Method for manufacturing balloon catheters

Abstract

To provide a manufacturing method of a balloon catheter provided with a protrusion part on a surface of a part of the balloon that expands to a relatively large extent when the balloon is inflated.SOLUTION: A manufacturing method of a balloon catheter includes: a process (A) for preparing a resin tubular body 21 having a first section 24 to a third section 26 from one side in a longitudinal direction and having protrusions 23 on the surface; a process (B1) for extending the first section 24 and the third section 26 of the resin tubular body 21 in the longitudinal direction; a process (C) for removing the protrusions 23 provided in the first section 24 and the third section 26 of the resin tubular body 21; a process for preparing a metal mold having a balloon-shaped lumen extending in an axial direction and in which a concave part is formed on the inner wall surface forming the lumen; a process (D) for arranging the resin tubular body 21 in the lumen of the metal mold; and a molding process (E) for expanding the first section 24 to the third section 26 of the resin tubular body 21 in the metal mold, and causing the protrusion 23 provided on the surface of the resin tubular body 21 to enter the concave part on the inner wall surface of the metal mold.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a balloon catheter, and more particularly, to a method for manufacturing a balloon catheter provided with a balloon having protrusions on its surface.

Background Art

[0002] It is known that stenosis occurs in blood vessels, which are channels for blood circulation in the body, and various diseases are caused by the stagnation of blood circulation. In particular, when stenosis occurs in the coronary arteries that supply blood to the heart, it may lead to serious diseases such as angina pectoris and myocardial infarction. As one method for treating such stenotic parts of blood vessels, there is angioplasty (PTA, PTCA, etc.) in which a balloon catheter is used to expand the stenotic part. There is a known balloon catheter in which protrusions are provided on the surface of the balloon. By using such a balloon catheter, when the balloon is expanded, the protrusions of the balloon can be made to bite into the stenotic part to create cracks in the stenotic part, thereby effectively expanding the stenotic part. As a method for manufacturing a balloon catheter having protrusions on the surface of the balloon, for example, in Patent Document 1, there is disclosed a manufacturing method having a step of inserting a resin parison into the inner cavity of a mold having grooves formed on the inner wall surface, a step of expanding the parison in the mold to allow the resin to enter the grooves of the mold, and a step of removing the parison from the mold before the resin of the parison reaches the bottom of the grooves.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a balloon catheter with protrusions on the surface of the balloon, it is preferable that the protrusions are provided on the portion of the balloon that expands significantly when the balloon is inflated, and not on the portion that does not expand significantly. This allows for effective expansion of the stenotic portion when the balloon is inflated, and when the balloon is deflated, it becomes easier to neatly fold the balloon, thereby improving the passability of the balloon into body cavities and endoscopic forceps channels. The present invention provides a method for manufacturing such a balloon catheter, and moreover, a method for manufacturing a balloon catheter in which protrusions are provided on the surface of the balloon, specifically on the portion of the balloon that expands relatively significantly when the balloon is inflated. [Means for solving the problem]

[0005] The present invention includes the following method for manufacturing a balloon catheter. [1] A step of preparing a resin tubular body having a longitudinal direction and a radial direction, having a first section, a second section and a third section from one side in the longitudinal direction, and having protrusions on its surface, A stretching step in which the resin tubular body is heated and the first section and third section of the resin tubular body are stretched in the longitudinal direction, After the stretching step, a protrusion removal step is performed to remove the protrusions provided in the first and third sections of the resin tubular body, The process of preparing a mold having a lumen extending in the axial direction, wherein the inner wall surface forming the lumen has a first sleeve forming portion, a first tapered forming portion, a straight tube forming portion, a second tapered forming portion, and a second sleeve forming portion from one side in the axial direction, wherein the inner diameter of the first tapered forming portion and the second tapered forming portion decreases as they move away from the straight tube forming portion, and a recess is formed on the inner wall surface of the straight tube forming portion, After the protrusion removal step, the first section, second section, and third section of the resin tubular body are placed in the lumen of the mold, A molding process in which the first section, second section and third section of the resin tubular body are expanded in the mold, the first section is brought into contact with the first tapered section and the first sleeve-forming section, the second section is brought into contact with the straight-tube-forming section, the third section is brought into contact with the second tapered section and the second sleeve-forming section, and the projection provided in the second section is brought into the recess. A method for manufacturing a balloon catheter having [a certain feature]. [2] A step of preparing a resin tubular body having a longitudinal direction and a radial direction, having a first section, a second section and a third section from one side in the longitudinal direction, and having protrusions on its surface, A step of removing the protrusions provided in the first and third sections of the resin tubular body, After the protrusion removal step, the resin tubular body is heated and stretched in the longitudinal direction in a stretching step, The process of preparing a mold having a lumen extending in the axial direction, wherein the inner wall surface forming the lumen has a first sleeve forming portion, a first tapered forming portion, a straight tube forming portion, a second tapered forming portion, and a second sleeve forming portion from one side in the axial direction, wherein the inner diameter of the first tapered forming portion and the second tapered forming portion decreases as they move away from the straight tube forming portion, and a recess is formed on the inner wall surface of the straight tube forming portion, After the stretching step, the first section, second section, and third section of the resin tubular body are placed in the cavity of the mold, A molding process in which the first section, second section and third section of the resin tubular body are expanded in the mold, the first section is brought into contact with the first tapered section and the first sleeve-forming section, the second section is brought into contact with the straight-tube-forming section, the third section is brought into contact with the second tapered section and the second sleeve-forming section, and the projection provided in the second section is brought into the recess. A method for manufacturing a balloon catheter having [a certain feature]. [3] A method for manufacturing a balloon catheter according to [1] or [2], wherein in the molding step, the first section, second section and third section of the resin tubular body are expanded in the longitudinal and radial directions. [4] A method for manufacturing a balloon catheter according to any one of [1] to [3], wherein in the molding step, the second section is brought into contact with at least one of the first tapered portion and the second tapered portion. [5] A method for manufacturing a balloon catheter according to any one of [1] to [4], wherein in the molding step, the second section of the resin tubular body is stretched in the longitudinal direction within the mold, and then the first section, second section and third section of the resin tubular body are expanded in the longitudinal and radial directions. [6] The resin tubular body disposed in the lumen of the mold is wherein the outer diameter of the second section is larger than the outer diameters of the first and third sections. [1] to [5] A method for manufacturing a balloon catheter. [7] A method for manufacturing a balloon catheter according to any one of [1] to [6], further comprising the step of removing the resin tubular body from the mold after the molding step, before the projection reaches the bottom of the recess. [Effects of the Invention]

[0006] According to the present invention, a balloon catheter can be easily manufactured in which a projection is provided on the surface of the straight tube portion of the balloon, which is the part that expands significantly when the balloon is inflated. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows an example of the configuration of a balloon catheter according to an embodiment of the present invention, and represents a side view of the balloon catheter. [Figure 2] This figure shows a perspective view of the balloon attached to the balloon catheter shown in Figure 1. [Figure 3] This shows a cross-sectional view (III-III) of the balloon catheter shown in Figure 1. [Figure 4] Figure 1 shows a cross-sectional view of the balloon catheter from point IV to point IV. [Figure 5] This diagram shows a schematic representation of the overall process for manufacturing a balloon catheter according to the first embodiment of the present invention. [Figure 6] This diagram shows a schematic representation of the overall process for manufacturing a balloon catheter according to a second embodiment of the present invention. [Figure 7] It shows a perspective view of a resin tubular body to be subjected to the resin tubular body preparation process. [Figure 8] It shows a radial cross-sectional view of the resin tubular body shown in FIG. 7. [Figure 9] It shows a schematic diagram of the stretching process of the first embodiment. [Figure 10] It shows a schematic diagram of the protrusion removal process of the first embodiment. [Figure 11] It shows a schematic diagram of the protrusion removal process of the second embodiment. [Figure 12] It shows a schematic diagram of the stretching process of the second embodiment. [Figure 13] It shows a schematic diagram of the mold preparation process and shows an axial cross-sectional view of the mold to be subjected to the mold preparation process. [Figure 14] It shows an example of the XIV-XIV cross-sectional view of the mold shown in FIG. 13 (including a partially enlarged view around the recess of the mold). [Figure 15] It shows another example of the XIV-XIV cross-sectional view of the mold shown in FIG. 13 (including a partially enlarged view around the recess of the mold). [Figure 16] It shows a schematic diagram of the pre-forming process. [Figure 17] It shows an example of the XVII-XVII cross-sectional view of the mold and the resin tubular body shown in FIG. 16. [Figure 18] It shows a schematic diagram of the forming process. [Figure 19] It shows an example of the XIX-XIX cross-sectional view of the mold and the resin tubular body shown in FIG. 18 (including a partially enlarged view around the recess of the mold and the protrusion of the resin tubular body).

Mode for Carrying Out the Invention

[0008] The present invention will be described in detail below based on the embodiments described below. However, the present invention is not limited by the embodiments described below, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority has been given to helping to understand the features of the present invention.

