Medical tubes and catheters

Abstract

A medical tube has flexibility and stretch resistance at a high level. The medical tube has a tubular core layer, and an outer layer composed of a resin and disposed on the outer periphery of the core layer, having an outer peripheral surface substantially parallel to the axial direction of the medical tube. The core layer has a tubular inner core layer composed of a fluorine-based resin, and an outer core layer composed of a resin having a higher Young's modulus than the fluorine-based resin, and disposed on the outer periphery of the inner core layer. The core layer has a specific structure in which a hill portion projecting toward the radial outer side of the medical tube and a valley portion projecting toward the radial inner side of the medical tube are repeatedly disposed in the axial direction of the medical tube.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a medical tube and catheter. Background Technology

[0002] A catheter is a long, narrow medical device inserted into tubular organs or tissues in the human body, such as blood vessels, the digestive tract, and ureters. A catheter may have, for example, a tubular hollow shaft, a tip that engages with the front end of the hollow shaft, and a connector that engages with the base end of the hollow shaft. The hollow shaft may have, for example, a tubular core layer and an outer layer disposed around the periphery of the core layer. The core layer is made of a resin (e.g., a fluoropolymer resin) with excellent lubricity and chemical resistance. The outer layer is made of a resin (e.g., a polyamide resin) with excellent formability and flexibility.

[0003] To minimize damage to the inner wall of blood vessels and improve vascular selectivity, the hollow shaft of the catheter needs to have high flexibility. Previously, to adjust the flexibility of the catheter, a technique was known to provide a concave-convex structure on the core layer of the hollow shaft, having multiple protrusions projecting radially inward and recesses surrounding these protrusions (see, for example, Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-236863. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In addition to the aforementioned flexibility, the inventors of this application have also focused on stretchability as a required performance characteristic of the hollow shaft of a catheter. Stretchability refers to the ability to resist forces that cause an object to elongate, making it difficult for the object to stretch. The inventors of this application have discovered that undesirable catheter movements can reduce its operability if the hollow shaft has low stretchability. For example, when pulling the base of the catheter towards the hand to remove it from the body, the catheter will not move due to the extension of the hollow shaft; if the base is pulled further towards the hand, the catheter will jump and move towards the base. In particular, in recent years, to reduce patient burden and ensure the size of the lumen for medical devices such as guidewires, thinner-walled hollow shafts have been required, and the reduction in stretchability caused by thinning the hollow shaft has become a problem.

[0009] While the aforementioned prior art improves the flexibility of the hollow shaft of the catheter, it does not consider the stretchability of the hollow shaft. In other words, the prior art suffers from the problem of not being able to achieve a high level of balance between the flexibility and stretchability of the catheter's hollow shaft. Furthermore, this problem is not limited to the hollow shaft constituting the catheter, but is a common issue for all medical catheters.

[0010] This specification discloses a technique that can solve the above-mentioned problems.

[0011] Methods for solving problems

[0012] The techniques disclosed in this specification can be implemented, for example, in the following ways.

[0013] (1) The medical tube disclosed in this specification comprises: a tubular core layer; and an outer layer made of resin and disposed on the outer periphery of the core layer, having an outer peripheral surface substantially parallel to the axial direction of the medical tube. The core layer comprises: a tubular inner core layer made of a fluoropolymer resin; and an outer core layer made of a resin with a higher Young's modulus than the fluoropolymer resin and disposed on the outer periphery of the inner core layer. The core layer has a specific structure in which ridges protruding radially outward toward the medical tube and valleys protruding radially inward toward the medical tube are repeatedly arranged along the axial direction of the medical tube.

[0014] Thus, the core layer of this medical tubing, in addition to an inner core layer made of fluoropolymer resin, also has an outer core layer made of resin with a higher Young's modulus than fluoropolymer resin, thereby possessing high tensile strength. Furthermore, due to the specific structure of the core layer of this medical tubing, which features a repeating arrangement of mountain and valley sections, it also possesses high flexibility despite having an outer core layer. Therefore, according to this medical tubing, both flexibility and tensile strength can be balanced to a high degree. Moreover, because the core layer of this medical tubing has a specific structure of repeating mountain and valley sections, the contact area between the inner periphery of the medical tubing and other medical devices inserted into the medical tubing can be reduced. As a result, the medical devices can move smoothly forward and backward relative to the medical tubing, thereby improving operability.

