JP2017063803A - Balloon and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balloon having excellent flexibility and capable of suppressing axial elongation of the balloon, and a manufacturing method thereof.SOLUTION: A balloon 30 to be disposed on a medical catheter includes a freely expandable cylindrical part 42 composed of a birefringent high polymer material. The ratio of the number of orientation distributions calculated by dividing the number of orientation distributions in a circumferential direction of the cylindrical part 42 by the number of orientation distributions in an axial direction of the cylindrical part 42 is adjusted to be less than 1.5 so that axial elongation percentage of the cylindrical part 42 is 6% or less under a condition of pressurization of 1-13 atm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a balloon and a manufacturing method thereof.

  The stent delivery system is a medical device used to improve a stenosis or occlusion generated in a lumen in a living body, and includes an expandable balloon disposed on the outer periphery of a distal end portion of a hollow shaft portion, And a stent disposed on the outer periphery. The stent is crimped and mounted on the balloon in a reduced diameter, and after reaching the target site (stenosis or occlusion) via the in vivo lumen, it is plastically deformed by expanding the balloon. It is left in contact with the inner surface of the site.

  Therefore, when the stent is plastically deformed and the balloon expands in the axial direction as the balloon expands, the cylindrical portion of the balloon protrudes from the stent edge, the stent placement position shifts, and the target site is adjacent. There is a risk of dilating healthy blood vessels. Therefore, by applying a polyurethane block copolymer that is difficult to stretch as a balloon material, axial elongation of the balloon is suppressed (for example, see Patent Document 1).

  Further, not limited to the stent delivery system, for example, percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA) are expanded. A balloon catheter with a deflatable balloon is used. Such a balloon catheter is inserted into a blood vessel from outside the body, and when the balloon reaches the stenosis of the target blood vessel, it is used to expand the balloon and expand the stenosis. Similarly, there is a risk of dilating healthy blood vessels adjacent to the target site.

JP 2006-110392 A

  However, since the polyurethane block copolymer has high hardness and the rigidity of the balloon is increased, there is a problem that it is difficult to ensure the flexibility of the balloon (following ability to bending of the lumen of the living body).

  The present invention has been made to solve the problems associated with the above-described prior art, and has an object to provide a balloon having good flexibility and capable of suppressing the axial elongation of the balloon and a method for manufacturing the same. To do.

  In order to achieve the above object, a uniform phase of the present invention is a balloon disposed on a medical catheter and has an expandable cylindrical portion made of a birefringent polymer material. The ratio of the number of orientation distributions calculated by dividing the number of circumferential orientation distributions of the cylindrical part by the number of axial orientation distributions of the cylindrical part is 1 to 13 atm. It is adjusted to be less than 1.5 so that the axial elongation rate is 6% or less.

  Another aspect of the present invention for achieving the above object is a method of manufacturing a balloon disposed on a medical catheter, wherein the balloon is formed by blow-molding a tubular parison made of a birefringent polymer material. A molding step of molding the expandable cylindrical portion. In the molding step, the cylindrical part having a ratio of the number of orientation distributions adjusted so that the axial elongation rate of the cylindrical part under a pressure of 1 to 13 atm is 6% or less is molded. The ratio of the orientation distribution number is calculated by dividing the circumferential orientation distribution number of the cylindrical part by the axial direction orientation distribution number of the cylindrical part, and the adjusted ratio of the orientation distribution number is: It is less than 1.5.

  According to the present invention, the axial elongation of the balloon tubular portion is 6% or less, which is achieved by molding the balloon to have a specific orientation distribution ratio of less than 1.5. Therefore, even when a birefringent polymer material having flexibility (followability to bending of a lumen in a living body) is applied as a balloon material, it is possible to suppress the axial extension of the balloon. Therefore, it is possible to provide a balloon having good flexibility and capable of suppressing the balloon in the axial direction and a method for manufacturing the same.