[0009] This invention relates to a method for manufacturing a balloon catheter equipped with a balloon having protrusions on its surface. Balloon catheters are medical devices mainly used in angioplasty (PTA, PTCA, etc.) to dilate narrowed areas of blood vessels, which are used in the treatment of narrowed areas of blood vessels. It is known that various diseases can occur when narrowing occurs in blood vessels, which are the pathways through which blood circulates in the body, causing blood circulation to stagnate. In particular, narrowing of the coronary arteries that supply blood to the heart can lead to serious diseases such as angina pectoris and myocardial infarction. Angioplasty is widely performed because it is a minimally invasive therapy that does not require open-heart surgery such as bypass surgery. The balloon catheter according to the present invention has protrusions on the surface of the balloon, which gives the balloon a scoring function. Therefore, when the balloon is expanded in a narrowed area, the protrusions of the balloon can bite into the narrowed area and cause a crack in the narrowed area, thereby effectively dilating the narrowed area.

[0010] Before describing the manufacturing method of the balloon catheter of the present invention, the structure of the balloon catheter that can be manufactured by the manufacturing method of the present invention will be described first. Note that the balloon catheter manufactured by the manufacturing method of the present invention is not limited to that shown in the drawings.

[0011] Figures 1 to 4 show examples of the configuration of a balloon catheter that can be manufactured by the manufacturing method of the present invention. Figure 1 shows a side view of the balloon catheter, Figure 2 shows a perspective view of the balloon provided in the balloon catheter shown in Figure 1, Figure 3 shows a III-III cross-sectional view of the balloon catheter shown in Figure 1, and Figure 4 shows an IV-IV cross-sectional view of the balloon catheter shown in Figure 1. Figure 1 shows an example of the configuration of a rapid exchange type balloon catheter.

[0012] The balloon catheter 1 has a shaft 2 and a balloon 10 provided on the outside of the shaft 2. The balloon catheter 1 has a proximal end and a distal end, with the balloon 10 provided at the distal end of the shaft 2. The proximal end of the balloon catheter 1 refers to the direction toward the user (operator) relative to the extending direction of the balloon catheter 1, and the distal end refers to the opposite direction from the proximal end, i.e., the direction toward the target of treatment. The direction from the proximal end to the distal end of the balloon catheter 1 is also called the longitudinal direction.

[0013] The balloon catheter 1 is configured to supply fluid to the inside of the balloon through the shaft 2, and the expansion and contraction of the balloon 10 can be controlled using an indefleror (balloon pressure / depressurization device). The fluid may be pressurized fluid pressurized by a pump or the like. Hereinafter, the fluid supplied to the inside of the balloon 10 will be referred to as the "balloon expansion fluid".

[0014] Shaft 2 is composed of, for example, an inner shaft 3 and an outer shaft 4. The inner shaft 3 is positioned within the lumen of the outer shaft 4. The inner shaft 3 can function as a passage for a guidewire that guides the advancement of shaft 2, and when using balloon catheter 1, the guidewire is inserted through the lumen of the inner shaft 3. The space between the inner shaft 3 and the outer shaft 4 can function as a passage for balloon inflation fluid.

[0015] In the rapid exchange type balloon catheter 1, a guidewire port 7 is provided midway from the distal to the proximal end of the shaft 2. The proximal end of the inner shaft 3 is connected to the guidewire port 7, and the distal end of the inner shaft extends to the distal part of the shaft 2, thereby forming a guidewire insertion passage that extends from the guidewire port 7 to the distal part of the shaft 2.

[0016] The outer shaft 4 may have a proximal outer shaft 4A and a distal outer shaft 4B, in which case it is preferable that the inner shaft 3 is positioned in the lumen of the distal outer shaft 4B. The proximal outer shaft 4A and the distal outer shaft 4B may be made of the same material or of different materials. For example, it is preferable that the proximal outer shaft 4A is made of resin or metal and the distal outer shaft 4B is made of resin. The outer shaft 4 may not be divided into a proximal outer shaft 4A and a distal outer shaft 4B, but may be made of a single member, or the proximal outer shaft 4A and the distal outer shaft 4B may be further made up of multiple tube members.

[0017] It is preferable that a hub 5 is provided on the proximal side of the shaft 2. The hub 5 preferably has a fluid injection section 6 that communicates with the flow path of the balloon expansion fluid in the shaft 2. The balloon 10, shaft 2 (inner shaft 3, outer shaft 4), and hub 5 can be joined using conventionally known joining methods such as adhesives or heat welding.

[0018] Although not shown in the drawings, the balloon catheter may be an over-the-wire type balloon catheter in which the inner shaft extends from the distal to the proximal end of the shaft, and a guidewire insertion passage is formed from the distal to the proximal end of the shaft. In this case, it is preferable that the flow path for the balloon inflation fluid and the guidewire insertion passage provided in the shaft extend to the hub, and that the hub is configured to have a fluid injection section communicating with the flow path for the balloon inflation fluid and a treatment section communicating with the guidewire insertion passage. It is preferable that the hub has a bifurcated structure, with the fluid injection section provided on one of the bifurcated ends and the treatment section on the other.

[0019] It is preferable that the outer surface of shaft 2 is coated. In rapid exchange type balloon catheter 1, it is preferable that the outer surface of one or both of the proximal outer shaft 4A and distal outer shaft 4B is coated, and it is more preferable that the outer surfaces of both the proximal outer shaft 4A and distal outer shaft 4B are coated. In over-the-wire type balloon catheter, it is preferable that the outer surface of the outer shaft is appropriately coated.

[0020] The coating can be hydrophilic or hydrophobic, depending on the purpose. The outer surface of the shaft 2 can be coated by immersing the shaft 2 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer surface of the shaft 2, or covering the outer surface of the shaft 2 with a hydrophilic or hydrophobic coating agent. The coating agent may contain chemicals or additives.

[0021] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether maleic anhydride copolymer, as well as hydrophilic coating agents made from any combination of these polymers.

[0022] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), ethylene fluoride propylene (FEP), perfluoroalkoxyalkanes (PFA), silicone oil, hydrophobic urethane resins, carbon coatings, diamond coatings, diamond-like carbon (DLC) coatings, ceramic coatings, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups.

[0023] It is preferable that a tip 8 is provided at the distal end of the balloon catheter 1. The tip 8 may be provided as a separate component from the inner shaft 3 distal to the distal end of the inner shaft 3, or the distal end of the inner shaft 3 may function as the tip 8 by extending the inner shaft 3 distal to the distal end of the balloon 10.

[0024] The shaft 2 may have radiopaque markers 9 positioned in the longitudinal direction of the balloon 10 to allow confirmation of the balloon 10's position under X-ray fluoroscopy. The radiopaque markers 9 can be positioned, for example, on the inner shaft 3 located inside the balloon 10, preferably at positions corresponding to both ends of the straight section of the balloon 10, or at a position corresponding to the center of the straight section of the balloon 10.

[0025] The balloon 10 has a longitudinal direction and a radial direction, and is formed in a cylindrical shape with openings on the proximal and distal sides (see Figure 2). The radial direction of the balloon 10 is the direction perpendicular to the longitudinal direction and means the direction extending radially from the center of the balloon 10. The balloon 10 also has a circumferential direction, which is the direction along the outer circumference of the expanded balloon 10 in a longitudinal cross-section of the balloon 10.

[0026] The balloon 10 has a proximal sleeve portion 11, a proximal tapered portion 12, a straight tube portion 13, a distal tapered portion 14, and a distal sleeve portion 15 in the longitudinal direction. The straight tube portion 13 is formed in a substantially cylindrical shape extending in the longitudinal direction and has the largest radial length (outer diameter) in the balloon 10. The proximal tapered portion 12 is located on the proximal side of the straight tube portion 13 and connects to the proximal end of the straight tube portion 13. The proximal tapered portion 12 is formed such that its outer diameter decreases as it moves away from the straight tube portion 13. The proximal sleeve portion 11 is located on the proximal side of the proximal tapered portion 12 and connects to the proximal end of the proximal sleeve portion 11. The proximal sleeve portion 11 is formed in a substantially cylindrical shape. The distal tapered portion 14 is located on the distal side of the straight tube portion 13 and connects to the distal end of the straight tube portion 13. The distal tapered section 14 is formed such that its outer diameter decreases as it moves away from the straight pipe section 13. The distal sleeve section 15 is located distal to the distal tapered section 14 and is connected to the distal end of the distal sleeve section 15. The distal sleeve section 15 is formed in a substantially cylindrical shape.

[0027] As described above, the balloon 10 is configured such that when the balloon 10 is expanded in a lesion such as a stenosis, the straight tube portion 13 makes sufficient contact with the lesion, making it easier to perform treatment such as dilation of the lesion. Furthermore, because the balloon 10 has a proximal tapered portion 12 and a distal tapered portion 14, when the balloon 10 is deflated, the outer diameters of the proximal and distal ends of the balloon 10 can be reduced, thereby reducing the step difference between the shaft 2 and the balloon 10, making it easier to insert the balloon 10 into a body cavity or into the forceps channel of an endoscope.

[0028] In the distal portion of the shaft 2, it is preferable that the inner shaft 3 extends distally from the distal end of the outer shaft 4, and that the inner shaft 3 extends through the internal space of the balloon 10 from the proximal sleeve portion 11 to the distal sleeve portion 15. Furthermore, it is preferable that the inner shaft 3 is joined to the inner surface of the distal sleeve portion 15 of the balloon 10, and the outer shaft 4 is joined to the inner surface of the proximal sleeve portion 11 of the balloon 10. With the distal portion of the shaft 2 configured in this way, the balloon expansion fluid can be supplied to the internal space of the balloon 10 through the space between the inner shaft 3 and the outer shaft 4.

