Medical balloon and catheter

Abstract

A medical balloon (1) has a length direction (x), a radial direction (y), and a circumferential direction (p). The medical balloon (1) has: an outer layer (2) made of a first polymer material; and an inner layer (3) disposed inside the outer layer (2) and made of a second polymer material. The birefringence of the inner layer (3) in a cross section perpendicular to the length direction (x) is higher than that of the outer layer (2) in a cross section perpendicular to the length direction (x). Here, the birefringence of the inner layer (3) refers to the absolute value of the difference between the circumferential refractive index and the radial refractive index of the inner portion when the inner layer (3) is bisected radially (y); the birefringence of the outer layer (2) refers to the absolute value of the difference between the circumferential refractive index and the radial refractive index of the inner portion when the outer layer (2) is bisected radially (y).

Description

Technical Field

[0001] This invention relates to a medical balloon and a catheter having the medical balloon. Background Technology

[0002] As a treatment for angina pectoris, myocardial infarction, and other conditions caused by vascular stenosis, angioplasty is performed using a medical balloon and a catheter equipped with that balloon to dilate the narrowed portion. In addition to blood vessels, various balloon catheters have been developed for dilating narrowed portions of body cavities such as the trachea and digestive tract. Treatment using balloon catheters is a minimally invasive procedure that does not require open-chest surgery like bypass surgery, and is therefore widely practiced.

[0003] In order to design the balloon to achieve the desired performance, Patent Documents 1-5 disclose balloons with a multi-layered balloon membrane.

[0004] Patent Document 1: International Publication No. 2013 / 47449

[0005] Patent Document 2: Japanese Patent Publication No. 2009-519810

[0006] Patent Document 3: Japanese Patent Publication No. 2016-502436

[0007] Patent Document 4: Japanese Patent Publication No. 2010-527700

[0008] Patent Document 5: Japanese Patent Publication No. 2009-534094 Summary of the Invention

[0009] The fundamental properties of a medical balloon include pressure resistance, which directly affects the ability to expand the lesion, and compliance, which allows the balloon shape to adapt to the shape of the body cavity and its diameter to change according to the load pressure. Pressure resistance can be expressed, for example, by tensile strength or breaking pressure. Pressure resistance and compliance are essentially in a tradeoff relationship; the stiffer the balloon membrane, the higher the pressure resistance, but the lower the compliance, thus limiting the types of lesions that can be treated. Therefore, the object of this invention is to provide a medical balloon with high pressure resistance and high compliance, as well as a catheter incorporating this medical balloon.

[0010] The medical balloon according to the embodiments of the present invention that can solve the above-mentioned problems is described below.

[0011] [1] A medical balloon having a longitudinal direction, a radial direction and a circumferential direction, wherein it has:

[0012] The outer layer is composed of a first polymer material; and

[0013] The inner layer, located further inside the outer layer, is made of a second polymer material.

[0014] The birefringence of the inner layer in a cross-section perpendicular to the length direction is higher than that of the outer layer in a cross-section perpendicular to the length direction.

[0015] Here, the birefringence of the inner layer in a cross-section perpendicular to the length direction refers to the absolute value of the difference between the circumferential refractive index of the inner portion and the radial refractive index of the inner portion when the inner layer is divided into an inner portion and an outer portion in the radial direction.

[0016] Birefringence of the outer layer in a cross section perpendicular to the length direction refers to the absolute value of the difference between the circumferential refractive index of the inner portion of the outer layer and the radial refractive index of the inner portion of the outer layer when the outer layer is divided into an inner portion and an outer portion in the radial direction.

[0017] Furthermore, the medical balloon involved in the implementation method is preferably any one of the following [2] to [8].

[0018] [2] According to the medical balloon described in [1], the birefringence of the inner layer in the cross section perpendicular to the length direction is 0.001 or more higher than that of the outer layer in the cross section perpendicular to the length direction.

[0019] [3] The medical balloon as described in [1] or [2], wherein the first polymer material is polyamide and the second polymer material is polyamide elastomer.

[0020] [4] A medical balloon according to any one of [1] to [3], wherein the compliance of the medical balloon is higher than that of a hypothetical single-layer balloon with the same outer diameter and membrane thickness as the medical balloon.

[0021] [5] A medical balloon according to any one of [1] to [4], wherein the tensile strength of the medical balloon is higher than the tensile strength of a hypothetical single-layer balloon with the same outer diameter and membrane thickness as the medical balloon.

[0022] [6] A medical balloon according to any one of [1] to [5], wherein the cross-sectional area of ​​the inner layer in a section perpendicular to the length direction is 20% or more of the cross-sectional area of ​​the outer layer in a section perpendicular to the length direction.

[0023] [7] A medical balloon according to any one of [1] to [6], wherein a coating is disposed at a position outside the outer layer, the coating containing a physiologically active agent.

[0024] [8] According to the medical balloon described in [7], the physiologically active agent has a crystalline structure.

[0025] The catheter according to the embodiments of the present invention that can solve the above-mentioned problems is described below.

[0026] [9] A catheter comprising any one of [1] to [8] a medical balloon.

[0027] Because the aforementioned medical balloon and the catheter equipped with the medical balloon have high pressure resistance and high compliance, they can be used in various treatments without the need for distinguishing between balloons and catheters corresponding to the type of lesion or the site of the organism. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view along the length of a medical balloon according to one embodiment of the present invention.

[0029] Figure 2 It is along Figure 1 Cross-sectional end view of the balloon along line II-II.

[0030] Figure 3 It means Figure 2 The cross-sectional end view of a modified example of the cross-section of the balloon shown.

[0031] Figure 4 This is an explanatory diagram showing the sample for birefringence measurement.

[0032] Figure 5 This is a cross-sectional view along the length of a hypothetical single-layer balloon.

[0033] Figure 6 It is along Figure 5 Cross-sectional end view of a hypothetical single-layer balloon along the VI-VI line.

[0034] Figure 7 It means Figure 2 A cross-sectional end view of another modified example of the cross-section of the balloon shown.

[0035] Figure 8 It has Figure 1 The diagram shows a catheter for the balloon.

[0036] Figure 9 This is an optical microscope photograph showing the cut position of the sample cut from the balloon in Example 1.

[0037] Figure 10 This is an optical microscope photograph showing the cut-out location of the sample cut from the balloon in Example 2.

[0038] Figure 11This is an optical microscope photograph showing the cut-out location of the sample cut from the balloon in Example 3.

[0039] Figure 12 This is an explanatory diagram showing the location where the delay was measured in the embodiment.

[0040] Figure 13 This is an optical microscope photograph showing the measurement location of the delay at the cross section of the sample of Example 1.

[0041] Figure 14 This is an optical microscope photograph showing the measurement location of the delay at the cross-section of the sample in Example 2.