  From the viewpoint of the flexibility of the balloon, the polymer material is preferably made of an elastic resin material having a Shore hardness of 60D or less.

  The elastic resin material is selected from, for example, polyamide, polyamide-based elastomer, polyolefin, polyolefin-based elastomer, polyester, polyester-based elastomer, polyurethane, polyurethane-based elastomer, polyimide, polyvinyl chloride, fluororesin, silicone rubber, latex rubber 1 One.

  A balloon having a specific orientation distribution number ratio of less than 1.5 is formed by, for example, blow-molding a tubular parison made of a birefringent polymer material to form an expandable tubular portion of the balloon. It is possible to manufacture by a manufacturing method having a molding step, and the molding step is a first stretching in which the tubular parison is stretched in the axial direction of the tubular parison at normal temperature in a state where pressure is applied to the inside of the tubular parison. And a second stretching step of bulging the tubular parison by the pressure applied to the inside of the tubular parison while stretching the heated tubular parison in the axial direction of the tubular parison after the first stretching step. Have.

It is a side view for demonstrating the balloon which concerns on embodiment of this invention. It is the schematic for demonstrating the medical catheter to which the balloon shown by FIG. 1 is applied. It is the schematic for demonstrating the stent shown by FIG. It is a graph for demonstrating the intersection angle of an orientation direction and an X-axis, the intersection angle of an orientation direction and a Y-axis, and the intersection angle of an orientation direction and a Z-axis. It is a graph for demonstrating the circumferential direction, thickness direction, and axial direction of the cylindrical part of a balloon. It is a flowchart for demonstrating the manufacturing method of the balloon which concerns on embodiment of this invention. It is a side view for demonstrating the necking process shown by FIG. It is sectional drawing for demonstrating the blow molding apparatus applied to the shaping | molding process shown by FIG. It is sectional drawing for demonstrating the arrangement | positioning process shown by FIG. It is sectional drawing for demonstrating the 1st extending | stretching process shown by FIG. It is sectional drawing for demonstrating the 2nd extending | stretching process shown by FIG. It is sectional drawing for demonstrating the cooling in the extraction process shown by FIG. It is sectional drawing for demonstrating the mold opening in the extraction process shown by FIG. It is a table which shows the ratio of the number of orientation distribution of specimens 1-4. It is a table which shows the manufacturing conditions of specimens 1-4. It is a table which shows the relationship between the axial direction elongation rate of a test body 1-4, and a pressure. It is a graph which shows the relationship between the axial direction elongation rate of a test body 1-4, and a pressure. It is a graph which shows the relationship between the axial direction elongation rate of specimens 1-4, and the ratio of the number of orientation distribution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view for explaining a balloon according to an embodiment of the present invention, FIG. 2 is a schematic view for explaining a medical catheter to which the balloon shown in FIG. 1 is applied, and FIG. It is the schematic for demonstrating the stent shown by FIG.

  The balloon 30 according to the embodiment of the present invention is applied to, for example, the stent delivery system 10 shown in FIG. The stent delivery system 10 is a medical catheter having a stent 16 disposed on the outer periphery of a balloon 30, for example, after percutaneous transaneous coronary angioplasty (PTCA) used for myocardial infarction or angina. It is applied to treatment aimed at preventing restenosis. The stent delivery system 10 is not limited to a form that is applied to a stenosis that occurs in the coronary artery of the heart, but can also be applied to a stenosis that occurs in other blood vessels, bile ducts, trachea, esophagus, urethra, and the like.

  The stent delivery system 10 is a rapid exchange (RX) type having a structure in which the guide wire 14 passes only through the distal end portion, and includes the distal end shaft 12 to which the balloon 30 is connected in a liquid-tight state. The tip shaft 12 has a lumen for introducing a balloon expansion fluid.