[0029] The balloon 10 is made of resin, specifically a thermoplastic resin. Examples of resins that make up the balloon 10 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomer; polyurethane resins such as polyurethane and polyurethane elastomer; polyamide resins such as polyphenylene sulfide resin, polyamide, and polyamide elastomer; fluororesin, silicone resin, and natural rubber such as latex rubber. These may be used individually or in combination of two or more. Among these, polyamide resins, polyester resins, and polyurethane resins are preferably used. In particular, it is preferable to use elastomer resins from the viewpoint of thinning the balloon 10 and its flexibility. For example, among polyamide resins, nylon 12 and nylon 11 are suitable materials for the balloon 10, and nylon 12 is preferably used because it can be molded relatively easily during blow molding. Also, from the viewpoint of thinning the balloon 10 and its flexibility, polyamide elastomers such as polyether ester amide elastomer and polyamide ether elastomer are preferably used. In particular, polyether ester amide elastomers are preferred due to their high yield strength and good dimensional stability of the balloon 10.

[0030] The balloon 10 has a projection 16 on the outer surface of the straight tube 13. The presence of the projection 16 on the outer surface of the straight tube 13 gives the balloon 10 a scoring function. When the balloon 10 is expanded, it can bite into the calcified stenosis, causing a crack in the stenosis. Therefore, it is possible to expand the stenosis while suppressing intima dissection. Furthermore, it is possible to increase the strength of the balloon 10 and suppress over-expansion during pressurization.

[0031] The projection 16 may also be provided on the outer surface of the proximal tapered portion 12 and / or the distal tapered portion 14, but it is preferable that the projection 16 is not provided on the side of the proximal tapered portion 12 and the distal tapered portion 14 that is farther from the straight tube portion 13. For example, in the proximal tapered portion 12, it is preferable that the projection 16 is not provided in the proximal 1 / 2 range of the proximal tapered portion 12, more preferably not in the proximal 2 / 3 range, and even more preferably not in the proximal 3 / 4 range. In the distal tapered portion 14, it is preferable that the projection 16 is not provided in the distal 1 / 2 range of the distal tapered portion 14, more preferably not in the distal 2 / 3 range, and even more preferably not in the distal 3 / 4 range. This makes it easier to neatly fold the balloon 10 when it is deflated, and for example, the balloon 10 can be folded so that the projection 16 is not exposed. Therefore, the ease of inserting the balloon 10 into the body cavity or the forceps channel of an endoscope can be improved. It is preferable that the protruding portion 16 is not provided on the proximal sleeve portion 11 and the distal sleeve portion 15.

[0032] The projections 16 are formed to protrude radially from the outer surface of the balloon 10. The projections 16 can be provided linearly or as dots on the outer surface of the straight tube portion 13, for example. In the former case, the projections 16 are provided as ridges. In the latter case, it is preferable to provide multiple dot-shaped projections 16, and it is more preferable to provide multiple dot-shaped projections 16 arranged in a row. By providing the projections 16 in this way, it becomes easier to control the direction in which cracks form in the constricted portion. The direction of extension of the linear projections 16 or the arrangement direction of the multiple dot-shaped projections 16 may be, for example, the longitudinal direction of the balloon 10, the direction extending spirally in the longitudinal direction, or the circumferential direction. However, from the viewpoint of ease of manufacturing the balloon 10 having the projections 16, it is preferable that the direction of extension of the linear projections 16 or the arrangement direction of the multiple dot-shaped projections 16 is the longitudinal direction of the balloon 10.

[0033] It is preferable that multiple projections 16 are provided at different positions in the circumferential direction on the straight tube portion 13 of the balloon 10. That is, it is preferable that the projections 16 are provided at multiple locations in the circumferential direction of the balloon 10. In this case, it is preferable that the projections 16 are arranged at approximately equal intervals in the circumferential direction of the straight tube portion 13 of the balloon 10. This makes it possible to create cracks at multiple locations in the constricted section when the balloon 10 is expanded. For example, it is preferable that linear projections 16 extending in the longitudinal direction are provided at multiple locations in the circumferential direction of the balloon 10, or that multiple point-shaped projections 16 arranged in the longitudinal direction form a group of projections, and that this group of projections is provided at multiple locations in the circumferential direction of the balloon 10. In the latter case, it is preferable that the circumferential spacing of the group of projections is wider than the longitudinal spacing of the multiple projections 16 included in one group of projections. It is preferable that the projections 16 are provided at two or more positions in the circumferential direction of the balloon 10, more preferably three or more, and preferably eight or fewer, and more preferably six or fewer. Furthermore, in this case, it is preferable that the circumferential spacing of the protrusions 16 is longer than the circumferential length of a single protrusion 16. In Figures 2 and 4, linearly extending protrusions 16 are provided at three locations in the circumferential direction of the straight tube portion 13 of the balloon 10.

[0034] In the straight tube section 13 of the balloon 10, the projection 16 is preferably provided in a range of 1 / 2 or more of the longitudinal direction of the straight tube section 13, more preferably in a range of 2 / 3 or more, and even more preferably in a range of 3 / 4 or more. This makes it possible to create cracks over a wide area of ​​the constricted section when the balloon 10 is expanded.

[0035] The cross-sectional shape of the projection 16 is not particularly limited. For example, the cross-sectional shape perpendicular to the longitudinal direction of the projection 16 can be a polygon such as a triangle or quadrilateral, a partial circular shape such as a semicircle or sector, a roughly circular shape, a wedge shape, a convex shape, a spindle shape, or an irregular shape. Polygons include not only those with clearly defined corner vertices and straight sides, but also rounded polygons with rounded corners and those with at least a portion of their sides being curved. It is preferable that the projection 16 is formed to narrow towards the tip, and it is particularly preferable that it is formed in this manner in the cross-section perpendicular to the longitudinal direction.

[0036] In the straight tube portion 13 of the balloon 10, it is preferable that the wall thickness of the portion where the projection 16 is provided is thicker than the wall thickness of the portion where the projection 16 is not provided. This enhances the scoring function provided by the projection 16. The wall thickness of the portion of the straight tube portion 13 of the balloon 10 where the projection 16 is provided is preferably 1.5 times or more, more preferably 2.0 times or more, and even more preferably 2.5 times or more, than the wall thickness of the portion of the straight tube portion 13 of the balloon 10 where the projection 16 is not provided. There is no particular upper limit to the wall thickness of the portion of the straight tube portion 13 of the balloon 10 where the projection 16 is provided; for example, it may be 30 times or less, 20 times or less, or 10 times or less, the wall thickness of the portion of the straight tube portion 13 of the balloon 10 where the projection 16 is not provided.

[0037] The balloon 10 may have an inner projection (not shown) that protrudes radially inward from the inner surface of the balloon 10. The projection 16 and the inner projection may be located at the same position with respect to the longitudinal and circumferential directions of the balloon 10, and it is preferable that they are integrally molded, which may result in a part of the balloon 10 being formed to be thicker.

[0038] The present invention provides a suitable method for manufacturing a balloon catheter equipped with a balloon having protrusions on its surface as described above, and provides the following manufacturing method according to the first embodiment and the manufacturing method according to the second embodiment. The manufacturing method for a balloon catheter according to the first embodiment of the present invention comprises the steps of: preparing a resin tubular body having protrusions on its surface (hereinafter referred to as the "resin tubular body preparation step"), stretching the resin tubular body by heating it and stretching a portion of the resin tubular body in the longitudinal direction, removing a portion of the protrusions provided on the resin tubular body after the stretching step, preparing a mold having a lumen with a balloon shape extending in the axial direction, and having a recess formed on the inner wall surface that forms the lumen (hereinafter referred to as the "mold preparation step"), arranging a portion of the resin tubular body including the portion with the protrusions in the lumen of the mold after the protrusion removal step (hereinafter referred to as the "pre-molding step"), and molding the resin tubular body inflated in the mold and causing the protrusions provided on the surface of the resin tubular body to enter the recess on the inner wall surface of the mold. A method for manufacturing a balloon catheter according to a second embodiment of the present invention comprises a resin tubular body preparation step, a protrusion removal step, a stretching step performed after the protrusion removal step, a mold preparation step, a pre-molding step performed after the stretching step, and a molding step. According to the manufacturing method of the present invention, a balloon catheter having protrusions provided on the surface of the straight tube portion of the balloon, which is the part that expands significantly when the balloon is inflated, can be easily manufactured.

[0039] The method for manufacturing a balloon catheter according to an embodiment of the present invention will be described in detail below with reference to Figures 5 to 19. Figure 5 shows a schematic diagram of the overall process of the method for manufacturing a balloon catheter according to the first embodiment, Figure 6 shows a schematic diagram of the overall process of the method for manufacturing a balloon catheter according to the second embodiment, Figures 7 and 8 show a perspective view and a radial cross-sectional view (a cross-sectional view perpendicular to the longitudinal direction) of the resin tubular body used in the resin tubular body preparation process, and Figures 9 to 19 show schematic diagrams of each process. In Figures 5 and 6, the overall process of manufacturing a balloon catheter is shown with the resin tubular body as the focus, and a cross-sectional view along the longitudinal direction of the resin tubular body is shown. In Figures 9 to 19, a cross-sectional view along the longitudinal direction or a cross-sectional view perpendicular to the longitudinal direction of the mold and resin tubular body are shown in each process.

