Medical Tubing and Catheters

Abstract

To achieve both flexibility and elongation resistance of a medical tube at a high level.SOLUTION: A medical tube includes a tube-like core layer and an external layer composed of resin, which is disposed on the outer periphery of the core layer and includes an outer peripheral surface roughly parallel to an axial direction of the medical tube. The core layer includes a tube-like inner core layer composed of a fluorine-based resin and an outer core layer composed of resin whose Young's modulus is higher than that of the fluorine-based resin, which is disposed on the outer periphery of the inner core layer. The core layer has a specific configuration in which crest parts convex toward the outside in a radial direction of the medical tube and trough parts convex toward the inside in the radial direction of the medical tube are disposed repetitively in an axial direction of the medical tube.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technology disclosed herein relates to medical tubes and catheters. [Background technology]

[0002] A catheter is a long medical device that is inserted into tubular organs or internal tissues of the human body, such as blood vessels, the digestive tract, and the urinary tract. A catheter includes, for example, a tubular hollow shaft, a distal tip joined to the distal end of the hollow shaft, and a connector joined to the proximal end of the hollow shaft. The hollow shaft includes, for example, a tubular core layer and an outer layer disposed on the outer periphery of the core layer. The core layer is made of a resin (for example, a fluorine-based resin) that has excellent slip properties and chemical resistance. The outer layer is made of a resin (for example, a polyamide-based resin) that has excellent moldability and flexibility.

[0003] A hollow shaft of a catheter is required to have high flexibility in order to prevent damage to the inner wall of a blood vessel and to improve blood vessel selectivity. A technique for adjusting the flexibility of a catheter is known in which a core layer of the hollow shaft is provided with an uneven structure having multiple protrusions protruding radially inward and recesses surrounding the multiple protrusions (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-236863 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present application have focused on the flexibility as well as the elongation resistance as a performance required for the hollow shaft of the catheter. Here, the elongation resistance means the performance of resisting the force that tries to elongate an object and not easily elongating. The inventors of the present application have found that if the elongation resistance of the hollow shaft is low, for example, when the base end of the catheter is pulled toward the hand side to pull the catheter out of the body, the hollow shaft elongates and the catheter does not move, and when the base end is pulled further toward the hand side, the catheter moves toward the base end in a bouncing manner, resulting in undesirable behavior of the catheter and reduced operability of the catheter. In particular, in recent years, there has been a demand for thinner hollow shafts in order to reduce the burden on patients and ensure the dimensions of the lumen for inserting medical devices such as guidewires, and it is considered that the reduction in elongation resistance due to the thinning of the hollow shaft will be a problem.

[0006] Although the above-mentioned conventional techniques can improve the flexibility of the hollow shaft of a catheter, they do not take into consideration the stretch resistance of the hollow shaft. In other words, the above-mentioned conventional techniques have the problem that they are unable to achieve a high level of both flexibility and stretch resistance of the hollow shaft of a catheter. This problem is not limited to hollow shafts that constitute catheters, but is a common problem for medical tubes in general.

[0007] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0008] The technology disclosed in this specification can be realized, for example, in the following forms.

[0009] (1) The medical tube disclosed in this specification comprises a tubular core layer, and an outer layer made of resin, disposed on the outer periphery of the core layer, and having an outer periphery surface approximately parallel to the axial direction of the medical tube. The core layer has a tubular inner core layer made of a fluororesin, and an outer core layer made of a resin having a higher Young's modulus than the fluororesin and disposed on the outer periphery of the inner core layer. The core layer has a specific configuration in which peaks convex toward the radially outer side of the medical tube and valleys convex toward the radially inner side of the medical tube are repeatedly arranged in the axial direction of the medical tube.

[0010] Thus, the medical tube has high elongation resistance because the core layer has an outer core layer made of a resin with a higher Young's modulus than the fluororesin in addition to an inner core layer made of a fluororesin. Furthermore, the medical tube has a specific configuration in which peaks and valleys are repeatedly arranged, so that the core layer has high flexibility despite having an outer core layer. Therefore, the medical tube can achieve a high level of both flexibility and elongation resistance. Furthermore, the medical tube has a specific configuration in which peaks and valleys are repeatedly arranged in the core layer, so that the contact area between the inner circumference of the medical tube and another medical device inserted into the medical tube can be reduced, and as a result, the medical device can be smoothly moved forward and backward relative to the medical tube, improving operability.

