Method for manufacturing balloons for balloon catheters and mold set

Abstract

To provide a manufacturing method of a balloon for a balloon catheter that can easily suppress a crack in a circumferential direction of a balloon that is acquired.SOLUTION: A manufacturing method of a balloon for a balloon catheter includes: a step for preparing a parison 30 having a central section 33; a step for preparing a post mold having a sleeve part A1, a sleeve part A2, and a straight piping part; a step for preparing a pre-mold 40 having a sleeve part B1, a sleeve part B2, and a mold enlarged diameter part 40E, the mold enlarged diameter part 40E having a mold first enlarged diameter part 41, a mold second enlarged diameter part 42, and a contracted diameter part 43; a first heating step for disposing the parison 30 in a lumen 40L of the pre-mold 40 so that the central section 33 is positioned at the contracted diameter part 43 of the pre-mold 40, and stretching at least the central section 33; a second heating step for heating a post-mold and biaxially stretching an enlarged diameter part 30E after the first heating step.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a balloon for a balloon catheter, and a mold set that can be used in said manufacturing method. [Background technology]

[0002] Angioplasty, a minimally invasive therapy that involves inserting a balloon catheter into a narrowed blood vessel and expanding the balloon to ensure blood flow, is widely performed. Angioplasty is used, for example, to treat diseases such as myocardial infarction caused by narrowing of the coronary arteries of the heart, and to treat narrowing in the shunt area used for dialysis. The balloons used for balloon catheters usually have a cylindrical shape that tapers at the distal and proximal ends, and the cylindrical portion with the largest diameter is used to expand the blood vessel.

[0003] When expanding a stenotic area with a balloon catheter, the appropriate expansion pressure is applied to the balloon according to the target area. However, if the balloon becomes overpressurized due to unexpected internal pressure during the procedure, it can rupture. In this case, if the balloon ruptures circumferentially, there is a serious risk that fragments of the balloon distal to the rupture site may remain in the body. Therefore, even if the balloon ruptures, a technique is needed to ensure that the rupture is longitudinal rather than circumferential.

[0004] For example, Patent Documents 1 to 3 disclose balloons in which pressure resistance has been improved by controlling the molecular orientation of the resin constituting the balloon. These documents disclose a method for manufacturing balloons in which, when stretching the parison longitudinally followed by radial stretching, the radial stretching ratio is set to be below a predetermined level relative to the longitudinal stretching ratio, a mold is moved in accordance with the change in stress applied to the parison in the axial direction, and a balloon having a desired orientation is obtained by controlling the stretching speed.

[0005] Furthermore, Patent Document 4 discloses that the membrane body of a balloon has an intermediate layer containing a non-elastomer and an outer layer and an inner layer containing elastomers arranged on the outer and inner surfaces of the intermediate layer, and that by setting the average thickness of the intermediate layer to 30% to 70% of the average thickness of the entire balloon, compliance is improved and a balloon with a balance between pressure resistance and passage performance is obtained. A method for manufacturing such a balloon is disclosed, which involves forming a three-layer parison by co-extrusion, stretching the parison axially at a temperature from the secondary transition temperature to the primary transition temperature of the non-elastomer and elastomer, further expanding it radially to biaxial stretching, and then cooling the parison to below the secondary transition temperature to shrink it and form a balloon. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-298354 [Patent Document 2] Japanese Patent Application Publication No. 9-38195 [Patent Document 3] International Publication No. 2014 / 141382 [Patent Document 4] International Publication No. 2013 / 145479 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In procedures using balloon catheters, if the balloon ruptures inside the body, there is a serious risk that fragments of the balloon distal to the rupture site may remain inside the body if the balloon ruptures circumferentially. Conventional balloons, as described above, had room for improvement in preventing circumferential rupture.

[0008] In view of the above circumstances, the present invention aims to provide a method for manufacturing balloons for balloon catheters that easily suppresses circumferential cracking of the resulting balloons. Furthermore, the present invention aims to provide a mold set that can be used in the manufacture of the balloons for balloon catheters described above. [Means for solving the problem]

[0009] One embodiment of the method for manufacturing a balloon for a balloon catheter according to the present invention, which can solve the above problems, is as follows. [1] A parison made of resin, extending in the longitudinal direction and having a lumen, comprising a sleeve portion P1, a sleeve portion P2, and an enlarged diameter portion located between the sleeve portion P1 and the sleeve portion P2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion P1 and greater than or equal to the inner diameter of the sleeve portion P2, wherein in the longitudinal direction, when the first end of the enlarged diameter portion is at the 0% position and the second end is at the 100% position, the enlarged diameter portion has a central section from the 40% position to the 60% position and a section further from the central section toward the first end The steps are: preparing a parison having a first section located therein and a second section located on the second end side of the central section; preparing a post mold having a bore extending in the longitudinal direction and having a sleeve portion A1, a sleeve portion A2, and a straight tube portion located between the sleeve portion A1 and the sleeve portion A2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion A1 and greater than or equal to the inner diameter of the sleeve portion A2; and preparing a post mold having a bore extending in the longitudinal direction and having a sleeve portion B1 and a sleeve portion B 2. A pre-mold having a mold diameter expansion portion located between the sleeve portion B1 and the sleeve portion B2 in the longitudinal axis direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion B1 and greater than or equal to the inner diameter of the sleeve portion B2, wherein the mold diameter expansion portion has a first mold diameter expansion portion, a second mold diameter expansion portion, and a reduction portion located between the first mold diameter expansion portion and the second mold diameter expansion portion in the longitudinal axis direction and having a maximum inner diameter smaller than the maximum inner diameter of the first mold diameter expansion portion and the second mold diameter expansion portion, and the parison in the center A method for manufacturing a balloon for a balloon catheter, comprising: a first heating step of placing the parison in the lumen of the pre-mold such that the section is located in the reduced diameter portion of the pre-mold, and heating the pre-mold to stretch at least the central section; and a second heating step of removing the parison from the lumen of the pre-mold after the first heating step, placing it in the lumen of the post-mold such that the enlarged diameter portion is located in the straight tube portion of the post-mold, and heating the post-mold to biaxially stretch the enlarged diameter portion in the longitudinal axis direction and the radial direction of the enlarged diameter portion.

[0010] In the first heating step, the parison is positioned in the lumen of the pre-mold so that its central section is located in the reduced diameter section of the pre-mold, and then heated and stretched. In the second heating step, the parison is positioned in the lumen of the post-mold so that its enlarged diameter section is located in the straight tube section of the post-mold, and the post-mold is heated to biaxially stretch the enlarged diameter section. This allows the central section of the enlarged diameter section of the parison to be stretched in the longitudinal direction while suppressing radial stretching in the first heating step, and the entire enlarged diameter section to be biaxially stretched in the second heating step. As a result, the balloon can be manufactured so that the resin molecules in the central section have a longitudinal orientation. This allows for the creation of a balloon that has a longitudinal molecular orientation in the central section, even if the balloon for the balloon catheter is damaged due to overpressure, etc., as it can initiate a longitudinal crack in the central section, and the internal pressure can be released by the longitudinal crack in the central section, thus preventing circumferential cracking. Consequently, the risk of fragments of the balloon for the balloon catheter remaining in the body can be avoided, and it becomes possible to manufacture a balloon for the balloon catheter that allows for safe treatment.

[0011] The method for manufacturing a balloon for a balloon catheter according to an embodiment of the present invention is preferably one of the following [2] to [7]. [2] A method for manufacturing a balloon for a balloon catheter according to [1], wherein in the first heating step, the pre-mold is heated to a temperature of Tg or higher and Tg + 30°C or lower than the glass transition temperature of the resin, and in the second heating step, the post-mold is heated to a temperature of Tg or higher and Tg + 30°C or lower than the glass transition temperature of the resin. [3] At the end of the first heating step, the maximum outer diameter of the central section of the enlarged portion is smaller than the maximum outer diameter of the first section and the maximum outer diameter of the second section. [1] or [2] A method for manufacturing a balloon for a balloon catheter. [4] A method for manufacturing a balloon for a balloon catheter according to any one of [1] to [3], wherein in the first heating step, the internal pressure of the enlarged diameter portion is maintained at 0 bar or more and 30 bar or less, and in the second heating step, an internal pressure higher than the internal pressure in the first heating step is applied to the enlarged diameter portion. [5] The method for manufacturing a balloon for a balloon catheter according to any one of [1] to [4], wherein at any point from the start to the end of the first heating step, the central section of the enlarged diameter portion is in contact with the inner wall of the reduced diameter portion of the pre-mold. [6] At the end of the first heating step, at least a portion of the first section of the enlarged diameter portion is in contact with the inner wall of the first enlarged diameter portion of the mold of the pre-mold, and at least a portion of the second section of the enlarged diameter portion is in contact with the inner wall of the second enlarged diameter portion of the mold of the pre-mold, a method for manufacturing a balloon for a balloon catheter according to any one of [1] to [5]. [7] A method for manufacturing a balloon for a balloon catheter according to [1] to [6], further comprising the step of raising the enlarged diameter portion to a temperature of the crystallization temperature Tc of the resin after the second heating step.