[0015] (2) In the above-described medical tubing, the specific structure can also be configured to include a structure in which the ridges of two mountain-shaped sections arranged along the axial direction of the medical tubing intersect to form a cross-section of the ridges of one mountain-shaped section. According to this medical tubing, the flexibility of the medical tubing can be further improved effectively, and the flexibility and stretchability of the medical tubing can be balanced at a higher level.

[0016] (3) In the above-mentioned medical tubing, the outer diameter of the medical tubing can also be configured to be 5 mm or less. According to this medical tubing, even in medical tubing that is difficult to process due to its extremely small outer diameter, the flexibility of the medical tubing can be improved by giving the core layer a specific structure.

[0017] (4) In the above-described medical tubing, the core layer may also be configured to have the specific structure in a portion of the axial direction of the medical tubing, but not in the remaining portion. According to this medical tubing, high overall tensile strength can be ensured while improving the flexibility of portions of the medical tubing where particular flexibility is required, thereby imparting the desired performance to the medical tubing.

[0018] (5) In the above-described medical tubing, the core layer may also be configured to have the specific structure in a portion of the front end containing the core layer, and not have the specific structure in the remaining portion. According to this medical tubing, high overall tensile strength can be ensured, while improving the flexibility of the front end portion of the medical tubing where flexibility is particularly required.

[0019] (6) In the above-mentioned medical tubing, the thickness of the outer core layer can also be configured to be thinner than the thickness of the inner core layer. According to this medical tubing, the reduction in the flexibility of the medical tubing caused by the presence of an outer core layer in the core layer can be suppressed, and the flexibility and stretchability of the medical tubing can be balanced at a higher level.

[0020] It should be noted that the technology disclosed in this specification can be implemented in various ways, such as by means of long strip-shaped medical devices such as medical tubes, catheters with medical tubes, and methods for manufacturing them. Attached Figure Description

[0021] Figure 1 This is an explanatory diagram that schematically shows the structure of the catheter 10 in this embodiment.

[0022] Figure 2 This is an explanatory diagram showing the detailed structure of the hollow shaft 100.

[0023] Figure 3 This is an explanatory diagram showing the detailed structure of the hollow shaft 100.

[0024] Figure 4 This is an explanatory diagram showing the appearance of the core layer 130 with a specific structure SC.

[0025] Figure 5 This is an explanatory diagram representing the performance evaluation results. Detailed Implementation

[0026] A. Implementation Method

[0027] A-1. Structure of catheter 10

[0028] Figure 1 This is an explanatory diagram that schematically illustrates the structure of the catheter 10 according to this embodiment. Figure 1 The side structure of catheter 10 is shown in the diagram. It should be noted that, for ease of explanation, [the following text is missing]. Figure 1 The diagram omits a portion of the structure of catheter 10. Figure 1 In this procedure, the positive Z-axis side is the distal end (distal side) of the insertion site, while the negative Z-axis side is the proximal end (proximal side) operated on by the surgeon. Although in Figure 1 The diagram shows that the catheter 10 is generally in a straight line parallel to the Z-axis direction, but the catheter 10 has a degree of flexibility that allows it to bend. In addition, in this specification, for the catheter 10 and its constituent components, the end on the front end side is referred to as the "front end", the front end and its vicinity are referred to as the "front end", the end on the base end side is referred to as the "base end", and the base end and its vicinity are referred to as the "base end".

[0029] The catheter 10 is a long, narrow medical device used for insertion into tubular organs or internal tissues such as blood vessels, the digestive tract, and ureters. The total length of the catheter 10 is, for example, approximately 1500 mm. The catheter 10 comprises: a hollow shaft 100; a flexible tip 20 connected to the front end of the hollow shaft 100; and a connector 30 connected to the base end of the hollow shaft 100. The hollow shaft 100 is an example of a medical tube as described in the claims.