[0040] A method for manufacturing a balloon catheter according to the first embodiment is shown in Figures 5, 7 to 10, and 13 to 19. The resin tubular body preparation step is shown in Figure 5(A), the stretching step is shown in Figures 5(A) to (B1) and 9, the protrusion removal step is shown in Figures 5(B1) to (C) and 10, the mold preparation step is shown in Figure 13, the pre-molding step is shown in Figure 16, and the molding step is shown in Figures 5(D) to (E) and 18.

[0041] A method for manufacturing a balloon catheter according to the second embodiment is shown in Figures 6 to 8 and Figures 11 to 19. The resin tubular body preparation step is shown in Figure 6(A), the projection removal step is shown in Figures 6(A) to (B2) and Figure 11, the stretching step is shown in Figures 6(B2) to (C) and Figure 12, the mold preparation step is shown in Figure 13, the pre-molding step is shown in Figure 16, and the molding step is shown in Figures 6(D) to (E) and Figure 18.

[0042] In the manufacturing method of the present invention, the shape of the resin tubular body changes as the process progresses. In Figures 5 to 19, the resin tubular body is labeled with symbols A to E according to its shape. Similarly, in the following description, the resin tubular body is labeled with symbols A to E according to its shape in each process. However, in the description of a resin tubular body that is common regardless of its shape, the resin tubular body is not labeled with symbols A to E.

[0043] In the resin tubular body preparation step, a resin tubular body 21 (21A) having protrusions 23 on its surface is prepared (see Figures 7 and 8). The resin tubular body 21A is a tubular object made of resin and has a lumen extending in the longitudinal direction. The resin constituting the resin tubular body 21A is described in the same way as the resin constituting the balloon 10 described above.

[0044] The resin tubular body 21 has a longitudinal direction and a radial direction. In the resin tubular body 21, the longitudinal direction corresponds to the direction of extension of the resin tubular body 21, and the radial direction is the direction perpendicular to the longitudinal direction, meaning the direction extending radially from the center of the resin tubular body 21 in a cross section perpendicular to the longitudinal direction of the resin tubular body 21. The resin tubular body 21 also has a circumferential direction, which is the direction along the outer circumference of the resin tubular body 21 in a cross section perpendicular to the longitudinal direction of the resin tubular body 21. The longitudinal direction, radial direction, and circumferential direction of the resin tubular body 21 correspond to the longitudinal direction, radial direction, and circumferential direction of the balloon 10, respectively.

[0045] The resin tubular body 21A can be manufactured by extrusion molding, injection molding, etc., and is preferably manufactured by extrusion molding. This facilitates mass production of the resin tubular body 21A and improves the production efficiency of balloon catheters. The resin tubular body 21A can be used as a precursor for parisons used in blow molding.

[0046] As shown in Figures 5, 6, 9, and 11, the resin tubular body 21 has a first section 24, a second section 25, and a third section 26 from one side in the longitudinal direction. The resin tubular body 21A used in the resin tubular body preparation process preferably has protrusions 23 on the surface of each section from the first section 24 to the third section 26. In the resin tubular body 21, the first section 24 and the third section 26 can be sections that are stretched in the longitudinal direction in the stretching process, and the second section 25 can be a section that is not stretched in the longitudinal direction in the stretching process. The length of each section can be appropriately set according to the manufacturing conditions and the size of the resulting balloon 10.

[0047] As shown in Figure 7, the resin tubular body 21A preferably has a shape in which a projection 23 is provided on the outer surface of the cylinder. The projection 23 is provided so as to protrude radially outward from the outer surface of the cylinder. The cross-sectional shape of the projection 23 is described in the above description of the cross-sectional shape of the projection 16 of the balloon 10, and preferably the projection 23 is formed to become narrower towards the tip. This makes it easier to improve the scoring function of the resulting balloon 10. The resin tubular body 21A is also preferably formed to be thicker in the portion where the projection 23 is provided than in the other portions. Hereinafter, the cylindrical portion of the resin tubular body 21A, i.e., the portion excluding the projection 23, will be referred to as the "cylindrical portion".

[0048] The outer diameter of the resin tubular body 21A and the size of the protrusions 23 prepared in the resin tubular body preparation process can be appropriately set according to the desired size and shape of the balloon 10 to be manufactured. The outer diameter of the cylindrical portion 22 of the resin tubular body 21A, i.e., the outer diameter of the resin tubular body 21A excluding the protrusions 23, should be approximately 0.1 mm to 5.0 mm. The wall thickness of the cylindrical portion 22 of the resin tubular body 21A, i.e., the wall thickness of the resin tubular body 21A excluding the portion where the protrusions 23 are provided, should be approximately 0.03 mm to 2.0 mm. The height (radial length) of the protrusions 23 of the resin tubular body 21A, i.e., the height of the protrusions 23 relative to the outer surface of the cylindrical portion 22 of the resin tubular body 21A, should be approximately 0.03 mm to 2.0 mm.

[0049] The resin tubular body 21A preferably has a projection height L1 of 23 that is 0.05 times or more the outer diameter of the cylindrical portion 22, more preferably 0.1 times or more, even more preferably 0.2 times or more, and preferably 1.0 times or less, more preferably 0.8 times or less, and even more preferably 0.5 times or less. If the resin tubular body 21A is formed in this manner, it becomes easy to remove the projection 23 in the projection removal process.

[0050] In the resin tubular body 21A, the height L1 of the projection 23 is preferably 0.5 times or more the width L2 of the base of the projection 23, more preferably 0.7 times or more, even more preferably 0.9 times or more, and preferably 3.0 times or less, more preferably 2.5 times or less, and even more preferably 2.0 times or less. If the projection 23 is formed in this manner, it becomes easier to cut off the projection 23 from the resin tubular body 21A in the projection removal process. From the viewpoint of forming a sharper projection 16 of the resulting balloon 10, the height L1 of the projection 23 is preferably 1.0 times or more the width L2 of the base of the projection 23, more preferably 1.1 times or more, and even more preferably 1.2 times or more. The height L1 of the projection 23 means the length that the projection 23 protrudes radially from the outer surface of the cylindrical portion 22, and the width L2 of the base of the projection 23 means the length in the circumferential direction of the resin tubular body 21A of the portion where the projection 23 contacts the outer surface of the cylindrical portion 22.

[0051] In the resin tubular body 21A, it is preferable that the projection 23 is made of the same resin as the cylindrical portion 22, and that the projection 23 and the cylindrical portion 22 are integrally molded. The cylindrical portion 22 of the resin tubular body 21A may have an inner layer and an outer layer, in which case it is preferable that the projection 23 is made of the same resin as the outer layer of the cylindrical portion 22. This prevents the projection 23 from unintentionally falling off during balloon manufacturing. Alternatively, the projection 23 and the cylindrical portion 22 may be made of different resins, provided that the resin constituting the projection 23 and the resin constituting the cylindrical portion 22 have a certain degree of compatibility.

[0052] In the resin tubular body 21A, it is preferable that the projections 23 are provided so as to extend in the longitudinal direction. That is, it is preferable that the projections 23 are provided as protrusions extending in the longitudinal direction. This makes it easier to manufacture the resin tubular body 21A having projections 23 on its surface, and also makes it easier to get the projections 23 into the recesses 39 of the inner wall surface 33 of the mold 31 when the resin tubular body 21D is expanded in the subsequent molding process. The projections 23 may be provided so as to extend intermittently in the longitudinal direction from the first section 24 to the third section 26, but it is preferable that they be provided so as to extend continuously in the longitudinal direction from the first section 24 to the third section 26 of the resin tubular body 21A. Furthermore, it is preferable that the cross-sectional shape perpendicular to the longitudinal direction of the resin tubular body 21A is substantially uniform in the longitudinal direction from the first section 24 to the third section 26.

[0053] In the resin tubular body 21A, it is preferable that multiple projections 23 are provided at different positions in the circumferential direction. In this case, it is preferable that the projections 23 are arranged at approximately equal intervals in the circumferential direction of the resin tubular body 21A. It is preferable that the projections 23 are provided at two or more positions in the circumferential direction of the resin tubular body 21A, more preferably three or more, preferably eight or fewer, and more preferably six or fewer. In Figures 7 and 8, the projections 23 are provided so as to extend in the longitudinal direction, and the projections 23 are provided at three locations in the circumferential direction of the resin tubular body 21A.

[0054] In a longitudinal cross-section of the resin tubular body 21A, it is preferable that the projection 23 is formed such that its width narrows towards the tip. That is, it is preferable that the length of the projection 23 in the circumferential direction of the resin tubular body 21A is formed such that it becomes shorter towards the tip. In this case, the projection 23 may have a portion in which its width does not change towards the tip. By forming the projection 23 in this manner, the scoring function of the resulting balloon 10 can be enhanced.