[0042] Figure 15 This is an optical microscope photograph showing the location of the delay measurement at the cross-section of the sample of Example 3. Detailed Implementation

[0043] The present invention will now be described in more detail based on the following embodiments. However, the present invention is not limited to the following embodiments, and can be implemented by appropriate modifications within the scope of the preceding and following text, all of which are included within the technical scope of the present invention. Furthermore, in the various drawings, for convenience, there are instances where shaded lines, component reference numerals, etc., are omitted. In such cases, refer to the specification or other drawings. Additionally, the dimensions of various components in the drawings are generally helpful in understanding the features of the present invention, and may differ from the actual dimensions.

[0044] One embodiment of the present invention relates to a medical balloon having dimensions in the longitudinal, radial, and circumferential directions. The key feature is that it comprises: an outer layer made of a first polymer material; and an inner layer disposed further inward than the outer layer, made of a second polymer material. The birefringence of the inner layer in a cross-section perpendicular to the longitudinal direction is higher than that of the outer layer in the same cross-section. Here, the birefringence of the inner layer in a cross-section perpendicular to the longitudinal direction refers to the absolute value of the difference between the circumferential refractive index and the radial refractive index of the inner portion of the inner layer when the inner layer is radially divided into an inner portion and an outer portion. Similarly, the birefringence of the outer layer in a cross-section perpendicular to the longitudinal direction refers to the absolute value of the difference between the circumferential refractive index and the radial refractive index of the inner portion of the outer layer when the outer layer is radially divided into an inner portion and an outer portion. The aforementioned medical balloons exhibit both high pressure resistance and high compliance, enabling them to be used for various treatments without requiring the use of balloons corresponding to specific types of lesions or body sites.

[0045] Reference Figures 1 to 8The following describes a medical balloon and catheter according to one embodiment of the present invention. Hereinafter, the medical balloon will sometimes be referred to simply as a balloon. Figure 1 This is a cross-sectional view along the length of a medical balloon according to one embodiment of the present invention. Figure 2 It is along Figure 1 Cross-sectional end view of the balloon along line II-II. Figure 3 It means Figure 2 The cross-sectional end view of a modified example of the cross-section of the balloon shown. Figure 4 This is an explanatory diagram showing the specimen used for measuring the circumferential refractive index. Figure 5 It is a cross-sectional view of a hypothetical single-layer balloon along its length. Figure 6 It is along Figure 5 Cross-sectional end view of a hypothetical single-layer balloon along the VI-VI line. Figure 7 It means Figure 2 A cross-sectional end view of another modified example of the cross-section of the balloon shown. Figure 8 It has Figure 1 A schematic diagram of the catheter for the balloon shown.

[0046] like Figure 1 As shown, the balloon 1 has a length direction x, a radial direction y, and a circumferential direction p. (As...) Figure 1 As shown, balloon 1 preferably has a distal end 5A and a proximal end 5B in the length direction x. The proximal side of balloon 1 refers to the direction relative to the user's or surgeon's hand side in the length direction x of balloon 1, and the distal side refers to the opposite direction of the proximal side, i.e., the direction towards the treatment target. Furthermore, in Figure 1 In the diagram, the right side represents the proximal side, and the left side represents the distal side. The radial direction y of balloon 1 refers to the radial direction of balloon 1. The inward direction of the radial direction y refers to the direction towards the center of the long axis of balloon 1, and the outward direction refers to the direction extending radially from the center of the long axis in the opposite direction. The circumferential direction p of balloon 1 refers to the direction around the long axis. Balloon 1 preferably has an outer surface 6A and an inner surface 6B.

[0047] like Figures 1-2 As shown, the balloon 1 has: an outer layer 2, made of a first polymer material; and an inner layer 3, disposed inside the outer layer 2, made of a second polymer material. In the radial direction y, the inner layer 3 is disposed inside the outer layer 2. The outer layer 2 can be disposed on the outermost side in the radial direction y. The inner layer 3 can be disposed on the innermost side in the radial direction y. Figure 2 As shown, in the radial direction y, the outer layer 2 and the inner layer 3 can abut against each other. One or more layers can be disposed between the outer layer 2 and the inner layer 3 in the radial direction y. For example, in... Figure 3 In the middle, an intermediate layer 4 is arranged between the outer layer 2 and the inner layer 3.

[0048] like Figure 2As shown, for balloon 1, the birefringence Δn of the inner layer 3 in a section perpendicular to the length direction x is... i (Ring) Birefringence Δn of the outer layer 2 in a section perpendicular to the length direction x o (Ring). Here, the birefringence Δn of the inner layer 3 in the section perpendicular to the length direction x. i (Ring) refers to the circumferential refractive index n of the inner portion 3A of the inner layer 3 when the inner layer 3 is divided into an inner portion 3A and an outer portion 3B in the radial y direction. ri The refractive index n of the radial y of the inner side 3A of the inner layer 3 di The absolute value of the difference, the birefringence Δn of the outer layer 2 in the section perpendicular to the length direction x. o (Ring) refers to the circumferential refractive index n of the inner portion 2A of the outer layer 2 when the outer layer 2 is divided into an inner portion 2A and an outer portion 2B in the radial direction y. ro The refractive index n of the radial y of the inner side 2A of the outer layer 2 is... do The absolute value of the difference. By setting the relationship between the birefringence of the outer layer 2 and the inner layer 3 in this way, the balloon 1 possesses both high pressure resistance and high compliance. Therefore, the balloon can be used for various treatments without the need for distinguishing between balloons corresponding to different types of lesions or biological sites.

[0049] In this specification, refractive index refers to relative refractive index. The birefringence Δn of the outer layer 2 in a cross-section perpendicular to the length direction x. o Birefringence Δn of (ring) and inner layer 3 i (Rings) can be determined by the following methods. For example... Figure 4 As shown, a balloon membrane obtained by cutting the balloon 1 along the length direction x and the radial direction y is used as the test specimen 15. The test specimen 15 is obtained by cutting the membrane of the balloon 1 using a knife or other cutting tool or a laser irradiation device. The size and shape of the test specimen 15 are arbitrary. Hereinafter, the section of the test specimen 15 perpendicular to the length direction x of the balloon 1 is sometimes referred to as the circumferential section 16, and the section of the test specimen 15 along the length direction x of the balloon 1 is referred to as the major axis section 17. The circumferential section 16 of the test specimen 15 is observed using a polarizing microscope, and the following is measured using a compensator (compensation device): (i) the delay R at the circumferential section 16 of the test specimen 15 in the inner side 2A of the outer layer 2. o (ii) The delay R at the circumferential section 16 of the specimen 15 in the inner side 3A of the inner layer 3. i (Ring). Additionally, the thickness t1 of specimen 15 is measured. Thickness t1 is the length of specimen 15 in the direction perpendicular to the circumferential section 16 of specimen 15. The unit of retardation is nm, and the unit of thickness t1 is μm. For example... Figure 4 As shown, delay R oSubstituting the ring into R in equations (1) to (2), and substituting the thickness t1 into t in equation (1), equations (1) to (3) can be used to calculate the birefringence Δn of the outer layer 2 in the annular section 16. o (Ring). Furthermore, delay R... i Substituting the ring into R in equations (1) to (2), and substituting the thickness t1 into t in equation (1), equations (1) to (3) can be used to calculate the birefringence Δn of the inner layer 3 in the circumferential section 16. i (Ring). Furthermore, in the following formula, C is a dimensionless constant that depends on the thickness of the crystal installed in the compensator (compensation device), and i is the correction angle (rad) of the compensation device.