[0012] The present invention also provides a mold set that can be used in a method for manufacturing balloons for balloon catheters that can solve the above problems. A mold set according to an embodiment of the present invention is as follows. [8] A mold set for manufacturing balloons for balloon catheters, comprising: a post mold extending in the longitudinal direction and having a lumen, having a sleeve portion A1, a sleeve portion A2, and a straight tube portion located between the sleeve portion A1 and the sleeve portion A2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion A1 and greater than or equal to the inner diameter of the sleeve portion A2; and a pre mold extending in the longitudinal direction and having a lumen, having a sleeve portion B1, a sleeve portion B2, and a mold diameter expansion portion located between the sleeve portion B1 and the sleeve portion B2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion B1 and greater than or equal to the inner diameter of the sleeve portion B2, wherein the mold diameter expansion portion comprises a first mold diameter expansion portion, a second mold diameter expansion portion, and a reduced diameter portion located between the first mold diameter expansion portion and the second mold diameter expansion portion in the longitudinal direction and having a maximum inner diameter smaller than the maximum inner diameter of the first mold diameter expansion portion and the second mold diameter expansion portion.

[0013] The mold set according to the embodiment of the present invention is preferably one of the following [9] to

[11] . [9] The mold set according to [8], wherein the pre-mold has a tapered portion T1 in which the internal diameter is reduced from the first enlarged portion of the mold to the reduced portion in the longitudinal axis direction, and a tapered portion T2 in which the internal diameter is increased from the reduced portion to the second enlarged portion of the mold.

[10] The mold set according to [8] or [9], wherein the pre-mold has a tapered portion T3 in which the internal diameter is widened from the sleeve portion B1 to the first enlarged diameter portion of the mold in the longitudinal axis direction, and a tapered portion T4 in which the internal diameter is narrowed from the second enlarged diameter portion of the mold to the sleeve portion B2.

[11] The post mold has a tapered portion T5 in which the diameter of the lumen expands from the sleeve portion A1 to the straight pipe portion in the longitudinal axis direction, and a tapered portion T6 in which the diameter of the lumen contracts from the straight pipe portion to the sleeve portion A2.[8] to

[10] The mold set according to any one of these. [Effects of the Invention]

[0014] According to the method for manufacturing the balloon for the balloon catheter and the mold set described above, by using the pre-mold in the first heating step and the post-mold in the second heating step, in the first heating step, the central section of the diameter-expanded portion of the parison is stretched in the longitudinal axis direction while suppressing the stretching in the radial direction, and in the second heating step, the entire diameter-expanded portion can be biaxially stretched. Therefore, the balloon can be manufactured such that the obtained balloon has a molecular orientation in the longitudinal axis direction in the central section. As a result, even when the balloon for the balloon catheter is broken due to overpressure or the like, a longitudinal axis direction crack can be caused in the central section, and the internal pressure can be released by the longitudinal axis direction crack generated in the central section. Therefore, a circumferential crack can be prevented. As a result, the risk that the broken pieces of the balloon for the balloon catheter remain in the body can be avoided, and it becomes possible to manufacture a balloon for the balloon catheter that enables a safe treatment.

Brief Description of Drawings

[0015] [Figure 1] It shows a plan view of a balloon catheter according to an embodiment of the present invention. [Figure 2] It shows a cross-sectional view in the longitudinal axis direction of a parison according to an embodiment of the present invention. [Figure 3] It shows a cross-sectional view in the longitudinal axis direction of a pre-mold according to an embodiment of the present invention. [Figure 4] In an embodiment of the present invention, it shows a cross-sectional view in the longitudinal axis direction of the parison and the pre-mold when the parison is disposed in the inner cavity of the pre-mold. [Figure 5] In an embodiment of the present invention, it shows another example of a cross-sectional view in the longitudinal axis direction of the parison and the pre-mold when the parison is disposed in the inner cavity of the pre-mold. [Figure 6] In an embodiment of the present invention, it shows a cross-sectional view in the longitudinal axis direction of the parison and the pre-mold when the first heating step is completed. [Figure 7] It shows a cross-sectional view in the longitudinal axis direction of a post-mold according to an embodiment of the present invention. [Figure 8]In an embodiment of the present invention, this figure shows a cross-sectional view of the parison and post-mold in the longitudinal direction when the parison is placed in the lumen of the post-mold after the first heating step. [Figure 9] In an embodiment of the present invention, this shows a cross-sectional view of the parison and post-mold in the longitudinal direction after the second heating step has been completed. [Modes for carrying out the invention]

[0016] The present invention will be described below based on embodiments, but 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 refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping to understand the features of the present invention.

[0017] A method for manufacturing a balloon for a balloon catheter according to an embodiment of the present invention is a parison made of resin, extending in the longitudinal direction and having a lumen, comprising: a sleeve portion P1, a sleeve portion P2, and an enlarged portion located between sleeve portions P1 and P2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of sleeve portion P1 and greater than or equal to the inner diameter of sleeve portion P2, wherein, when the first end of the enlarged portion is at the 0% position and the second end is at the 100% position in the longitudinal direction, the enlarged portion has a central section from the 40% position to the 60% position, a first section located closer to the first end than the central section, and a second section located closer to the second end than the central section; and a post mold, extending in the longitudinal direction and having a lumen, comprising: a sleeve portion A1, a sleeve portion A2, and a straight tube portion located between sleeve portions A1 and A2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of sleeve portion A1 and greater than or equal to the inner diameter of sleeve portion A2. The mold comprises a part that extends in the longitudinal direction and has a lumen, a sleeve part B1, a sleeve part B2, and a mold enlargement part located between sleeve parts B1 and B2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of sleeve part B1 and greater than or equal to the inner diameter of sleeve part B2, wherein the mold enlargement part comprises a first mold enlargement part, a second mold enlargement part, and a reduced diameter part located between the first mold enlargement part and the second mold enlargement part in the longitudinal direction and having a maximum inner diameter smaller than the maximum inner diameter of the first mold enlargement part and the second mold enlargement part. The method includes the steps of: preparing a pre-mold having a parison; a first heating step of placing the parison in the lumen of the pre-mold such that the central section is located in the reduced diameter section of the pre-mold, and heating the pre-mold to stretch at least the central section; and a second heating step of removing the parison from the lumen of the pre-mold after the first heating step, placing it in the lumen of the post-mold such that the enlarged section is located in the straight pipe section of the post-mold, and heating the post-mold to biaxially stretch the enlarged section in the longitudinal axis direction and the radial direction of the enlarged section.

[0018] Since the pre-mold has a first diameter-expanding section, a second diameter-expanding section, and a diameter-reducing section between the first and second diameter-expanding sections in the longitudinal direction, by placing the parison in the lumen of the pre-mold in the first heating step such that the central section of the parison is located in the diameter-reducing section of the pre-mold and heating the pre-mold, radial stretching of the central section of the expanded diameter section of the parison can be suppressed in the first heating step. As a result, the central section of the parison can be stretched in the longitudinal direction while suppressing radial stretching in the first heating step. By placing the parison in this state in the lumen of the post-mold and heating it in the second heating step, the entire expanded diameter section can be biaxially stretched. By going through these first and second heating steps, it is possible to manufacture a balloon such that the resulting balloon has a molecular orientation of the resin in the longitudinal direction in the central section. As a result, even if the balloon for the balloon catheter is ruptured due to overpressure or other reasons, a longitudinal crack can be initiated in the central section, and the internal pressure can be released by the longitudinal crack that occurs in the central section, thus preventing circumferential cracking.

