melt extruded to an OD of 1.830 mm and a wall thickness of 0.036 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3.

[0096] Comparative Example 6: Polyethylene blend tubing containing 20 wt% HDPE 1 / 80 wt% binder resin 2 was melt extruded to an OD of 1.780 mm and a wall thickness of 0.038 mm. The polyethylene tubing was used to fabricate catheters and tested for adhesion using the method described above. Average values ​​are reported in Table 3.

[0097] Example of polyethylene blend plaque Plaque Example 1: 100% HDPE polyethylene plaques were prepared by melt pressing the resin to a thickness of 0.200 mm at a temperature of 175 °C. A PTFE release sheet was used on one side and a stainless steel (SS) release sheet was used on the other side. Both sides of the plaques were examined by FTIR and contact angle. The results are reported in Table 4.

[0098] Plaque Example 2: Polyethylene blend plaques of 90% HDPE 1 / 10% binder resin 1 were prepared using the method described in Plaque Example 1. Both sides of the plaques were examined by FTIR and contact angle. The results are reported in Table 4.

[0099] Plaque Example 3: Polyethylene blend plaques of 50% HDPE 1 / 50% binder resin 1 were prepared using the method described in Plaque Example 1. Both sides of the plaques were examined by FTIR and contact angle. The results are reported in Table 4.

[0100] [Table 1]

[0101] [Table 2]

[0102] The incorporation of UHMWPE and / or binder resin reduces the COF in saline, reaching a COF comparable to that of PTFE (approximately 0.07). The COF of the PE blend tubing material does not change significantly at ambient temperature or 40°C.

[0103] [Table 3]

[0104] The data show that the bond strength between the sample and the UHMWPE and binder resin was higher than the sample containing only the binder resin and no UHMWPE.

[0105] [Table 4]

[0106] The data from the plaques (Table 4) show that the binder resin has a higher affinity for stainless steel. This can be exploited to create tubing with more selective distribution of the binder layer on the inner and outer surfaces of the tubing. Example 11 shows that when PE blend tubing is extruded onto a PTFE core, the OD layer contains more binder resin than the ID layer, as seen by the difference in FTIR absorbance.

[0107] Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing description. It is to be understood, therefore, that the invention is not to be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A tube comprising a blend of two or more polyethylenes, the tube having an average wall thickness of 0.1 mm or less; UHMWPE in an amount of 20 weight percent or less; at least 80 weight percent of at least one second polyethylene resin selected from the group consisting of LLDPE, LDPE, MDPE, and HDPE; Tube containing a blend of.

2. 10. The tube of claim 1 in the form of a tube on a wire or mandrel.

3. 10. The tube of claim 1 having an average wall thickness of less than 0.075 mm.

4. 10. The tube of claim 1 having an average wall thickness of less than 0.050 mm.

5. 10. The tube of claim 1 comprising no more than 10 weight percent UHMWPE.

6. 10. The tube of claim 1 comprising no more than 5 weight percent UHMWPE.

7. 10. The tubing of claim 1, wherein the at least one second polyethylene resin comprises HDPE.

8. 10. The tubing of claim 1, wherein the two or more polyethylenes include at least one chemically modified polyethylene.

9. 9. The tubing of claim 8, wherein the chemically modified polyethylene is maleic anhydride grafted polyethylene.

10. 10. The tube of claim 1, further comprising one or more additives selected from the group consisting of one or more antioxidants, antimicrobials, processing aids, colorants, slip aids, and combinations thereof.

11. 10. The tubing of claim 1, further comprising a continuous layer on the interior or exterior surface, the continuous layer comprising a second blend, the second blend comprising chemically modified polyethylene.

12. 12. The tube of claim 11, comprising a first continuous layer on the interior surface and a second continuous layer on the exterior surface, the first and second continuous layers being the same or different.

13. 10. The tubing of claim 1, exhibiting a coefficient of friction in air at 23°C of 0.2 or less.

14. 10. The tubing of claim 1, which exhibits a coefficient of friction in saline at 23°C of 0.2 or less.

15. 10. The tubing of claim 1, which exhibits a coefficient of friction in saline at 23°C of 0.1 or less.

16. A medical device comprising the tube of claim 1.

17. 10. A method for preparing the tube of claim 1, comprising: Providing two or more polyethylenes; and Extruding two or more polyethylenes through an extruder to form a tube A method comprising:

18. 18. The method of claim 17, wherein the two or more polyethylenes are in the form of a blended material.

19. 20. The method of claim 18, wherein the blended material has an MFI of 3.0 g / 10 min or less.

20. 20. The method of claim 18, wherein the blended material has an MFI of 2.5 g / 10 min or less.

21. The blended material is 0.94 g / cm ３ ~0.96 g / cm ３ 20. The method of claim 18, having a calculated density of

22. 18. The method of claim 17, wherein the two or more polyethylenes are individual components that are combined immediately prior to extrusion.

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