[0050] Δn=R / t ・・・(1)

[0051] R=C×f(i)・・・(2)

[0052] f(i)=sin²i(1+0.2041×sin²i+0.0627×sin 4 i) ・・・(3)

[0053] The birefringence Δn of the outer layer 2 in the major axis section 17 can be determined using the following method. o (Length) and birefringence Δn of inner layer 3 i (Length). First, the long axis section 17 of the specimen 15 is observed using a polarizing microscope, and the following is measured using a compensator (compensation device): (iii) the retardation R at the long axis section 17 of the specimen 15 in the inner part 2A of the outer layer 2. o (iv) The retardation R at the major axis section 17 of the specimen 15 in the inner side 3A of the inner layer 3. i (Length). At this time, the thickness t2 of specimen 15 is also measured. Thickness t2 is the length of specimen 15 in the direction perpendicular to the major axis section 17 of specimen 15. The specimen used for the delay measurement at the circumferential section 16 can be the same specimen used for the delay measurement at the major axis section 17, or they can be specimens cut separately from the balloon. The unit of delay is nm, and the unit of thickness t2 is μm. The delay R... o Substituting the length into R in equations (1) to (2), and substituting the thickness t2 into t in equation (1), we can calculate equations (1) to (3) and thus determine the birefringence Δn of the outer layer 2 in the major axis section 17. o (Long). Furthermore, R will be delayed. i Substituting the length into R in equations (1) to (2), and substituting the thickness t_2 into t in equation (1), equations (1) to (3) can be used to calculate the birefringence Δn of the inner layer 3 in the major axis section 17. i (long).

[0054] Birefringence Δn of outer layer 2 in circumferential section 16 o (Ring) and the birefringence Δn of the outer layer 2 in the major axis section 17 o (Length) is expressed by the following formulas (4) to (6). In the following formulas, n ro The refractive index (dimensionless) on the circumferential p of the outer layer 2 spherical capsule 1, n do n is the refractive index (dimensionless) along the thickness direction (radial y) of the outer layer 2, sphere 1. Lo n is the refractive index (dimensionless) along the length x direction of the outer layer 2 spherical capsule 1. o It is the average refractive index of outer layer 2 (dimensionless).

[0055] Δn o (Ring) = |n ro -n do | ・・・(4)

[0056] Δn o (Length) = |n Lo -n do | ・・・(5)

[0057] n o =(n ro ²+n Lo ²+n do ²) / 3 ・・・(6)

[0058] Birefringence Δn of inner layer 3 in circumferential section 16 o (Ring) and the birefringence Δn of the inner layer 3 in the major axis section 17 o (Length) is expressed by equations (7) to (9). In the following equations, n ri The refractive index (dimensionless) on the circumferential p of the inner layer 3 of the spherical capsule 1, n di n is the refractive index (dimensionless) along the thickness direction (radial y) of the inner layer 3 of the spherical capsule 1. Li n is the refractive index (dimensionless) along the length x direction of the inner layer 3 of the spherical capsule 1. i It is the average refractive index (dimensionless) of inner layer 3.

[0059] Δn i (Ring) = |n ri -n di | ・・・(7)

[0060] Δn i (Length) = |n Li -n di | ・・・(8)

[0061] n i =(n ri ²+nLi ²+n di ²) / 3 ・・・(9)

[0062] Furthermore, by solving equations (4) to (9) as shown in equations (10) to (14), the refractive index n on the circumferential p of the spherical bladder 1 can be obtained. r .

[0063] [Formula 1]

[0064]

[0065] n L =n d +Δn (length) ・・・(11)

[0066] nd=n r -Δn (ring) ・・・ (12)

[0067] b = 2Δn (length) - 4Δn (ring) ・・・(13)

[0068] c = 2(Δn(ring))² + Δn(length))² - 2Δn(ring) × Δn(length) - 3n² ・・・(14)

[0069] The delay value at each cross section of the sample in the inner side portion 2A of the outer layer 2 is preferably the delay at the inner side of the radial y in the inner side portion 2A, more preferably the delay at the innermost region of the radial y when the inner side portion 2A is bisected in the radial y of the balloon 1, even more preferably the delay at the innermost region of the radial y when the inner side portion 2A is trisected in the radial y of the balloon 1, and even more preferably the delay at the innermost region of the radial y when the inner side portion 2A is quadrupled in the radial y of the balloon 1.

[0070] The delay value at each cross section of the sample in the inner side portion 3A of the inner layer 3 is preferably the delay at the inner side position of the radial y in the inner side portion 3A, more preferably the delay at the innermost region of the radial y when the inner side portion 3A is bisected in the radial y of the balloon 1, even more preferably the delay at the innermost region of the radial y when the inner side portion 3A is trisected in the radial y of the balloon 1, and even more preferably the delay at the innermost region of the radial y when the inner side portion 3A is quadrupled in the radial y of the balloon 1.

[0071] The refractive indices (n) of the inner part 2A of outer layer 2 ro n do n LoThe refractive index is preferably located at the inner side of the radial y direction in the inner side portion 2A, more preferably at the region of the innermost side of the radial y direction when the inner side portion 2A is bisected in the radial y direction of the balloon 1, even more preferably at the region of the innermost side of the radial y direction when the inner side portion 2A is trisected in the radial y direction of the balloon 1, and even more preferably at the region of the innermost side of the radial y direction when the inner side portion 2A is quadrupled in the radial y direction of the balloon 1.

[0072] The refractive indices (n) of the inner side portion 3A of inner layer 3 ri n di n Li The refractive index is preferably located at the inner side of the radial y direction in the inner side portion 3A, more preferably at the region of the innermost side of the radial y direction when the inner side portion 3A is bisected in the radial y direction of the balloon 1, even more preferably at the region of the innermost side of the radial y direction when the inner side portion 3A is trisected in the radial y direction of the balloon 1, and even more preferably at the region of the innermost side of the radial y direction when the inner side portion 3A is quadrupled in the radial y direction of the balloon 1.

