Medical tube and method for manufacturing the same

Abstract

The present invention provides a medical tube and a method for manufacturing the same that can suppress the risk of separation of the two tubes. [Solution] The device comprises a rigid resin tube 11 and a flexible resin tube 12 joined to the distal side of the rigid resin tube 11. The rigid resin tube 11 has a reduced diameter portion 24 at its distal end, where the outer diameter decreases toward the distal end, and is joined to the flexible resin tube 12 by a heat-welded surface 24a on the reduced diameter portion 24. The flexible resin tube 12 has an outer resin layer 32 and an inner resin layer 31 formed inside the outer resin layer 32, which has a higher material hardness than the outer resin layer 32. The inner resin layer 31 is formed along the heat-welded surfaces 24a and 41a, and the difference in material hardness between the inner resin layer 31 and the rigid resin tube 11 when the heat-welded surfaces 24a and 41a are the material interface is 16D or less on the Shore D hardness scale.

Description

[[Technical Field]]

[0001] The present invention relates to a medical tube and a method for manufacturing the same. [[Background Art]]

[0002] Conventionally, there is a catheter formed by mutually joining two tubes made of different materials (see Patent Document 1). This catheter comprises a first tube and a second tube joined to a proximal side of the first tube, and the first tube is joined to the second tube by welding the first tube to a joining surface of the second tube. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2010-162290 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, with conventional catheters, when bending stress is generated at the joined portion of the two tubes, there has been a problem that the joining surface peels off due to the difference in material hardness between the first tube and the second tube, resulting in a risk that the two tubes separate.

[0005] Accordingly, an object of the present invention is to provide a medical tube capable of suppressing the separation risk of the two tubes and a method for manufacturing the same. [[Means for Solving the Problem]]

[0006] To achieve the above objective, the present invention provides a medical tube comprising a rigid tube and a flexible tube joined to one side in the longitudinal direction of the rigid tube, wherein the rigid tube has a reduced diameter portion at the end on the one side, where the outer diameter decreases toward the one side, and is joined to the flexible tube by a joining surface on the reduced diameter portion, and the flexible tube has an outer resin layer and an inner resin layer formed inside the outer resin layer and having a higher material hardness than the outer resin layer, wherein the inner resin layer is formed along the joining surface, and the difference in material hardness between the inner resin layer and the rigid tube when the joining surface is the material interface is 16D or less on the Shore D hardness scale.

[0007] Furthermore, in order to achieve the above objective, the present invention provides a method for manufacturing a medical tube, comprising: a diameter reduction portion forming step of forming the diameter reduction portion at one end of the rigid tube; and a heat welding step of heat welding the flexible tube to the diameter reduction portion. [Effects of the Invention]

[0008] According to the medical tube and its manufacturing method according to the present invention, the risk of separation of the two tubes can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1(a) shows a plan view (a) and a cross-sectional view (b) of line A-A' in Figure 1(a), illustrating a medical tube according to one embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating an example of the use of medical tubing. [Figure 3] Figure 3(a) shows a plan view of the rigid resin tube and the flexible resin tube before joining, and Figure 3(a) shows a cross-sectional view along line B-B' (b). [Figure 4] This is a cross-sectional view taken along line A-A' in Figure 1(a), showing the area around the joint. [Figure 5] This is a flowchart illustrating the manufacturing method of medical tubing. [Figure 6]This is an explanatory diagram showing the first part of the manufacturing method for medical tubing. [Figure 7] This is an explanatory diagram showing the latter half of the manufacturing method for medical tubing. [Figure 8] This is a cross-sectional view taken along line A-A' in Figure 1(a), showing a medical tube of the first modified example. [Figure 9] (a) is a plan view showing the medical tube of the second modified example, (b) is a plan view showing the rigid resin tube and flexible resin tube before joining in the medical tube of the second modified example, and (c) is a cross-sectional view of the medical tube of the second modified example taken along the line C-C' in Figure 9(a). [Figure 10] (a) is a plan view showing the medical tube of the third modified example, and (b) is a schematic diagram showing an example of use of the medical tube of the third modified example. [Figure 11] This is an explanatory diagram showing a modified example of the method for forming the reduced diameter portion. [Modes for carrying out the invention]

[0010] The following describes a medical tube according to one embodiment of the present invention and its manufacturing method, with reference to the attached drawings. This medical tube is a tube inserted into a lumen in the body (e.g., the digestive tract, bile duct, pancreatic duct, blood vessel, ureter, etc.) to introduce fluids into the body, discharge fluids from the body, or assist in the flow of fluids, and is intended to be used as a catheter (e.g., a contrast catheter), a drainage tube, or a stent. In particular, this medical tube employs a separation risk suppression structure at the joint where a rigid resin tube and a flexible resin tube are joined, thereby suppressing the risk of separation of the two resin tubes. This medical tube is primarily intended to be used as a catheter, drainage tube, or stent after being partially modified.