[0019] The method for manufacturing a balloon for a balloon catheter according to an embodiment of the present invention will be described below with reference to Figures 1 to 9. Figure 1 is a plan view of a balloon catheter according to an embodiment of the present invention. Figure 2 is a cross-sectional view in the longitudinal direction of a parison according to an embodiment of the present invention. Figure 3 is a cross-sectional view in the longitudinal direction of a pre-mold according to an embodiment of the present invention. Figure 4 is a cross-sectional view in the longitudinal direction of a parison and pre-mold when the parison is placed in the lumen of the pre-mold before the start of the first heating step, according to an embodiment of the present invention. Figure 5 is another example of a cross-sectional view in the longitudinal direction of a parison and pre-mold when the parison is placed in the lumen of the pre-mold before the start of the first heating step, according to an embodiment of the present invention. Figure 6 is a cross-sectional view in the longitudinal direction of a parison and pre-mold when the first heating step is completed, according to an embodiment of the present invention. Figure 7 is a cross-sectional view in the longitudinal direction of a post-mold according to an embodiment of the present invention. Figure 8 is a cross-sectional view in the longitudinal direction of a parison and post-mold when the parison is placed in the lumen of the post-mold after the first heating step and at the start of the second heating step, according to an embodiment of the present invention. Figure 9 shows a cross-sectional view in the longitudinal direction of the parison and post mold when the second heating step is completed, according to an embodiment of the present invention.

[0020] In this specification, the balloon for the balloon catheter may be simply referred to as the "balloon." The balloon catheter balloon 20, parison 30, pre-mold 40, and post-mold 50 each have a longitudinal axis direction, a radial direction, and a circumferential direction. However, for ease of understanding, in this specification, all components are described as having the same longitudinal axis direction x, radial direction y, and circumferential direction z as the balloon catheter balloon 20 shown in Figure 1. However, this does not necessarily mean that all components are positioned in the same direction; the longitudinal axis direction, radial direction, and circumferential direction of each component may differ from one another. The circumferential direction z of the balloon 20 is the direction along the outer circumference of the expanded balloon 20 in a cross section perpendicular to the longitudinal axis direction x, and the radial direction y of the balloon 20 is the direction connecting the centroid of the outer edge of the expanded balloon 20 and a point on the outer edge of the balloon 20 in a cross section perpendicular to the longitudinal axis direction x. In the longitudinal axis x, the direction of the balloon catheter 1 toward the user's proximal side is referred to as the proximal side, and the opposite side, i.e., the side toward the person being treated, is referred to as the distal side.

[0021] A method for manufacturing a balloon for a balloon catheter according to an embodiment of the present invention is a method for manufacturing a balloon 20 used in a balloon catheter 1 as shown in Figure 1. The balloon 20 is connected to the distal end of a shaft 3, and the balloon 20 can be expanded by introducing fluid through the lumen of the shaft 3 and deflated by discharging the fluid. The fluid is introduced or discharged using an indeflerator (balloon pressurizer) to control the expansion and contraction of the balloon 20. The fluid may be a pressurized fluid pressurized by a pump or the like.

[0022] By stretching a parison 30 made of resin to manufacture a balloon 20, the balloon 20 can have a structure made of resin having molecular orientation. Preferably, the balloon 20 has an expandable portion 22, a proximal sleeve portion 21 located proximal to the expandable portion 22, and a distal sleeve portion 23 located distal to the expandable portion 22. While the expandable portion 22 is the part that expands upon the introduction of fluid, it is preferable that the proximal sleeve portion 21 and the distal sleeve portion 23 do not expand, and the balloon 20 can be connected to the shaft 3 by fixing at least a part of the proximal sleeve portion 21 and the distal sleeve portion 23 to the shaft 3.

[0023] Examples of materials that make up the balloon 20 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; polyphenylene sulfide resin; polyamide resins such as 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 preferred, polyamide resins such as nylon 12 and nylon 11 are more preferred, and nylon 12 is particularly preferred. From the viewpoint of thinning the balloon 20 and improving its flexibility, it is preferable to use an elastomer resin, and polyamide elastomers such as polyamide ether elastomers are suitably used.

[0024] The outer diameter of the balloon 20 is preferably 0.5 mm or more, more preferably 1 mm or more, and even more preferably 1.5 mm or more. The lower limit of the outer diameter of the balloon 20 being within this range allows for sufficient dilation of the narrowed portion within the blood vessel. Furthermore, the outer diameter of the balloon 20 is preferably 35 mm or less, more preferably 30 mm or less, and even more preferably 25 mm or less. The upper limit of the outer diameter of the balloon 20 being within this range facilitates insertion of the balloon 20 into the body cavity.

[0025] The length of the balloon 20 in the longitudinal direction x is preferably 5 mm or more, more preferably 10 mm or more, and even more preferably 15 mm or more. By having the lower limit of the length of the balloon 20 in the longitudinal direction x be within the above range, it is possible to increase the area of ​​the stenosis that can be expanded at once and shorten the time required for the procedure. Furthermore, the length of the balloon 20 in the longitudinal direction x is preferably 300 mm or less, more preferably 200 mm or less, and even more preferably 100 mm or less. By having the upper limit of the length of the balloon 20 in the longitudinal direction x be within the above range, it is possible to reduce the volume of fluid introduced into the balloon 20 to expand the stenosis and shorten the time required to fully expand the balloon 20.

[0026] The thickness of the balloon 20 is preferably 5 μm or more, more preferably 7 μm or more, even more preferably 10 μm or more, and preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. By having the thickness of the balloon 20 within the above range, a balance can be achieved between the strength and flexibility of the balloon 20.

[0027] Examples of materials that make up the shaft 3 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluororesins, vinyl chloride resins, silicone resins, and natural rubber. These may be used individually or in combination of two or more. In particular, it is preferable that the material making up the shaft 3 be at least one of polyamide resins, polyolefin resins, and fluororesins. This improves the slipperiness of the surface of the shaft 3 and improves the ease of insertion of the balloon catheter 1 into the body cavity.

[0028] The balloon 20 and the shaft 3 can be joined by adhesive bonding, welding, or by attaching a ring-shaped member to the overlapping area of ​​the balloon 20 and the shaft 3 and crimping it. Among these, it is preferable that the balloon 20 and the shaft 3 are joined by welding. By welding the balloon 20 and the shaft 3, the joint between the balloon 20 and the shaft 3 is less likely to come undone even if the balloon 20 is repeatedly expanded or contracted, and the joint strength between the balloon 20 and the shaft 3 can be easily increased.

[0029] As shown in Figure 1, in the balloon catheter 1, a hub 4 may be provided on the proximal side of the shaft 3, and it is preferable that the hub 4 is provided with a fluid injection section 6 that communicates with the fluid flow path supplied to the inside of the balloon 20. The hub 4 may also be provided with a guidewire insertion section 5 that communicates with the guidewire insertion passage. With this configuration, operations such as supplying fluid to the inside of the balloon 20 to expand or deflate the balloon 20, and operations such as delivering the balloon catheter 1 to the treatment site along the guidewire can be easily performed. Figure 1 shows a so-called over-the-wire type balloon catheter 1 in which the guidewire is inserted from the distal side to the proximal side of the shaft 3, but the balloon 20 can also be applied to a so-called rapid-exchange type balloon catheter in which the guidewire is inserted partway from the distal side to the proximal side of the shaft 3.

[0030] The shaft 3 and hub 4 can be joined by, for example, adhesive bonding or welding. In particular, it is preferable that the shaft 3 and hub 4 are joined by adhesive bonding. By bonding the shaft 3 and hub 4, the bonding strength between them can be increased, improving the durability of the balloon catheter 1, especially when the materials constituting the shaft 3 and hub 4 are different, such as when the shaft 3 is made of a highly flexible material and the hub 4 is made of a highly rigid material.

[0031] A method for manufacturing a balloon 20 for a balloon catheter according to an embodiment of the present invention includes the step of preparing a parison 30 made of resin, extending in the longitudinal axis direction x and having a lumen 30L. The balloon 20 can be manufactured by pressurizing the inside of the parison 30 to expand the lumen 30L. For the resin constituting the parison 30, refer to the section on materials constituting the balloon 20 above. The parison 30 can be manufactured by known methods such as extrusion molding or injection molding, but it is preferable to manufacture it by extrusion molding.