[0011] (2) In the above medical tubing, the specific configuration may be a configuration including an intersection portion where ridgelines of two peaks aligned in the axial direction of the medical tubing intersect to form a single peak line. This medical tubing can more effectively improve the flexibility of the medical tubing, and can achieve an even higher level of both flexibility and elongation resistance of the medical tubing.

[0012] (3) In the above medical tube, the outer diameter of the medical tube may be 5 mm or less. According to this medical tube, even in the case of a medical tube that is difficult to process due to its extremely small outer diameter, the flexibility of the medical tube can be improved by imparting a specific structure to the core layer.

[0013] (4) In the above medical tube, the core layer may have the specific configuration in a portion in the axial direction of the medical tube, and the remaining portion may not have the specific configuration. This medical tube can ensure high elongation resistance overall while improving the flexibility of the medical tube in the portion where flexibility is particularly required, thereby imparting the desired performance to the medical tube.

[0014] (5) In the above medical tubing, the core layer may have the specific configuration in a portion including the tip of the core layer, and the remaining portion may not have the specific configuration. This medical tubing can ensure high elongation resistance as a whole while improving the flexibility of the tip portion, where flexibility is particularly required in the medical tubing.

[0015] (6) In the above medical tubing, the thickness of the outer core layer may be thinner than the thickness of the inner core layer. This medical tubing can suppress a decrease in flexibility of the medical tubing caused by the core layer having the outer core layer, and can achieve a higher level of both flexibility and elongation resistance of the medical tubing.

[0016] The technology disclosed in this specification can be realized in various forms, for example, in the form of long medical devices such as medical tubes, catheters equipped with medical tubes, and methods of manufacturing the same. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a catheter 10 according to the present embodiment. [Diagram 2] FIG. 1 is an explanatory diagram showing a detailed configuration of a hollow shaft 100. [Diagram 3] FIG. 1 is an explanatory diagram showing a detailed configuration of a hollow shaft 100. [Figure 4] FIG. 1 is an explanatory diagram showing a schematic appearance of a core layer 130 having a specific structure SC. [Diagram 5] Diagram showing the performance evaluation results DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A. Embodiment: A-1. Configuration of catheter 10: FIG. 1 is an explanatory diagram showing a schematic configuration of a catheter 10 in this embodiment. FIG. 1 shows a side configuration of the catheter 10. Note that in FIG. 1, for convenience, illustration of a part of the configuration of the catheter 10 is omitted. In FIG. 1, the positive Z-axis direction side is the tip end side (distal side) inserted into the body, and the negative Z-axis direction side is the base end side (proximal side) operated by an operator such as a doctor. In FIG. 1, the catheter 10 is shown in a state in which it is linearly parallel to the Z-axis direction as a whole, but the catheter 10 has flexibility to the extent that it can be curved. Note that in this specification, the tip end of the catheter 10 and each of its components is referred to as the "tip end", the tip end and its vicinity are referred to as the "tip portion", the base end end is referred to as the "base end", and the base end and its vicinity are referred to as the "base end portion".

[0019] The catheter 10 is a long medical device that is inserted into tubular organs or internal tissues of the human body, such as blood vessels, the digestive tract, and the urinary tract. The total length of the catheter 10 is, for example, about 1500 mm. The catheter 10 includes a hollow shaft 100, a flexible distal tip 20 connected to the distal end of the hollow shaft 100, and a connector 30 connected to the proximal end of the hollow shaft 100. The hollow shaft 100 is an example of a medical tube as defined in the claims.

[0020] A-2. Configuration of hollow shaft 100: Figures 2 and 3 are explanatory diagrams showing a detailed configuration of the hollow shaft 100. Figure 2 shows an enlarged cross-sectional configuration of part X1 in Figure 1 (the cross-sectional configuration including the central axis AX of the hollow shaft 100), and Figure 3 shows an enlarged cross-sectional configuration of part X2 in Figure 2 (similarly, the cross-sectional configuration including the central axis AX of the hollow shaft 100).