[0011] (Composition of medical tubing) As shown in Figure 1, the medical tube 1 is a tube with an outer diameter of 3.5 Fr (approximately 1.17 mm) or more and a material hardness of 20D to 80D on the Shore D hardness scale. It comprises a proximal rigid resin tube 11 and a distal flexible resin tube 12 joined to the distal side (one side in the longitudinal direction) of the rigid resin tube 11. In other words, the medical tube 1 has a configuration as a connecting tube, with the rigid resin tube 11 and the flexible resin tube 12 linked in the longitudinal direction. Figure 2 is a schematic diagram showing an example of use when the medical tube 1 is used as a catheter or drainage tube. As shown in the figure, the medical tube 1 is mainly intended to be used by inserting the entire flexible resin tube 12 and the distal end of the rigid resin tube 11 into the living body P.

[0012] In this specification, "proximal side" refers to the side closer to the operator (manipulator), and "distal side" refers to the side further from the operator (the side inserted into the living body P). "Distal side of rigid resin tube 11" is an example of "one side in the longitudinal direction of rigid resin tube 11," and "proximal side of flexible resin tube 12" is an example of "the side of flexible resin tube 12 that is on the rigid resin tube 11 side." In this specification, Fr (French catheter scale) is used as a unit to represent the outer diameter of catheter tubes, drainage tubes, etc. (tubular members), and 1 Fr is 1 / 3 mm (i.e., 3 Fr = 1 mm). Also, rigid resin tube 11 is an example of a rigid tube, and flexible resin tube 12 is an example of a flexible tube.

[0013] As shown in FIGS. 1 and 3, the hard resin tube 11 has a material hardness of 50D to 80D in Shore D hardness and a three-layer structure with a wall thickness of 0.1 mm to 0.8 mm, and comprises a thin inner resin layer 21 (inner layer), a braid 22 (reinforcement layer) formed outside the inner resin layer 21, and an outer resin layer 23 (outer layer) formed outside the braid 22 and covering the inner resin layer 21 and the braid 22. At the distal end of the hard resin tube 11, the braid 22 is omitted, and the distal end of the hard resin tube 11 has a two-layer structure consisting of the inner resin layer 21 and the outer resin layer 23. In addition, the inner resin layer 21 is an example of a hard inner resin layer, and the outer resin layer 23 is an example of a hard outer resin layer.

[0014] The inner resin layer 21 is formed, for example, of PA12 (polyamide 12) having a material hardness of 74D Shore D hardness, and is molded into a cylindrical shape. The inner resin layer 21 has, for example, a lumen with a diameter of 1.10 mm and an outer diameter of 1.30 mm. It is preferable that the inner resin layer 21 contains 40% by weight of a contrast agent such as barium sulfate or tungsten as a material. The inner resin layer 21 may be configured to be formed of a material that does not contain a contrast agent.

[0015] The braid 22 is formed, for example, by braiding 16 strands (metal wires) each having a diameter of 0.03 mm, and functions as a reinforcement layer that reinforces the hard resin tube 11.

[0016] The outer resin layer 23 is formed, for example, of PAE (polyamide elastomer) having a material hardness of 72D Shore D hardness, and is formed into a cylindrical shape with a diameter of 1.4 mm to 2.4 mm. The outer resin layer 23 has, for example, an outer diameter of 1.68 mm. It is preferable that the outer resin layer 23 contains 40% by weight of a contrast agent such as barium sulfate or tungsten as a material. The outer resin layer 23 may be configured to be formed of a material that does not contain a contrast agent.

[0017] Further, the hard resin tube 11 has, at a distal end portion thereof, a reduced diameter portion 24 whose outer diameter decreases toward the distal side. The reduced diameter portion 24 is formed in an inclined shape (tapered shape) whose outer diameter gradually decreases toward the distal side, and the inclined surface serves as a heat-welded surface 24a to which the soft resin tube 12 is heat-welded. The hard resin tube 11 is joined to the soft resin tube 12 via the heat-welded surface 24a on the reduced diameter portion 24. That is, the soft resin tube 12 is joined to the distal side of the hard resin tube 11 by heat-welding the proximal end portion of the soft resin tube 12 to the heat-welded surface 24a of the reduced diameter portion 24. Note that the heat-welded surface 24a is an example of a joining surface. Further, the dimension of the reduced diameter portion 24 in the axial direction (longitudinal direction) is 3 mm to 10 mm (for example, 6 mm), and the inclination angle (taper angle) is 0.5° to 15° (preferably 0.57° to 14.91°). Further, the smaller the wall thickness at the most distal end of the reduced diameter portion 24 is, the more preferable it is, but considering workability, the wall thickness is desirably 0.05 mm or less. Further, the reduced diameter portion 24 is formed over the entire wall thickness region of the hard resin tube 11, and the heat-welded surface 24a extends from the outer peripheral surface to the inner peripheral surface of the hard resin tube 11.