  The stent 16 is an in-vivo indwelling object that holds a lumen by being placed in close contact with the inner surface of the stenosis, and has an annular body 17 composed of wavy struts 18 as shown in FIG. . The annular bodies 17 are sequentially juxtaposed along the axial direction l, and the adjacent annular bodies 17 are integrated with each other by a link portion 19 so as to be expandable.

  The stent 16 is made of a biocompatible material. Examples of the biocompatible material include nickel-titanium alloy, cobalt-chromium alloy, stainless steel, iron, titanium, aluminum, tin, and zinc-tungsten alloy.

  The balloon 30 is configured to expand and expand the diameter of the stent 16 disposed on the outer periphery thereof, and as illustrated in FIG. 1, as illustrated in FIG. 1, a tubular portion 42 and a taper located on both sides of the tubular portion 42. Part 44. The cylindrical portion 42 is configured to be expandable by a balloon expansion fluid introduced via the lumen of the tip shaft 12.

  The outer diameter of the cylindrical portion 42 is set to 1.0 to 10 mm, preferably 1.0 to 5.0 mm, when expanded. The length of the cylindrical portion 42 is 5 to 50 mm, preferably 10 to 40 mm. The overall length of the balloon 30 is 10 to 200 mm, preferably 20 to 40 mm.

  The cylindrical portion 42 has an axial elongation rate of 6% or less under a pressure condition of 1 to 13 atm, and this has a specific orientation distribution ratio of less than 1.5, as will be described later. A birefringent polymer material having flexibility (followability with respect to bending of a living body lumen) can be applied as a balloon material. Therefore, the balloon 30 can suppress elongation in the axial direction l while having good flexibility. The number of orientation distributions is the number of molecular chains per unit cross-sectional area of the balloon constituent material, and the ratio of the number of orientation distributions is the number of circumferential orientation distributions of the cylindrical part 42 and the number of axial orientation distributions of the cylindrical part 42. It is calculated by dividing by.

  From the viewpoint of the flexibility of the balloon 30, it is preferable that the tubular portion 42 has a film thickness of 20 μm or less, and the polymer material is made of an elastic resin material having a Shore hardness of 60 D or less.

  The elastic resin material is selected from, for example, polyamide, polyamide-based elastomer, polyolefin, polyolefin-based elastomer, polyester, polyester-based elastomer, polyurethane, polyurethane-based elastomer, polyimide, polyvinyl chloride, fluororesin, silicone rubber, latex rubber 1 One.

  The polyamide is not particularly limited as long as it is a polymer having an amide bond. For example, polycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 66), polyundecanolactam (nylon 11), polydodecanolactam A homopolymer such as (Nylon 12). The polyamide elastomer is, for example, a block copolymer having nylon 6, nylon 66, nylon 11, nylon 12 or the like as a hard segment and polyalkylene glycol, polytetramethylene ether glycol, polyether, aliphatic polyester or the like as a soft segment. It is.

  The medical catheter to which the balloon 30 is applied is not limited to the stent delivery system 10.

  Next, a method for calculating the number of circumferential orientation distributions and the number of axial orientation distributions will be described in detail.

  FIG. 4 is a graph for explaining the crossing angle between the orientation direction and the X axis, the crossing angle between the orientation direction and the Y axis, and the crossing angle between the orientation direction and the Z axis, and FIG. It is a graph for demonstrating the circumferential direction, thickness direction, and an axial direction.

  The number of orientation distributions (number of molecular chains per unit cross-sectional area of the balloon material) is related to the anisotropy of polarizability, and the anisotropy of polarizability is the anisotropy of refractive index (optical anisotropy). is connected with. Therefore, the number of orientation distributions can be estimated using the phenomenon of birefringence.

  For example, when light is incident on an optical isomer, it is divided into two refracted lights that vibrate in directions perpendicular to each other, so the difference (birefringence) between the two refracted lights is measured to calculate the refractive index. Thus, the number of orientation distributions is analyzed. However, the comparison by the refractive index can be used for the alignment comparison by the same material and the same condition, but it is not suitable for the comparison between different kinds of resins and lacks versatility. For this reason, in the present embodiment, physical properties that can suppress circumferential cracking are defined by the ratio of the number of orientation distributions.