[0021] The hollow shaft 100 is a tubular (e.g., cylindrical) member with an opening at the tip and base ends. In this specification, the term "tubular (cylindrical)" does not mean a completely tubular (cylindrical) shape, but means an approximately tubular shape as a whole (approximately cylindrical, for example, a slightly conical shape or a shape with some irregularities). The hollow part of the hollow shaft 100 functions as a lumen 102 for inserting a medical device such as a guidewire. In this embodiment, the outer diameter of the hollow shaft 100 is 0.1 mm or more and 5.0 mm or less. It is more preferable that the outer diameter of the hollow shaft 100 is 0.5 mm or more and 3.0 mm or less.

[0022] The hollow shaft 100 is composed of a tubular core layer 130 and an outer layer 140 arranged on the outer periphery of the core layer 130. The outer layer 140 is arranged so as to cover the entire outer periphery of the core layer 130. In this embodiment, the outer layer 140 is arranged so as to be in contact with the outer periphery of the core layer 130. Note that another member (for example, a reinforcing member such as a braid in which a plurality of wires are woven together) may be interposed between the outer layer 140 and the core layer 130.

[0023] The outer layer 140 has an outer circumferential surface that is approximately parallel to the axial direction (Z-axis direction) of the hollow shaft 100. In this embodiment, the outer layer 140 constitutes the outermost layer of the hollow shaft 100, and therefore the hollow shaft 100 also has an outer circumferential surface that is approximately parallel to the axial direction of the hollow shaft 100.

[0024] The outer layer 140 is made of a resin. Examples of the resin that can be used to make up the outer layer 140 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, aromatic polyether ketone resins, and polycarbonate resins. These may be used alone or in combination of two or more. Examples of the polyamide resins include polyamide and polyamide elastomers. Examples of the polyurethane resins include polyurethane and polyurethane elastomers. Examples of the polyester resins include polybutylene terephthalate and polyester elastomers. Examples of the polyolefin resins include polyethylene, polypropylene, and ethylene-propylene copolymers. Examples of the aromatic polyether ketone resins include polyether ether ketone (PEEK). From the viewpoints of moldability and flexibility, the outer layer 140 is preferably made up of a polyamide resin or a polyurethane resin, and more preferably made up of a polyamide resin. The outer layer 140 may contain any component other than the polyamide resin and the polyurethane resin, but preferably contains 90% by mass or more of the polyamide resin and the polyurethane resin. It is more preferable that the outer layer 140 contains 90% by mass or more of the polyamide resin. The Young's modulus of the resin constituting the outer layer 140 is not particularly limited, but is preferably lower than the Young's modulus of the resin constituting the outer core layer 120 described later (resin having a higher Young's modulus than the fluororesin). The Young's modulus of the resin constituting the outer layer 140 is preferably less than 1.0 GPa from the viewpoint of ensuring flexibility. The Young's modulus of the resin constituting the outer layer 140 can be obtained by preparing a test piece in accordance with JIS K 7161 and measuring it.

[0025] The thickness t4 of the outer layer 140 (average thickness, hereinafter the same applies to thickness unless otherwise specified) is, for example, preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 30 μm or more, from the viewpoint of ensuring the rigidity of the hollow shaft 100. In addition, the thickness t4 of the outer layer 140 is, for example, preferably 700 μm or less, more preferably 350 μm or less, and even more preferably 200 μm or less, from the viewpoint of suppressing the wall thickness of the hollow shaft 100 from becoming excessively large and reducing the outer diameter of the hollow shaft 100 while ensuring the inner diameter of the lumen 102. In this embodiment, the thickness t4 of the outer layer 140 is thicker than the thickness t3 of the core layer 130. However, the thickness t4 of the outer layer 140 may be thinner than the thickness t3 of the core layer 130. The thickness of a relatively thin portion of the outer layer 140 (a portion facing a peak portion 130A described later) may be, for example, 5 μm or more and 100 μm or less, 15 μm or more and 80 μm or less, or 20 μm or more and 60 μm or less. The thickness of a relatively thick portion of the outer layer 140 (a portion facing a valley portion 130B described later) may be, for example, 50 μm or more and 800 μm or less, 60 μm or more and 600 μm or less, or 70 μm or more and 400 μm or less.