[0018] On the other hand, the soft resin tube 12 has a material hardness of 20D to 65D in terms of Shore D hardness and has a two-layer structure, comprising an outer resin layer 32 (outer layer), and a thin inner resin layer 31 (inner layer) formed inside the outer resin layer 32 and having a material hardness higher than that of the outer resin layer 32. That is, in the soft resin tube 12, the outer resin layer 32 covers the inner resin layer 31.

[0019] The inner resin layer 31 is formed of, for example, PAE having a material hardness of 63D in terms of Shore D hardness, and is molded into a cylindrical shape. The inner resin layer 31 has, for example, a lumen with a diameter of 1.10 mm and an outer diameter of 1.30 mm. It is preferable that the inner resin layer 31 contains 40% by weight of a contrast agent such as barium sulfate or tungsten as a material. Note that the inner resin layer 31 may be configured to be formed of a material that does not contain a contrast agent.

[0020] The outer resin layer 32 is formed of PAE with a material hardness of 40D on the Shore D scale, for example, and is cylindrical in shape. The outer resin layer 32 has an outer diameter of, for example, 1.68 mm. Preferably, the outer resin layer 32 contains 40% by weight of a contrast agent such as barium sulfate or tungsten as a material. However, the outer resin layer 32 may also be formed of a material that does not contain a contrast agent.

[0021] Furthermore, the flexible resin tube 12 has an enlarged diameter section 41 at its proximal end (the side facing the rigid resin tube 11), where the inner diameter increases towards the proximal end. The enlarged diameter section 41 is formed in an inclined shape (tapered hole shape) where the inner diameter gradually increases towards the proximal end, and its inclined surface becomes a heat-welding surface 41a that heat-welds to the heat-welding surface 24a of the rigid resin tube 11. Since the enlarged diameter section 41 of the flexible resin tube 12 has a complementary shape to the reduced diameter section 24 of the rigid resin tube 11, when the enlarged diameter section 41 of the flexible resin tube 12 is joined to the reduced diameter section 24 of the rigid resin tube 11, as shown in Figure 1(b), the outer and inner surfaces are continuous in the longitudinal direction without any steps, forming a single, integrated tube shape.

[0022] Furthermore, the enlarged diameter portion 41 of the flexible resin tube 12 is formed to be slightly smaller than the reduced diameter portion 24 of the rigid resin tube 11, and the enlarged diameter portion 41 of the flexible resin tube 12 is configured to be fittable (tight fit or standard fittable) onto the reduced diameter portion 24 of the rigid resin tube 11. Therefore, when heat-welding the flexible resin tube 12 to the distal side of the rigid resin tube 11, the enlarged diameter portion 41 of the flexible resin tube 12 is fitted onto the reduced diameter portion 24 of the rigid resin tube 11 and heated, thereby heat-welding the heat-welding surface 41a of the enlarged diameter portion 41 to the heat-welding surface 24a of the reduced diameter portion 24. Hereinafter, the joint portion between the rigid resin tube 11 and the flexible resin tube 12, consisting of the reduced diameter portion 24 of the rigid resin tube 11 and the enlarged diameter portion 41 of the flexible resin tube 12, will be referred to as the joint portion 13.

[0023] (Explanation of the separation risk mitigation structure) Next, with reference to Figure 4, a structure for suppressing the risk of separation at the joint 13 will be described. In conventional medical tubes 1, when bending stress occurs at the joint 13, the bending stress concentrates on the heat-welded surfaces 24a and 41a due to the difference in material hardness between the rigid resin tube 11 and the flexible resin tube 12. This causes the heat-welded surfaces 24a and 41a to peel off, resulting in the separation of the two resin tubes 11 and 12. In contrast, in this medical tube 1, the inner resin layer 31 of the soft resin tube 12 is formed along the heat-sealed surfaces 24a and 41a, and the difference in material hardness between the inner resin layer 31 and the hard resin tube 11 with the heat-sealed surfaces 24a and 41a as the material interface is set to 16D or less (preferably 15D or less) on the Shore D hardness scale, thereby suppressing the risk of separation between the two resin tubes 11 and 12.