[0032] As shown in Figure 2, the parison 30 has a sleeve portion P1, a sleeve portion P2, and an enlarged diameter portion 30E located between sleeve portions P1 and P2 in the longitudinal axis direction x, having an inner diameter greater than or equal to the inner diameter of sleeve portion P1 and greater than or equal to the inner diameter of sleeve portion P2. The enlarged diameter portion 30E of the parison 30 is the portion that becomes the expanded portion 22 of the balloon 20 when the balloon 20 is made from the parison 30. Sleeve portions P1 and P2 of the parison 30 include portions that become the proximal sleeve portion 21 and distal sleeve portion 23 of the balloon 20 when the balloon 20 is made from the parison 30. In sleeve portions P1 and P2, the inner diameters of the parison 30 may be the same or different along the longitudinal axis direction x, but it is preferable that they be substantially the same. Also, the inner diameters of sleeve portion P1 and sleeve portion P2 may be the same or different, but it is preferable that they be substantially the same. This makes it easier to manufacture the parison 30. Here, "substantially the same" means that the rate of change of the inner diameter ([maximum inner diameter - minimum inner diameter] / average inner diameter) is 0.2 or less. The rate of change of the inner diameter may also be 0.18 or less, 0.15 or less, 0.1 or less, 0.08 or less, 0.05 or less, 0.02 or less, or even 0. Hereafter, when the inner diameter of the parison 30 or mold is said to be "substantially the same," it means that the rate of change of the inner diameter is within the above range. Similarly, when the outer diameter is said to be substantially the same, it means that the rate of change of the outer diameter is within the above range.

[0033] The maximum inner diameter of the enlarged portion 30E is preferably larger than the maximum inner diameter of the sleeve portion P1 and the maximum inner diameter of the sleeve portion P2. Here, the maximum inner diameter of the enlarged portion 30E refers to the inner diameter at the point where the enlarged portion 30E has its maximum inner diameter in the longitudinal axis direction x. Similarly, the maximum inner diameter of the sleeve portion P1 and the maximum inner diameter of the sleeve portion P2 refer to the inner diameters at the points where the sleeve portion P1 and the sleeve portion P2 each have their maximum inner diameters in the longitudinal axis direction x. Hereafter, when referring to the maximum inner diameter of a predetermined member or predetermined section, the same explanation can be applied, which states that the maximum inner diameter is the inner diameter at the point where the predetermined member or predetermined section has its maximum inner diameter in the longitudinal axis direction x.

[0034] The enlarged diameter portion 30E of the parison 30 has its first end at position D0 at 0% and its second end at position D0 at 100% in the longitudinal axis x. 100 In that case, position D at 40% 40 60% from position D 60 The parison 30 has a central section 33, a first section 31 located on the first end side of the central section 33, and a second section 32 located on the second end side of the central section 33. The first section 31, the second section 32, and the central section 33 are determined by the position x in the longitudinal axis direction in the initial state after the parison 30 has been manufactured by a known method such as extrusion molding or injection molding, and before being subjected to the first heating step. One of the features of the manufacturing method of the balloon catheter balloon 20 according to the embodiment of the present invention is that the first heating step involves positioning the parison 30 in the lumen 40E of the pre-mold 40 such that the central section 33 of the parison 30 in this initial state is located in the reduced diameter section 43 of the pre-mold 40, which will be described later.

[0035] When the parison 30 is stretched in the first and second heating steps, which will be described in detail later, the central section 33 before stretching and the central section after stretching may be slightly different due to the difference in the amount of stretching in the longitudinal axis direction x. In this case, the first end of the enlarged diameter section 30E of the parison 30 at each point in time is at position D0 at 0%, and the second end is at position D0 at 100%. 100 For example, position D at 40% 40 60% from position D 60 The section up to is designated as the central section 33, the section located to the first end of the central section 33 is designated as the first section 31, and the section located to the second end of the central section 33 is designated as the second section 32.

[0036] As shown in Figure 3, a method for manufacturing a balloon 20 for a balloon catheter according to an embodiment of the present invention includes the step of preparing a pre-mold 40 which extends in the longitudinal axis direction x and has a lumen 40L, and has a sleeve portion B1, a sleeve portion B2, and a mold diameter expansion portion 40E located between the sleeve portion B1 and the sleeve portion B2 in the longitudinal axis direction x and having an inner diameter greater than or equal to the inner diameter of the sleeve portion B1 and greater than or equal to the inner diameter of the sleeve portion B2, wherein the mold diameter expansion portion 40E has a first mold diameter expansion portion 41, a second mold diameter expansion portion 42, and a reduced diameter portion 43 located between the first mold diameter expansion portion 41 and the second mold diameter expansion portion 42 in the longitudinal axis direction x and having a maximum inner diameter smaller than the maximum inner diameter of the first mold diameter expansion portion 41 and the second mold diameter expansion portion 42.

[0037] In sleeve portions B1 and B2, the inner diameters of the pre-mold 40 may be the same or different along the longitudinal axis x, but it is preferable that they be substantially the same. Also, the inner diameters of sleeve portion B1 and sleeve portion B2 may be the same or different. The inner diameter of the mold expansion portion 40E is preferably greater than or equal to the inner diameter of sleeve portion B1 and greater than or equal to the inner diameter of sleeve portion B2. The inner diameters of the first mold expansion portion 41 and the second mold expansion portion 42 may be the same or different, but if the expanded portion 22 of the balloon 20 to be manufactured is to be a cylindrical balloon 20 having substantially the same outer diameter in the longitudinal axis x, it is preferable that the inner diameters of the first mold expansion portion 41 and the second mold expansion portion 42 are substantially the same. The inner diameter of the reduced diameter portion 43, which is positioned between the first enlarged diameter portion 41 and the second enlarged diameter portion 42 of the mold in the longitudinal axis direction x, may be the same or different along the longitudinal axis direction x, but it is preferable that it be substantially the same, and the maximum inner diameter of the reduced diameter portion 43 is smaller than the maximum inner diameter of the first enlarged diameter portion 41 of the mold and smaller than the maximum inner diameter of the second enlarged diameter portion 42 of the mold. It is preferable that the inner diameter of the reduced diameter portion 43 is larger than the inner diameter of the sleeve portion B1 and the inner diameter of the sleeve portion B2.

[0038] In the pre-molded mold 40, the length x in the longitudinal direction of the mold's enlarged diameter portion 40E can be determined according to the length x in the longitudinal direction of the expanded portion 22 of the balloon 20 to be manufactured. Furthermore, the inner diameter of the mold's enlarged diameter portion 40E can be determined according to the outer diameter of the expanded portion 22 of the balloon 20 to be manufactured.

[0039] As shown in Figures 4 and 5, in the first heating step, the parison 30 is placed in the lumen 40L of the pre-mold 40 such that the central section 33 of the parison 30 is located in the reduced-diameter section 43 of the pre-mold 40, and the pre-mold 40 is heated to stretch at least the central section 33 of the parison 30 in the longitudinal axis direction x. At this time, as shown in Figure 4, at the start of the first heating step, the outer wall of the central section 33 of the parison 30 and the inner wall of the reduced-diameter section 43 of the pre-mold 40 are in contact, and the reduced-diameter section 43 may have an inner diameter such that there is no room for the central section 33 to be stretched radially y. Alternatively, as shown in Figure 5, at the start of the first heating step, the outer wall of the central section 33 of the parison 30 and the inner wall of the reduced-diameter section 43 of the pre-mold 40 are not in contact, and the reduced-diameter section 43 may have an inner diameter such that the central section 33 is slightly stretched radially y. In either case, the central section 33 is positioned within the reduced diameter section 43 of the pre-mold 40, and since the inner diameter of the reduced diameter section 43 is smaller than the inner diameter of the first enlarged diameter section 41 and the second enlarged diameter section 42 of the mold, the central section 33 can be stretched in the longitudinal axis direction x while being less stretched in the radial direction y than the portion positioned within the lumen of the first enlarged diameter section 41 and the second enlarged diameter section 42 of the mold.