[0026] The core layer 130 is composed of a tubular inner core layer 110 and an outer core layer 120 arranged on the outer periphery of the inner core layer 110. That is, the hollow shaft 100 of this embodiment is a three-layer tube in which the inner core layer 110 constitutes the innermost layer and the outer layer 140 constitutes the outermost layer. The outer core layer 120 is arranged so as to cover the entire outer periphery of the inner core layer 110. In this embodiment, the outer core layer 120 is arranged so as to contact the outer periphery surface of the inner core layer 110.

[0027] The inner core layer 110 is made of a fluororesin, which is a resin having excellent lubricity and chemical resistance. Here, the fluororesin is a general term for synthetic resins containing fluorine, such as thermoplastic resins containing fluorine, fluoroelastomers, etc. Examples of fluororesins include PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkylvinylether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), etc. Note that the inner core layer 110 being made of a fluororesin means that the inner core layer 110 contains 90% by mass or more of a fluororesin, although it may contain any component other than the fluororesin.

[0028] The thickness t1 of the inner core layer 110 is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more, from the viewpoint of ensuring the slipperiness and chemical resistance of the inner surface. The thickness t1 of the inner core layer 110 is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of preventing the wall thickness of the hollow shaft 100 from becoming excessive and reducing the outer diameter of the hollow shaft 100 while ensuring the inner diameter of the lumen 102. The Young's modulus of the fluororesin constituting the inner core layer 110 is preferably less than 1.0 GPa, and even more preferably 500 MPa or less. The Young's modulus of the fluororesin constituting the inner core layer 110 may be 200 MPa or less. The Young's modulus of the fluororesin constituting the inner core layer 110 can be measured in accordance with JIS K 7161.

[0029] The outer core layer 120 is made of a resin having a higher Young's modulus than fluorine-based resin (hereinafter, referred to as "high Young's modulus resin"). The Young's modulus of the high Young's modulus resin constituting the outer core layer 120 is preferably 1.0 GPa or more. Examples of the high Young's modulus resin include polyimide-based resins, aromatic polyether ketone-based resins such as PEEK, and polyamide-based resins having a high Young's modulus such as TR55. The polyimide-based resin is a polymer having an imide bond in the main chain, and examples of the resin include polyimide, polyamideimide, polyesterimide, and polyetherimide. These resins are usually used alone, but two or more types may be mixed and used. Among the polyimide-based resins, it is preferable to use polyimide, which has particularly excellent mechanical properties, and among the polyimides, it is more preferable to use aromatic polyimide. This aromatic polyimide may be thermoplastic or non-thermoplastic. The fact that the outer core layer 120 is made of a high Young's modulus resin means that the outer core layer 120 contains 90 mass% or more of a high Young's modulus resin, although it may contain any component other than the high Young's modulus resin. Furthermore, the resin constituting the outer core layer 120 is preferably a resin having a higher Young's modulus than the resin constituting the outer layer 140. The Young's modulus of the high Young's modulus resin is more preferably 1.5 GPa or more, and even more preferably 2.0 GPa or more. The Young's modulus of the high Young's modulus resin may be 2.5 GPa or more. The Young's modulus of the high Young's modulus resin can be measured in accordance with JIS K 7161.

[0030] The outer core layer 120 is a layer added to improve the elongation resistance of a conventional hollow shaft for catheter, that is, a two-layer structure of a core layer made of a fluorine-based resin and an outer layer arranged on the outer periphery of the core layer. From the viewpoint of effectively improving the elongation resistance of the hollow shaft 100, the thickness t2 of the outer core layer 120 is preferably, for example, 0.5 μm or more, more preferably 1.5 μm or more, and even more preferably 3 μm or more. From the viewpoint of suppressing the decrease in flexibility of the hollow shaft 100 caused by the presence of the outer core layer 120 and from the viewpoint of facilitating the formation of the specific configuration SC described later, the thickness t2 of the outer core layer 120 is, for example, preferably 30 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. From the same viewpoint, the thickness t2 of the outer core layer 120 is preferably thinner than the thickness t1 of the inner core layer 110.