[0073] In this specification, the delay R can be measured at any position along the length x of the balloon 1, but it is preferable to measure it at the straight tube portion 11A of the balloon 1, and more preferably at the portion of the straight tube portion of the balloon 1 including the central position along the length x. That is, it is preferable to cut the test sample 15 from the straight tube portion 11A of the balloon 1. The straight tube portion 11A will be described later.

[0074] Preferably, the birefringence Δn of the inner layer 3 is in a cross-section perpendicular to the length direction x (circumferential section 16). i (Ring) Birefringence Δn of the outer layer 2 in a section perpendicular to the length direction x (ring section 16) o (Ring) Height 0.001 or higher. By setting the size relationship of the birefringence in this way, it is easier to obtain a balloon 1 with both high pressure resistance and high compliance performance.

[0075] Birefringence Δn of inner layer 3 in circumferential section 16 i (The ring) can have a birefringence Δn in the outer layer 2 of the ring section 16. o The (ring) height can be 0.002 or higher, 0.003 or higher, 0.006 or higher, 0.008 or higher, or 0.010 or higher, or it can be lower than 0.030, 0.025 or lower, 0.020 or lower, 0.018 or lower, or 0.014 or lower. By setting the birefringence size relationship in this way, it is easier to obtain a balloon 1 that has both high pressure resistance and high compliance performance.

[0076] Examples of polymer materials constituting the balloon 1 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomers; polyurethane resins such as polyurethane and polyurethane elastomers; polyphenylene sulfide resins; polyamide resins such as polyamide and polyamide elastomers; fluorinated resins; silicone resins; and natural rubber such as latex rubber. Only one type of these resin may be used, or two or more may be used in combination. Polyamide resins, polyester resins, and polyurethane resins are preferred. In particular, from the viewpoint of the balloon 1's thin-film properties and flexibility, elastomer resins are preferred. For example, among polyamide resins, nylon 12 and nylon 11 are suitable as resins constituting the balloon 1, and nylon 12 is more preferred due to its ease of molding during blow molding. Furthermore, from the viewpoint of the balloon 1's thin-film properties and flexibility, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferred. Among these considerations, polyether ester amide elastomer is preferred because it provides high yield strength and good dimensional stability of the balloon 1.

[0077] The first polymer material constituting the outer layer 2 and the second polymer material constituting the inner layer 3 can be of the same type, but preferably they are different types. Among the aforementioned polymer materials, it is preferable that both the first and second polymer materials are polyamide resins. Furthermore, it is preferable that the first polymer material is polyamide and the second polymer material is a polyamide elastomer. By selecting the materials for the outer layer 2 and the inner layer 3 in this way, a balloon 1 with both high pressure resistance and high compliance can be obtained.

[0078] like Figure 3 As shown, when the balloon 1 has an intermediate layer 4 between the outer layer 2 and the inner layer 3, the intermediate layer 4 can also be made of the aforementioned polymer material. The third polymer material constituting the intermediate layer 4 can be of the same type as the first polymer material constituting the outer layer 2, but is preferably a different type. The third polymer material constituting the intermediate layer 4 can be of the same type as the second polymer material constituting the inner layer 3, but is preferably a different type.

[0079] The balloon 1 can be manufactured by molding a polymer material. For example, the balloon 1 can be manufactured by placing an extruded tube in a mold and performing biaxial stretch blow molding. The balloon 1 can be formed into any shape depending on the shape of the mold. In addition to biaxial stretch blow molding, the balloon 1 can also be manufactured by molding methods such as dip molding, injection molding, and compression molding.

[0080] The membrane thickness of balloon 1 can be, for example, 10 μm or more, 30 μm or more, or 50 μm or more, and is also permitted to be 150 μm or less, 120 μm or less, or 100 μm or less. The numerical range described herein can be the membrane thickness after expansion, but is preferably the membrane thickness before expansion. In addition, the membrane thickness of balloon 1 can be measured using a known displacement gauge.

[0081] The compliance (in mm / atm) of the preferred balloon 1 is higher than that of a hypothetical monolayer balloon 50 with the same outer diameter and membrane thickness. Therefore, compared to existing monolayer balloons, a wider range of vessel diameters can be covered with a single product. Furthermore, because it is more flexible than existing monolayer balloons, damage to blood vessels can be prevented, and it also offers good responsiveness to manipulations on the hand side when the balloon 1 is inserted into the body. Figures 5-6 The structure of a hypothetical single-layer balloon 50 is shown. Furthermore, the material of the balloon membrane of the hypothetical single-layer balloon 50 is not particularly limited, but it can be made of the same material as the outer layer 2, inner layer 3, or intermediate layer 4 of the balloon 1. Figures 5-6 A monolayer balloon 50 consisting of a polyamide layer 51 is shown.

[0082] The compliance of balloon 1 is preferably 1.03 times or more, more preferably 1.05 times or more, more preferably 1.07 times or more, more preferably 1.10 times or more, more preferably 1.30 times or more, and may also be 1.50 times or more. Alternatively, the compliance of balloon 1 may be 5.00 times or less, 4.00 times or less, 3.00 times or less, or 2.70 times or less, the compliance of a hypothetical single-layer balloon 50 with the same outer diameter and membrane thickness as balloon 1.

[0083] The compliance of balloon 1 is expressed by the slope (mm / atm) of a compliance curve that shows the relationship between the increase in the outer diameter of balloon 1 and the increase in expansion pressure (atm) applied to the interior of balloon 1 within a specified operating range, for example, from 1 atm to the burst diameter. Furthermore, the outer diameter of balloon 1 can be measured using known measuring instruments such as vernier calipers.

[0084] The preferred balloon 1 has a tensile strength (in MPa) higher than that of a hypothetical single-layer balloon 50 with the same outer diameter and membrane thickness. Therefore, it can be used even when high pressure is applied inside the balloon 1, resulting in high expansion force and making it suitable for dilating hard lesions such as calcified areas. Furthermore, due to its good pushability, the balloon 1 is easily advanced even through narrowed areas when inserted into the body.

[0085] The tensile strength of balloon 1 is expressed as "rupture pressure × balloon outer diameter before rupture / balloon membrane thickness". The pressure of the fluid supplied to the balloon is measured while the balloon is being expanded. The rupture pressure (unit: MPa) is the pressure at which the balloon ruptures. The balloon membrane thickness is the membrane thickness under conditions where no load other than gravity is applied to the balloon, and is the membrane thickness before fluid is supplied to the balloon.

[0086] The tensile strength of the balloon 1 is preferably 1.02 times or more than that of the tensile strength of a hypothetical monolayer balloon 50 with the same outer diameter and membrane thickness as the balloon 1, more preferably 1.05 times or more, even more preferably 1.10 times or more, and even more preferably 1.15 times or more. In addition, it is also permissible to have a tensile strength of 3.00 times or less, 2.50 times or less, 2.00 times or less, or 1.80 times or less.