Specifically, as shown in FIG. 4, the crossing angle between the alignment direction D and the X axis, the crossing angle between the alignment direction D and the Y axis, and the crossing angle between the alignment direction D and the Z axis are represented by φ _x , In terms of φ _y and φ _z , the circumferential direction orientation distribution number, the axial direction orientation distribution number, and the thickness direction orientation distribution number are defined by the following equations.

Circumferential orientation distribution number, as the n _x and n _z required for calculating the axial orientation distribution number and thickness direction orientation distribution number, shown in Figure 5, the refractive index of the circumferential direction r, the thickness direction When the refractive index of d and the refractive index in the axial direction l are expressed by nr, nd, and nl, the intrinsic birefringence Δn ^* , which is the birefringence value when the molecules are oriented 100%, is used, and is calculated by the following formula: Is done. The refractive index is calculated by measuring retardation (phase difference) with a polarizing microscope, for example.

  Next, a method for manufacturing a balloon according to an embodiment of the present invention will be described.

  FIG. 6 is a flowchart for explaining a balloon manufacturing method according to an embodiment of the present invention.

  The balloon manufacturing method according to the embodiment of the present invention includes a necking process, a molding process, and a trimming process, as shown in FIG.

  In the necking step, the diameter of the end 24 of the tubular parison 20 that is the material (preform) of the balloon 30 is reduced using the necking device 50. At this time, since the central portion 22 is not deformed, a bulging ball shape is exhibited. For example, the tubular parison 20 is made of a nylon elastomer having a Shore hardness of 56D. The ball-shaped length of the central portion 22 is referred to as the ball length.

  The necking device 50 includes, for example, chuck portions 52 and 55 and heater portions 58 and 59. The chuck portions 52 and 55 are arranged so as to be close to and away from each other in the axial direction of the tubular parison 20, and are used to grip the vicinity of the end face 24 of the tubular parison 20. The heater portions 58 and 59 are used to heat the end 24 of the tubular parison 20 and raise the temperature to a temperature at which the end 24 is plasticized.

  Therefore, in a state where the end portion 24 of the tubular parison 20 is heated by the heater portions 58 and 59, the chuck portions 52 and 55 that grip the vicinity of the end face of the end portion 24 of the tubular parison 20 are separated in the axial direction l, thereby forming the tubular parison. Since the 20 ends 24 are stretched, it is possible to reduce their diameter.

  When the necking step is completed, the tubular parison 20 is taken out after the gripping by the chuck portions 52 and 55 is released.

  The molding process includes an arrangement process, a first stretching process, a second stretching process, an annealing process, and an extraction process, and the tubular parison is molded into a shape that substantially matches the outer shape of the balloon 30 by blow molding. At this time, the ratio of the number of orientation distributions (less than 1.5) adjusted so that the axial elongation rate of the balloon 30 (cylindrical portion 42) under a pressurized condition of 1 to 13 atm is 6% or less. To be molded.

  In the trimming step, the balloon 30 is formed by cutting the end of the molded tubular parison 20. For example, the balloon size is φ3.0 × 15 mm, the film thickness is about 17 μm, and the axial elongation (1 to 13 atm) is 5.7% (0.068 mm / atm).

  Next, a blow molding apparatus applied to the molding process will be described.

  FIG. 8 is a cross-sectional view for explaining a blow molding apparatus applied to the molding step shown in FIG.

  The blow molding apparatus 60 includes molding dies (blow molding dies) 62 and 66 and chuck portions 80 and 82. The molds 62 and 66 have cavity surfaces 64 and 68, heater portions 70 and 72, and cooling jackets 74 and 76.

  The cavity surfaces 64 and 68 integrally correspond to the outer shape of the balloon 30, and when the molds 62 and 66 are clamped, the cavity surfaces 64 and 68 have a shape that substantially matches the outer shape of the balloon 30. Present.