[0031] A-3. Detailed configuration of the core layer 130: Next, the detailed configuration of the core layer 130 will be described. As shown in FIG. 3, the core layer 130 has a configuration (hereinafter referred to as a "specific configuration SC") in which a peak portion 130A that is convex toward the radially outer side of the hollow shaft 100 (in other words, convex toward the outer layer 140) and a valley portion 130B that is convex toward the radially inner side of the hollow shaft 100 (in other words, convex toward the lumen 102) are repeatedly arranged in the axial direction (Z-axis direction) of the hollow shaft 100. In other words, the specific configuration SC of the core layer 130 is a configuration in which the core layer 130 has a wave shape in a cross section including the central axis AX (see FIG. 2) of the hollow shaft 100. The formation pitch of the peak portions 130A may be, for example, 0.01 mm to 3.0 mm. The height Ha of the peak portion 130A may be, for example, 0.01 mm to 2.0 mm. The height Ha of the peak 130A is the distance from the apex P1 of the peak 130A to the virtual straight line VL connecting the bottom points P2 of the two valleys 130B sandwiching the peak 130A. The peak 130A is formed by folding each part of the core layer 130 into a mountain shape, and can also be expressed as a "mountain fold," while the valley 130B is formed by folding each part of the core layer 130 into a valley shape, and can also be expressed as a "valley fold." Note that the specific configuration SC is not shown in FIG. 2.

[0032] FIG. 4 is an explanatory diagram showing a schematic appearance of the core layer 130 having a specific configuration SC. As shown in FIG. 4, the peaks 130A and valleys 130B constituting the specific configuration SC are formed over the entire circumference of the core layer 130. However, in this embodiment, only a part of the core layer 130, specifically, a part including the tip of the core layer 130 (a part constituting the distal part DP of the hollow shaft 100 shown in FIG. 1) has the specific configuration SC, and the remaining part of the core layer 130 (a part constituting the proximal part PP of the hollow shaft 100 shown in FIG. 1) does not have the specific configuration SC. In the hollow shaft 100 of this embodiment, the part of the core layer 130 constituting the distal part DP of the hollow shaft 100 has the specific configuration SC, so that the flexibility of the distal part DP of the hollow shaft 100 is improved.

[0033] 4, the specific configuration SC of the core layer 130 includes an intersection CP where the ridgelines of two peaks 130A aligned in the axial direction (Z-axis direction) of the hollow shaft 100 intersect to form a single peak 130A. In other words, the specific configuration SC of the core layer 130 is configured to have unevenness in the circumferential direction of the hollow shaft 100 (core layer 130). Examples of shapes having an intersection CP where the ridgelines of two peaks 130A aligned in the axial direction of the hollow shaft 100 intersect to form a single peak 130A include Miura folds and Yoshimura patterns.

[0034] As shown in FIG. 3, in this embodiment, the apex of the peak 130A is eccentric in the axial direction (Z-axis direction) of the hollow shaft 100. That is, when one peak 130A and two valleys 130B sandwiching the peak 130A are taken into consideration, the distance L1 from the bottom of one valley 130B to the apex of the peak 130A (the distance along the axial direction of the hollow shaft 100, the same applies below) is shorter than the distance L2 from the bottom of the other valley 130B to the apex of the peak 130A. However, the distance L1 and the distance L2 may be the same. The distance L1 and the distance L2 may satisfy the relationship 0.5≦L1 / L2≦1.0, 0.6≦L1 / L2≦0.9, or 0.7≦L1 / L2≦0.8. Similarly, in this embodiment, the bottom of the valley portion 130B is eccentric in the axial direction of the hollow shaft 100. That is, when one valley portion 130B and two peak portions 130A sandwiching the valley portion 130B are taken into consideration, the distance L2 from the apex of one peak portion 130A to the bottom of the valley portion 130B is longer than the distance L3 from the apex of the other peak portion 130A to the bottom of the valley portion 130B. However, the distance L2 and the distance L3 may be the same. The distance L2 and the distance L3 may satisfy the relationship 0.5≦L3 / L2≦1.0, may satisfy the relationship 0.6≦L3 / L2≦0.9, or may satisfy the relationship 0.7≦L3 / L2≦0.8.