[0030] A-2. Structure of hollow shaft 100:

[0031] Figure 2 and Figure 3 This is an explanatory diagram showing the detailed structure of the hollow shaft 100. Figure 2 In the middle, a magnified view is shown Figure 1 The cross-sectional structure of section X1 (including the cross-section of the central axis AX of the hollow shaft 100). Figure 3 In the middle, a magnified view is shown Figure 2 The cross-sectional structure of the X2 section (similarly, the structure including the cross-section of the central axis AX of the hollow shaft 100).

[0032] The hollow shaft 100 is a tubular (e.g., cylindrical) component with openings at both the front and base ends. Furthermore, in this specification, "tubular (cylindrical)" is not limited to a completely tubular shape (cylindrical shape), but can also be generally tubular (generally cylindrical, for example, generally conical, or partially convex or concave). The hollow portion of the hollow shaft 100 can function as a lumen 102 for inserting medical devices such as guidewires. In this embodiment, the outer diameter of the hollow shaft 100 is 0.1 mm or more and 5.0 mm or less. More preferably, the outer diameter of the hollow shaft 100 is 0.5 mm or more and 3.0 mm or less.

[0033] The hollow shaft 100 is composed of a tubular core layer 130 and an outer layer 140 disposed on the outer periphery of the core layer 130. The outer layer 140 is configured to cover the entire outer periphery of the core layer 130. In this embodiment, the outer layer 140 is configured to contact the outer peripheral surface of the core layer 130. Alternatively, other components (e.g., a braided layer or other reinforcing material made of multiple wires braided together) may be sandwiched between the outer layer 140 and the core layer 130.

[0034] The outer layer 140 has an outer peripheral surface that is substantially parallel to the axial direction (Z-axis direction) of the hollow shaft 100. In this embodiment, since the outer layer 140 constitutes the outermost layer of the hollow shaft 100, the hollow shaft 100 also has an outer peripheral surface that is substantially parallel to the axial direction of the hollow shaft 100.

[0035] The outer layer 140 is composed of resin. Examples of resins constituting the outer layer 140 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, aromatic polyetherketone resins, and polycarbonate resins. Only one type of resin may be used, or two or more may be used in combination. Examples of polyamide resins include polyamides and polyamide elastomers. Examples of polyurethane resins include polyurethanes and polyurethane elastomers. Examples of polyester resins include polybutylene terephthalate and polyester elastomers. Examples of polyolefin resins include polyethylene, polypropylene, and ethylene-propylene copolymers. Examples of aromatic polyetherketone resins include polyetheretherketone (PEEK). From the viewpoint of formability and flexibility, the outer layer 140 is preferably configured to contain a polyamide resin or a polyurethane resin, and more preferably, it is configured to contain a polyamide resin. Furthermore, the outer layer 140 may contain any component other than polyamide resins and polyurethane resins, but it is preferable to contain 90% by mass or more of a polyamide resin and a polyurethane resin. Furthermore, a polyamide-based resin containing 90% by mass or more is preferred. The Young's modulus of the resin constituting the outer layer 140 is not particularly limited; for example, it is preferable to have a lower Young's modulus than the resin constituting the outer core layer 120 (a resin with a higher Young's modulus than fluorinated resins). Additionally, from the viewpoint of ensuring flexibility, the Young's modulus of the resin constituting the outer layer 140 is preferably less than 1.0 GPa. The Young's modulus of the resin constituting the outer layer 140 can be determined by preparing test specimens according to JIS K 7161 and measuring them.

[0036] From the viewpoint of ensuring the stiffness of the hollow shaft 100, for example, the thickness (average thickness, hereinafter, the same unless otherwise specified) t4 of the outer layer 140 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 30 μm or more. Furthermore, from the viewpoint of preventing the wall thickness of the hollow shaft 100 from becoming excessively thick, ensuring the inner diameter of the cavity 102 while reducing the outer diameter of the hollow shaft 100, for example, the thickness t4 of the outer layer 140 is preferably 700 μm or less, more preferably 350 μm or less, and even more preferably 200 μm or less. 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 also be thinner than the thickness t3 of the core layer 130. Furthermore, the thickness of the relatively thinner portion of the outer layer 140 (the portion opposite to the mountain portion 130A described later) can 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. Conversely, the thickness of the relatively thicker portion of the outer layer 140 (the portion opposite to the valley portion 130B described later) can 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.

[0037] The core layer 130 is composed of a tubular inner core layer 110 and an outer core layer 120 disposed on the outer periphery of the inner core layer 110. That is, the hollow shaft 100 of this embodiment is a tube with a three-layer structure, in which the inner core layer 110 forms the innermost layer and the outer layer 140 forms the outermost layer. The outer core layer 120 is configured to cover the entire outer periphery of the inner core layer 110. In this embodiment, the outer core layer 120 is configured to contact the outer peripheral surface of the inner core layer 110.

[0038] The inner core layer 110 is composed of a fluorinated resin, which is excellent in terms of lubrication and chemical resistance. Fluorinated resins are a general term for fluorinated synthetic resins, including fluorinated thermoplastic resins and fluorinated elastomers. Examples of fluorinated resins include PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and ETFE (ethylene-tetrafluoroethylene copolymer). Furthermore, "the inner core layer 110 is composed of a fluorinated resin" means that the inner core layer 110 contains 90% or more of a fluorinated resin by mass, but it may also contain any component other than a fluorinated resin.

[0039] From the viewpoint of ensuring the smoothness and chemical resistance of the inner surface, 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. Furthermore, from the viewpoint of preventing the wall thickness of the hollow shaft 100 from becoming excessively thick, and ensuring the inner diameter of the lumen 102 while reducing the outer diameter of the hollow shaft 100, 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. The Young's modulus of the fluorinated resin constituting the inner core layer 110 is preferably less than 1.0 GPa, and even more preferably 500 MPa or less. Alternatively, the Young's modulus of the fluorinated resin constituting the inner core layer 110 may also be 200 MPa or less. The Young's modulus of the fluorinated resin constituting the inner core layer 110 can be measured according to JIS K 7161.

[0040] The outer core layer 120 is composed of a resin with a higher Young's modulus than that of fluorinated resins (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 higher. Examples of high Young's modulus resins include polyimide resins, aromatic polyetherketone resins such as PEEK, and polyamide resins with high Young's modulus such as TR55. Polyimide resins are polymers having imide bonds in their main chain, and examples include polyimides, polyamide imides, polyester imides, and polyether imides. These resins are usually used alone or in mixtures of two or more. Among polyimide resins, polyimides with excellent mechanical properties are particularly preferred, and aromatic polyimides are even more preferred. These aromatic polyimides can be either thermoplastic or non-thermoplastic. Furthermore, the outer core layer 120 being composed of a high Young's modulus resin means that the outer core layer 120 contains 90% by mass or more of a high Young's modulus resin, but may also contain any component other than a high Young's modulus resin. Additionally, the resin constituting the outer core layer 120 is preferably a resin with 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. Furthermore, the Young's modulus of the high Young's modulus resin may also be 2.5 GPa or more. The Young's modulus of the high Young's modulus resin can be determined according to JIS K 7161.

[0041] Compared to the conventional hollow shaft structure for catheters, which consists of a two-layer structure with a core layer made of fluoropolymer resin and an outer layer disposed around the core layer, the outer core layer 120 is an additional layer added to improve stretch resistance. From the viewpoint of effectively improving the stretch resistance of the hollow shaft 100, the thickness t2 of the outer core layer 120 is preferably 0.5 μm or more, more preferably 1.5 μm or more, and even more preferably 3 μm or more. Furthermore, from the viewpoint of suppressing the reduction in the flexibility of the hollow shaft 100 caused by the presence of the outer core layer 120, and from the viewpoint of easily forming the specific structure SC described later, the thickness t2 of the outer core layer 120 is preferably 30 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. Additionally, from the above viewpoints, the thickness t2 of the outer core layer 120 is preferably thinner than the thickness t1 of the inner core layer 110.

[0042] A-3. Detailed structure of core layer 130

[0043] Next, the detailed structure of the core layer 130 will be explained. For example... Figure 3As shown, the core layer 130 has a structure (hereinafter referred to as "specific structure SC") consisting of a mountain portion 130A that protrudes radially outward (in other words, protrudes towards the outer layer 140) and a valley portion 130B that protrudes radially inward (in other words, protrudes towards the lumen 102) along the axial direction (Z-axis direction) of the hollow axis 100. In other words, the specific structure SC of the core layer 130 is located on the central axis AX (refer to the hollow axis 100). Figure 2 In the cross-section of the core layer 130, the core layer 130 has a wave-shaped structure. The spacing between the formations of the hills 130A can be, for example, 0.01 mm to 3.0 mm. Furthermore, the height Ha of the hills 130A can be, for example, 0.01 mm to 2.0 mm. It should be noted that the height Ha of the hills 130A refers to the distance from the apex P1 of the hill 130A to the imaginary straight line VL connecting the bottom points P2 of the two valleys 130B that enclose the hill 130A. The hills 130A are formed by convex folds in the core layer 130, and can also be described as "convex folds." The valleys 130B are formed by concave folds in the core layer 130, and can also be described as "concave folds." Additionally, in... Figure 2 The illustration of the specific structure SC is omitted in the text.

[0044] Figure 4 This is an illustrative diagram schematically showing the appearance of the core layer 130 with a specific structure SC. For example... Figure 4 As shown, the mountain portion 130A and valley portion 130B constituting the specific structure SC are formed over the entire circumference of the core layer 130. However, in this embodiment, a portion of the core layer 130, specifically, the portion of the core layer 130 that includes only the front end (constituting...) Figure 1 The distal portion DP of the hollow shaft 100 shown has a specific structure SC, and the remaining portion of the core layer 130 (constituting) Figure 1 The proximal portion PP of the hollow shaft 100 shown does not have the specific structure SC. In the hollow shaft 100 of this embodiment, since the portion of the core layer 130 constituting the distal portion DP of the hollow shaft 100 has the specific structure SC, the flexibility of the distal portion DP of the hollow shaft 100 is improved.

[0045] In addition, such as Figure 4 As shown, the specific structure SC of the core layer 130 includes a cross section CP formed by the intersection of the ridges of two hills 130A arranged along the axial direction (Z-axis direction) of the hollow axis 100, which constitutes a single ridge of hill 130A. In other words, the specific structure SC of the core layer 130 also has a concave-convex structure in the circumferential direction of the hollow axis 100 (core layer 130). Furthermore, examples of the shape having a cross section CP formed by the intersection of the ridges of two hills 130A arranged along the axial direction of the hollow axis 100, which constitutes a single ridge of hill 130A, include the Miura fold or the Yoshimura pattern.

[0046] In addition, such as Figure 3 As shown, in this embodiment, the apex of the mountain 130A is eccentric along the axial direction (Z-axis direction) of the hollow shaft 100. That is, when considering a mountain 130A and the two valleys 130B sandwiching it, the distance L1 from the bottom point of one valley 130B to the apex of the mountain 130A (which is the distance along the axial direction of the hollow shaft 100, the same below) is shorter than the distance L2 from the bottom point of the other valley 130B to the apex of the mountain 130A. However, distances L1 and L2 can also be the same. Furthermore, distances L1 and L2 can 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 point of the valley 130B is eccentric along the axial direction of the hollow shaft 100. That is, when considering a valley 130B and two mountains 130A sandwiching the valley 130B, the distance L2 from the vertex of one mountain 130A to the bottom of the valley 130B is longer than the distance L3 from the vertex of the other mountain 130A to the bottom of the valley 130B. However, distances L2 and L3 can also be the same. Furthermore, distances L2 and L3 can satisfy the following relationships: 0.5 ≤ L3 / L2 ≤ 1.0, 0.6 ≤ L3 / L2 ≤ 0.9, and 0.7 ≤ L3 / L2 ≤ 0.8.

[0047] A-4. Manufacturing method of hollow shaft 100

[0048] Next, an example of a method for manufacturing the hollow shaft 100 will be described. First, an inner core layer 110 is formed around the mandrel. Next, the inner core layer 110 formed around the mandrel is immersed in a liquid containing a material forming an outer core layer 120, and then removed from the liquid. Then, the outer core layer 120 is formed by firing the material forming the outer core layer 120 attached to the inner core layer 110. Thus, a core layer 130 composed of the inner core layer 110 and the outer core layer 120 is formed around the mandrel.