  The heater units 70 and 72 are made of, for example, a planar heater, and indirectly heat the tubular parison 20 disposed in the internal space of the cavity surfaces 64 and 68 by raising the temperature of the molds 62 and 66 to form a tubular shape. Used to raise the temperature to a temperature at which the parison 20 is plasticized.

  The cooling jackets 74 and 76 are arranged on the outer circumferences of the heater portions 70 and 72 and are configured to allow the refrigerant to circulate. The refrigerant is used to indirectly cool the tubular parison 20 disposed in the internal space of the cavity surfaces 64 and 68 by lowering the temperature of the molds 62 and 66. The refrigerant is, for example, a liquid such as water or a gas such as air.

  The chuck portions 80 and 82 are disposed so as to be close to and away from each other in the axial direction of the tubular parison 20 and are used to grip the end portion 24 of the tubular parison 20. The chuck portion 80 has an injection port 86, and the chuck portion 82 has a discharge port 88. The injection port 86 is used to inject a molding fluid into the tubular parison 20 and apply pressure (increase the internal pressure) to the inside of the tubular parison 20. The discharge port 88 is used to discharge molding fluid from the tubular parison 20 and return the interior of the tubular parison 20 to atmospheric pressure. The forming fluid is, for example, air or nitrogen.

  Next, each process which comprises a shaping | molding process is explained in full detail one by one.

  9 is a cross-sectional view for explaining the arrangement step shown in FIG. 6, FIG. 10 is a cross-sectional view for explaining the first stretching step shown in FIG. 6, and FIG. 11 is a first view shown in FIG. FIG. 12 and FIG. 13 are sectional views for explaining cooling and mold opening in the extraction step shown in FIG. 6.

  In the arranging step, as shown in FIG. 9, the tubular parison 20 is arranged in the internal space formed by the cavity surfaces 64 and 68 of the molds 62 and 66, and its end portion 24 is formed by the chuck portions 80 and 82. The molds 62 and 66 are held and clamped.

  In the first stretching step, as shown in FIG. 10, the tubular parison 20 is kept at room temperature (for example, 30 ° C.), and the chuck portions 80 and 82 holding the end 24 are separated from each other. The tubular parison 20 is stretched in the axial direction l. At this time, the central portion 22 of the tubular parison 20 is not heated (heated up) and thus does not expand. Further, by applying pressure to the inside of the tubular parison 20 by the molding fluid injected from the injection port 86, the collapse (collapse) of the tubular parison 20 is suppressed. For example, the molding pressure is 3.5 Mpa, and the stretching distance and stretching speed of the chuck portions 80 and 82 are 10 mm and 30 mm / sec.

  In the second stretching step, the pressure applied to the inside of the tubular parison 20 is maintained, while the heater parts 70 and 72 are operated to raise the temperature of the molds 62 and 66, thereby increasing the inside of the cavity surfaces 64 and 68. When the central portion 22 of the tubular parison 20 disposed in the space is indirectly heated and the temperature is raised to a temperature at which the tubular parison 20 is plasticized, the chuck portions 80 and 82 are further separated, and the central portion 22 of the tubular parison 20 is moved. Stretch in the axial direction l. As a result, the film thickness of the central portion 22 of the tubular parison 20 is reduced (thinned), and bulges at the moment of losing the pressure applied to the inside of the tubular parison 20, and as shown in FIG. It is formed into a shape that substantially matches the outer shape. For example, the molding temperature is 82 ° C., and the stretching distance and stretching speed of the chuck portions 80 and 82 are 5 mm and 150 mm / sec. Since the molding pressure is the same as in the first stretching step, it is 3.5 Mpa.