[0040] The maximum inner diameter of the reduced diameter portion 43 is preferably 95% or less of the maximum inner diameter of the first enlarged diameter portion 41 of the mold, more preferably 90% or less, even more preferably 80% or less, and also acceptable to be 70% or less or 60% or less. Furthermore, the maximum inner diameter of the reduced diameter portion 43 is preferably 95% or less of the maximum inner diameter of the second enlarged diameter portion 42 of the mold, more preferably 90% or less, even more preferably 80% or less, and also acceptable to be 70% or less or 60% or less. By having the upper limit of the ratio of the maximum inner diameter of the reduced diameter portion 43 to the maximum inner diameter of the first enlarged diameter portion 41 and the maximum inner diameter of the second enlarged diameter portion 42 of the mold be within the above range, in the first heating step, the central section 33 of the parison 30 can be stretched in the longitudinal axis direction x while suppressing stretching in the radial direction y, while the portion of the parison 30 other than the central section 33 can be stretched in the radial direction y.

[0041] The maximum inner diameter of the reduced diameter portion 43 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more, of the maximum inner diameter of the first enlarged diameter portion 41 of the mold. Furthermore, the maximum inner diameter of the reduced diameter portion 43 is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more, of the maximum inner diameter of the second enlarged diameter portion 42 of the mold. By having the lower limit of the ratio of the maximum inner diameter of the reduced diameter portion 43 to the maximum inner diameter of the first enlarged diameter portion 41 and the maximum inner diameter of the second enlarged diameter portion 42 of the mold within the above range, it becomes easier to extend the central section 33 in the radial direction y in the second heating step after the first heating step to finally obtain the balloon 20.

[0042] The pre-mold 40 can be heated by known methods, such as heating it with a heater placed on the outside of the pre-mold 40, or heating the pre-mold 40 itself by induction heating. The stretching in the longitudinal axis direction x in the first heating step can be performed, for example, by pulling the sleeve portion P1 and sleeve portion P2 of the parison 30 apart from each other in the longitudinal axis direction x while heating. At this time, the inside of the parison 30 may or may not be pressurized, but it is preferable that the inside of the parison 30 be pressurized in the first heating step in order to facilitate stretching in the second heating step.

[0043] Preferably, the sleeve portions P1 and P2 of the parison 30 are positioned in the lumens of the sleeve portions B1 and B2 of the pre-mold 40, respectively. This facilitates the formation of the sleeve portions P1 and P2 of the parison 30 in the proximal sleeve portion 21 and distal sleeve portion 23 of the balloon 20. Preferably, at least a portion of the first section 31 and at least a portion of the second section 32 of the enlarged diameter portion 30E of the parison 30 are positioned in the lumens of the first enlarged diameter portion 41 and the second enlarged diameter portion 42 of the mold, respectively. This ensures that space is secured for the first section 31 and the second section 32 to be extended in the radial direction y, so that when the first heating step is completed, the parison 30 is formed in a state where the radial extension of the first section 31 and the second section 32 is relatively large, and the radial extension of the central section 33 is suppressed.

[0044] As shown in Figure 6, it is preferable that at the end of the first heating step, the enlarged portion 30E of the parison 30 is biaxially stretched to conform to the inner lumen 40L of the pre-mold 40.

[0045] As shown in Figure 7, a method for manufacturing a balloon 20 for a balloon catheter according to an embodiment of the present invention includes the step of preparing a post mold 50 which extends in the longitudinal axis direction x and has a lumen 50L, and has a sleeve portion A1, a sleeve portion A2, and a straight tube portion 51 which is located between the sleeve portion A1 and the sleeve portion A2 in the longitudinal axis direction x and has an inner diameter greater than or equal to the inner diameter of the sleeve portion A1 and greater than or equal to the inner diameter of the sleeve portion A2.

[0046] In sleeve portions A1 and A2, the inner diameters of the post mold 50 may be the same or different along the longitudinal axis x, but it is preferable that they be substantially the same. Also, the inner diameters of sleeve portion A1 and sleeve portion A2 may be the same or different, but it is preferable that they be different. For example, if the inner diameter of sleeve portion A1 is larger than the inner diameter of sleeve portion A2, sleeve portion A1 forms the proximal sleeve portion 21 of the balloon 20 and sleeve portion A2 forms the distal sleeve portion 23 of the balloon 20. This makes it possible to increase the diameter of the proximal sleeve portion 21 of the balloon 20 to make it easier to fix to the shaft 3, and decrease the diameter of the distal sleeve portion 23 to make it easier to close the distal end of the balloon 20. The inner diameter of the straight tube portion 51 is preferably greater than or equal to the inner diameter of sleeve portion A1 and greater than or equal to the inner diameter of sleeve portion A2. The inner diameter of the straight tube section 51 may be the same or different along the longitudinal axis x, but if the expanded portion 22 of the balloon 20 to be manufactured is to be a cylindrical balloon 20 having substantially the same outer diameter along the longitudinal axis x, then it is preferable that the inner diameter of the straight tube section 51 be substantially the same along the longitudinal axis x.

[0047] In the post-molding mold 50, the length x in the longitudinal direction of the straight tube section 51 can be determined according to the length x in the longitudinal direction of the expansion section 22 of the balloon 20 to be manufactured. Also, the inner diameter of the straight tube section 51 can be determined according to the outer diameter of the expansion section 22 of the balloon 20 to be manufactured.

[0048] As shown in Figure 8, in the second heating step, after the first heating step, the parison 30 is removed from the lumen 40L of the pre-mold 40, and the parison 30 is placed in the lumen 50L of the post-mold 50 so that the enlarged diameter portion 30E is located in the straight tube portion 51 of the post-mold 50. The post-mold 50 is then heated to biaxially stretch the enlarged diameter portion 30E in the longitudinal axis direction x and the radial direction y. As a result, as shown in Figure 9, the parison 30 can be molded into a shape that conforms to the lumen 50L of the post-mold 50, and the balloon 20 can be produced.

[0049] The maximum inner diameter of the straight pipe section 51 of the post mold 50 is preferably 105% or more, more preferably 110% or more, even more preferably 115% or more, preferably 150% or less, more preferably 140% or less, and even more preferably 130% or less, of the maximum inner diameter of the first enlarged diameter section 41 of the pre mold 40. Furthermore, the maximum inner diameter of the straight pipe section 51 of the post mold 50 is preferably 105% or more, more preferably 110% or more, even more preferably 115% or more, even more preferably 150% or less, more preferably 140% or less, and even more preferably 130% or less, of the maximum inner diameter of the second enlarged diameter section 42 of the pre mold 40. By having the ratio of the maximum inner diameter of the straight pipe section 51 of the post mold 50 to the maximum inner diameter of the enlarged diameter section 40E of the pre mold 40 be within the above range, it becomes easier to biaxially stretch the parison 30 in the second heating step.

[0050] The balloon 20 obtained through the above-described first and second heating steps can have a strong molecular orientation in the longitudinal axis direction in the central section of the expanded portion 22 by biaxially stretching the central section 33 in the longitudinal axis direction x and radial direction in the second heating step, while suppressing the stretching in the radial direction y in the first heating step. This is thought to be because, by stretching the central section 33 in the longitudinal axis direction x while suppressing the stretching in the radial direction y in the first heating step, the molecular chains of the resin in the central section 33 extend and align in the longitudinal axis direction x.

[0051] In contrast, the first section 31 and the second section 32 of the parison 30 may have a weaker molecular orientation of the resin in the longitudinal axis direction x compared to the central section 33. As a result, the expanded portion 22 of the resulting balloon 20 can be manufactured with a stronger molecular orientation of the resin in the longitudinal axis direction x in the central section than at the ends near the sleeve portion. Furthermore, since the central section 33 of the parison 30 is stretched in the longitudinal axis direction x in the first heating step, and then further stretched in the longitudinal axis direction x and radial direction y in the second heating step, the resulting balloon 20 can have a thinner film thickness in the central section than at the ends. As a result, even if the balloon 20 is destroyed due to overpressure or the like, a crack in the longitudinal axis direction x can be initiated in the central section, and the internal pressure can be released by the crack in the longitudinal axis direction x that occurs in the central section, thus preventing cracking in the circumferential direction z.