[0024] Specifically, as shown in Figure 4, in this medical tube 1, the inner resin layer 31 of the flexible resin tube 12 is formed along the heat-welded surface 24a, and the inner resin layer 31 is formed over the entire heat-welded surface 24a so as to cover the entire heat-welded surface 24a. As a result, the inner resin layer 21 with a material hardness of 74D and the outer resin layer 23 with a material hardness of 72D in the rigid resin tube 11 are adjacent to and in contact with the inner resin layer 31 with a material hardness of 63D in the flexible resin tube 12 at the heat-welded surfaces 24a and 41a. As a result, the difference in material hardness between the inner resin layer 31 of the flexible resin tube 12 and the rigid resin tube 11, when the heat-welded surfaces 24a and 41a are considered the material interface, becomes 16D or less on the Shore D hardness scale (11D or less in this embodiment), and the difference in material hardness between the rigid resin tube 11 and the flexible resin tube 12, when the entire heat-welded surfaces 24a and 41a are considered the material interface, becomes 16D or less on the Shore D hardness scale. With this configuration, stress concentration of bending stress caused by the difference in material hardness can be suppressed, preventing delamination of the heat-welded surfaces 24a and 41a when bending stress occurs at the joint 13, and reducing the risk of separation of both resin tubes 11 and 12 when bending stress occurs.

[0025] In this configuration, the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11 were formed from PA12 with a material hardness of 74D and PAE with a material hardness of 72D, respectively, and the inner resin layer 31 of the flexible resin tube 12 was formed from PAE with a material hardness of 63D, thereby reducing the difference in material hardness at the heat-welded surfaces 24a and 41a to 16D or less. However, this configuration is not limited to this. For example, the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11 were formed from a PA12-PAE mixed resin with a material hardness of 69D and PAE with a material hardness of 72D, respectively, and the inner resin layer 31 of the flexible resin tube 12 was formed from PAE with a material hardness of 57D, thereby reducing the difference in material hardness at the heat-welded surfaces 24a and 41a to 16D or less.

[0026] (Explanation of the manufacturing method of medical tubing) Next, the manufacturing method for the medical tube 1 will be described with reference to Figures 5 to 7. As shown in Figure 5, in the manufacturing method for the medical tube 1, the medical tube 1 is manufactured by performing a diameter reduction step S1, a diameter expansion step S2, and a heat welding step S3 on a rigid resin tube 11 and a flexible resin tube 12 created by extrusion molding or the like.

[0027] As shown in Figure 5, in the manufacturing method of the medical tube 1, first, a reduced diameter portion 24 is formed at the distal end of the rigid resin tube 11 (reduced diameter portion formation step S1). In the reduced diameter portion formation step S1, for example, the outer circumferential surface of the distal end of the rigid resin tube 11 is ground in an inclined manner to form the reduced diameter portion 24 (see Figure 6(b)).

[0028] Next, an enlarged diameter portion 41 is formed at the proximal end of the flexible resin tube 12 (enlarged diameter portion formation step S2). In the enlarged diameter portion formation step S2, for example, first, the outer circumferential surface of the proximal end of the flexible resin tube 12 is ground in an inclined shape so that the thickness of the flexible resin tube 12 gradually decreases towards the proximal end (see Figure 6(c)), and then the proximal end of the flexible resin tube 12 is heated and expanded (thermal deformation) using a heater such as a tapered soldering iron to form the enlarged diameter portion 41 (see Figure 7(a)). Note that if the flexible resin tube 12 is made of a relatively soft material, the enlarged diameter portion 41 may be formed by expanding the proximal end of the flexible resin tube 12 without applying heat.

[0029] After forming a reduced diameter portion 24 and a widened diameter portion 41 in the rigid resin tube 11 and the flexible resin tube 12, the widened diameter portion 41 of the flexible resin tube 12 is heat-welded to the reduced diameter portion 24 of the rigid resin tube 11 (heat welding step S3). For example, using a core material 51 (mandrel) with the same diameter as the lumen of the rigid resin tube 11 and the flexible resin tube 12, the core material 51 is inserted into the rigid resin tube 11, and the flexible resin tube 12 is moved toward the rigid resin tube 11 side, thereby fitting the widened diameter portion 41 of the flexible resin tube 12 into the reduced diameter portion 24 of the rigid resin tube 11 (see Figure 7(b)). Subsequently, the outer mold 52, such as a heat-shrinkable tube, is placed around the joint 13, and the joint 13 is heated with a heater (e.g., a mold heater, hot air heater, or infrared heater) to heat-weld (melt and integrate) the heat-welding surfaces 24a and 41a (see Figure 7(c)). After cooling to room temperature, the core material 51 and outer mold 52 are removed. This joins the flexible resin tube 12 to the distal side of the rigid resin tube 11, thereby manufacturing the medical tube 1. It is also possible to heat the core material 51 and outer mold 52 using IH (induction heating) as a method of heating the joint 13. Furthermore, the cooling method for the resin tubes 11 and 12 after heat welding is preferably selected appropriately from rapid cooling (e.g., immersion in a refrigerant at a predetermined temperature) or slow cooling (e.g., leaving at room temperature) depending on the resin material of the resin tubes 11 and 12. For example, if the resin material of the resin tubes 11 and 12 is a polyamide resin, the resin tubes 11 and 12 may be cooled by rapid cooling, and if the resin material of the resin tubes 11 and 12 is a polyethylene resin, the resin tubes 11 and 12 may be cooled by slow cooling. In addition, the method of joining the two resin tubes 11 and 12 may be a configuration in which the two resin tubes 11 and 12 are joined by ultrasonic welding.