[0087] The preferred balloon 1 has a higher burst pressure than a hypothetical single-layer balloon 50 with the same outer diameter and membrane thickness. Therefore, it can be used even when high pressure is applied inside the balloon 1, resulting in high expansion force and making it suitable for dilating hard lesions such as calcified areas. Furthermore, due to its good pushability, the balloon 1 is easily advanced even through narrowed areas when inserted into the body.

[0088] The burst pressure of balloon 1 is preferably 1.1 times or more than the burst pressure of a hypothetical monolayer balloon 50 with the same outer diameter and membrane thickness as balloon 1, more preferably 1.2 times or more, and even more preferably 1.3 times or more. In addition, it is also permissible to be 5.0 times or less, 4.0 times or less, 3.0 times or less, 2.8 times or less, or 2.5 times or less.

[0089] according to Figure 2 As can be understood, the cross-sectional area of ​​the inner layer 3 in the section perpendicular to the length direction x is preferably 20% or more of the cross-sectional area of ​​the outer layer 2 in the section perpendicular to the length direction x. By setting the cross-sectional area ratio of the outer layer 2 to the inner layer 3 in this way, it is easy to obtain a balloon 1 that has both high pressure resistance and high compliance performance. Here, the section perpendicular to the length direction x used for comparing the cross-sectional area ratio refers to a section at any position in the length direction x of the balloon 1, but it can be, for example, a section at the center position in the length direction x of the balloon 1. The same applies in the following description.

[0090] according to Figure 2As can be understood, the cross-sectional area of ​​the inner layer 3 in the section perpendicular to the length direction x is more preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. Furthermore, the cross-sectional area of ​​the inner layer 3 in the section perpendicular to the length direction x is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. By setting the cross-sectional area ratio of the outer layer 2 to the inner layer 3 in this way, it is easier to obtain a balloon 1 with both higher pressure resistance and higher compliance performance.

[0091] like Figure 1 As shown, the balloon 1 may have: an expansion portion 11; a distal sleeve portion 12A located distal to the expansion portion 11; and a proximal sleeve portion 12B located closer to the expansion portion 11. Preferably, the distal sleeve portion 12A and / or the proximal sleeve portion 12B are fixed to the shaft 30 described later.

[0092] according to Figure 1 As can be understood, in the entire length x of the expansion portion 11 of the balloon 1, the cross-sectional area of ​​the inner layer 3 in the section perpendicular to the length x is preferably 20% or more, more preferably 30% or more, further preferably 40% or more, and even more preferably 50% or more. Furthermore, in the entire length x of the expansion portion 11 of the balloon 1, the cross-sectional area of ​​the inner layer 3 in the section perpendicular to the length x is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. By setting the cross-sectional area ratio of the outer layer 2 to the inner layer 3 of the expansion portion 11 in this way, it is easier to obtain a balloon 1 with both higher pressure resistance and higher compliance performance.

[0093] The thickness ratio of the outer layer 2 to the inner layer 3 of the balloon 1 (thickness of outer layer 2 / thickness of inner layer 3) can be greater than 1 / 9, greater than 2 / 8, greater than 3 / 7, greater than 4 / 6, or less than 9 / 1, less than 8 / 2, less than 7 / 3, less than 6 / 4.

[0094] The membrane thickness of balloon 1, including the outer layer 2 and the inner layer 3, can be, for example, 10 μm or more, 30 μm or more, or 50 μm or more, and is also permitted to be 150 μm or less, 120 μm or less, or 100 μm or less. The numerical range described herein can be the membrane thickness after expansion, but is preferably the membrane thickness before expansion. Furthermore, the membrane thickness described herein is preferably the minimum membrane thickness of balloon 1. Additionally, the membrane thickness of balloon 1 can be measured using a known displacement gauge.

[0095] like Figure 7As shown, in balloon 1, a coating 20 can be disposed at a position further outward than the outer layer 2. The slippage of the outer surface of balloon 1 is improved by the presence of coating 20, thereby improving the insertion permeability of balloon 1 when it is inserted into the body cavity.

[0096] The material forming the coating 20 can be hydrophilic or hydrophobic, but is preferably hydrophilic. As a hydrophilic coating agent, hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether-maleic anhydride copolymer, or hydrophilic coating agents made from any combination thereof, can be used. Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), silicone oil, hydrophobic polyurethane resin, carbon coatings, diamond coatings, diamond-like carbon (dLC) coatings, ceramic coatings, and substances with low surface free energy terminated by alkyl or perfluoroalkyl groups.

[0097] The preferred coating 20 contains a physiologically active pharmaceutical agent. The presence of a physiologically active pharmaceutical agent in the coating 20 of the balloon 1 improves treatment efficiency.

[0098] Examples of physiologically active substances used in physiologically active pharmaceutical agents include paclitaxel, docetaxel, sirolimus, tesimolimus, everolimus, zotamolimus, biolimus A9, cilostazol, cyclosporine, and NF-κB decoy oligonucleotides. These physiologically active substances can be used as monomers or in combination. Furthermore, the physiologically active substance can be coated onto the balloon 1 alone, or appropriately combined with additives.

[0099] Preferably, the physiologically active agent has a crystalline structure. Because the agent has a crystalline structure, it is easily retained on the surface of the balloon 1 during delivery. Furthermore, since the positions of the agent molecules within the crystalline structure are defined, the agent is stable relative to environmental and temperature changes. Moreover, by having a crystalline structure, the physiologically active agent's brittleness is increased, making it easier for it to detach from the outer surface of the balloon 1 when it is inflated.

[0100] When using physiologically active pharmaceutical agents with a crystalline structure, the physiologically active substance is preferably crystalline. Examples of crystalline physiologically active substances include paclitaxel, sirolimus, everolimus, and zotamolimus. Furthermore, additives included with the physiologically active substance are also preferably crystalline. Examples of crystalline additives include sugars, urea, salts such as potassium iodide, ascorbic acid, polylactic acid, and polyglycolic acid.

[0101] Although not illustrated, the balloon 1 may have a balloon body and a protrusion extending outward in a radial direction (y) towards the balloon body. The protrusion is the portion of the balloon 1 that protrudes outward in a radial direction (y) beyond the outer surface of the balloon body when the balloon 1 is inflated. The protrusion facilitates the formation of an incision of appropriate depth in narrow sections, making cutting easier. Furthermore, it increases the strength of the balloon 1 and suppresses excessive inflation during pressurization. When the balloon 1 has a balloon body and a protrusion, it is preferable that the balloon body has the aforementioned outer layer 2 and inner layer 3. The protrusion may be made of the same material as the balloon body or a different material.

[0102] like Figure 1 As shown, the expansion portion 11 of the balloon 1 may have: a straight tube portion 11A; a distal conical portion 11B located distal to the straight tube portion 11A; and a proximal conical portion 11C located closer to the straight tube portion 11A. Preferably, the outer diameters of the distal conical portion 11B and the proximal conical portion 11C decrease as they move away from the straight tube portion 11A.