  In the annealing process, the separation operation of the chuck portions 80 and 82 is stopped and the pressure applied to the inside of the tubular parison 20 is maintained, while the heater portions 70 and 72 are used until the temperature of the tubular parison 20 reaches the annealing temperature. The molds 62 and 66 are further heated to anneal. Thereby, the distortion (internal stress) of the tubular parison 20 is removed. For example, the annealing temperature is 110 ° C. The annealing pressure is 3.5 Mpa because it is the same as the first and second stretching steps.

  In the extraction process, as shown in FIG. 12, the heating by the heater units 70 and 72 is stopped, and the refrigerant is introduced into the cooling jackets 74 and 76. The refrigerant indirectly cools the tubular parison 20 by lowering the temperature of the molds 62 and 66. Then, as shown in FIG. 13, the forming fluid is discharged from the discharge port 88, the inside of the tubular parison 20 is returned to atmospheric pressure, the forming dies 62 and 66 are opened, and the tubular parison 20 is taken out. At this time, the tubular parison 20 has a shape that substantially matches the outer shape of the balloon 30 except for the shape of the end 24, and as described above, the end 24 is cut in the subsequent trimming process. As a result, the balloon 30 is obtained.

  Next, the relationship between the axial elongation rate and the ratio of the number of orientation distributions will be described.

  FIG. 14 is a table showing the ratio of the orientation distribution numbers of the specimens 1 to 4, FIG. 15 is a table showing the manufacturing conditions of the specimens 1 to 4, and FIGS. FIG. 18 is a graph showing the relationship between the axial elongation of specimens 1 to 4 and the ratio of the number of orientation distributions.

  The refractive index necessary for calculating the ratio of the number of orientation distributions is obtained by measuring the retardation (phase difference) of a sample piece prepared by embedding specimens 1 to 4 in a resin and slicing them with a polarizing microscope. Calculated.

  Specimens 1 to 3 and Specimen 4 correspond to the comparative example and the present embodiment, and are generally different with respect to the conditions of the first and second stretching steps as shown in FIG. Specifically, for the first stretching step, the specimen 4 is carried out at room temperature, the specimens 1 to 3 are carried out under heating, and the specimen 4 is the specimen 1 for the second stretching process. Compared to ~ 3, the stretching temperature and the stretching speed are set larger.

  As shown in FIG. 14, the ratio of the number of orientation distributions of Specimen 1, Specimen 2, Specimen 3 and Specimen 4 varies depending on the measurement location, and is 0.597 to 1.660, 0, respectively. .702 to 2.363, 0.568 to 1.400 and 0.540 to 1.310. That is, the ratio of the number of orientation distributions of the specimen 4 according to this embodiment is smaller than that of the specimens 1 to 3 according to the comparative example.

  As shown in FIG. 16, the elongation in the axial direction (1 to 13 atm) of Specimen 1, Specimen 2, Specimen 3 and Specimen 4 is 7.655%, 9.752%, 7.101% and 5.663%. As can be understood from the fact that the inclination in the axial direction of the specimen 4 according to the present embodiment is the smallest in the graph shown in FIG. 17, it is smaller than those of the specimens 1 to 3 according to the comparative example. The value is 6% or less.

  Specimen 4 according to the present embodiment shows the relationship between the ratio of the number of orientation distributions of specimens 1 to 4 shown in FIG. 14 and the axial elongation of specimens 1 to 4 shown in FIG. As can be clearly understood from FIG. 18, the ratio of the number of orientation distributions is less than 1.5 and the axial elongation rate is 6% or less, and the axial elongation of the balloon can be suppressed. In addition, the test bodies 1-3 which concern on a comparative example have shown the axial direction elongation rate exceeding 6%.

  As described above, in the present embodiment, the axial extension rate of the cylindrical portion of the balloon is 6% or less, which is a balloon having a specific orientation distribution number ratio of less than 1.5. Even if a birefringent polymer material having flexibility (followability to bending of a lumen in a living body) is applied as a balloon material, the axial expansion of the balloon is suppressed. It is possible. Therefore, it is possible to provide a balloon having good flexibility and capable of suppressing the balloon in the axial direction and a method for manufacturing the same.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, the medical catheter is not limited to the rapid exchange type, and an over-the-wire (OTW) type can also be applied. In this case, since the guide wire passes from the tip to the hand, the guide wire can be exchanged and operated easily.