[0030] (Effects and workings of the embodiment) As described above, according to the configuration of the embodiment, the inner resin layer 31 of the flexible resin tube 12 is formed along the heat-welded surfaces 24a and 41a, and the difference in material hardness between the inner resin layer 31 and the rigid resin tube 11 is made to 16D or less, thereby making the difference in material hardness between the rigid resin tube 11 and the flexible resin tube 12 at the heat-welded surfaces 24a and 41a 16D or less. This makes it possible to suppress stress concentration of bending stress due to the difference in material hardness (difference in elongation when bending stress occurs) when bending stress occurs at the joint 13, and to suppress delamination of the heat-welded surfaces 24a and 41a. This makes it possible to suppress the risk of separation between the rigid resin tube 11 and the flexible resin tube 12 when bending stress occurs, and to provide a medical tube 1 with high safety in a medical tube 1 formed by joining a rigid resin tube 11 and a flexible resin tube 12. Furthermore, by keeping the material of the inner resin layer 31 the same and appropriately changing the material of the outer resin layer 32 and the wall thickness of each layer 31 and 32, it is possible to obtain appropriate flexibility while suppressing the risk of separation of both resin tubes 11 and 12. In other words, since the flexibility can be improved by changing the material hardness of the outer resin layer 32 and the wall thickness of each layer 31 and 32 while maintaining the effect of suppressing the risk of separation, it is possible to achieve both safety and flexibility, and to provide a safe medical tube 1 with appropriate flexibility.

[0031] Table 1 shows the evaluation results for the separation resistance of medical tube 1. In the evaluation in Table 1, medical tube 1 of Example 1 and Comparative Example 1 according to the above embodiment was prepared, and a bending test was performed on the medical tube 1 of Example 1 and Comparative Example 1 at room temperature to evaluate the separation resistance of the medical tube 1 of Example 1 and Comparative Example 1. In the bending test, a test mandrel (diameter -0.1 mm of the inner diameter of medical tube 1) that had been pre-bent to R5 and 90° was used to bend the medical tube 1 at the joint 13 to a 90° position, and then the medical tube 1 was rotated 360° in the circumferential direction to generate bending stress at the joint 13. In that state, the presence or absence of changes in appearance related to the separation of both resin tubes 11 and 12 was evaluated, and based on this evaluation, the separation resistance of the medical tube 1 of Example 1 and Comparative Example 1 when bending stress was generated was evaluated as "○ (good)" or "× (poor)". Example 1 is based on the above embodiment shown in Figures 1 to 4, and the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11, and the inner resin layer 31 and outer resin layer 32 of the flexible resin tube 12 are formed of PA12 with a material hardness of 74D, PAE with a material hardness of 72D, PAE with a material hardness of 63D, and PAE with a material hardness of 40D, respectively. On the other hand, Comparative Example 1 is the same as Example 1 except for the material of each resin layer, and in Comparative Example 1, the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11, and the inner resin layer 31 and outer resin layer 32 of the flexible resin tube 12 are formed of PAE with a material hardness of 72D, PA12 with a material hardness of 74D, PAE with a material hardness of 55D, and PAE with a material hardness of 40D, respectively. Furthermore, PA12 was made using Diamide® manufactured by Daicel-Evonik Corporation, and PAE was made using Pebax® manufactured by Arkema Corporation. In addition, all materials used contained 40% by weight of contrast agents such as barium sulfate and tungsten. The Shore D hardness of each resin layer 21, 23, 31, and 32 was measured using the measurement method specified in, for example, JIS K7215 or ISO 868:2003. [Table 1]

[0032] As shown in Table 1, in Comparative Example 1, medical tube 1 showed whitening and indentation at the joint 13 when a bending test was performed. This is thought to be due to delamination of the heat-welded surfaces 24a and 41a, and based on this, the separation resistance of Comparative Example 1 when bending stress is generated was "× (poor)". In contrast, in Example 1, medical tube 1 did not show whitening or indentation at the joint 13 when a bending test was performed. Based on this, the separation resistance of Example 1 when bending stress is generated was "○ (good)". In this way, by making the difference in material hardness between the inner resin layer 31 and the rigid resin tube 11 16D or less, and by making the difference in material hardness at the heat-welded surfaces 24a and 41a between the rigid resin tube 11 and the flexible resin tube 12 16D or less, the separation resistance of the medical tube 1 when bending stress occurs at the joint 13 can be improved, and the risk of separation of both resin tubes 11 and 12 when bending stress occurs can be suppressed. Note that the separation resistance evaluation in Table 1 is a test of separation resistance when the medical tube 1 is rotated in the circumferential direction while bent, so it can be said that separation resistance can be improved when bending stress occurs, and it can also be said that separation resistance can be improved when the medical tube 1 is rotated while bent.