[0103] The shape of the expansion portion 11 of the balloon 1 is not particularly limited, and can be spherical, ellipsoidal, cylindrical, conical, frustum-shaped, or a combination thereof.

[0104] like Figure 8 As shown, in one embodiment of the present invention, the catheter 40 includes the aforementioned balloon 1. The catheter 40 with the balloon 1 has high pressure resistance and compliance, enabling it to be used for the treatment of various lesions without requiring the use of balloons 1 corresponding to specific lesion types or body sites.

[0105] like Figure 8 As shown, the preferred catheter 40 has a shaft 30 and a balloon 1 disposed outside the shaft 30. The preferred catheter 40 has a distal side and a proximal side, with the balloon 1 disposed distal to the shaft 30. The catheter 40 is configured to supply fluid to the interior of the balloon 1 through the shaft 30, and the expansion and contraction of the balloon 1 can be controlled using a pressurizing device (balloon pressurizer). The fluid can be a pressurized fluid, such as a pump.

[0106] In addition to providing a flow path for fluid to expand the balloon, shaft 30 may also have a guidewire insertion path. For example, according to... Figure 8As can be understood, shaft 30 may have an outer tube 31 and an inner tube 32 disposed within the cavity of the outer tube 31. In this case, the cavity of the inner tube 32 can function as an insertion passage for the guidewire, and the space between the inner tube 32 and the outer tube 31 can function as a flow path for fluid. When shaft 30 has an outer tube 31 and an inner tube 32, preferably the inner tube 32 extends from the distal end of the outer tube 31 and extends to a position distal to the balloon 1, with the distal side of the balloon 1 engaged with the inner tube 32 and the proximal side of the balloon 1 engaged with the outer tube 31.

[0107] Examples of materials constituting the shaft 30 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluorinated resins, vinyl chloride resins, silicone resins, and natural rubber. Only one type of these may be used, or two or more may be used in combination. Preferably, the material constituting the shaft 30 is at least one of polyamide resins, polyolefin resins, and fluorinated resins. This improves the slipperiness of the shaft 30 surface and enhances the insertion portability of the catheter 40 within the body cavity.

[0108] Examples of joining balloon 1 and shaft 30 include adhesive bonding, welding, installing annular components at the overlapping portion of balloon 1 and shaft 30, and suturing.

[0109] like Figure 8 As shown, a hub 35 can be provided proximal to the shaft 30 in the catheter 40. The hub 35 may have a fluid injection section 37 communicating with the flow path of fluid supplied to the balloon 1. Preferably, the hub 35 has a guidewire insertion section 36 communicating with the guidewire insertion path. This allows for easy operation of supplying fluid to the balloon 1 to inflate or deflate it, and easy delivery of the catheter 40 along the guidewire to the treatment site. Figure 8 The image shows an example of a so-called integral exchange catheter 40 in which the balloon 1 is used to insert the guidewire from the distal side of the shaft 30 to the proximal side. However, the balloon 1 can also be used in a so-called rapid exchange catheter in which the guidewire is inserted from the distal side of the shaft to the proximal side midway.

[0110] This application claims a benefit based on priority of Japanese Patent Application No. 2024-53838, filed on March 28, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-53838, filed on March 28, 2024, are incorporated herein by reference.

[0111] Example

[0112] Embodiments and comparative examples of the present invention will be described. However, the medical balloon according to one embodiment of the present invention is not limited to the descriptions of the embodiments and comparative examples.

[0113] (Balloon fabrication)

[0114] Example 1

[0115] A double-layered tube was formed, with an outer layer of polyamide (Rilsamid AESNO MED, Arkema) and an inner layer of polyamide elastomer (PEBAX 6333, Arkema). Dry nitrogen gas at 120°C was blow-molded into the resulting tube at a pressure of 5.0 MPa for 60 seconds. This produced a balloon with an outer diameter of 4.00 mm and a film thickness of 40.0 μm. Furthermore, the outer diameter shown here refers to the mold diameter; the same applies to Examples 2-3 and Comparative Examples 12-14.

[0116] Example 2

[0117] A double-layer tube was fabricated using the same material composition and molding conditions as in Example 1. Under the same blow molding conditions as in Example 1, a double-layer balloon with an outer diameter of 6.00 mm and a film thickness of 40.0 μm was fabricated.

[0118] Example 3

[0119] A double-layer tube was fabricated using the same material composition and molding conditions as in Example 1. Under the same blow molding conditions as in Example 1, a double-layer balloon with an outer diameter of 8.00 mm and a film thickness of 40.0 μm was fabricated.

[0120] Comparative Examples 12-14

[0121] A monolayer balloon, Rilsamid AESNO MED (outer diameter 6.00 mm, membrane thickness 30 μm), made of polyamide manufactured by Arkema, was fabricated (Comparative Example 12); a monolayer balloon, SHIDEN HP (outer diameter 5.00 mm, membrane thickness 40 μm), made of polyamide manufactured by Kaneka Corporation, was fabricated (Comparative Example 13); and a monolayer balloon, PEBAX6333 (outer diameter 3.50 mm, membrane thickness 30 μm), made of polyamide elastomer manufactured by Arkema, was fabricated (Comparative Example 14).

[0122] The physical properties of the balloons in Examples 1-3 and Comparative Examples 12-14 (size of the tubing used for balloon manufacturing, thickness ratio of each layer of the balloon in the radial direction relative to the overall membrane thickness, expansion ratio (mold diameter / tubing size), membrane thickness, burst pressure, outer diameter of the balloon at 0.1 MPa, outer diameter of the balloon at RBP, outer diameter of the balloon at burst, tensile strength, compliance, elongation, birefringence of the outer layer in a section perpendicular to the length direction, and birefringence of the inner layer in a section perpendicular to the length direction) were measured and calculated by the following methods. Furthermore, the physical properties of the balloons in Comparative Examples 1-11 were either converted from the data described in Examples 1-9 and Comparative Examples 1-2 of Patent Document 1 (International Publication No. 2013 / 47449), or converted after unit conversion, or the required physical property values ​​were calculated based on that data. The results are shown in Tables 2 and 3.

[0123] (Pipe fitting dimensions)

[0124] For Examples 1-3 and Comparative Examples 12-14, the inner and outer diameters of the tubing used for balloon manufacturing were measured using an AxisPro optical microscope manufactured by Micro Support. Furthermore, for Comparative Examples 1-11, the dimensions of the tubing described in Examples 1-9 and Comparative Examples 1-2 of Patent Document 1 were copied (for example, φ0.37×0.47×0.82×0.88mm in Example 1 of Patent Document 1).