[0035] A-4. Manufacturing method of hollow shaft 100: Next, an example of a manufacturing method of the hollow shaft 100 will be described. First, the inner core layer 110 is formed around the core bar. Next, the inner core layer 110 formed around the core bar is immersed in a liquid containing a material for forming the outer core layer 120, and then pulled out of the liquid. Then, the material for forming the outer core layer 120 attached around the inner core layer 110 is fired to form the outer core layer 120. As a result, a core layer 130 composed of the inner core layer 110 and the outer core layer 120 is formed around the core bar.

[0036] Next, the specific configuration SC is formed in the core layer 130. Specifically, one end of the portion of the core layer 130 that forms the specific configuration SC is fixed, the other end is pushed toward the one end, and then pulled back, thereby forming the specific configuration SC in the core layer 130 in which the peaks 130A and valleys 130B are repeated in the axial direction.

[0037] Next, outer layer 140 is formed on the outer periphery of core layer 130 formed around the mandrel, thereby forming hollow shaft 100 composed of core layer 130 and outer layer 140 around the mandrel. Finally, the mandrel is pulled out. For example, hollow shaft 100 can be manufactured by the above manufacturing method.

[0038] A-5.Performance evaluation: The hollow shaft was evaluated for its elongation resistance and flexibility. Figure 5 is an explanatory diagram showing the results of the performance evaluation.

[0039] As shown in FIG. 5, three samples (S1 to S3) of hollow shafts were used for performance evaluation. Sample S1 is an example of the hollow shaft 100 of the above-mentioned embodiment. That is, sample S1 is a three-layer tube composed of a core layer 130 consisting of an inner core layer 110 and an outer core layer 120, and an outer layer 140, and the core layer 130 has a specific structure SC (a structure in which peaks 130A and valleys 130B are repeated in the axial direction). PTFE was used as the material for the inner core layer 110, polyimide was used as the material for the outer core layer 120, and polyamide elastomer (pebax35 by ARKEMA) was used as the material for the outer layer 140. In addition, the thickness of the inner core layer 110 is approximately 10 μm, the thickness of the outer core layer 120 is approximately 3 μm, and the thickness of the outer layer 140 is approximately 40 μm in the relatively thin portion (the portion facing the peak portion 130A) and approximately 80 μm in the relatively thick portion (the portion facing the valley portion 130B).

[0040] Samples S2 and S3 are comparative examples. That is, sample S2 is a three-layer tube similar to sample S1, but the core layer 130 does not have the specific structure SC. That is, in sample S2, the inner core layer 110 and the outer core layer 120 constituting the core layer 130 are both configured to have an outer circumferential surface substantially parallel to the axial direction of the hollow shaft. Also, sample S3 is a two-layer tube in which the core layer 130 is composed only of the inner core layer 110 and is composed of the core layer 130 and the outer layer 140. That is, sample S3 does not have the outer core layer 120 composed of a resin having a higher Young's modulus than the fluororesin. Also, in sample S3, the core layer 130 does not have the specific structure SC. That is, in sample S3, the inner core layer 110 constituting the core layer 130 is configured to have an outer circumferential surface substantially parallel to the axial direction of the hollow shaft. The materials and thicknesses of the layers of samples S2 and S3 are the same as those of sample S1.

[0041] For each sample, Young's modulus, breaking load, and bending modulus were measured according to methods in accordance with JIS K 7161-2014 and JIS K 7171, and the average value was calculated for N=5. The higher the average Young's modulus, the higher the elongation resistance of the hollow shaft can be evaluated, and the lower the average bending modulus, the higher the flexibility can be evaluated. The average breaking load of sample S3 was not measured.

[0042] The average Young's modulus value of sample S1 was lower than that of sample S2 not having the specific component SC, but was sufficiently higher than that of sample S3 not having the outer core layer 120. Therefore, it was confirmed that sample S1 had sufficiently high elongation resistance. Since the outer core layer 120 was composed of a high Young's modulus resin, it is considered that the Young's modulus of sample S1 having the outer core layer 120 was sufficiently high. The average breaking load value of sample S1 was equivalent to that of sample S2 not having the specific component SC. Therefore, it can be said that the presence or absence of the specific component SC has almost no effect on the breaking load.