[0033] Furthermore, according to the configuration of the above embodiment, by joining a rigid resin tube 11 made of a hard resin and a flexible resin tube 12 made of a soft resin to form the medical tube 1, high torque transmission and pushability can be obtained at the proximal end, while high flexibility can be obtained at the distal end. Therefore, it is possible to provide a medical tube 1 that is easy to operate with a guide wire, for example, and easy to perform procedures on.

[0034] Furthermore, according to the configuration of the above embodiment, by providing a reduced diameter portion 24 at the distal end (joint end) of the rigid resin tube 11, where the outer diameter decreases toward the distal end, a portion with lower hardness can be provided on the side of the rigid resin tube 11 closer to the flexible resin tube 12, thereby smoothing out the variation in hardness along the longitudinal direction of the medical tube 1. This can alleviate stress concentration due to tensile stress caused by variations in hardness, and suppress the risk of separation of both resin tubes 11 and 12. Note that "variation in hardness" as used herein can also be rephrased as "variation in the amount of deformation when the same tensile stress is applied."

[0035] Furthermore, according to the configuration of the above embodiment, by forming the reduced diameter portion 24 in a tapered shape where the outer diameter gradually decreases toward the distal end, the variation in hardness along the longitudinal direction of the medical tube 1 can be made smoother. This further reduces stress concentration due to tensile stress caused by variations in hardness, and further suppresses the risk of separation of the two resin tubes 11 and 12. In addition, the area of ​​the heat-welded surfaces 24a and 41a can be increased, thereby improving the joint strength. Moreover, a medical tube 1 that is less prone to buckling at the joint portion 13 can be provided.

[0036] Furthermore, according to the configuration of the above embodiment, by providing an enlarged diameter portion 41 corresponding to the reduced diameter portion 24 at the proximal end of the flexible resin tube 12, the medical tube 1 can be made to have a shape in which the outer and inner circumferential surfaces are continuous without steps in the longitudinal direction. In addition, the proximal end of the flexible resin tube 12 can be fitted to the distal end of the rigid resin tube 11.

[0037] (Regarding other embodiments) Although embodiments of the present invention have been described above, these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. The present invention can be implemented with appropriate modifications without departing from its spirit.

[0038] For example, in the above embodiment, the rigid resin tube 11 had an inner resin layer 21 and an outer resin layer 23, but as shown in Figure 8, the rigid resin tube 11 may be made of a single resin layer.

[0039] Furthermore, in the above embodiment, the reduced diameter portion 24 was formed in a sloping manner in which the outer diameter gradually decreases toward the distal side, but it is not limited to this configuration. For example, the reduced diameter portion 24 may be formed in a stepped manner in which it gradually decreases toward the distal side.

[0040] Furthermore, as shown in Figure 9, the inner resin layer 21 of the rigid resin tube 11 may have a protruding portion that extends distally from the outer resin layer 23, and the reduced diameter portion 24 may be formed by this protruding portion. In this case, the outer circumferential surface of the inner resin layer 21 at the protruding portion becomes the heat-welded surface 24a. Also, the enlarged diameter portion 41 of the flexible resin tube 12 is formed to gradually increase in inner diameter toward the proximal side, following the example of the reduced diameter portion 24, and the inner circumferential surface facing the outer circumferential surface of the inner resin layer 21 becomes the heat-welded surface 41a. The inner resin layer 31 of the flexible resin tube 12 is formed along the outer circumferential surface of the inner resin layer 21, which is the heat-welded surface 24a. Furthermore, the inner resin layer 31 of the flexible resin tube 12 is adjacent only to the inner resin layer 21 of the rigid resin tube 11 at the heat-welded surfaces 24a and 41a, and the difference in material hardness between the inner resin layer 31 and the inner resin layer 21 of the rigid resin tube 11 is 16D or less on the Shore hardness scale. As a result, the difference in material hardness between the inner resin layer 31 and the rigid resin tube 11 at the material interface with the heat-welded surfaces 24a and 41a is 16D or less on the Shore hardness scale. Specifically, for example, the inner resin layer 21 of the rigid resin tube 11 is formed of a PA12·PAE mixed resin with a material hardness of 69D on the Shore D scale, and the inner resin layer 31 of the flexible resin tube 12 is formed of PAE with a material hardness of 55D on the Shore D scale.