[0125] (The ratio of the thickness of each layer of the balloon relative to the overall membrane thickness in the radial direction)

[0126] For Examples 1-3 and Comparative Examples 12-14, the overall membrane thickness of the balloon was measured using a Mitutoyo digital micrometer K330721A. Additionally, for Examples 1-3 and Comparative Examples 12-14, the thickness of each layer of the balloon was measured using an Axis Pro optical microscope manufactured by Micro Support. Then, the thickness ratio (%) of each layer of the balloon relative to the overall membrane thickness in the radial direction was calculated. For Comparative Examples 1-11, the thickness ratio of each layer of the balloon relative to the overall membrane thickness was calculated based on the dimensions of the tubing described in Examples 1-9 of Patent Document 1 and Comparative Examples 1-2 (e.g., φ0.37×0.47×0.82×0.88mm in Example 1 of Patent Document 1).

[0127] (Expansion ratio (mold diameter / fitting size))

[0128] For Examples 1-3 and Comparative Examples 1-14, the expansion ratio was calculated based on the mold diameter and pipe size, respectively. The mold diameter is also listed in Table 2. The mold diameters for Examples 1-3 and Comparative Examples 12-14 were measured using a Mitutoyo digital micrometer K330721A. The mold diameters for Comparative Examples 1-11 were calculated using the formula "pipe innermost diameter × inner diameter expansion ratio". For example, in Comparative Example 1 (Example 1 of Patent Document 1), the innermost diameter of the pipe was 0.37 mm, and the inner diameter expansion ratio was 8.2 times; therefore, the mold diameter was 3.03 mm.

[0129] (film thickness)

[0130] For Examples 1-3 and Comparative Examples 12-14, the overall membrane thickness of the balloon was measured using a Mitutoyo digital micrometer K330721A. For Comparative Examples 1-11, the membrane thickness was calculated based on the dimensions of the tubing described in Examples 1-9 of Patent Document 1 and Comparative Examples 1-2 (for example, φ0.37×0.47×0.82×0.88mm in Example 1 of Patent Document 1).

[0131] (Destructive pressure)

[0132] For the balloons of Examples 1-3 and Comparative Examples 12-14, the pressure of the fluid supplied to the inside of the balloon was measured while the balloon was expanded, and the pressure applied to the balloon immediately before failure was taken as the failure pressure (MPa). The failure pressures of Examples 1-3 and Comparative Examples 12-14 were measured using a leak tester 1000 manufactured by Crescent Design. The failure pressures of Comparative Examples 1-11 were obtained by converting the pressure resistance (balloon failure pressure) values ​​described in the examples of Patent Document 1 from atm to MPa.

[0133] (Ball outer diameter at 0.1 MPa, balloon outer diameter during RBP, balloon outer diameter at rupture)

[0134] For Examples 1-3 and Comparative Examples 12-14, the outer diameter of the balloon at 0.1 MPa and the outer diameter of the balloon at rupture were measured. The measurements were performed using a Crescent Design Leak Tester 1000 and a Keyence High-Precision Dimensioning Instrument LS-3100. For Comparative Examples 1-11, the outer diameter at the maximum pressure of 22 atm (the outer diameter at 12 atm + the outer diameter when expanded to RBP (22 atm) according to the described compliance) was calculated as the outer diameter of the balloon at RBP. For example, in Comparative Example 1 (Example 1 of Patent Document 1), it was 3.00 + 0.01 × 10 = 3.1 mm. Here, RBP (Rated Burst Pressure) refers to the lower limit pressure at which the balloon ruptures with a 99.9% or higher confidence level.

[0135] (Tensile strength)

[0136] The tensile strength (MPa) of the balloons in Examples 1-3 and Comparative Examples 12-14 was calculated using the formula: "Tensile strength = Failure pressure × {(Balloon outer diameter at rupture - membrane thickness × 2) / 2} / membrane thickness". For Comparative Examples 1-11, since Patent Document 1 does not specify the balloon inner diameter at rupture, the outer diameter at the maximum pressure calculated from Patent Document 1 (i.e., 22 atm) was used as the outer diameter at rupture, and the tensile strength was calculated using the above formula.

[0137] (Accommodation)

[0138] The compliance of Examples 1-3 and Comparative Examples 12-14 was calculated using the formula: "(outer diameter of the balloon at rupture (mm) - outer diameter of the balloon at 0.1 MPa (mm)) / rupture pressure (MPa)". The compliance of Comparative Examples 1-11 was calculated using the formula: "(outer diameter of the balloon at RBP (mm) - mold diameter (mm)) / pressure at RBP (MPa)". In general, compliance refers to the result of calculating the change in pressure per unit from the nominal pressure (12 atm in the embodiment of Patent Document 1) to the RBP pressure (22 atm in the embodiment of Patent Document 1) as described in Patent Document 1. The nominal pressure refers to the pressure at which the balloon expands to its nominal outer diameter. However, (1) the outer diameter and pressure resistance characteristics of the balloons in the embodiments of the present invention are different from those in the embodiments of Patent Document 1 and the comparative examples. In addition, (2) the working range of the expansion pressure used to calculate the above-mentioned general compliance value can be freely set to a certain extent by those skilled in the art. Furthermore, (3) since the outer diameter of the balloon changes non-linearly until it breaks, setting the numerical value according to the working range of the balloon expansion pressure may lead to a favorable interpretation. In view of the above (1) to (3), we believe that it is not preferable to compare with general compliance (nominal pressure to RBP pressure). Therefore, in this specification, the range from the minimum outer diameter to the maximum outer diameter, which can be measured or calculated experimentally, is calculated using the change in pressure per unit. The same applies to the elongation described later.

[0139] (Elongation)

[0140] Elongation (%) is the ratio of the balloon's outer diameter to the mold's inner diameter. Furthermore, for Examples 1-3 and Comparative Examples 12-14, the outer diameter of the balloon at rupture and at 0.1 MPa pressure were measured using a Crescent Design Leak Tester 1000 and a Keyence High-Precision Dimensioning Instrument LS-3100. The elongation was calculated using the formula: "(Outer diameter of the balloon at rupture – Outer diameter of the balloon at 0.1 MPa pressure) / Outer diameter of the balloon at 0.1 MPa pressure". The elongation for Comparative Examples 1-11 was calculated using the formula: "(Outer diameter of the balloon at RBP – Mold diameter) / Mold diameter". The reason for this calculation in Comparative Examples 1 to 11 is that Patent Document 1 only records the average elongation from the nominal pressure to RBP. Therefore, the maximum value that can be calculated and controlled, namely the outer diameter at RBP (the outer diameter is 3.1 mm at 2.2 MPa (22 atm) in Comparative Example 1), is used as the maximum diameter, and the mold diameter is used as the minimum value to calculate the elongation.