[0052] The post-mold 50 can be heated by known methods, such as heating it with a heater placed outside the post-mold 50 or heating the post-mold 50 itself by induction heating. The biaxial stretching in the longitudinal axis direction x and radial direction y in the second heating step can be performed by pressurizing the inside of the parison 30 while heating. Methods for pressurizing the inside of the parison 30 include supplying a fluid such as a gas like air or nitrogen gas, or a liquid like pure water or physiological saline solution, into the lumen 30L of the parison 30. A pump can be used to pressurize the fluid, for example. Among these, it is preferable to use compressed gas when pressurizing the inside of the parison 30. In other words, it is preferable that the balloon 20 is manufactured by blow molding the parison 30 in the second heating step. Since the balloon 20 can be manufactured by supplying compressed gas to the parison 30 and pressurizing the inside, the manufacturing efficiency of the balloon 20 can be increased.

[0053] It is preferable that sleeve portions P1 and P2 of the parison 30 be positioned in the lumens of sleeve portions A1 and A2 of the post mold 50, respectively. This makes it easier to form sleeve portions P1 and P2 of the parison 30 in the proximal sleeve portion 21 and distal sleeve portion 23 of the balloon 20.

[0054] As shown in Figure 9, it is preferable that at the end of the second heating step, the enlarged portion 30E of the parison 30 is biaxially stretched to follow the lumen 50L of the post mold 50. This makes it easier to design the shape of the balloon 20 obtained by the shape of the lumen 50L of the post mold 50.

[0055] In the first heating step, it is preferable to heat the pre-mold 40 at a temperature above the glass transition temperature Tg of the resin constituting the parison 30 and below the glass transition temperature Tg + 30°C, and in the second heating step, it is preferable to heat the post-mold 50 at a temperature above the glass transition temperature Tg of the resin constituting the parison 30 and below the glass transition temperature Tg + 30°C.

[0056] In the first heating step, the temperature at which the pre-mold 40 is heated is more preferably below the glass transition temperature Tg + 25°C of the resin constituting the parison 30, even more preferably below the glass transition temperature Tg + 20°C, and may also be below the glass transition temperature Tg + 10°C. By heating the pre-mold 40 to a temperature within the above range in the first heating step, the central section 33 of the parison 30 is made easier to stretch in the longitudinal axis direction x, while the shape of the lumen 40L of the pre-mold 40 can suppress the stretching of the central section 33 in the radial direction y.

[0057] In the second heating step, the temperature at which the post mold 50 is heated is more preferably below the glass transition temperature Tg + 25°C of the resin constituting the parison 30, even more preferably below the glass transition temperature Tg + 20°C, and may also be below the glass transition temperature Tg + 10°C. By heating the post mold 50 within the above temperature range in the second heating step, the enlarged diameter portion 30E of the parison 30 can be easily biaxially stretched.

[0058] As described above, even if the pre-mold 40 and post-mold 50 are heated in the first and second heating steps at temperatures within the above range, which are above the glass transition temperature Tg of the resin, the pre-mold 40 and post-mold 50 each have lumens with predetermined shapes. Therefore, in the first heating step, the central section 33 of the parison 30 can be stretched in the longitudinal axis direction x while suppressing stretching in the radial direction y. As a result, it is possible to mold the parison 30 so that the molecular orientation of the resin in the enlarged diameter section 30E differs along the longitudinal axis direction x at the end of the second heating step, and the central section 33 of the enlarged diameter section 30E can be configured to have a strong orientation in the longitudinal axis direction x.

[0059] The glass transition temperature (Tg) is measured in accordance with JIS K7121. A 5 mg resin sample is heated at a rate of 20 °C / min in the temperature range of 0 °C to 250 °C using a differential scanning calorimeter, and the extrapolated glass transition onset temperature obtained from the DSC curve can be defined as the glass transition temperature (Tg).

[0060] For example, when a polyamide resin is used as the resin constituting parison 30, the glass transition temperature Tg is 40°C to 60°C. When other resins are used as the resin constituting parison 30, the temperature is not limited to the above, and the glass transition temperature Tg can be determined according to the above method.

[0061] In the first heating step, it is preferable to maintain the internal pressure of the enlarged diameter portion 30E of the parison 30 at 0 bar (0 MPa) or more and 30 bar (3 MPa) or less, and in the second heating step, to apply an internal pressure higher than the internal pressure in the first heating step to the enlarged diameter portion 30E of the parison 30. Note that the internal pressure is not absolute pressure, but gauge pressure, i.e., atmospheric pressure plus pressure.

[0062] In the first heating step, the internal pressure applied to the enlarged diameter portion 30E of the parison 30 is more preferably 2 bar (0.2 MPa) or more, even more preferably 5 bar (0.5 MPa) or more, and may be 7 bar (0.7 MPa) or more, or 10 bar (1 MPa) or more. By having the lower limit of the internal pressure applied to the enlarged diameter portion 30E in the first heating step be within the above range, the enlarged diameter portion 30E of the parison 30 is stretched to some extent in the radial direction y in the first heating step, making biaxial stretching in the second heating step easier. Furthermore, in the first heating step, the internal pressure applied to the enlarged diameter portion 30E of the parison 30 is more preferably 25 bar (2.5 MPa) or less, even more preferably 20 bar (2 MPa) or less, and may be 15 bar or less (1.5 MPa). In the first heating step, even if the upper limit of the internal pressure applied to the enlarged diameter portion 30E is within the above range, the internal cavity 40L of the pre-mold 40 has a predetermined shape, so the enlarged diameter portion 30E can be biaxially stretched while suppressing the radial stretching of the central section 33 in the y direction.

[0063] In the second heating step, the internal pressure applied to the enlarged diameter portion 30E of the parison 30 is preferably 10 bar (1 MPa) or more, more preferably 15 bar (1.5 MPa) or more, even more preferably 30 bar (3 MPa) or more, and also preferably 60 bar (6 MPa) or less, more preferably 50 bar (5 MPa) or less, and even more preferably 40 bar (4 MPa) or less. By applying an internal pressure within the above range, which is greater than the internal pressure in the first heating step, to the enlarged diameter portion 30E of the parison 30 in the second heating step, it becomes easy to obtain the balloon 20 by biaxially stretching the enlarged diameter portion 30E, including the lumen of the central section 33 of the parison 30, where the radial y-direction stretching was suppressed in the first heating step.

[0064] As shown in Figures 6 and 8, at the end of the first heating step, it is preferable that the maximum outer diameter of the central section 33 of the enlarged diameter portion 30E of the parison 30 is smaller than the maximum outer diameter of the first section 31 and the maximum outer diameter of the second section 32. Here, the maximum outer diameter of the central section 33 refers to the outer diameter at the point where the central section 33 has the largest outer diameter in the longitudinal axis direction x. Hereafter, when referring to the maximum outer diameter of a predetermined member or predetermined section, the maximum outer diameter refers to the outer diameter at the point where the predetermined member or predetermined section has the largest outer diameter in the longitudinal axis direction x.

[0065] The maximum outer diameter of the central section 33 at the end of the first heating step is kept small because the radial y-direction stretching of the central section 33 is suppressed due to the predetermined shape of the lumen 40L of the pre-mold 40. However, the first section 31 and the second section 32 can be stretched more radially y-direction than the central section 33, and therefore can have a larger maximum outer diameter than the central section 33. As a result, the resin orientation can be formed differently in the first section 31 and the second section 32 and in the central section 33, and the resulting balloon 20 can be manufactured so that it has an orientation in the longitudinal axis direction x in the central section.

[0066] At the end of the first heating step, it is preferable that the film thickness in the central section 33 is substantially the same as the film thickness in the first section 31 and the second section 32. In the first heating step, the central section 33 is stretched in the longitudinal axis direction x while stretching in the radial direction y is suppressed, and the first section 31 and the second section 32 may be stretched in the radial direction y. Therefore, at the end of the first heating step, the parison 30 can be stretched so that the film thickness in the central section 33, the first section 31, and the second section is substantially the same. When such an enlarged diameter section 30E is biaxially stretched in the second heating step, the central section 33, which had already been stretched in the longitudinal axis direction x in the first heating step, is further biaxially stretched, and the film thickness in the central section 33 can be made thinner than the film thickness in the first section 31 and the second section 32.

[0067] As shown in Figures 4 to 6, it is preferable that the central section 33 of the enlarged diameter portion 30E is in contact with the inner wall of the reduced diameter portion 43 of the pre-mold 40 at any point from the start to the end of the first heating step. As shown in Figure 4, the central section 33 may be in contact with the inner wall of the reduced diameter portion 43 at the start of the first heating step. This makes it easier to suppress the radial extension of the central section 33 in the y-direction and extend it in the longitudinal axis direction x. Alternatively, as shown in Figure 5, the central section 33 may not be in contact with the inner wall of the reduced diameter portion 43 at the start of the first heating step, and may come into contact with the inner wall of the reduced diameter portion 43 at any point until the end of the first heating step. Even in this case, since the reduced diameter portion 43 has an inner diameter of a predetermined size or less, it is possible to suppress the radial extension of the central section 33 in the y-direction and extend it in the longitudinal axis direction x.