[0041] Table 2 shows the evaluation results for the separation resistance of the modified medical tube 1. In the evaluation in Table 2, medical tube 1 of Example 2 and Comparative Example 2 related to the modified example was prepared, and a bending test was performed under the same conditions as in the evaluation in Table 1 to evaluate the separation resistance of medical tube 1 of Example 2 and Comparative Example 2 when bending stress was generated. Example 2 was created based on the modified example, and the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11, and the inner resin layer 31 and outer resin layer 32 of the flexible resin tube 12 are formed from PA12·PAE mixed resin with a material hardness of 69D, PAE with a material hardness of 72D, PAE with a material hardness of 55D, and TPU (thermoplastic polyurethane elastomer) with a material hardness of 20D, respectively. Comparative Example 2 is identical to Example 2 except for the materials of each resin layer, and the inner resin layer 21 and outer resin layer 23 of the rigid resin tube 11, and the inner resin layer 31 and outer resin layer 32 of the flexible resin tube 12 are formed from PA12·PAE mixed resin with a material hardness of 59D, PAE with a material hardness of 74D, PAE with a material hardness of 35D, and TPU with a material hardness of 20D, respectively. Furthermore, PA12 was made using Diamide® manufactured by Daicel-Evonik Corporation, PAE was made using Pebax® manufactured by Arkema Corporation, and TPU was made using Peresene® manufactured by Nippon Unipolymer Corporation. In addition, all materials used contained 40% by weight of contrast agents such as barium sulfate and tungsten. [Table 2]

[0042] As shown in Table 2, in Comparative Example 2, medical tube 1 showed whitening and indentation at the joint 13 when a bending test was performed. Based on this, the separation resistance of Comparative Example 2 when bending stress is applied was "× (poor)". In contrast, in Example 2, medical tube 1 did not show whitening or indentation at the joint 13 when a bending test was performed. Based on this, the separation resistance of Example 2 when bending stress is applied was "○ (good)". In this modified example of the medical tube 1, by making the difference in material hardness between the inner resin layer 31 of the flexible resin tube 12 and the inner resin layer 21 of the rigid resin tube 11 16D or less, and by making the difference in material hardness at the heat-welded surfaces 24a and 41a between the rigid resin tube 11 and the flexible resin tube 12 16D or less, the separation resistance of the medical tube 1 when bending stress occurs at the joint 13 can be improved, and the risk of separation of both resin tubes 11 and 12 when bending stress occurs can be suppressed.

[0043] Furthermore, in the above embodiment, the flexible resin tube 12 was joined to only one side of the rigid resin tube 11 in the longitudinal direction. However, as shown in Figure 10(a), the flexible resin tube 12 may be joined to both sides of the rigid resin tube 11 in the longitudinal direction. In this case, a reduced diameter portion 24 is formed at both ends of the rigid resin tube 11 in the longitudinal direction, where the outer diameter decreases toward the outward direction in the longitudinal direction. Also, in this case, as shown in Figure 10(b), it is assumed that the entire medical tube 1 is implanted in a living body P for use.

[0044] Furthermore, while the above embodiments illustrate configurations using PA12, PAE, PA12-PAE mixed resin, and TPU as materials for the rigid resin tube 11 and the flexible resin tube 12, the invention is not limited to these. In other words, the combination of materials for the rigid resin tube 11 and the flexible resin tube 12 is not limited to the combinations in the above embodiments, as long as the combination of resins is generally thermoplastic and can be welded or bonded. For example, the rigid resin tube 11 (each resin layer 21, 23) and the flexible resin tube 12 (each resin layer 31, 32) may be made of fluororesin or polyester resin.

[0045] Furthermore, in the above embodiment, the method for forming the reduced-diameter portion 24 was illustrated by grinding the outer surface of the rigid resin tube 11, but the method is not limited to this. For example, the reduced-diameter portion 24 may be formed by thermoforming using a mold 61. Specifically, as shown in Figure 11, a mold 61 having a tapered hole shape 61a and a core material 62 are used, and the core material 62 is inserted into the lumen of the rigid resin tube 11 and the rigid resin tube 11 is introduced into the mold 61. While heating the mold 61, the distal end of the rigid resin tube 11 is pushed into the tapered hole shape 61a, thereby thermoforming the distal end of the rigid resin tube 11 to form the reduced-diameter portion 24. In such a case, the outer resin layer 23 overtakes the inner resin layer 21 and flows to the distal end, so as shown in Figure 11(c), the outer resin layer 23 is formed along the inclined surface (heat-welded surface 24a) of the reduced diameter portion 24, and the outer resin layer 23 is positioned at the distal end of the reduced diameter portion 24. Such a configuration is effective in reducing the difference in material hardness at the heat-welded surfaces 24a and 41a when the material hardness of the outer resin layer 23 is lower than that of the inner resin layer 21.