[0141] (The outer layer of birefringence Δn in a section perpendicular to the length direction) o (Ring), the birefringence Δn of the inner layer in a cross-section perpendicular to the length direction (circumferential section) i (ring))

[0142] Examples 1-3

[0143] like Figure 4 As shown in specimen 15, a cuboid balloon piece obtained by cutting the central portion of the straight tube of the balloon produced in Examples 1 to 3 along the length and circumference is used as the specimen for measurement. Here, the specimen used for the delay measurement at the circumferential section 16 is not the same specimen used for the delay measurement at the long axis section 17, but is a specimen cut separately from the balloon. Figure 9 , Figure 10 , Figure 11 The cut locations of the specimens cut from the balloons used in Examples 1, 2, and 3 are shown respectively. The circumferential cross-sections of the specimens were observed using a Nikon OPTIPHOT-POL polarizing microscope. Figure 4 The following was measured using a compensator (compensation device) at the circumferential section 16 of the outer layer: (i) the retardation R at the circumferential section of the specimen in the inner part of the outer layer. o (ii) The delay R at the circumferential section of the specimen in the inner part of the inner layer. i (Ring). Outer layer delay R o The (ring) is measured at a position one-third of the thickness of the outer layer, radially outward from the inner surface of the outer layer. The retardation R of the inner layer... i The (ring) is measured at a position one-third of the thickness of the inner layer, radially outward from the inner surface of the inner layer. Figure 12 In the diagram, P1 represents the measurement location of the outer layer's delay, and P2 represents the measurement location of the inner layer's delay. Figure 13 , Figure 14 , Figure 15 The locations for measuring the retardation at the circumferential and major axis sections of the specimens from Examples 1, 2, and 3 are shown, respectively. The thickness t1 of the specimens was also measured using an Olympus LEXT OLS4100 laser microscope. Thickness t1 is the length of the specimen in the direction perpendicular to the circumferential section. Table 1 shows the dimensions of the specimens used in Examples 1-3. C (a constant depending on the thickness of the crystals installed in the compensator (compensation device)) is 0.713822 × 10⁻⁶. 4 The average refractive index n is 1.515. Based on the above equations (1) to (3), the birefringence Δn of the outer layer in the cross section (circumferential section) perpendicular to the length direction was measured. o (Ring), the birefringence Δn of the inner layer in a cross-section perpendicular to the length direction (circumferential section) i (ring).

[0144] [Table 1]

[0145]

[0146] (The outer layer of birefringence Δn in a section perpendicular to the length direction) o (Ring), the birefringence Δn of the inner layer in a cross-section perpendicular to the length direction (circumferential section) i (ring))

[0147] Comparative Examples 1-11

[0148] The circumferential refractive index n of the inner surface (measurement position 1) of the polyamide layer in the middle layer described in Examples 1-9 and Comparative Examples 1-2 of Patent Document 1 was measured. ro The circumferential refractive index n of the inner surface of the inner polyamide elastomer layer (measurement position 0) ri Substituting the average refractive index n: 1.51 into equations (4) to (9) above, we can calculate the birefringence Δn of the outer layer in the cross section perpendicular to the length direction. o (Ring) and the birefringence Δn in the inner layer of the cross-section perpendicular to the length direction (circumferential section) i (ring).

[0149] [Table 2]

[0150]

[0151] [Table 3]

[0152]

[0153] (Summarize)

[0154] As in Examples 1-3, it can be seen that the birefringence Δn of the inner layer in the cross-section perpendicular to the length direction is... i (Ring) The birefringence Δn of the outer layer in the cross-section perpendicular to the length direction o The (ring) balloon has both high pressure resistance (breaking pressure, tensile strength) and high compliance. On the other hand, it is known that balloons with a higher circumferential refractive index on the inner side of the outer layer than on the inner side of the inner layer, as in Comparative Examples 1-11, and single-layer balloons such as Comparative Examples 12-14, have reduced pressure resistance (breaking pressure, tensile strength) and compliance.

[0155] Explanation of reference numerals in the attached figures:

[0156] 1…Balloon; 2…Outer layer; 2A…Inner part; 2B…Outer part; 3…Inner layer; 3A…Inner part; 3B…Outer part; 4…Intermediate layer; 5A…Distal end; 5B…Proximal end; 6A…Outer surface; 6B…Inner surface; 11…Expansion section; 11A…Straight tube section; 11B…Distal conical section; 11C…Proximal conical section; 12A…Distal sleeve section; 12B…Proximal sleeve section; 15…Sample; 16…Circumferential section; 17…Long axis section; 20…Coating; 30…Shaft; 35…Hub section; 40…Conduit; 50…Imaginary single-layer balloon; 51…Polyamide layer; x…Length direction; y…Radial direction; p…Circumferential direction.

Claims

1. A medical balloon, having longitudinal, radial, and circumferential directions, characterized in that, have: The outer layer is composed of a first polymer material; and The inner layer, located further inside the outer layer, is made of a second polymer material. The birefringence of the inner layer in a cross-section perpendicular to the length direction is higher than that of the outer layer in a cross-section perpendicular to the length direction. Birefringence of the inner layer in a cross-section perpendicular to the length direction refers to the absolute value of the difference between the circumferential refractive index of the inner portion and the radial refractive index of the inner portion when the inner layer is divided into an inner portion and an outer portion in the radial direction. Birefringence of the outer layer in a cross section perpendicular to the length direction refers to the absolute value of the difference between the circumferential refractive index of the inner portion of the outer layer and the radial refractive index of the inner portion of the outer layer when the outer layer is divided into an inner portion and an outer portion in the radial direction.

2. The medical balloon according to claim 1, characterized in that, The birefringence of the inner layer in a cross-section perpendicular to the length direction is 0.001 or more higher than that of the outer layer in a cross-section perpendicular to the length direction.

3. The medical balloon according to claim 1 or 2, characterized in that, The first polymer material is polyamide. The second polymer material is a polyamide elastomer.

4. The medical balloon according to claim 1 or 2, characterized in that, The compliance of the medical balloon is higher than that of a hypothetical monolayer balloon with the same outer diameter and membrane thickness as the medical balloon.

5. The medical balloon according to claim 1 or 2, characterized in that, The tensile strength of the medical balloon is higher than that of a hypothetical single-layer balloon with the same outer diameter and membrane thickness as the medical balloon.

6. The medical balloon according to claim 1 or 2, characterized in that, The cross-sectional area of ​​the inner layer in a section perpendicular to the length direction is more than 20% of the cross-sectional area of ​​the outer layer in a section perpendicular to the length direction.

7. The medical balloon according to claim 1 or 2, characterized in that, A coating containing a physiologically active agent is disposed at a position outside the outer layer.

8. The medical balloon according to claim 7, characterized in that, The physiologically active agent has a crystalline structure.

9. A catheter, characterized in that, It has the medical balloon as described in claim 1 or 2.

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