[0055] In the manufacturing method of the first embodiment, a stretching step is performed after the resin tubular body preparation step. In the stretching step of the first embodiment, the resin tubular body 21A is heated and the first section 24 and the third section 26 are stretched in the longitudinal direction (see Figure 9). The stretching step yields a resin tubular body 21 (21B) in which the first section 24 and the third section 26 are stretched in the longitudinal direction.

[0056] In the stretching process, the first section 24 and the third section 26 of the resin tubular body 21A are heated to a temperature above the glass transition temperature of the constituent resin of the resin tubular body 21, while the second section 25 is not heated, or is heated below the glass transition temperature of the constituent resin of the resin tubular body 21, thereby selectively stretching the first section 24 and the third section 26 in the longitudinal direction. In the present invention, the sections stretched longitudinally in the stretching process can be the first section 24 and the third section 26. The resin tubular body 21A is heated, and the first section 24 and the third section 26 are stretched longitudinally by pulling the resin tubular body 21A from one or both sides in the longitudinal direction. Heating of the resin tubular body 21A can be done by known heating means such as a heater or hot air. From the viewpoint of selectively heating the first section 24 and the third section 26, it is preferable to heat the resin tubular body 21A from the outside.

[0057] In the manufacturing method of the first embodiment, it is preferable that the outer diameter of the second section 25 of the resin tubular body 21B obtained in the stretching step is larger than the outer diameters of the first section 24 and the third section 26. This makes it easier to blow mold the resin tubular body 21B with the second section 25 as the center in the molding step. In the resin tubular body 21B, the outer diameter of the second section 25 is preferably 1.2 times or more, more preferably 1.5 times or more, and preferably 5.0 times or less, and more preferably 4.0 times or less, of the outer diameters of the first section 24 and the third section 26. The outer diameter described herein refers to the maximum outer diameter passing through the centroid of the outer edge of the lumen in a longitudinal cross-section of the resin tubular body 21B.

[0058] In the manufacturing method of the first embodiment, a protrusion removal step is performed after the stretching step. In the protrusion removal step of the first embodiment, as shown in Figure 10, the protrusions 23 provided in the first section 24 and the third section 26 of the resin tubular body 21B are removed. By going through the stretching step and the protrusion removal step, the first section 24 and the third section 26 are stretched in the longitudinal direction, and a resin tubular body 21 (21D) is obtained in which the protrusions 23 of the first section 24 and the third section 25 have been removed. By performing the protrusion removal step after the stretching step, it becomes easier to selectively remove the protrusions 23 provided in the first section 24 and the third section 26, while not removing the protrusion 23 provided in the second section 25.

[0059] In the protrusion removal process, it is sufficient to remove at least a portion of the protrusions 23 provided in each of the first section 24 and third section 26 of the resin tubular body 21B. However, it is preferable to remove all of the protrusions 23 provided in the first section 24 and third section 25 that will be placed inside the mold 31 in the subsequent pre-molding process. In the protrusion removal process, a portion of the protrusions 23 provided in the second section 25 may also be removed. For example, the protrusions 23 at both ends in the longitudinal direction of the second section 25 may be removed, while the protrusions 23 in the portion between them remain. In this case, it is preferable that the protrusions 23 in the central 1 / 2 range of the second section 25 (the range of the two central sections when the second section 25 is divided into four equal parts in the longitudinal direction) remain unremoved with respect to the longitudinal direction of the resin tubular body 21B, it is more preferable that the protrusions 23 in the central 2 / 3 range of the second section 25 remain unremoved, and it is even more preferable that the protrusions 23 in the central 3 / 4 range of the second section 25 remain unremoved. In the protrusion removal process, it is also preferable that the protrusion 23 provided in the second section 25 is not removed.

[0060] In the protrusion removal process, the protrusions 23 can be removed using known cutting means such as a cutter, laser light, or heat wire. In the first section 24 and the third section 26, the protrusions 23 provided on the surface of the resin tubular body 21B can be easily removed by applying the cutting means such as a cutter to the resin tubular body 21B and moving the cutting means in the longitudinal direction relative to the resin tubular body 21B. In the protrusion removal process, the position of the resin tubular body 21B may be fixed and the protrusions 23 may be removed by moving the cutting means such as a cutter in the longitudinal direction of the resin tubular body 21B, or the cutting means such as a cutter may be fixed in place and the protrusions 23 may be removed by moving the resin tubular body 21B in one longitudinal direction while moving the cutting means such as a cutter in the other longitudinal direction of the resin tubular body 21B.

[0061] In the projection removal step, the entire projection 23 in the height direction (i.e., the radial direction of the resin tubular body 21B) may be removed, or only a portion of the projection 23 in the height direction may be removed. Preferably, at least 1 / 3 of the projection 23 in the height direction is removed, more preferably at least 1 / 2, and even more preferably at least 2 / 3. This makes it easier to form smooth surfaces on the first section 24 and the third section 26 when the projection 23, from which a portion in the height direction has been removed, is pressed against the inner wall surface 33 of the mold 31 in the subsequent molding step, as the projection 23 is crushed. In this case, smooth projections lower in height than the projections 16 of the straight pipe section 13 are formed on the first section 24 and the third section 26, and inner projections may be formed at the same positions in the longitudinal and circumferential directions.

[0062] In the manufacturing method of the second embodiment, after the resin tubular body preparation step, a protrusion removal step is performed first. In the protrusion removal step of the second embodiment, as shown in Figure 11, the protrusions 23 provided in the first section 24 and the third section 26 of the resin tubular body 21A are removed. As a result, a resin tubular body 21 (21C) is obtained from which the protrusions 23 in the first section 24 and the third section 25 have been removed. Performing the protrusion removal step prior to the stretching step makes it easier to remove the protrusions 23 from the resin tubular body 21.

[0063] Details of the protrusion removal process in the second embodiment can be found in the description of the protrusion removal process in the first embodiment above. However, "resin tubular body 21B" should be read as "resin tubular body 21A".

[0064] In the manufacturing method of the second embodiment, a stretching step is performed after the protrusion removal step. In the stretching step of the second embodiment, the resin tubular body 21C is heated and the first section 24 and the third section 26 are stretched in the longitudinal direction (see Figure 12). By going through the protrusion removal step and the stretching step, the protrusions 23 of the first section 24 and the third section 25 are removed, and a resin tubular body 21 (21D) is obtained in which the first section 24 and the third section 26 are stretched in the longitudinal direction.

[0065] Details of the stretching process in the second embodiment are provided in the description of the stretching process in the first embodiment above. However, "resin tubular body 21A" should be read as "resin tubular body 21C".

[0066] In the manufacturing methods of the first and second embodiments, it is preferable that the outer diameter of the second section 25 of the resin tubular body 21D obtained through the stretching and protrusion removal steps is larger than the outer diameters of the first section 24 and the third section 26. This makes it easier to blow mold the resin tubular body 21D with the second section 25 as the center during the molding process. In the resin tubular body 21D, the outer diameter of the second section 25 is preferably 1.2 times or more than the outer diameters of the first section 24 and the third section 26, more preferably 1.5 times or more, and more preferably 5.0 times or less, and more preferably 4.0 times or less. The outer diameter described herein refers to the maximum outer diameter passing through the centroid of the outer edge of the lumen in a longitudinal cross-section of the resin tubular body 21D.

[0067] In the mold preparation step, a mold 31 is prepared for molding the resin tubular body 21D into a balloon shape in the molding step (see Figure 13). The mold 31 has a lumen 32 corresponding to the outer shape of the balloon 10, and a recess 39 is formed in the inner wall surface 33 that forms the lumen 32. Specifically, the mold 31 has a lumen 32 that extends in the axial direction, and the inner wall surface 33 that forms the lumen 32 has a first sleeve forming section 34, a first tapered forming section 35, a straight tube forming section 36, a second tapered forming section 37, and a second sleeve forming section 38 from one side in the axial direction, and the first tapered forming section 35 and the second tapered forming section 37 are formed such that their inner diameter decreases as they move away from the straight tube forming section 36, and a recess 39 is formed in the inner wall surface 33 of the straight tube forming section 36. In the mold 31, the straight tube forming section 36 forms the straight tube portion 13 of the balloon 10, the first tapered portion 35 and the second tapered portion 37 form the proximal tapered portion 12 and the distal tapered portion 14 of the balloon 10, respectively, and the first sleeve forming section 34 and the second sleeve forming section 38 form the proximal sleeve portion 11 and the distal sleeve portion 15 of the balloon 10, respectively. The axial direction of the mold 31 corresponds to the longitudinal direction of the resin tubular body 21 and the balloon 10. The mold 31 also has radial and circumferential directions that correspond to the radial and circumferential directions of the resin tubular body 21 and the balloon 10, respectively.

[0068] In the mold 31, it is preferable that the inner wall surface 33 of the straight pipe forming section 36 forms a substantially cylindrical internal space, and that the inner diameter is largest in the straight pipe forming section 36. In the mold 31, it is preferable that the inner wall surfaces 33 of the first tapered forming section 35 and the second tapered forming section 37 form a truncated cone-shaped internal space, and that the inner diameter decreases as it moves away from the straight pipe forming section 36. In the mold 31, it is preferable that the inner wall surfaces 33 of the first sleeve forming section 34 and the second sleeve forming section 38 form a substantially cylindrical internal space. In the first sleeve forming section 34, it is preferable that the inner diameter is substantially the same as the inner diameter at the connection between the first sleeve forming section 34 and the first tapered forming section 35, and in the second sleeve forming section 38, it is preferable that the inner diameter is substantially the same as the inner diameter at the connection between the second sleeve forming section 38 and the second tapered forming section 37.