[0049] Next, a specific structure SC is formed in the core layer 130. Specifically, one end of the portion in the core layer 130 where the specific structure SC is formed is fixed, and the other end is pushed toward the aforementioned end and then pulled back, thereby forming a specific structure SC on the core layer 130 that repeats the mountain portion 130A and valley portion 130B along the axial direction.

[0050] Next, by forming an outer layer 140 around the core layer 130 formed around the mandrel, a hollow shaft 100 consisting of the core layer 130 and the outer layer 140 is formed around the mandrel. Finally, the mandrel is pulled out. For example, the hollow shaft 100 can be manufactured by the above manufacturing method.

[0051] A-5. Performance Evaluation

[0052] The tensile strength and flexibility of the hollow shaft were evaluated. Figure 5 This is an explanatory diagram representing the performance evaluation results.

[0053] like Figure 5 As shown, performance was evaluated using three samples (S1 to S3) of the hollow shaft. Sample S1 is an embodiment of the hollow shaft 100 of this embodiment described above. That is, sample S1 is a three-layer structure tube consisting of a core layer 130 and an outer layer 140. The core layer 130 has a specific structure SC (a structure that repeats the mountain section 130A and valley section 130B along the axial direction), wherein the core layer 130 is composed of an inner core layer 110 and an outer core layer 120. In addition, PTFE was used as the forming material of the inner core layer 110, polyimide was used as the forming material of the outer core layer 120, and polyamide elastomer (ARKEMA's Pebax 35) was used as the forming material of the outer layer 140. In addition, the thickness of the inner core layer 110 is about 10 μm, the thickness of the outer core layer 120 is about 3 μm, the thickness of the outer layer 140 is about 40 μm in the relatively thin part (the part opposite to the mountain 130A), and the thickness of the outer layer 140 is about 80 μm in the relatively thick part (the part opposite to the valley 130B).

[0054] Samples S2 and S3 are comparative examples. Sample S2 is a three-layer tube with the same structure as sample S1, but the core layer 130 does not have the specific structure SC. Specifically, in sample S2, both the inner core layer 110 and the outer core layer 120 constituting the core layer 130 are configured to have an outer peripheral surface that is substantially parallel to the axial direction of the hollow shaft. Sample S3 is a two-layer tube consisting of a core layer 130 and an outer layer 140, wherein the core layer 130 is composed only of the inner core layer 110. That is, sample S3 does not have an outer core layer 120 made of a resin with a higher Young's modulus than fluorinated resins. Furthermore, in sample S3, the core layer 130 does not have the specific structure SC. Specifically, in sample S3, the inner core layer 110 constituting the core layer 130 is configured to have an outer peripheral surface that is substantially parallel to the axial direction of the hollow shaft. Additionally, the forming materials and thicknesses of each layer in samples S2 and S3 are the same as in sample S1.

[0055] Using each sample as an example, Young's modulus, fracture load, and flexural modulus were determined based on methods according to JIS K 7161-2014 and JIS K 7171, and the average values ​​were calculated for N=5. A higher average Young's modulus indicates higher tensile strength of the hollow shaft, while a lower average flexural modulus indicates higher flexibility. The average fracture load of sample S3 was not measured.

[0056] While the average Young's modulus of sample S1 is lower than that of sample S2 without the specific structure SC, it is sufficiently high compared to that of sample S3 without the outer core layer 120. Therefore, sample S1 is confirmed to have sufficiently high tensile strength. Since the outer core layer 120 is composed of a high Young's modulus resin, the Young's modulus of sample S1 with the outer core layer 120 can be considered sufficiently high. Furthermore, the average fracture load of sample S1 is equal to that of sample S2 without the specific structure SC. Therefore, it can be said that the presence or absence of the specific structure SC has almost no effect on the fracture load.

[0057] Furthermore, while the average flexural modulus of sample S1 is higher than that of sample S3 (which does not have the outer core layer 120), it is sufficiently low compared to that of sample S2 (which does not have the specific structure SC). Therefore, it is confirmed that sample S1 has sufficiently high flexibility. Since the specific structure SC is a structure that repeats the mountain section 130A and valley section 130B along the axial direction, it is a structure that improves flexibility; therefore, the flexural modulus of sample S1 with the specific structure SC can be considered sufficiently low.

[0058] As described above, based on the results of this performance evaluation, in the hollow shaft 100 having a core layer 130 and an outer layer 140, the core layer 130 has an inner core layer 110 made of fluorinated resin and an outer core layer 120 made of a resin with a Young's modulus higher than that of fluorinated resin. Furthermore, when the core layer 130 has a specific structure SC that repeats the mountain portion 130A and valley portion 130B along the axial direction, it has been confirmed that the flexibility and stretchability of the hollow shaft 100 can be balanced at a high level.

[0059] A-6. Effects of this implementation method

[0060] As described above, the hollow shaft 100 constituting the conduit 10 of this embodiment includes: a tubular core layer 130; and an outer layer 140 made of resin and disposed on the outer periphery of the core layer 130, having an outer peripheral surface substantially parallel to the axial direction of the hollow shaft 100. The core layer 130 includes: a tubular inner core layer 110 made of fluorinated resin; and an outer core layer 120 made of a resin with a higher Young's modulus than fluorinated resin and disposed on the outer periphery of the inner core layer 110. The core layer 130 has a specific structure SC with a mountain portion 130A protruding radially outward toward the hollow shaft 100 and a valley portion 130B protruding radially inward toward the hollow shaft 100, which are repeatedly arranged along the axial direction of the hollow shaft 100.

[0061] Thus, in the hollow shaft 100 of this embodiment, the core layer 130, in addition to having an inner core layer 110 made of fluorinated resin, also has an outer core layer 120 made of a resin with a higher Young's modulus than fluorinated resin, thereby possessing high tensile strength. Furthermore, in the hollow shaft 100 of this embodiment, since the core layer 130 has a specific structure SC with repeated configurations of mountain portions 130A and valley portions 130B, it also possesses high flexibility despite having an outer core layer 120. Therefore, according to the hollow shaft 100 of this embodiment, both flexibility and tensile strength of the hollow shaft 100 can be achieved at a high level.

[0062] Furthermore, in the hollow shaft 100 of this embodiment, the specific structure SC of the core layer 130 includes a cross portion CP of two mountain 130A ridges arranged along the axial direction of the hollow shaft 100 intersecting to form a single mountain 130A ridge. Therefore, according to the hollow shaft 100 of this embodiment, the flexibility of the hollow shaft 100 can be further improved effectively, and the flexibility and stretchability of the hollow shaft 100 can be balanced at a higher level.

[0063] Furthermore, the outer diameter of the hollow shaft 100 in this embodiment is 5 mm or less. Thus, even in 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 a specific structure SC on the core layer 130 using the method described above.

[0064] Furthermore, in the hollow shaft 100 of this embodiment, the core layer 130 has a specific structure SC in a portion of the axial direction of the hollow shaft 100, but not in the remaining portion. Therefore, the hollow shaft 100 according to this embodiment can ensure high overall tensile strength while improving the flexibility of the portion where flexibility is particularly required, thereby giving the hollow shaft 100 the desired performance. More specifically, in the hollow shaft 100 of this embodiment, the core layer 130 has a specific structure SC in a portion of the front end containing the core layer 130, but not in the remaining portion. Therefore, the hollow shaft 100 according to this embodiment can ensure high overall tensile strength while improving the flexibility of the front end portion where flexibility is particularly required.

[0065] 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, the reduction in the flexibility of the hollow shaft 100 caused by the core layer 130 having the outer core layer 120 can be suppressed, and the flexibility and stretchability of the hollow shaft 100 can be balanced at a higher level.

[0066] Furthermore, since the catheter 10 of this embodiment has the hollow shaft 100 with the above-described structure, it is possible to balance the flexibility and stretchability of the hollow shaft 100 constituting the catheter 10 at a high level.