[0043] In addition, the average flexural modulus value of sample S1 was higher than that of sample S3 not having the outer core layer 120, but was sufficiently lower than that of sample S2 not having the specific configuration SC. Therefore, it was confirmed that sample S1 has sufficiently high flexibility. The specific configuration SC is a configuration in which the peaks 130A and valleys 130B are repeated in the axial direction, which is a configuration that improves flexibility, and therefore it is believed that the flexural modulus of sample S1 having the specific configuration SC was sufficiently low.

[0044] As described above, the results of this performance evaluation confirmed that in a hollow shaft 100 comprising a core layer 130 and an outer layer 140, when the core layer 130 has an inner core layer 110 made of a fluorine-based resin and an outer core layer 120 made of a resin having a higher Young's modulus than that of the fluorine-based resin, and when the core layer 130 has a specific configuration SC in which the peak portions 130A and the valley portions 130B are repeated in the axial direction, the hollow shaft 100 can achieve both high levels of flexibility and elongation resistance.

[0045] A-6. Advantages of this embodiment: As described above, the hollow shaft 100 constituting the catheter 10 of this embodiment includes a tubular core layer 130 and an outer layer 140 made of resin, disposed on the outer periphery of the core layer 130, and having an outer periphery surface approximately parallel to the axial direction of the hollow shaft 100. The core layer 130 includes a tubular inner core layer 110 made of a fluororesin, and an outer core layer 120 made of a resin having a higher Young's modulus than the fluororesin and disposed on the outer periphery of the inner core layer 110. The core layer 130 has a specific configuration SC in which a peak portion 130A convex toward the radially outer side of the hollow shaft 100 and a valley portion 130B convex toward the radially inner side of the hollow shaft 100 are repeatedly arranged in the axial direction of the hollow shaft 100.

[0046] Thus, the hollow shaft 100 of this embodiment has high elongation resistance because the core layer 130 has, in addition to the inner core layer 110 made of a fluorine-based resin, the outer core layer 120 made of a resin with a higher Young's modulus than that of the fluorine-based resin. Furthermore, the hollow shaft 100 of this embodiment has high flexibility because the core layer 130 has a specific configuration SC in which the peaks 130A and the valleys 130B are repeatedly arranged. Therefore, the hollow shaft 100 of this embodiment can achieve both flexibility and elongation resistance at a high level.

[0047] Furthermore, in the hollow shaft 100 of this embodiment, the specific configuration SC of the core layer 130 is configured to include an intersection point CP where the ridgelines of two peaks 130A aligned in the axial direction of the hollow shaft 100 intersect to form the ridgeline of a single peak 130A. Therefore, according to the hollow shaft 100 of this embodiment, the flexibility of the hollow shaft 100 can be further effectively improved, and the hollow shaft 100 can achieve both flexibility and elongation resistance at an even higher level.

[0048] The outer diameter of the hollow shaft 100 in this embodiment is 5 mm or less. Even in the case of a hollow shaft 100 that is difficult to process due to its extremely small outer diameter, the flexibility of the hollow shaft 100 can be improved by forming the specific configuration SC in the core layer 130 by the above-mentioned method.

[0049] Moreover, in the hollow shaft 100 of this embodiment, the core layer 130 has the specific configuration SC in a portion in the axial direction of the hollow shaft 100, and does not have the specific configuration SC in the remaining portion. Therefore, according to the hollow shaft 100 of this embodiment, it is possible to improve the flexibility of the portion where flexibility is particularly required while ensuring high elongation resistance as a whole, and it is possible to impart the desired performance to the hollow shaft 100. More specifically, in the hollow shaft 100 of this embodiment, the core layer 130 has the specific configuration SC in a portion including the tip of the core layer 130, and does not have the specific configuration SC in the remaining portion. Therefore, according to the hollow shaft 100 of this embodiment, it is possible to improve the flexibility of the tip side portion where flexibility is particularly required while ensuring high elongation resistance as a whole.

[0050] Furthermore, in the hollow shaft 100 of this embodiment, the thickness t2 of the outer core layer 120 is thinner than the thickness t1 of the inner core layer 110. Therefore, according to the hollow shaft 100 of this embodiment, it is possible to suppress a decrease in flexibility of the hollow shaft 100 caused by the core layer 130 having the outer core layer 120, and it is possible to achieve a higher level of compatibility between flexibility and elongation resistance of the hollow shaft 100.