[0046] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals, etc., from the embodiments. However, the reference numerals, etc., in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0047] (1) A medical tube (1) comprising a rigid tube (11) and a flexible tube (12) joined to one side in the longitudinal direction of the rigid tube (11), wherein the rigid tube (12) has a reduced diameter portion (24) at the end on the one side, the outer diameter of which decreases toward the one side, and is joined to the flexible tube by a joining surface (24a) on the reduced diameter portion (24), and the flexible tube (12) has an outer resin layer (32) and an inner resin layer (31) formed inside the outer resin layer (32) and having a higher material hardness than the outer resin layer (32), wherein the inner resin layer (31) is formed along the joining surface (24a), and the difference in material hardness between the rigid tube (11) and the joining surface (24a) as the material interface is 16D or less on the Shore D hardness scale. (2) The medical tube (1) according to (1), characterized in that the difference in material hardness between the inner resin layer (31) and the rigid tube (11) when the joint surface (24a) is the material interface is 15D or less on the Shore D hardness scale. (3) The reduced diameter portion (24) is formed in an inclined shape such that the outer diameter gradually decreases toward one side, as described in (1) or (2). (4) The rigid tube (11) comprises a rigid inner resin layer (21) and a rigid outer resin layer (23) formed on the outside of the rigid inner resin layer (21), the rigid inner resin layer (21) has a protruding portion that protrudes from the rigid outer resin layer (23) to one side, and the reduced diameter portion (24) is formed by the protruding portion, as described in any one of (1) to (3). (5) The medical tube (1) according to any one of (1) to (4), characterized in that the flexible tube (12) has an enlarged diameter portion (41) at the end on the rigid tube side, the inner diameter of which increases toward the rigid tube side. (6) The medical tube (1) according to any one of (1) to (5), characterized in that the rigid tube (11) has a material hardness of 50D to 80D on the Shore D scale, and the flexible tube (12) has a material hardness of 20D to 65D on the Shore D scale. A method for manufacturing a medical tube (1) as described in any one of (7), (1) to (6), comprising: a diameter reduction portion forming step (S1) of forming the diameter reduction portion (24) at one end of the rigid tube (11); and a heat welding step (S3) of heat welding the flexible tube (12) to the diameter reduction portion (24). [Explanation of Symbols]

[0048] 1: Medical tube, 11: Hard resin tube, 12: Soft resin tube, 13: Joint part, 21: Inner resin layer, 22: Braided body, 23: Outer resin layer, 24: Reduced diameter part, 24a: Heat welding surface, 31: Inner resin layer, 32: Outer resin layer, 41: Expanded diameter part, 41a: Heat welding surface, S1: Reduced diameter part forming process, S2: Expanded diameter part forming process, S3: Heat welding process

Claims

1. A rigid tube and The rigid tube comprises a flexible tube joined to one side in the longitudinal direction of the rigid tube, The rigid tube has a reduced diameter portion at one end where the outer diameter decreases toward that end, and is joined to the flexible tube by a joint surface on the reduced diameter portion. The aforementioned flexible tube is Outer resin layer, It has an inner resin layer formed inside the outer resin layer, which has a higher material hardness than the outer resin layer, The medical tube is characterized in that the inner resin layer is formed along the joint surface, and the difference in material hardness between the joint surface and the rigid tube, with the joint surface as the material interface, is 16D or less on the Shore D hardness scale.

2. The medical tube according to claim 1, characterized in that the difference in material hardness between the inner resin layer and the rigid tube, with the joint surface as the material interface, is 15D or less on the Shore D hardness scale.

3. The medical tube according to claim 1, characterized in that the reduced diameter portion is formed in an inclined shape such that the outer diameter gradually decreases toward one side.

4. The rigid tube mentioned above is A hard inner resin layer, It has a hard outer resin layer formed on the outside of the hard inner resin layer, The hard inner resin layer has a protruding portion that extends from the hard outer resin layer to one side. The medical tube according to claim 1, characterized in that the reduced diameter portion is formed by the protruding portion.

5. The medical tube according to claim 1, characterized in that the flexible tube has an enlarged diameter portion at the end on the rigid tube side, with the inner diameter increasing toward the rigid tube side.

6. The rigid tube has a material hardness of 50D to 80D on the Shore D hardness scale. The medical tube according to claim 1, characterized in that the flexible tube has a material hardness of 20D to 65D on the Shore D hardness scale.

7. A method for manufacturing a medical tube according to any one of claims 1 to 6, A diameter reduction portion forming step in which the diameter reduction portion is formed at one end of the rigid tube, A method for manufacturing a medical tube, characterized by comprising a heat welding step of heat welding the soft tube to the reduced diameter portion.

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