[0068] As shown in Figure 6, it is preferable that at the end of the first heating step, the central section 33 of the enlarged diameter section 30E is in contact with the inner wall of the reduced diameter section 43 of the pre-mold 40. This allows the outer diameter of the central section 33 at the end of the first heating step to be the same as the inner diameter of the reduced diameter section 43 of the pre-mold 40, and the maximum magnification of the radial stretch of the central section 33 at the end of the first heating step can be determined by the inner diameter of the reduced diameter section 43 of the pre-mold 40. This makes it easier to stretch the central section 33 in the longitudinal axis direction x while suppressing the radial stretch in the y direction.

[0069] In addition to the above, it is preferable that at the end of the first heating step, at least a portion of the first section 31 of the enlarged diameter portion 30E is in contact with the inner wall of the first enlarged diameter portion 41 of the pre-mold 40, and at least a portion of the second section 32 of the enlarged diameter portion 30E is in contact with the inner wall of the second enlarged diameter portion 42 of the pre-mold 40. This allows the outer diameter of the central section 33, the maximum outer diameter of the first section 31, and the maximum outer diameter of the second section 32 at the end of the first heating step to be determined by the shape of the lumen 40L of the pre-mold 40, thereby suppressing the radial stretching of the central section 33 in the y-direction at the end of the first heating step, while making the radial stretching ratio of at least a portion of the first section 31 and at least a portion of the second section 32 greater than the radial stretching ratio of the central section 33 in the y-direction. This makes it possible to obtain a parison 30 with different stretching states in the central section 33 and the first section 31 and second section 32 at the end of the first heating step, and by biaxially stretching such a parison 30 in the second heating step, it becomes easy to obtain a balloon 20 in which the central section is oriented in the longitudinal axis direction x.

[0070] In this case, it is preferable that the entirety of the first section 31 and the second section 32 are in contact with the inner walls of the first diameter-expanding section 41 and the second diameter-expanding section 42 of the mold, respectively. This makes it easier to determine the shape of the parison 30 at the end of the first heating step by the shape of the inner cavity 40L of the pre-mold 40, and thus makes it easier to control the stretched state of the parison 30 in the first heating step.

[0071] Alternatively, although not shown in the diagram, at the end of the first heating step, the central section 33 of the parison 30 is in contact with the inner wall of the reduced diameter section 43 of the pre-mold 40, but either or both of the first section 31 and the second section 32 do not need to be in contact with the first enlarged diameter section 41 and the second enlarged diameter section 42 of the mold, respectively. Even in this state, the radial extension of the central section 33 in the y-direction is suppressed by the reduced diameter section 43 of the pre-mold 40, so the central section 33 can be extended in the longitudinal axis direction x while suppressing radial extension in the y-direction.

[0072] In the manufacturing method of the balloon 20 for a balloon catheter according to an embodiment of the present invention, it is preferable to further include a step of raising the enlarged diameter portion 30E to a temperature of Tc or higher than the crystallization temperature of the resin after the second heating step. This step may be performed by heating the post mold 50 to a temperature of Tc or higher. At the end of the second heating step, the enlarged diameter portion 30E of the parison 30 is molded to the shape of the expanded portion 22 of the balloon 20, but by raising the enlarged diameter portion 30E of the parison 30 to a temperature of Tc or higher than the crystallization temperature of the resin after this, the crystallization of the resin can be promoted and the shape of the enlarged diameter portion 30E can be fixed. This is thought to be because the shape can be fixed by promoting the bonding by intermolecular forces between molecules that are oriented at the end of the second heating step. If this step is not performed, the balloon 20 molded from the parison 30 may shrink when it is removed from the post mold 50.

[0073] The crystallization temperature Tc is measured in accordance with JIS K7121. Using a differential scanning calorimeter, a 5 mg resin sample is heated at a rate of 20 °C / min in the temperature range of 0 °C to 250 °C, maintained at this temperature for 10 minutes, and then cooled at a rate of 20 °C / min to a temperature approximately 50 °C lower than the end of the crystallization peak. The extrapolation onset temperature obtained from the DSC curve can be defined as the crystallization temperature Tc.

[0074] For example, when a polyamide resin is used as the resin constituting parison 30, the crystallization temperature Tc is 130°C to 155°C. When other resins are used as the resin constituting parison 30, the crystallization temperature Tc is not limited to the above temperature and can be determined according to the above method.

[0075] Next, a mold set according to an embodiment of the present invention will be described. In the description of the mold set, any parts that overlap with the description of the method for manufacturing the balloon for the balloon catheter described above will be omitted.

[0076] As shown in Figures 3 and 7, the mold set for manufacturing balloons for balloon catheters includes a post mold 50 that extends in the longitudinal axis x direction and has a lumen 50L, and has a sleeve portion A1, a sleeve portion A2, and a straight tube portion 51 that is located between sleeve portions A1 and A2 in the longitudinal axis x direction and has an inner diameter greater than or equal to the inner diameter of sleeve portion A1 and greater than or equal to the inner diameter of sleeve portion A2, and a post mold 50 that extends in the longitudinal axis x direction and has a lumen 40L, and has a sleeve portion B1, a sleeve portion B2, and longitudinal The mold has a diameter-expanding section 40E located between sleeve section B1 and sleeve section B2 in the axial direction x, having an inner diameter greater than or equal to the inner diameter of sleeve section B1 and greater than or equal to the inner diameter of sleeve section B2, and the mold diameter-expanding section 40E has a first diameter-expanding section 41, a second diameter-expanding section 42, and a diameter-reducing section 43 located between the first diameter-expanding section 41 and the second diameter-expanding section 42 in the longitudinal direction x, having a maximum inner diameter smaller than the maximum inner diameter of the first diameter-expanding section 41 and the second diameter-expanding section 42.

[0077] The pre-mold 40 may be composed of one component or multiple components. For example, the pre-mold 40 may be composed of multiple halves, multiple segments may be connected in the circumferential direction z, or multiple segments may be connected in the longitudinal direction x. For example, if multiple mold components are configured to be divisibly connected in the longitudinal direction x, it becomes possible to independently set each mold component to a different temperature when the mold itself generates heat to heat the parison 30 placed in the lumen 40L of the pre-mold 40, making it easier to control the stretching of the parison 30.

[0078] The post-mold 50 may be composed of one member or multiple members. For example, the post-mold 50 may be composed of multiple halves, multiple segments may be configured to be connected in the circumferential direction z, or multiple segments may be configured to be connected in the longitudinal direction x. For example, if the segments of multiple mold members are configured to be divisibly connected in the longitudinal direction x, then when a method is adopted in which the parison 30 placed in the lumen 50L of the post-mold 50 is heated by the heat generated by the mold itself, it becomes possible to independently set each mold member to a different temperature, making it easier to control the stretching of the parison 30.

[0079] As shown in Figure 3, it is preferable that the pre-mold 40 has a tapered portion T1 in the longitudinal axis direction x, where the lumen 40L is reduced in diameter from the first enlarged portion 41 to the reduced portion 43, and a tapered portion T2 in the longitudinal axis direction x, where the lumen 40L is increased in diameter from the reduced portion 43 to the second enlarged portion 42. In this way, having the tapered portion T1 and tapered portion T2 at both ends of the reduced portion 43 of the pre-mold 40 makes it possible to smoothly transition the molecular orientation from the central section 33 to both ends of the enlarged portion 30E of the parison 30 in the first heating step. Therefore, it is preferable that the molecular orientation from the central section 33 to both ends also transitions smoothly when biaxial stretching is performed in the second heating step. By smoothly transitioning the molecular orientation from the central section 33 to both ends, stress concentration due to abrupt changes in molecular orientation can be avoided, and the mechanical strength and moldability of the resulting balloon 20 can be improved.