[0051] Furthermore, since the catheter 10 of this embodiment includes the hollow shaft 100 having the configuration described above, the hollow shaft 100 constituting the catheter 10 can achieve both a high level of flexibility and elongation resistance.

[0052] B. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0053] The configuration of the catheter 10 in the above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, the hollow shaft 100 constituting the catheter 10 is composed of the core layer 130 and the outer layer 140, but may further include a second outer layer disposed on the outer periphery of the outer layer 140. In such a configuration, another member (for example, a reinforcing member such as a braid in which a plurality of wires are woven together) may be interposed between the outer layer 140 and the second outer layer.

[0054] In the above embodiment, the core layer 130 is composed of the inner core layer 110 and the outer core layer 120, but the core layer 130 may further include another layer. The other layer may be disposed on the inner circumference of the inner core layer 110, may be disposed between the inner core layer 110 and the outer core layer 120, or may be disposed on the outer circumference of the outer core layer 120.

[0055] In the above embodiment, only the portion of the core layer 130 including the tip (the portion constituting the distal portion DP of the hollow shaft 100) has the specific configuration SC, but the portion of the core layer 130 having the specific configuration SC can be changed as appropriate depending on the performance required of the hollow shaft 100. In addition, the core layer 130 may have the specific configuration SC over its entire length.

[0056] In the above embodiment, the specific configuration SC of the core layer 130 includes an intersection point CP where the ridgelines of two peak portions 130A aligned in the axial direction of the hollow shaft 100 intersect to form the ridgeline of a single peak portion 130A, but the specific configuration SC does not necessarily have to include the intersection point CP.

[0057] The thicknesses of the components of the hollow shaft 100 in the above embodiment and the relationship between the thicknesses of the components are merely examples and can be modified in various ways. Furthermore, the materials of the components of the hollow shaft 100 in the above embodiment are merely examples and other materials can be used. Furthermore, the manufacturing method of the hollow shaft 100 in the above embodiment is merely examples and other manufacturing methods can be adopted.

[0058] In the above embodiment, the hollow shaft 100 constituting the catheter 10 has been described as an example of a medical tube, but the technology disclosed in this specification is similarly applicable to other medical tubes (e.g., hollow shafts constituting balloon catheters, tubes for indwelling needles, etc.). [Explanation of symbols]

[0059] 10: Catheter 20: Tip 30: Connector 100: Hollow shaft 102: Lumen 110: Inner core layer 120: Outer core layer 130: Core layer 130A: Peak portion 130B: Valley portion 140: Outer layer CP: Cross portion DP: Distal portion PP: Proximal portion SC: Specific configuration

Claims

1. A medical tube, comprising: A tubular core layer; an outer layer made of resin, disposed around the outer periphery of the core layer, and having an outer periphery surface that is approximately parallel to the axial direction of the medical tubing; Equipped with The core layer is A tubular inner core layer made of a fluorine-based resin; an outer core layer made of a resin having a higher Young's modulus than the fluororesin and disposed on an outer periphery of the inner core layer; having the core layer has a specific tubular configuration that is continuous in the circumferential and axial directions of the medical tube, in which peaks that protrude radially outwardly of the medical tube and valleys that protrude radially inwardly of the medical tube are repeatedly arranged in the axial direction of the medical tube; The specific configuration includes an intersection portion where ridgelines of two of the peaks arranged in the axial direction of the medical tube intersect to form a single ridgeline of the peak. Medical tubing.

2. 2. The medical tube according to claim 1, The outer diameter of the medical tube is 5 mm or less. Medical tubing.

3. The medical tube according to claim 1 or 2, The core layer has the specific configuration in a portion in the axial direction of the medical tube, and does not have the specific configuration in the remaining portion. Medical tubing.

4. The medical tube according to claim 3, the core layer has the specific structure in a portion including a tip of the core layer, and does not have the specific structure in the remaining portion; Medical tubing.

5. The medical tube according to any one of claims 1 to 4, The thickness of the outer core layer is less than the thickness of the inner core layer. Medical tubing.

6. A catheter comprising the medical tube according to any one of claims 1 to 5.

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