[0069] The mold 31 is preferably made of metal. Examples of metals that make up the mold 31 include iron, copper, aluminum, and their alloys (e.g., stainless steel, brass, duralumin, etc.). If the mold 31 is made of metal, in the molding process, heating the mold 31 from the outside makes it easier to uniformly heat the resin tubular body 21D placed in the lumen 32 of the mold 31, and makes it easier to mold the resin tubular body 21D to match the shape of the lumen 32 of the mold 31. The mold 31 can be heated by known heating means such as a heater, hot air, or electromagnetic induction heating.

[0070] Preferably, the mold 31 is composed of multiple segments. That is, it is preferable that multiple mold segments are combined to form the mold 31. This makes it easier to place the resin tubular body 21D in the lumen 32 of the mold 31, and to remove the balloon-shaped resin tubular body 21E from the mold 31 after inflating the resin tubular body 21D in the mold 31 to form a balloon shape.

[0071] The mold 31 may be divided into multiple sections in the circumferential direction or in the axial direction. That is, the mold 31 may be formed by arranging multiple mold segments in the circumferential direction or by arranging multiple mold segments in the axial direction. In the former case, for example, multiple half-pipe shaped mold segments can be arranged in the circumferential direction to form at least a part of the axial direction of the mold 31. In the latter case, for example, as shown in Figure 13, the mold 31 can be formed by arranging mold segment 31A which gives the first sleeve forming section 34, mold segment 31B which gives the first taper forming section 35, mold segment 31C which gives the straight pipe forming section 36, mold segment 31D which gives the second taper forming section 37, and mold segment 31E which gives the second sleeve forming section 38 in this order in the axial direction. By configuring the mold 31 in this way, balloons 10 of various shapes according to the purpose can be manufactured by replacing each mold segment. The mold 31 may be formed by arranging multiple mold segments in the circumferential direction and multiple mold segments in the axial direction.

[0072] The mold 31 has a recess 39 formed in the inner wall surface 33 of the straight tube forming section 36, and the inner wall surface 33 of the straight tube forming section 36 is formed to be recessed radially outward in the recess 39. The recess 39 is provided to allow the projection 23 provided in the second section 25 of the resin tubular body 21D to enter the recess 39 when the resin tubular body 21D is expanded during the molding process. As a result, when the resin tubular body 21D is expanded in the mold 31, the projection 23 provided in the second section 25 is not crushed by the inner wall surface 33 of the mold 31, and a balloon 10 having projections 16 on the outer surface of the straight tube section 13 can be formed.

[0073] In the straight tube forming section 36, it is preferable that the recess 39 be provided as a groove extending in the axial direction of the mold 31. This makes it easier to insert the projection 23 provided in the second section 25 into the recess 39 when the resin tubular body 21D is expanded during the molding process. Specifically, in the pre-molding process, the position of the projection 23 provided on the surface of the second section 25 of the resin tubular body 21D and the position of the recess 39 formed in the straight tube forming section 36 of the mold 31 are aligned in the circumferential direction. Then, by expanding the resin tubular body 21D during the molding process in this state, even if the resin tubular body 21D is stretched in the longitudinal direction, it becomes easier to insert the projection 23 provided on the surface of the second section 25 of the resin tubular body 21D into the recess 39 of the straight tube forming section 36 of the mold 31. When the recess 39 is provided as a groove extending in the axial direction, the axial length of the recess 39 (groove) is preferably 1 / 2 or more of the axial length of the straight pipe forming portion 36, more preferably 2 / 3 or more, and even more preferably 3 / 4 or more. It is particularly preferable that the recess 39 (groove) is provided so as to extend over the entire axial length of the straight pipe forming portion 36.

[0074] The cross-sectional shape of the recess 39 is not particularly limited, but it is preferable that the recess 39 has a portion that narrows in width toward the radially outward direction. Examples of such cross-sectional shapes of the recess 39 include a V-shape and a U-shape. When the recess 39 is formed as a groove, it is formed as a V-shaped groove or a U-shaped groove. Figures 14 and 15 show examples of the XIV-XIV cross-sectional view of the mold 31 shown in Figure 13, with Figure 14 showing an example in which a U-shaped recess 39 is provided, and Figure 15 showing an example in which a V-shaped recess 39 is provided. By forming the recess 39 in this way, it becomes easier to form a balloon 10 having a sharp projection 16 on its outer surface.

[0075] As shown in Figure 14, it is preferable that the recess 39 has a portion near its entrance that either maintains a constant width or widens radially outward. For example, it is preferable that the recess 39 has a portion in at least a part of the radially inner 1 / 2 of the recess 39 that either maintains a constant width or widens radially outward. This makes it less likely for the projection 23 provided on the resin tubular body 21D to hit the recess 39 when it is inserted into the recess 39 during the molding process, thus preventing the projection 23 from deforming or cracking. Preferably, the recess 39 has a portion in at least a part of the radially inner 1 / 2 of the recess 39 that either maintains a constant width or widens radially outward, and the portion that maintains a constant width or widens radially outward is formed to have a length of at least 1 / 3 of the radial length of the recess 39.

[0076] In the inner wall surface 33 of the straight pipe forming section 36, it is preferable that multiple recesses 39 are provided at different positions in the circumferential direction. In this case, it is preferable that the recesses 39 are arranged at approximately equal intervals in the circumferential direction on the inner wall surface 33 of the straight pipe forming section 36. It is preferable that the recesses 39 are provided at two or more positions in the circumferential direction on the inner wall surface 33 of the straight pipe forming section 36, more preferably three or more, and preferably eight or fewer, and even more preferably six or fewer. Furthermore, in the axial vertical cross-section of the straight pipe forming section 36, it is preferable that the spacing between the multiple recesses 39 arranged in the circumferential direction (the separation length along the inner wall surface 33) is longer than the maximum length of the recess 39 in the circumferential direction. In Figures 14 and 15, the recesses 39 are provided at three locations in the circumferential direction on the inner wall surface 33 of the straight pipe forming section 36. This corresponds to the number of protrusions 23 provided on the surface of the resin tubular body 21D in the circumferential direction of the resin tubular body 21D.

[0077] The depth L3 of the recess 39, that is, the radial length from the inner wall surface 33 of the mold 31 to the bottom of the recess 39, is preferably longer than the height L1 of the projection 23 provided on the surface of the resin tubular body 21D, that is, the radial length of the projection 23 of the resin tubular body 21D (see Figures 8, 14, and 15). This prevents the tip of the projection 23 from hitting the bottom of the recess 39 when the projection 23 provided on the resin tubular body 21D is inserted into the recess 39 during the molding process. It also prevents the projection 23 from cracking when it hits the bottom of the recess 39. Therefore, it becomes easier to form a balloon 10 having a sharp projection 16 on its outer surface. The depth L3 of the recess 39 is preferably 1.1 times or more the height L1 of the projection 23, more preferably 1.2 times or more, even more preferably 1.3 times or more, and preferably 3.0 times or less, more preferably 2.5 times or less, and even more preferably 2.0 times or less. The bottom of the recess 39 refers to the radially outer portion of the recess 39 relative to the mold 31.

[0078] The width L4 (length in the circumferential direction) of the entrance to the recess 39 in a cross section perpendicular to the axial direction of the mold 31 is preferably the same as or longer than the width L2 of the base of the projection 23 in a cross section perpendicular to the longitudinal direction of the resin tubular body 21D (see Figures 8, 14, and 15). The width L4 of the entrance to the recess 39 is preferably 1.0 times or more, more preferably 1.05 times or more, even more preferably 1.1 times or more, and preferably 2.0 times or less, more preferably 1.8 times or less, and even more preferably 1.5 times or less of the width L2 of the base of the projection 23. This makes it easier to insert the projection 23 provided on the resin tubular body 21D into the recess 39 during the molding process.

[0079] The mold 31 may also be provided with recesses 39 in the first tapered portion 35 and / or the second tapered portion 37, but it is preferable that the inner wall surface 33 of the first tapered portion 35 and the inner wall surface 33 of the second tapered portion 37 are not provided with recesses 39. Furthermore, it is preferable that the inner wall surface 33 of the first sleeve forming portion 34 and the inner wall surface 33 of the second sleeve forming portion 38 are not provided with recesses 39.

[0080] After the mold preparation process, a pre-molding process is performed. In the pre-molding process, as shown in Figure 16, the first section 24, second section 25, and third section 26 of the resin tubular body 21D are placed in the lumen 32 of the mold 31 prepared in the mold preparation process. Preferably, a portion of the first section 24 and a portion of the third section 26 of the resin tubular body 21D are placed outside the lumen 32 of the mold 31, and the first section 24 and third section 26 are held outside the mold 31 by fasteners. This allows the resin tubular body 21D to be positioned approximately at the center of the lumen 32 of the mold 31 in a vertical cross-section in the axial direction of the mold 31, as shown in Figure 17, making it easier to uniformly expand the resin tubular body 21D in the radial direction during the molding process. Figure 17 shows an example in which the resin tubular body 21D is placed in the lumen 32 of the mold 31 shown in Figure 14.

[0081] The second section 25 of the resin tubular body 21D is preferably located in the range from the first tapered section 35 to the second tapered section 37 of the mold 31 with respect to the axial direction of the mold 31, and more preferably located only in the straight pipe section 36 of the mold 31. The first section 24 of the resin tubular body 21D is preferably located in the first sleeve section 34 and the first tapered section 35 with respect to the axial direction of the mold 31, and more preferably located in the first sleeve section 34, the first tapered section 35, and the straight pipe section 36. The third section 26 of the resin tubular body 21D is preferably located in the second sleeve section 38 and the second tapered section 37 with respect to the axial direction of the mold 31, and more preferably located in the second sleeve section 38, the second tapered section 37, and the straight pipe section 36. This makes it easier to position the resin tubular body 21D in the lumen 32 of the mold 31. The outer diameter of the second section 25 of the resin tubular body 21D is preferably smaller than the inner diameter of the straight pipe forming section 36 of the mold 31, the outer diameter of the first section 24 of the resin tubular body 21D is preferably smaller than the inner diameters of the first sleeve forming section 34 and the first tapered section 35 of the mold 31, and the outer diameter of the third section 26 of the resin tubular body 21D is preferably smaller than the inner diameters of the second sleeve forming section 38 and the second tapered section 37 of the mold 31.

[0082] The longitudinal length of the resin tubular body 21D from the first section 24 to the third section 26 is preferably 1.1 times or more, more preferably 1.2 times or more, and even more preferably 1.3 times or more, the axial length of the lumen 32 of the mold 31. This makes it easy to hold a portion of the first section 24 and a portion of the third section 26 of the resin tubular body 21D outside the lumen 32 of the mold 31. There is no particular upper limit to the longitudinal length of the resin tubular body 21D from the first section 24 to the third section 26, but from the viewpoint of reducing the amount of resin used when manufacturing the balloon 10, it is preferably 10 times or less, more preferably 8 times or less, and even more preferably 5 times or less, the axial length of the lumen 32 of the mold 31.

[0083] After the pre-molding process, the molding process is performed. In the molding process, as shown in Figure 18, the first section 24, second section 25, and third section 26 of the resin tubular body 21D are expanded in the mold 31, the first section 24 is brought into contact with the first tapered section 35 and the first sleeve-forming section 34, the second section 25 is brought into contact with the straight-tube-forming section 36, and the third section 26 is brought into contact with the second tapered section 37 and the second sleeve-forming section 38, causing the projection 23 provided on the second section 25 to enter the recess 39 of the mold 31. Through the molding process, a resin tubular body 21 (21E) is obtained, which is formed in a balloon shape with projections 23 on the surface of the straight-tube section. In the molding process, the first section 24 to the third section 26 of the resin tubular body 21D are pressed against the first sleeve forming section 34, the first taper forming section 35, the straight tube forming section 36, the second taper forming section 37, and the second sleeve forming section 38 of the mold 31 to form the proximal sleeve section 11, proximal tapered section 12, straight tube section 13, distal tapered section 14, and distal sleeve section 15 of the balloon 10.

[0084] In the molding process, it is preferable to heat the first section 24 to the third section 26 of the resin tubular body 21D and introduce a fluid into the lumen of the resin tubular body 21D to expand the first section 24 to the third section 26 of the resin tubular body 21D. The first section 24 to the third section 26 of the resin tubular body 21D can be heated by heating the mold 31 with the first section 24 to the third section 26 of the resin tubular body 21D placed in the lumen 32 of the mold 31.

[0085] It is preferable that the heating temperature be above the glass transition temperature of the resin constituting the resin tubular body 21. If the mold 31 is formed from a plurality of mold segments 31 arranged in the axial direction, the mold segment 31 in which the first section 24 to the third section 26 of the resin tubular body 21D are located may be heated to a higher temperature, which makes it easier to preferentially heat the section of the resin tubular body 21D that is to be expanded. For example, in the example shown in Figure 18, it is preferable to heat the mold segment 31C in which the first section 24 to the third section 26 of the resin tubular body 21D are located to a higher temperature than mold segments 31A, 31B, 31D, and 31E. Alternatively, the mold 31 may be heated so that mold segments 31B to 31D are at a higher temperature than mold segments 31A and 31E.

[0086] The fluid introduced into the lumen of the resin tubular body 21D may be a gas such as air or nitrogen gas, or a liquid such as water. By introducing fluid into the lumen of the resin tubular body 21D, the inside of the resin tubular body 21D is pressurized, causing the resin tubular body 21D to expand, and thus enabling so-called blow molding. Pressurization of the inside of the resin tubular body 21D can be performed, for example, by closing one end of the resin tubular body 21D in the longitudinal direction and introducing fluid from the other end, or by introducing fluid from both ends of the resin tubular body 21D in the longitudinal direction.

[0087] When the resin tubular body 21D is expanded in the mold 31, the pressure inside the lumen of the resin tubular body 21D is preferably, as a gauge pressure, 1.0 MPa or more, more preferably 1.5 MPa or more, even more preferably 2.0 MPa or more, and preferably 6.0 MPa or less, and more preferably 5.5 MPa or less.

[0088] In the molding process, when the resin tubular body 21D is expanded, the first section 24 is brought into contact with at least the first tapered forming section 35 and the first sleeve forming section 34 of the mold 31, the second section 25 is brought into contact with at least the straight pipe forming section 36 of the mold 31, and the third section 26 is brought into contact with at least the second tapered forming section 37 and the second sleeve forming section 38 of the mold 31. The first section 24 may also come into contact with the straight pipe forming section 36. The second section 25 may come into contact with one or both of the first tapered forming section 35 and the second tapered forming section 37. The third section 26 may also come into contact with the straight pipe forming section 36. It is preferable that the second section 25 does not come into contact with the first sleeve forming section 34 and the second sleeve forming section 38. For the first section 24 and the third section 26, it is sufficient if at least a portion of the part placed inside the mold 31 is expanded.

[0089] In the molding process, it is preferable that the second section 25 abuts against at least one of the first tapered section 35 and the second tapered section 37. In the preceding stretching process, the resin tubular body 21D is stretched longitudinally in the first section 24 and the third section 26, so the wall thickness of the first section 24 and the third section 26 becomes thinner than the wall thickness of the second section 25. Therefore, the balloon 10 obtained by inflating it will have thinner wall thickness in the parts originating from the first section 24 and the third section 26, and if the first section 24 and the third section 26 form part of the straight pipe section 13, the wall thickness will be particularly thin near the boundary between the proximal tapered section 12 and the straight pipe section 13, and near the boundary between the distal tapered section 14 and the straight pipe section 13. Therefore, the breaking strength of the balloon 10 may decrease in those parts. In contrast, if the second section 25 forms part of the proximal tapered section 12 and / or part of the distal tapered section 14 together with the straight tube section 13 of the balloon 10, the formation of a particularly thin section of the balloon 10 can be suppressed, making it easier to ensure the breaking strength of the balloon 10. From this viewpoint, in the molding process, it is preferable to bring the second section 25 into contact with at least one of the first tapered section 35 and the second tapered section 37 of the mold 31, and more preferably to bring it into contact with both the first tapered section 35 and the second tapered section 37.

[0090] When the resin tubular body 21D is expanded as described above, the boundary between the first section 24 and the second section 25 will come into contact with the first tapered portion 35, and / or the boundary between the second section 25 and the third section 26 will come into contact with the second tapered portion 37. However, in the resin tubular body 21E obtained in the molding process, it is preferable that the boundary between the first section 24 and the second section 25 is located closer to the straight tube forming portion 36 than the first sleeve forming portion 34 with respect to the axial direction of the mold 31, and that the boundary between the second section 25 and the third section 26 is located closer to the straight tube forming portion 36 than the second sleeve forming portion 37 with respect to the axial direction of the mold 31. This reduces the proportion in which the protrusion 23 provided on the surface of the second section 25 comes into contact with the first tapered portion 35 and / or the second tapered portion 36, and also reduces the amount of resin used in the proximal tapered portion 12 and / or distal tapered portion 14 of the balloon 10.

[0091] In the molding process, it is preferable to expand the first section 24, second section 25, and third section 26 of the resin tubular body 21D in the longitudinal and radial directions. This makes it easier to mold the first section 24 to the third section 26 of the resin tubular body 21D to the first sleeve forming section 34, first taper forming section 35, straight tube forming section 36, second taper forming section 37, and second sleeve forming section 38 of the mold 31 to match the shape of the lumen 32 of the mold 31 when the resin tubular body 21D is expanded. In order to expand the first section 24 to the third section 26 of the resin tubular body 21D in the longitudinal direction, it is preferable to introduce fluid into the lumen of the resin tubular body 21D while pulling the resin tubular body 21D in the longitudinal direction, thereby expanding the resin tubular body 21D.

[0092] In the molding process, after stretching the second section 25 of the resin tubular body 21D in the longitudinal direction within the mold 31, the first section 24, second section 25, and third section 26 of the resin tubular body 21D may be expanded in the longitudinal and radial directions. This makes it easier to bring the first section 24 of the resin tubular body 21D into contact with the first sleeve forming section 34 of the mold 31, and to bring the third section 26 of the resin tubular body 21D into contact with the second sleeve forming section 38 of the mold 31. Furthermore, in the straight tube section 13 of the balloon 10 molded in this way, the orientation direction of the polymer constituting the resin tends to be oriented in the longitudinal direction. That is, in the straight tube section 13, the orientation direction of the polymer constituting the resin has a greater proportion of components in the longitudinal direction. In this case, when the balloon 10 bursts, the balloon 10 is more likely to break along the longitudinal direction than along the circumferential direction in the straight tube section 13. Therefore, even if balloon 10 is ruptured due to overpressure or other reasons during use, balloon 10 will rupture safely, making it less likely that fragments of balloon 10 will damage the inner wall of the body cavity.

[0093] In the molding process, the resin tubular body 21D is expanded in the mold 31, causing the second section 25 to come into contact with the straight tube forming section 36, and the protrusions 23 on the surface of the second section 25 to enter the recesses 39 of the straight tube forming section 36. At this time, as shown in Figure 19, it is preferable that the protrusions 23 on the surface of the second section 25 do not come into contact with the bottom of the recesses 39 of the straight tube forming section 36, thereby making it less likely for the protrusions 23 of the resin tubular body 21E to be unintentionally distorted or crushed after blow molding. As a result, it becomes easier to form a balloon 10 having sharp protrusions 16 on its outer surface. Figure 19 shows an example in which the resin tubular body 21E is formed by blow molding using the mold 31 shown in Figure 14.

[0094] It is preferable to include a step (hereinafter referred to as the "mold removal step") to remove the balloon-shaped resin tubular body 21E from the mold 31 after the molding process. In the mold removal step, the mold 31 may be removed from the resin tubular body 21E while the resin tubular body 21E is fixed, or the resin tubular body 21E may be removed from the mold 31 while the mold 31 is fixed. In the mold removal step, it is preferable to lower the temperature of the mold 31 to below the glass transition temperature of the resin constituting the resin tubular body 21 before removing the resin tubular body 21E from the mold 31.

[0095] In the mold removal process, it is preferable to remove the resin tubular body 21E from the mold 31 before the projection 23 reaches the bottom of the recess 39 of the mold 31. This makes it less likely that the projection 23 of the resin tubular body 21E after blow molding will be unintentionally distorted or crushed. As a result, the resulting balloon 10 will have a sharp projection 16 on the outer surface of the straight tube portion, making it easier for the balloon 10 to bite into the calcified stenosis and cause a crack in the stenosis when it is expanded during angioplasty.

[0096] After the mold removal process, it is preferable to include a cutting process in which the resin tubular body 21E is cut in the first section 24 and the third section 26 (see Figures 5(E)-(F) and 6(E)-(F)). This makes it possible to obtain a balloon 10 having protrusions 16 on its surface. It is preferable to cut the resin tubular body 21E substantially perpendicular to the longitudinal direction of the resin tubular body 21E. The resin tubular body 21E can be cut using known cutting means such as a cutter.

[0097] In the manufacturing method of the present invention, a balloon catheter 1 can be manufactured by attaching the balloon 10 obtained in the cutting step to the distal part of the shaft 2. Therefore, it is preferable that the manufacturing method of the present invention includes a step of attaching the balloon 10 obtained in the cutting step to the distal part of the shaft 2.

[0098] The manufacturing method of the present invention may further include one or more of the following steps: a protrusion surface polishing step, a protrusion surface roughening step, and a protrusion sharpening step. These steps may be performed at any time after the resin tubular body preparation step and before the pre-molding step, or after the mold removal step, but it is preferable to perform them after the mold removal step.

[0099] In the protrusion surface polishing process, the surface of the protrusion 23 is polished using a polishing machine or the like. This makes the surface of the protrusion 16 of the resulting balloon 10 smooth, making it easier to make cuts in the calcified constricted area when the balloon 10 is expanded.

[0100] In the protrusion surface roughening process, the surface of the protrusion 23 is roughened with a file or the like. This increases the resistance friction of the surface of the protrusion 16 of the resulting balloon 10, making it easier for the protrusion 16 to bite into the calcified constricted area without slipping when the balloon 10 is expanded.

[0101] In the projection sharpening process, the tips of the projections 23 are sharpened by cutting with a cutter or laser. This makes it possible to form sharp tips on the projections 16 of the resulting balloon 10, making it easier to make cuts in the calcified constricted area when the balloon 10 is expanded.

[0102] The manufacturing method of the present invention may further include a protrusion division step. In the protrusion division step, the protrusion 23, which is provided as a convex ridge, is divided into multiple parts by making an incision. The depth of the incision does not need to be greater than the height of the protrusion 23. This makes it possible to form a balloon 10 in which multiple point-shaped protrusions 16 are arranged in a row. The protrusion division step may be performed at any time after the resin tubular body preparation step and before the pre-molding step, or after the mold removal step. [Explanation of Symbols]

[0103] 1: Balloon catheter 2: Shaft 5: Hub 10: Balloon 11: Proximal sleeve section 12: Proximal tapered section 13: Straight pipe section 14: Distal tapered section 15: Distal sleeve portion 16:Protrusion 21, 21A~21E: Resin tubular body 22: Cylindrical section 23: Protrusion 24: Section 1 25: Section 2 26: Third section 31: Mold 31A~31E: Mold segment 32: lumen 33: Interior wall surface 34: First sleeve forming section 35: First tapered section 36: Straight pipe forming part 37: Second tapered section 38: Second sleeve forming section 39: Recess

Claims

1. A resin tubular body having a longitudinal direction and a radial direction, having a first section, a second section, and a third section from one side in the longitudinal direction, and having protrusions on its surface, a step of preparing a resin tubular body, A stretching step in which the resin tubular body is heated and the first section and third section of the resin tubular body are stretched in the longitudinal direction, After the stretching step, a protrusion removal step is performed to remove the protrusions provided in the first and third sections of the resin tubular body, The steps of preparing a mold having a lumen extending in the axial direction, wherein the inner wall surface forming the lumen has a first sleeve forming portion, a first tapered forming portion, a straight tube forming portion, a second tapered forming portion, and a second sleeve forming portion from one side in the axial direction, wherein the inner diameter of the first tapered forming portion and the second tapered forming portion decreases as they move away from the straight tube forming portion, and a recess is formed on the inner wall surface of the straight tube forming portion, The process after the protrusion removal step involves arranging the first section, second section, and third section of the resin tubular body in the lumen of the mold, A molding process in which the first section, second section and third section of the resin tubular body are expanded in the mold, the first section is brought into contact with the first tapered section and the first sleeve-forming section, the second section is brought into contact with the straight-tube-forming section, the third section is brought into contact with the second tapered section and the second sleeve-forming section, and the projection provided in the second section is inserted into the recess. A method for manufacturing a balloon catheter having [a certain feature].

2. A resin tubular body having a longitudinal direction and a radial direction, having a first section, a second section, and a third section from one side in the longitudinal direction, and having protrusions on its surface, a step of preparing a resin tubular body, A step of removing the protrusions provided in the first and third sections of the resin tubular body, After the protrusion removal step, the resin tubular body is heated and stretched in the longitudinal direction in a stretching step, The steps of preparing a mold having a lumen extending in the axial direction, wherein the inner wall surface forming the lumen has a first sleeve forming portion, a first tapered forming portion, a straight tube forming portion, a second tapered forming portion, and a second sleeve forming portion from one side in the axial direction, wherein the inner diameter of the first tapered forming portion and the second tapered forming portion decreases as they move away from the straight tube forming portion, and a recess is formed on the inner wall surface of the straight tube forming portion, After the stretching step, the first section, second section, and third section of the resin tubular body are placed in the cavity of the mold, A molding process in which the first section, second section and third section of the resin tubular body are expanded in the mold, the first section is brought into contact with the first tapered section and the first sleeve-forming section, the second section is brought into contact with the straight-tube-forming section, the third section is brought into contact with the second tapered section and the second sleeve-forming section, and the projection provided in the second section is inserted into the recess. A method for manufacturing a balloon catheter having [a certain feature].

3. A method for manufacturing a balloon catheter according to claim 1 or 2, wherein in the molding step, the first section, second section, and third section of the resin tubular body are expanded in the longitudinal and radial directions.

4. The method for manufacturing a balloon catheter according to claim 1 or 2, wherein in the molding step, the second section is brought into contact with at least one of the first tapered portion and the second tapered portion.

5. A method for manufacturing a balloon catheter according to claim 1 or 2, wherein, in the molding step, the second section of the resin tubular body is stretched longitudinally within the mold, and then the first section, second section, and third section of the resin tubular body are expanded longitudinally and radially.

6. The method for manufacturing a balloon catheter according to claim 1 or 2, wherein the resin tubular body disposed in the lumen of the mold has an outer diameter in the second section that is larger than the outer diameters of the first and third sections.

7. A method for manufacturing a balloon catheter according to claim 1 or 2, further comprising the step of removing the resin tubular body from the mold before the projection reaches the bottom of the recess, after the molding step.

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