[0080] Preferably, the pre-mold 40 has a tapered section T3 in which the internal diameter 40L expands from the sleeve section B1 to the first enlarged diameter section 41 of the mold, and a tapered section T4 in which the internal diameter 40L contracts from the second enlarged diameter section 42 of the mold to the sleeve section B2, in the longitudinal axis direction x. In this way, because the pre-mold 40 has tapered sections T3 and T4 at both ends of the enlarged diameter section 40E of the mold, the shape transition from both ends of the enlarged diameter section 30E to the tapered sections P1 and P2 can be made smooth in the first heating step, thus facilitating biaxial stretching in the second heating step.

[0081] As shown in Figure 7, it is preferable that the post mold 50 has a tapered section T5 in which the lumen 50L expands in the longitudinal axis direction x from the sleeve section A1 to the straight tube section 51, and a tapered section T6 in which the lumen 50L contracts in the longitudinal axis direction x from the straight tube section 51 to the sleeve section A2. In this way, having tapered sections T5 and T6 at both ends of the straight tube section 51 of the post mold 50 allows for a smooth transition of shape and molecular orientation from both ends of the expanded diameter section 30E to the tapered sections P1 and P2 in the second heating step. This avoids stress concentration due to abrupt changes in shape and molecular orientation, thereby improving the mechanical strength and moldability of the resulting balloon 20. [Explanation of symbols]

[0082] 1: Balloon catheter 3: Shaft 4: Hub 5: Guidewire insertion section 6:Fluid injection part 20: Balloon 21: Proximal sleeve portion of the balloon 22: Balloon expansion section 23: Distal sleeve portion of the balloon 30: Parison 30E: Enlarged section of parison 30L: Parison's lumen 31: Parison's first section 32: Parison's second leg 33: The central section of Parison 40: Pre-molded 40E: Mold diameter expansion section 40L: Luminous part of pre-molded mold 41: First diameter enlargement section of the mold 42: Second diameter enlargement section of the mold 43: Reduced diameter section of pre-molded mold 50: Post-molding 50L: Luminous part of post-molding 51: Straight pipe section of post-molding A1: Sleeve portion of post mold A2: Post mold sleeve section B1: Sleeve part of the pre-molded mold B2: Sleeve part of the pre-mold P1: Sleeve part of the parison P2: Sleeve part of the parison T1: Taper part of the pre-mold T2: Taper part of the pre-mold T3: Taper part of the pre-mold T4: Taper part of the pre-mold T5: Taper part of the post-mold T6: Taper part of the post-mold D0: Position at 0% D 40 : Position at 40% D 60 : Position at 60% D 100 : Position at 100% x: Longitudinal axis direction y: Radial direction z: Circumferential direction

Claims

1. A parison made of resin, extending in the longitudinal direction and having a lumen, comprising: a sleeve portion P1; a sleeve portion P2; and an enlarged diameter portion located between the sleeve portion P1 and the sleeve portion P2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion P1 and greater than or equal to the inner diameter of the sleeve portion P2, wherein, in the longitudinal direction, when the first end of the enlarged diameter portion is at the 0% position and the second end is at the 100% position, the enlarged diameter portion has a central section from the 40% position to the 60% position, a first section located closer to the first end than the central section, and a second section located closer to the second end than the central section, The steps include preparing a post mold having a sleeve portion A1, a sleeve portion A2, and a straight tube portion that extends in the longitudinal direction and has a lumen, and is located between the sleeve portion A1 and the sleeve portion A2 in the longitudinal direction and has an inner diameter greater than or equal to the inner diameter of the sleeve portion A1 and greater than or equal to the inner diameter of the sleeve portion A2, The steps of preparing a pre-mold, which extends in the longitudinal direction and has a lumen, and comprises a sleeve portion B1, a sleeve portion B2, and a mold enlargement portion located between the sleeve portion B1 and the sleeve portion B2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion B1 and greater than or equal to the inner diameter of the sleeve portion B2, wherein the mold enlargement portion comprises a first mold enlargement portion, a second mold enlargement portion, and a reduced diameter portion located between the first mold enlargement portion and the second mold enlargement portion in the longitudinal direction and having a maximum inner diameter smaller than the maximum inner diameter of the first mold enlargement portion and the second mold enlargement portion, A first heating step involves placing the parison in the lumen of the pre-mold such that the central section is located in the reduced diameter portion of the pre-mold, and heating the pre-mold to stretch at least the central section. A method for manufacturing a balloon for a balloon catheter, comprising: a second heating step after the first heating step, removing the parison from the lumen of the pre-mold, placing it in the lumen of the post-mold so that the enlarged portion is located in the straight tube portion of the post-mold, and heating the post-mold to biaxially extend the enlarged portion in the longitudinal direction and the radial direction of the enlarged portion.

2. A method for manufacturing a balloon for a balloon catheter according to claim 1, wherein in the first heating step, the pre-mold is heated to a temperature of Tg or higher and Tg + 30°C or lower than the glass transition temperature of the resin, and in the second heating step, the post-mold is heated to a temperature of Tg or higher and Tg + 30°C or lower than the glass transition temperature of the resin.

3. A method for manufacturing a balloon catheter according to claim 1 or 2, wherein at the end of the first heating step, the maximum outer diameter of the central section of the enlarged portion is smaller than the maximum outer diameter of the first section and the maximum outer diameter of the second section.

4. A method for manufacturing a balloon for a balloon catheter according to claim 1 or 2, wherein in the first heating step, the internal pressure of the enlarged diameter portion is maintained at 0 bar or more and 30 bar or less, and in the second heating step, an internal pressure higher than the internal pressure in the first heating step is applied to the enlarged diameter portion.

5. A method for manufacturing a balloon for a balloon catheter according to claim 1 or 2, wherein at any point from the start to the end of the first heating step, the central section of the enlarged diameter portion is in contact with the inner wall of the reduced diameter portion of the pre-mold.

6. A method for manufacturing a balloon for a balloon catheter according to claim 5, wherein at the end of the first heating step, at least a portion of the first section of the enlarged diameter portion is in contact with the inner wall of the first enlarged diameter portion of the mold of the pre-mold, and at least a portion of the second section of the enlarged diameter portion is in contact with the inner wall of the second enlarged diameter portion of the mold of the pre-mold.

7. Furthermore, the method for manufacturing a balloon for a balloon catheter according to claim 1 or 2, further comprising a step of raising the enlarged diameter portion to a temperature equal to or higher than the crystallization temperature Tc of the resin after the second heating step.

8. A mold set for manufacturing balloons for balloon catheters, A post mold having a bore extending in the longitudinal direction and comprising a sleeve portion A1, a sleeve portion A2, and a straight tube portion located between the sleeve portion A1 and the sleeve portion A2 in the longitudinal direction and having an inner diameter greater than or equal to the inner diameter of the sleeve portion A1 and greater than or equal to the inner diameter of the sleeve portion A2, A mold set comprising a pre-mold having a sleeve portion B1 and a sleeve portion B2, which extend in the longitudinal direction and have a lumen, and which is located between the sleeve portion B1 and the sleeve portion B2 in the longitudinal direction and has an inner diameter greater than or equal to the inner diameter of the sleeve portion B1 and greater than or equal to the inner diameter of the sleeve portion B2, wherein the mold enlargement portion has a first mold enlargement portion, a second mold enlargement portion, and a reduction portion having a maximum inner diameter smaller than the maximum inner diameter of the first mold enlargement portion and the second mold enlargement portion, located between the first mold enlargement portion and the second mold enlargement portion in the longitudinal direction.

9. The mold set according to claim 8, wherein the pre-mold has a tapered portion T1 in which the internal diameter is reduced from the first enlarged portion to the reduced portion of the mold in the longitudinal axis direction, and a tapered portion T2 in which the internal diameter is increased from the reduced portion to the second enlarged portion of the mold.

10. The mold set according to claim 9, wherein the pre-mold has a tapered portion T3 in which the internal diameter expands from the sleeve portion B1 to the first enlarged diameter portion of the mold in the longitudinal axis direction, and a tapered portion T4 in which the internal diameter contracts from the second enlarged diameter portion of the mold to the sleeve portion B2.

11. The mold set according to claim 9 or 10, wherein the post mold has a tapered portion T5 in which the diameter of the lumen expands from the sleeve portion A1 to the straight pipe portion in the longitudinal axis direction, and a tapered portion T6 in which the diameter of the lumen contracts from the straight pipe portion to the sleeve portion A2.

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