[0067] B. Variations

[0068] The technology disclosed in this specification is not limited to the above-described embodiments. Various modifications can be made without departing from its spirit, such as the following modifications.

[0069] The structure of the conduit 10 in the above embodiment is merely an example and can be modified in various ways. For example, in the above embodiment, the hollow shaft 100 constituting the conduit 10 is composed of a core layer 130 and an outer layer 140, but it may also have a second outer layer disposed on the outer periphery of the outer layer 140. In such a structure, other components (e.g., a braided layer or other reinforcing material made by weaving multiple wires together) may also be sandwiched between the outer layer 140 and the second outer layer.

[0070] In the above embodiment, the core layer 130 is composed of an inner core layer 110 and an outer core layer 120, but the core layer 130 may also have other layers. The other layers may be disposed on the inner periphery of the inner core layer 110, between the inner core layer 110 and the outer core layer 120, or on the outer periphery of the outer core layer 120.

[0071] In the above embodiment, the portion of the core layer 130 that includes only the front end (the portion constituting the distal portion DP of the hollow shaft 100) has a specific structure SC, but the portion of the core layer 130 with the specific structure SC can be appropriately modified according to the performance requirements of the hollow shaft 100. Alternatively, the core layer 130 may also have the specific structure SC along its entire length.

[0072] In the above embodiment, the specific structure SC of the core layer 130 includes the intersection of the ridges of two mountain 130A arranged axially along the hollow axis 100 to form a cross portion CP of the ridge of a mountain 130A, but the specific structure SC may not necessarily include the cross portion CP.

[0073] The thicknesses of the structural components constituting the hollow shaft 100 and the thickness relationships between the components in the above embodiments are merely examples, and various modifications are possible. Furthermore, the materials used for the structural components constituting the hollow shaft 100 in the above embodiments are merely examples, and other materials can also be used. Additionally, the manufacturing methods for the hollow shaft 100 in the above embodiments are merely examples, and other manufacturing methods can also be employed.

[0074] In the above embodiments, the hollow shaft 100 constituting the catheter 10 was described as an example of a medical tube, but the technology disclosed in this specification can also be applied to other medical tubes (e.g., the hollow shaft constituting a balloon catheter, an indwelling needle tube, etc.).

[0075] Explanation of reference numerals in the attached figures

[0076] 10: conduit 20: tip 30: connector 100: hollow shaft 102: lumen 110: inner core layer 120: outer core layer 130: core layer 130A: mountain 130B: valley 140: outer layer CP: cross section DP: distal section PP: proximal section SC: specific structure

Claims

1. A medical tube, wherein, The medical tubing has the following features: Tubular core layer; and The outer layer, made of resin, is disposed on the outer periphery of the core layer and has an outer peripheral surface substantially parallel to the axial direction of the medical tube. The core layer has: A tubular inner core layer made of fluorinated resin; and An outer core layer, wherein the outer core layer is composed of a resin with a higher Young's modulus than the fluorinated resin, and is disposed on the outer periphery of the inner core layer. The core layer has a specific structure in which hillsides protruding radially outward toward the medical tube and valleys protruding radially inward toward the medical tube are repeatedly arranged along the axial direction of the medical tube. The specific structure comprises a cross section of two mountain ridges arranged along the axial direction of the medical tube, which intersect to form a single mountain ridge.

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

3. The medical tubing according to claim 1, wherein, The core layer has the specific structure in a portion of the axial direction of the medical tube, but does not have the specific structure in the remaining portion.

4. The medical tubing according to claim 1, wherein, The core layer has the specific structure in a portion of the front end containing the core layer, but does not have the specific structure in the remaining portion.

5. The medical tubing according to claim 3, wherein, The core layer has the specific structure in a portion of the front end containing the core layer, but does not have the specific structure in the remaining portion.

6. The medical tubing according to claim 1, wherein, The outer core layer is thinner than the inner core layer.

7. The medical tubing according to claim 3, wherein, The outer core layer is thinner than the inner core layer.

8. The medical tubing according to claim 4, wherein, The outer core layer is thinner than the inner core layer.

9. A catheter comprising any one of claims 1 to 8.

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