  The balloon (cylindrical portion) can have a multi-layer structure by applying a multi-layer tubular parison made of different polymer materials as necessary.

  The stent can be coated with a drug (bioactive substance) on its outer surface. Drugs include, for example, anticancer agents, immunosuppressive agents, antibiotics, anti-rheumatic agents, antithrombotic agents, HMG-CoA reductase inhibitors, ACE inhibitors, calcium antagonists, antihyperlipidemic agents, integrin inhibitors, anti From allergic agents, antioxidants, GPIIbIIIa antagonists, retinoids, flavonoids, carotenoids, lipid improvers, DNA synthesis inhibitors, tyrosine kinase inhibitors, antiplatelet drugs, anti-inflammatory drugs, biomaterials, interferons, NO production promoters At least one compound selected from the group consisting of:

  The present invention can be applied to a stent delivery system, but is not limited to a stent, and it is needless to say that the present invention can also be applied to a balloon catheter as described above.

10 Stent delivery system,
12 Tip shaft,
14 Guide wire,
16 stent,
17 annulus,
18 struts,
19 Link part,
20 tubular parison,
22 Central part,
24 end,
26 taper part,
30 balloon,
42 cylindrical part,
44 taper part,
50 Necking device 52, 55 Chuck part,
58, 59 heater section,
60 blow molding equipment,
62,66 mold (blow mold),
64, 68 cavity surface,
70, 72 heater section,
74,76 Cooling jacket,
80, 82 chuck part,
86 injection port,
88 discharge port,
D orientation direction,
d thickness direction,
l Axial direction,
r circumferential direction,
φ _x , φ _y , φ _z crossing angle.

Claims (6)

A balloon placed on a medical catheter,
It has an expandable cylindrical part composed of a birefringent polymer material,
The ratio of the number of orientation distributions calculated by dividing the number of circumferential orientation distributions of the cylindrical part by the number of axial orientation distributions of the cylindrical part is the axis of the cylindrical part under a pressure condition of 1 to 13 atm. The balloon characterized by being adjusted to less than 1.5 so that direction elongation rate may be 6% or less.   The balloon according to claim 1, wherein the polymer material is made of an elastic resin material having a Shore hardness of 60D or less.   The elastic resin material is one selected from polyamide, polyamide elastomer, polyolefin, polyolefin elastomer, polyester, polyester elastomer, polyurethane, polyurethane elastomer, polyimide, polyvinyl chloride, fluororesin, silicone rubber, latex rubber The balloon according to claim 2, wherein   The said medical catheter is a balloon catheter used in order to indwell a stent in a body, The balloon of any one of Claims 1-3 characterized by the above-mentioned. A method of manufacturing a balloon to be placed on a medical catheter,
Blow molding a tubular parison composed of a birefringent polymer material, and having a molding step of molding the expandable tubular portion of the balloon,
In the molding step, the cylindrical part having a ratio of the number of orientation distributions adjusted so that an axial elongation rate of the cylindrical part under a pressure condition of 1 to 13 atm is 6% or less is molded,
The ratio of the orientation distribution number is calculated by dividing the circumferential orientation distribution number of the tubular portion by the axial orientation distribution number of the tubular portion,
The adjusted ratio of the number of orientation distributions is less than 1.5. The molding step includes
A first stretching step in which the tubular parison is stretched in the axial direction of the tubular parison at room temperature with pressure applied to the inside of the tubular parison;
After the first stretching step, a second stretching step of expanding the tubular parison by the pressure applied to the inside of the tubular parison while stretching the heated tubular parison in the axial direction of the tubular parison; ,
The method for producing a balloon according to claim 5, comprising: