Balloon for balloon catheter and balloon catheter equipped therewith

Abstract

To provide a balloon for a balloon catheter in which an expansion efficiency of a narrow part is improved by easily maintaining an expansion force of the balloon, and when an inner pressure is applied by introducing fluid into a lumen of the balloon after being delivered to a lesioned part, the balloon is prevented from being damaged due to an improved pressure-resistance.SOLUTION: A balloon (20) for a balloon catheter includes a first layer (20a) and a second layer (20b) made of a material having higher Shore D hardness than that of the first layer (20a). The second layer (20b) is provided 360° in the whole peripheral direction z1. The first layer (20a) is positioned inside a radial direction y1 with resect to the second layer (20b). On a cross-section vertical with respect to a longitudinal axial direction x1, there are provided: at least one first part (21) made of the first layer (20a) and the second layer (20b); and at least one second part (22) solely made of the second layer (20b). The range in which the second part (22) is provided in the peripheral direction z1 is 90°or less of the 360° in the peripheral direction z1.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present invention relates to a balloon for a balloon catheter and a balloon catheter provided with the same. 【Background Art】 【0002】 When a stenosis is formed in the inner wall of a blood vessel, diseases such as angina pectoris and myocardial infarction may be caused. As one of the treatment methods for these, there are angioplasties such as percutaneous transluminal coronary angioplasty (PTCA) and percutaneous transluminal angioplasty (PTA) in which a stenosis is expanded using a balloon catheter. Angioplasty is a minimally invasive treatment method that does not require a thoracotomy such as bypass surgery and is widely performed. 【0003】 In angioplasty, the distal end of a balloon provided at the distal portion of a balloon catheter is inserted from a puncture site such as the femoral artery or brachial artery, and the balloon is delivered to the lesion through the blood vessel lumen by an operation from the proximal side of the balloon catheter. For this reason, balloon catheters having balloons with improved insertability or balloons having protrusions capable of expanding a stenosis have been developed. For example, Patent Document 1 discloses a balloon catheter in which the balloon is made of the same material throughout and the diameter of the balloon is reduced to improve insertability, and Patent Document 2 discloses a balloon catheter in which an expansion function is imparted to a protrusion having higher rigidity than the balloon wall. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2014-155657 【Patent Document 2】 U.S. Patent Application Publication No. 2016 / 0128718 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, conventional balloon catheters have problems such as difficulty maintaining balloon expansion force in hard stenotic areas like calcified lesions, and balloon rupture when fluid is introduced into the balloon lumen and internal pressure is applied in areas with complex lumen shapes such as stenotic areas. 【0006】 In view of the above circumstances, the present invention aims to provide a balloon for a balloon catheter that can easily maintain the expansion force of the balloon against hard narrowed areas such as calcified lesions, thereby improving the efficiency of narrowing of narrowed areas, and that is less likely to break when fluid is introduced into the lumen of the balloon after delivery to the lesion and internal pressure is applied, thereby improving pressure resistance, and a balloon catheter equipped with the same. [Means for solving the problem] 【0007】 The balloon for a balloon catheter according to an embodiment of the present invention that solves the above problems is as follows. [1] A balloon for a balloon catheter having longitudinal axis direction, radial direction and circumferential direction, and comprising a first layer and a second layer made of a material with a higher Shore D hardness than the first layer, wherein the second layer is arranged over the entire 360° of the circumferential direction, the first layer is located radially inward of the second layer, and in a cross section perpendicular to the longitudinal axis direction, it has at least one first part made of the first layer and the second layer and at least one second part made of only the second layer, and the range in the circumferential direction in which the second part is arranged is 90° or less of the 360° of the circumferential direction. [2] The balloon for a balloon catheter according to [1], wherein the second part extends in the longitudinal direction. [3] A balloon for a balloon catheter according to [1] or [2], having a plurality of first parts and a plurality of second parts, wherein the second parts are spaced apart in the circumferential direction such that the circumferential outer length of one of the first parts is at least twice the circumferential outer length of one of the second parts. [4] The balloon for a balloon catheter according to any one of [1] to [3], wherein the first part further comprises a portion P1 in which T1 is greater than 50% of T and a portion P2 in which T2 is greater than 50% of T, when the radial thickness of the first layer is T1, the radial thickness of the second layer is T2, and the sum of T1 and T2 is T. [5] The balloon for a balloon catheter according to [4], wherein the first part further comprises a first layer rich portion in which the circumferential outer length of the portion P1 is 15% or more of the circumferential outer length of each of the first parts, and two or more second layer rich portions in which the circumferential outer length of the portion P2 is 15% or more of the circumferential outer length of each of the first parts, and the first layer rich portion is sandwiched between the second layer rich portions in the circumferential direction. 【0008】 The present invention also provides the following: [6] A balloon catheter equipped with a balloon for a balloon catheter as described in any of [1] to [5] above. [Effects of the Invention] 【0009】 The balloon for the balloon catheter described above, and the balloon catheter equipped therewith, make it possible to easily maintain the balloon's expansion force against hard stenotic areas such as calcified lesions, thereby improving the efficiency of stenosis expansion. Furthermore, it is possible to provide a balloon for a balloon catheter and a balloon catheter equipped therewith that are less prone to rupture when fluid is introduced into the lumen of the balloon after delivery to the lesion and internal pressure is applied, thereby improving pressure resistance. [Brief explanation of the drawing] 【0010】 [Figure 1] This shows a side view of a balloon catheter according to one embodiment of the present invention. [Figure 2] Figure 1 shows a cross-sectional view of the balloon catheter at line II-II. [Figure 3] This cross-sectional view shows a modified version of the II-II cross-sectional view. [Figure 4]It represents an enlarged view of the first part of the cross-sectional view shown in FIG. 3. [Figure 5] It represents a perspective view of a parison before biaxial stretching according to an embodiment of the present invention. [Figure 6] It represents a VI-VI cross-sectional view of the parison shown in FIG. 5. [Figure 7] It represents a cross-sectional view perpendicular to the longitudinal axis of the parison mold used for manufacturing the parison shown in FIG. 6. [Figure 8] It represents a cross-sectional view perpendicular to the longitudinal axis after cutting off the protruding part of the parison shown in FIG. 6. [Figure 9] It represents a cross-sectional view showing a modified example of the VI-VI cross-sectional view. [Figure 10] It represents a cross-sectional view perpendicular to the longitudinal axis of the parison mold used for manufacturing the parison shown in FIG. 9. [Figure 11] It represents a cross-sectional view perpendicular to the longitudinal axis after cutting off the protruding part of the parison shown in FIG. 9. [Figure 12] It represents a cross-sectional view in the longitudinal axis direction of the mold according to an embodiment of the present invention. [Figure 13] It represents the XIII-XIII cross-sectional view of FIG. 12. 【Mode for Carrying Out the Invention】 【0011】 Hereinafter, the present invention will be described based on embodiments. However, the present invention is not limited by the following embodiments, and it is of course possible to appropriately modify and implement it within the range that conforms to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present invention. In each drawing, for the sake of convenience, hatching, member numbers, etc. may be omitted, but in such cases, reference shall be made to the specification and other drawings. Also, the dimensions of various members in the drawings may differ from the actual dimensions because priority is given to facilitating the understanding of the features of the present invention. 【0012】 1. Balloon for balloon catheter The balloon for a balloon catheter according to an embodiment of the present invention has a longitudinal axis direction, a radial direction, and a circumferential direction, and has a first layer and a second layer made of a material having a higher Shore D hardness than the first layer. The second layer is arranged over the entire 360° in the circumferential direction, the first layer is located radially inside the second layer, and in a cross-section perpendicular to the longitudinal axis direction, it has at least one first part composed of the first layer and the second layer, and at least one second part composed only of the second layer. The range in which the second part is arranged in the circumferential direction is 90° or less out of 360° in the circumferential direction. 【0013】 To expand a stenotic portion with a balloon catheter, after inserting a balloon provided at the distal end of the balloon catheter into the blood vessel lumen and delivering it to the stenotic portion, fluid is introduced into the balloon to expand the balloon. At this time, it may be difficult to maintain the expanding force of the balloon against a hard stenotic portion such as a calcified lesion. However, according to the balloon for a balloon catheter described above, in a cross-section perpendicular to the longitudinal axis direction, since it has at least one second part composed only of the second layer having a high Shore D hardness, the second part functions like the framework of an umbrella, so that the balloon can be supported against a hard stenotic portion and the expanding force of the balloon can be improved. As a result, the expanding force of the balloon can be improved without increasing the outer diameter of the balloon, so that it is possible to improve the expansion efficiency of the stenotic portion while ensuring the insertability of the balloon. Further, the first layer having a low Shore D hardness is located radially inside the second layer, and the range in which the second part composed only of the second layer is arranged in the circumferential direction is 90° or less out of 360° in the circumferential direction. Therefore, the existence range of the first part including the first layer having a low Shore D hardness can be made at least 270° in the circumferential direction. For this reason, when the balloon expands at a site with a distorted lumen shape such as a stenotic portion, the balloon can have a margin for expansion and contraction in the first part. As a result, when fluid is introduced into the lumen of the balloon to apply internal pressure, the balloon is less likely to be damaged and can be made into a balloon with improved pressure resistance. 【0014】 In this specification, the balloon for a balloon catheter may sometimes be simply referred to as a "balloon". 【0015】 The balloon for a balloon catheter according to an embodiment of the present invention will be described below with reference to Figures 1 to 4. Figure 1 is a side view of a balloon catheter according to one embodiment of the present invention. Figure 2 shows a II-II cross-sectional view of the balloon catheter shown in Figure 1. In Figure 2, the boundary between the area where the first part and the second part are located is shown by a dotted line. Figure 3 shows a cross-sectional view showing a modified example of the II-II cross-sectional view, where the boundary between the area where the first part and the second part are located is shown by a dotted line, and the boundary between the area where the first layer rich portion and the second layer rich portion are located is shown by a dashed line. Figure 4 shows an enlarged view of the first part of the cross-sectional view shown in Figure 3, where the boundary between the area where the first layer rich portion and the second layer rich portion are located is shown by a dashed line. The inner shaft is omitted in Figure 4. 【0016】 As shown in Figure 1, the balloon 20 is located at the distal end of the balloon catheter 10. The balloon 20 is connected to the distal end of the shaft 30, and the balloon 20 can be expanded by introducing fluid through the lumen of the shaft 30 and deflated by releasing the fluid. To control the expansion and contraction of the balloon 20, an indeflerator (balloon pressurizer) can be used to introduce or release fluid. The fluid may be pressurized fluid pressurized by a pump or the like. The balloon catheter 10 will be described in detail in section 2, "Balloon Catheter". 【0017】 The balloon 20 has a longitudinal axis direction x1, a radial direction y1 connecting the centroid 20C of the outer edge of the balloon 20 to a point on the outer edge in a cross section perpendicular to the longitudinal axis direction x1, and a circumferential direction z1 along the outer edge of the balloon 20 in a cross section perpendicular to the longitudinal axis direction x1. In this specification, the direction toward the user's hand in the longitudinal axis direction x1 is referred to as the proximal side, and the opposite side from the proximal side, i.e., the direction toward the person being treated, is referred to as the distal side. 【0018】 Each component and part other than the balloon 20 has a longitudinal axis direction, a radial direction, and a circumferential direction, which may or may not be the same as the longitudinal axis direction x1, radial direction y1, and circumferential direction z1 of the balloon 20. However, for the sake of clarity, in this specification, all components and parts are described as having the same longitudinal axis direction x1, radial direction y1, and circumferential direction z1 as the balloon 20. 【0019】 As shown in Figure 2, the balloon 20 has a first layer 20a and a second layer 20b made of a material with a higher Shore D hardness than the first layer 20a, the second layer 20b is arranged over the entire 360° in the circumferential direction z1, the first layer 20a is located inward in the radial direction y1 than the second layer 20b, and in a cross section perpendicular to the longitudinal axis x1, it has at least one first part 21 consisting of the first layer 20a and the second layer 20b, and at least one second part 22 consisting only of the second layer 20b. 【0020】 In a cross-section perpendicular to the longitudinal axis x1, the balloon 20 has at least one second part 22 consisting only of the second layer 20b. This allows the highly rigid second part 22 to function like the framework of an umbrella, supporting the balloon 20 against rigid stenoses and improving the balloon's expansion force. This improves the balloon's expansion force without increasing its outer diameter, thus improving the efficiency of stenosis expansion while ensuring the balloon 20's passability within the vascular lumen. Furthermore, the high Shore D hardness of the second layer 20b is continuously arranged over the entire 360° circumferential direction z1, thereby improving the balloon's rigidity. 【0021】 In the circumferential direction z1, the area where the second part 22 is located is less than 90° of the 360° of the circumferential direction z1. Therefore, the area in the circumferential direction z1 where the first part 21, which includes the first layer 20a with low Shore D hardness, exists is at least 270° of the 360° of the circumferential direction z1. As a result, when the balloon 20 expands in a part with an irregular lumen shape, such as a constricted area, the balloon 20 has room to expand and contract in the first part 21. This makes it possible to create a balloon 20 that is less likely to break when fluid is introduced into the lumen of the balloon 20 and internal pressure is applied, thus improving the pressure resistance of the balloon 20. 【0022】 The range in which the second part 22 is arranged in the circumferential direction z1 is preferably 80° or less, more preferably 70° or less, and even more preferably 60° or less out of 360° in the circumferential direction z1. If the upper limit of the range in which the second part 22 is arranged is as described above, it is possible to secure a range in which the first part 21 is arranged in a predetermined or greater extent, and when the balloon 20 expands in a part with an irregular lumen shape such as a constriction, there is room for expansion and contraction in the first part 21 including the first layer 20a with low Shore D hardness, thus easily improving the pressure resistance of the balloon 20. Furthermore, the range in which the second part 22 is arranged in the circumferential direction z1 is preferably 5° or more, more preferably 10° or more, even more preferably 15° or more, and may also be 20° or more, or 30° or more out of 360° in the circumferential direction z1. If the lower limit of the range in which the second part 22 is arranged is as described above, the second part 22 functions like the frame of an umbrella, making it easy to support the balloon 20 against a rigid constriction and improve the expansion force of the balloon 20. If multiple second parts 22 are provided in the circumferential direction z1, the range in which each second part 22 is arranged in the circumferential direction z1 may be the same or different from one another. 【0023】 At least one second part 22 is provided in the circumferential direction z1, and the number of second parts 22 in the circumferential direction z1 is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. One second part 22 is a portion consisting only of the second part 22, i.e., the second layer 20b, that exists continuously in the circumferential direction z1, and the first part 21 exists between two second parts 22 in the circumferential direction z1. Since the portion of the balloon 20 other than the second part 22 is the first part 21, the number of first parts 21 provided in the circumferential direction z1 is the same as the number of second parts 22 provided in the circumferential direction z1. 【0024】 The area in which the second part 22 is located can be defined as the smaller of the two line segments formed by the centroid 20C of the balloon 20 and the two ends of the second part 22 at the outer edge of the balloon 20, in a cross section perpendicular to the longitudinal axis x1, as shown in Figure 2. If there is one second part 22 in the circumferential direction z1, the area in which the second part 22 is located coincides with that angle. If there are multiple second parts 22 in the circumferential direction z1, the above angle is determined for each second part 22, and the area in which the second part 22 is located in the circumferential direction z1 is the sum of the angles of each second part 22. For example, as shown in Figure 2, if there are three second parts 22 in the circumferential direction z1, the sum of angles θ1, θ2, and θ3 is the area in which the second part 22 is located in the circumferential direction z1. Therefore, when multiple second parts 22 are provided in the circumferential direction z1, the balloon 20 has multiple second parts 22 such that the sum of the angles of all the second parts 22 is 90° or less. The more second parts 22 are provided in the circumferential direction z1, the smaller the angle of each second part 22, i.e., the smaller the range over which each second part 22 is provided. 【0025】 As shown in Figure 2, the balloon 20 may consist only of a first layer 20a and a second layer 20b. Alternatively, although not shown, the balloon 20 may have layers other than the first layer 20a and the second layer 20b. If the balloon 20 has layers other than the first layer 20a and the second layer 20b, the balloon 20 may have a configuration in which the first balloon membrane, composed only of the first layer 20a and the second layer 20b, has a first part 21 and a second part 22, and the second balloon membrane and the third balloon membrane are arranged inside or outside the radial direction y1 of the first balloon membrane. Even with such a configuration, as long as the first balloon membrane has the first part 21 and the second part 22 within the above range, a balloon with such a configuration having multiple membranes is included in the balloon 20 according to the embodiment of the present invention. 【0026】 The Shore D hardness of the first layer 20a is preferably 20 or higher, 25 or higher, 30 or higher, 35 or higher, or 40 or higher, and also preferably 70 or lower, 65 or lower, 60 or lower, or 55 or lower. The Shore D hardness of the second layer 20b is preferably greater than 70, 72 or higher, 74 or higher, or 75 or higher, and also preferably 90 or lower, 85 or lower, or 80 or lower. If the Shore D hardness of the first layer 20a is within the above range, the first part 21 can contribute to improving the elasticity of the balloon 20. If the Shore D hardness of the second layer 20b is within the above range, it can contribute to improving the expansion force of the balloon 20. 【0027】 The Shore D hardness can be measured, for example, using a Type D durometer based on the description in JIS K6253-2:2012. Furthermore, the Shore D hardness of the first layer 20a and the second layer 20b may be the Shore D hardness of the material at the stage before it is molded into the balloon 20. 【0028】 Suitable materials for the second layer 20b include polyamide resins such as nylon 11 and nylon 12; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; and polyurethane resins. For the first layer 20a, a thermoplastic elastomer is preferred from the viewpoint of low Shore D hardness; for example, a polyamide elastomer such as a polyether block amide copolymer is suitable. 【0029】 As shown in Figure 1, the balloon 20 preferably has a proximal end and a distal end in the longitudinal axis direction x1, and comprises a straight tube section 23, a proximal tapered section 22 located proximal to the straight tube section 23, a proximal sleeve section 21 located proximal to the proximal tapered section 22, a distal tapered section 24 located distal to the straight tube section 23, and a distal sleeve section 25 located distal to the distal tapered section 24. The straight tube section 23 is preferably substantially cylindrical with approximately the same diameter in the longitudinal axis direction x1, but may have different diameters in the longitudinal axis direction x1. The proximal tapered section 22 and the distal tapered section 24 are preferably formed in a substantially conical or frustoconical shape, decreasing in diameter as they move away from the straight tube section 23. Because the straight section 23 has the largest diameter, when the balloon 20 is expanded in a lesion such as a stenosis, the straight section 23 makes sufficient contact with the stenosis, making it easier to perform treatment such as dilation of the stenosis. Furthermore, because the proximal tapered section 22 and the distal tapered section 24 are reduced in diameter, when the balloon 20 is deflated, the outer diameter of the proximal and distal ends of the balloon 20 is reduced, thereby reducing the step between the shaft 30 and the balloon 20, making it easier to insert the balloon 20 into the body cavity. 【0030】 While the proximal tapered portion 22, the straight tube portion 23, and the distal tapered portion 24 are the parts that expand when fluid is introduced into the balloon 20, it is preferable that the proximal sleeve portion 21 and the distal sleeve portion 25 do not expand. This makes it possible to fix at least a part of the proximal sleeve portion 21 to the distal end of the shaft 30, and at least a part of the distal sleeve portion 25 to the inner shaft 60, which will be described later. 【0031】 It is preferable that the second part 22 extends in the longitudinal axis direction x1. This makes it easier for the second part 22 to function like the frame of an umbrella, supporting the balloon 20 against the constricted area and making it easier to improve the expansion force of the balloon 20. 【0032】 The second part 22 may be provided along the entire longitudinal axis x1 of the balloon 20, or it may be provided in part along the longitudinal axis x1. If the second part 22 is provided along the entire longitudinal axis x1 of the balloon 20, the second part 22 can function like the frame of an umbrella along the entire longitudinal axis x1 of the balloon 20, thereby improving the expansion force of the balloon 20. Alternatively, if the second part 22 is provided in part along the longitudinal axis x1 of the balloon 20, the part provided with the second part 22 will have a strong expansion force, while the flexibility of the other parts will be improved, making it possible to apply it to constricted sections of various shapes. 【0033】 For example, the second part 22 can be provided on the straight pipe section 23. By providing the second part 22 on the straight pipe section 23, the second part 22 can support the balloon 20 at its most expanded portion, which is advantageous for improving the expansion force of the balloon 20. The second part 22 may extend over the entire length of the straight pipe section 23 from the proximal end to the distal end in the longitudinal axis direction x1, or it may extend over only a portion and not be provided in other parts. 【0034】 Alternatively, the second section 22 can be provided from the straight section 23 to the distal tapered section 24. By providing the second section 22 from the straight section 23 to the distal tapered section 24, the distal expansion force of the balloon 20 can be improved. Alternatively, the second section 22 can be provided from the straight section 23 to the proximal tapered section 22. By providing the second section 22 from the straight section 23 to the proximal tapered section 22, the proximal expansion force of the balloon 20 can be improved. 【0035】 The second part 22 may extend over the entire length of the tapered section from the proximal end to the distal end in the longitudinal axis direction x1, or it may extend over a portion of the section and not be provided in other parts. When the second part 22 extends over a portion of the tapered section in the longitudinal axis direction x1, the second part 22 may be provided on the distal side with respect to the midpoint of the proximal tapered section 22 and not on the proximal side, or it may be provided on the proximal side with respect to the midpoint of the distal tapered section 24 and not on the distal side. In other words, the second part 22 may be provided on the straight pipe section 23 side of the tapered section and not on the sleeve section side. With such a configuration, the expansion force of the more expanding portion within the tapered section can be improved. Alternatively, it may be provided on the proximal side with respect to the midpoint of the proximal tapered section 22 and not on the distal side, and on the distal side with respect to the midpoint of the distal tapered section 24 and not on the proximal side. In other words, the second part 22 may be provided on the sleeve side rather than on the straight pipe side of the tapered section 23. This configuration improves the rigidity of the base and tip portions of the balloon 20, making it easier to support the balloon 20. 【0036】 Part 22 may extend over the entire length of the sleeve from the proximal end to the distal end in the longitudinal axis direction x1, or it may extend over only a portion and not be provided in other parts. By providing Part 22 at the base or tip of the sleeve portion of the balloon 20, it becomes easier to support the balloon 20. 【0037】 Part 22 may extend linearly along the longitudinal axis x1 or helically. Furthermore, Part 22 may be provided continuously or discontinuously along the longitudinal axis x1. 【0038】 It is preferable that the first part 21 also extends in the longitudinal axis direction x1. Since the balloon 20 may consist of parts other than the second part 22 as the first part 21, the extension of the second part 22 in the longitudinal axis direction x1 makes it easier for the first part 21 to extend in the longitudinal axis direction x1. The extension of the first part 21 in the longitudinal axis direction x1 makes it easier for the balloon 20 to expand and contract in the radial direction y1, and thus makes it easier to improve the pressure resistance of the balloon 20. 【0039】 As shown in Figure 2, in a cross-section perpendicular to the longitudinal axis x1, the balloon 20 has a plurality of first parts 21 and a plurality of second parts 22, and it is preferable that the second parts 22 are spaced apart in the circumferential direction z1 such that the outer circumference length L1 of each first part 21 in the circumferential direction z1 is at least twice the outer circumference length L2 of each second part 22 in the circumferential direction z1. 【0040】 The second part 22 is more preferably arranged at a distance in the circumferential direction z1 such that the outer circumference length L1 of each first part 21 in the circumferential direction z1 is 2.5 times or more the outer circumference length L2 of each second part 22 in the circumferential direction z1, even more preferably 3 times or more, and particularly preferably 4 times or more. There is no particular upper limit to the ratio of L1 to L2, but it can be, for example, 50 times or less, 30 times or less, 10 times or less, etc. 【0041】 By arranging the second part 22 at a distance greater than a predetermined interval in the circumferential direction z1, the second part 22 can support the balloon 20 while providing it with a certain degree of flexibility, making it easier to improve the expansion force and pressure resistance of the balloon 20. 【0042】 As shown in Figures 3 and 4, it is preferable that the balloon 20, in its first part 21, further has a portion P1 where T1 is more than 50% of T and a portion P2 where T2 is more than 50% of T, where T is the thickness of the first layer 20a in the radial direction y1, T2 is the thickness of the second layer 20b in the radial direction y1, and T is the sum of T1 and T2. Since T is the sum of T1 and T2, the first part 21 is composed of portions P1 and P2, excluding the portion where T1 and T2 are 50% of T. When the balloon 20 is composed only of the first layer 20a and the second layer 20b, that is, when the balloon 20 has only the first balloon membrane described above, T is equal to the thickness of the balloon 20. 【0043】 Because the balloon 20 has a portion P1 and a portion P2 in the first part 21, the flexibility and pressure resistance of the balloon 20 can be improved in portion P1 due to the low rigidity of the first layer 20a, and the expansion force of the balloon 20 can be improved in portion P2 due to the high rigidity of the second layer 20b. In this way, the presence of a less rigid portion P1 and a more rigid portion P2 in the first part 21 that contributes to the expansion and contraction of the balloon 20 makes it possible to improve the expansion force of the balloon 20 while improving the pressure resistance of the balloon 20 by the first part 21. 【0044】 The thickness of the balloon 20 is preferably 12 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and also preferably 60 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. If the balloon 20 is composed only of a first layer 20a and a second layer 20b, it is preferable that T is within the above range. 【0045】 The thickness of the second layer 20b in Part 2 22 can be the same as the thickness of the balloon 20. 【0046】 The thickness of the first layer 20a in Part 1 21 can be in a range less than the thickness of the balloon 20, for example, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, and 55 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, and 20 μm or less. The thickness of the second layer 20b in Part 1 21 can be in a range less than the thickness of the balloon 20, for example, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, and 55 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, and 20 μm or less. If parts P1 and P2 are provided in Part 1 21, the thicknesses of the first layer 20a and the second layer 20b should be varied within the above ranges. 【0047】 Preferably, the rate of change of the film thickness Tx of the balloon 20 at any position x in the circumferential direction z1 relative to the average film thickness Ta of the balloon 20 at any position x in the longitudinal direction x1 is 15% or less (|Tx-Ta| / Ta)×100). More preferably, the rate of change of the film thickness Tx of the balloon 20 is 10% or less, even more preferably 8% or less, and particularly preferably 5% or less. This makes it possible to configure the balloon 20 so that its outer surface does not protrude outward in the radial direction y1, and the outer wall of the balloon 20 can be easily made to conform to the lumen shape of the constricted portion. Ideally, the lower limit of the rate of change of the film thickness Tx of the balloon 20 is 0%, but it can substantially be 1% or more, 2% or more, 3% or more, etc. 【0048】 The film thickness of the balloon 20, the thickness T1 of the first layer 20a in the radial direction y1, and the thickness T2 of the second layer 20b in the radial direction y1 can be measured by observing a cross-section of the balloon 20 perpendicular to the longitudinal axis x. For observation, for example, an optical microscope can be used, and the thickness can be obtained from the measured thickness and observation magnification of the obtained observation image. 【0049】 The average film thickness Ta of the balloon 20 is obtained by measuring the thickness at 24 points spaced 15° apart within the 360° circumferential direction z1 of the balloon 20, and calculating the average value of these 24 points. The 24 points spaced 15° apart can be determined by drawing line segments radially y1 from the centroid 20C of the balloon 20 to the outer edge of the balloon 20, such that the smaller of the central angles between the line segments connecting the centroid 20C of the balloon 20 and the outer edge of the balloon 20 is 15°. The number of points measured to obtain the average film thickness Ta is not limited to 24; it may be fewer or more, but it is preferable to have at least 8 points. 【0050】 The thickness is preferably measured by observing the balloon 20 in its expanded state. The method for maintaining the balloon 20 in its expanded state is not particularly limited, but examples include embedding the expanded balloon 20 in a curable resin for observation, exposing a cross section perpendicular to the longitudinal axis x1, and observing the cross section. Alternatively, the balloon 20 may be observed directly without embedding it in a curable resin, or the balloon 20 may be observed in its deflated state as long as the central angle can be determined. 【0051】 The film thickness Tx of the balloon 20 at any position x in the circumferential direction z1 can be obtained not only at the point measured when determining the average film thickness Ta, but also by observing the film thickness at any position x in the circumferential direction z1 in the same manner as described above. 【0052】 The thickness T1 of the first layer 20a in the radial direction y1 and the thickness T2 of the second layer 20b in the radial direction y1 can be measured in the same way as the thickness of the balloon 20. Since the first layer 20a and the second layer 20b are formed from different resins, the boundary between the layers can be observed by microscopic observation, and the thickness of each layer can be determined. 【0053】 As shown in Figure 3, the balloon 20 has a first part 21 in which the outer circumference length L of the circumferential direction z1 of part P1 is P1 The first layer rich portion 20A is 15% or more of the outer circumference length L1 in the circumferential direction z1 of each part 21, and the outer circumference length L of part P2 is 15% or more of the outer circumference length L in the circumferential direction z1 P2The balloon 20 further comprises a second rich portion 20B which is 15% or more of the outer circumference length L1 in the circumferential direction z1 for each of the first portions 21, and it is preferable that the first rich portion 20A is sandwiched between the second rich portion 20B in the circumferential direction z1. It is preferable that the balloon 20 has at least one first rich portion 20A and two or more second rich portions 20B in the first portion 21. This allows the balloon 20 to have a configuration in which the flexible first rich portion 20A is sandwiched between the highly rigid second rich portion 20B in the first portion 21 which occupies a wide area of ​​at least 270° out of 360° in the circumferential direction z1. As a result, it becomes possible to have a balloon 20 with a good balance of flexibility and expandability. 【0054】 Outer circumference length L of portion P1 in the circumferential direction z1 in the first layer rich portion 20A P1 It is more preferable that the outer circumference length L1 in the circumferential direction z1 for each of the first parts 21 be 20% or more, and may be 30% or more. Also, the outer circumference length L in the circumferential direction z1 of the portion P2 in the second layer rich part 20B for each P2 It is more preferable that this is 18% or more of the outer circumference length L1 in the circumferential direction z1 for each of the first parts 21, and may be 20% or more. 【0055】 Next, a method for manufacturing the balloon 20 according to an embodiment of the present invention will be described with reference to Figures 5 to 13. Figure 5 shows a perspective view of a parison before biaxial stretching according to one embodiment of the present invention. Figure 6 shows a VI-VI cross-sectional view of the parison shown in Figure 5, and represents a cross-sectional view of a parison used in the manufacture of a balloon having the cross-section shown in Figure 2. Figure 7 shows a cross-sectional view perpendicular to the longitudinal axis of a parison mold used in the manufacture of the parison shown in Figure 6. Figure 8 shows a cross-sectional view perpendicular to the longitudinal axis of the parison after the protruding portion of the parison shown in Figure 6 has been removed. Figure 9 shows a cross-sectional view showing a modified example of the VI-VI cross-sectional view, and represents a cross-sectional view of a parison used in the manufacture of a balloon having the cross-section shown in Figure 3. Figure 10 shows a cross-sectional view perpendicular to the longitudinal axis of a parison mold used in the manufacture of the parison shown in Figure 9. Figure 11 shows a cross-sectional view perpendicular to the longitudinal axis of the parison after the protruding portion of the parison shown in Figure 9 has been removed. Figure 12 shows a cross-sectional view in the longitudinal axis direction of a mold according to one embodiment of the present invention used during biaxial stretching of the parison. Figure 13 shows the cross-sectional view of line XIII-XIII in Figure 12. 【0056】 First, prepare the parison 200. The parison 200 is made of resin and is a cylindrical member having a lumen 205, as shown in Figure 5. The parison 200 has a first end 201 and a second end 202, and extends in the longitudinal axis direction x2 from the first end 201 to the second end 202. The parison 200 has a radial direction y2 and a circumferential direction z2, similar to the balloon 20. 【0057】 As shown in Figure 6, the parison 200 has a second layer 200b and a first layer 200a made of a material with a lower Shore D hardness than the second layer 200b. Preferably, the first layer 200a and the second layer 200b are continuous over the entire circumferential direction z2. For information on the materials constituting the first layer 200a and the second layer 200b, and their Shore D hardness, refer to the description of the resins constituting the first layer 20a and the second layer 20b of the balloon 20, and the description of their Shore D hardness. 【0058】 As shown in Figures 5 and 6, the parison 200 preferably has a protruding region R1 including a protruding portion 208 that protrudes inward in the radial direction y2 and extends in the longitudinal direction x2, and a non-protruding region R2 other than the protruding region R1. In a cross section perpendicular to the longitudinal direction x2, it is preferable that the inner edge of the second layer 200b protrudes inward in the radial direction y2 along the protruding portion 208. That is, it is preferable that the second layer 200b has a small thickness portion 220 in the non-protruding region R2 and a large thickness portion 210 in the protruding region R1 that is thicker than the small thickness portion 220. 【0059】 As shown in Figure 6, there may be multiple protrusions 208 in the circumferential direction z2, or there may be one protrusion 208 in the circumferential direction z2, although this is not shown. When there are multiple protrusions 208 in the circumferential direction z2, it is preferable that the multiple protrusions 208 are spaced apart in the circumferential direction z2, and more preferably that they are arranged at equal intervals in the circumferential direction z2. 【0060】 Such a parison 200 can be manufactured, for example, by extruding resin using a parison mold 250 as shown in Figure 7. As shown in Figure 7, the parison mold 250 has a first cylindrical member 251, a second cylindrical member 252, and a third cylindrical member 253. The first cylindrical member 251 has a cylindrical shape with a projection that protrudes radially inward so as to form the inner cavity 205 and protrusion 208 of the parison 200. The second cylindrical member 252 has a cylindrical shape with a projection that protrudes radially inward so as to form the large thickness portion 210 and the small thickness portion 220 of the second layer 200b. Preferably, the third cylindrical member 253 has a cylindrical shape. As a result, by introducing a resin to form the first layer 200a into the space between the outer surface of the first cylindrical member 251 and the inner surface of the second cylindrical member 252, and introducing a resin to form the second layer 200b into the space between the outer surface of the second cylindrical member 252 and the inner surface of the third cylindrical member 253, and then extruding the resin, a parison 200 having a lumen 205, a first layer 200a, and a second layer 200b, wherein the second layer 200b has a large thickness portion 210 in the protruding region R1 and a small thickness portion 220 in the non-protruding region R2, it is possible to manufacture a parison 200. 【0061】 The material constituting the parison mold 250 is preferably metal, more preferably iron, copper, aluminum, or an alloy thereof. For example, stainless steel is an example of an iron alloy, brass is an example of a copper alloy, and duralumin is an example of an aluminum alloy. Due to its sufficient strength and ease of processing, the parison mold 250 is preferably made of stainless steel. 【0062】 Before biaxial stretching of the parison 200, the protruding portion 208 is cut along the longitudinal axis x2 to form a parison 200 having a portion of the second layer 200b exposed inward in the radial direction y2 in a cross section perpendicular to the longitudinal axis x2, as shown in Figure 8. By biaxial stretching such a parison 200, the first part 21 is formed by the portion of the second layer 200b of the parison 200 having a small thickness portion 220, and the second part 22 is formed by the portion of the second layer 200b of the parison 200 having a large thickness portion 210, thereby manufacturing a balloon 20 having a cross section as shown in Figure 2. 【0063】 Alternatively, the parison 200 may have a configuration as shown in Figure 9. That is, in a cross section perpendicular to the longitudinal axis x2, the second layer 200b may have a medium-thickness portion 230 in a non-protruding region R2 that is thicker than the small-thickness portion 220 and thinner than the large-thickness portion 210, and the parison 200 may have a configuration in which the small-thickness portion 220 is located between the medium-thickness portions 230 in the circumferential direction z2 of the non-protruding region R2. 【0064】 A parison 200 as shown in Figure 9 can be manufactured, for example, by extruding resin using a parison mold 250 as shown in Figure 10. In the parison mold 250 shown in Figure 10, it is preferable that the second cylindrical member 252 has a cylindrical shape with a portion that protrudes radially outward in the central region of the part forming the non-protruding region R2, so that it can form a small thickness portion 220 and a medium thickness portion 230. This makes it possible to manufacture a parison 200 having a lumen 205, a first layer 200a, and a second layer 200b, where the second layer 200b has a large thickness portion 210 in the protruding region R1, and the second layer 200b has a small thickness portion 220 and a medium thickness portion 230 in the non-protruding region R2, by the same method as described above. 【0065】 Before biaxial stretching the parison 200 shown in Figure 9, the protruding portion 208 can be cut along the longitudinal axis x2 to form a parison 200 having a portion of the second layer 200b exposed inward in the radial direction y2 in a cross section perpendicular to the longitudinal axis x2, as shown in Figure 11. By biaxial stretching such a parison 200, the first part 21 is formed by the portion of the second layer 200b of the parison 200 having a small thickness portion 220 and a medium thickness portion 230, and the second part 22 is formed by the portion of the second layer 200b of the parison 200 having a large thickness portion 210, thereby manufacturing a balloon 20 having a cross section as shown in Figure 3. 【0066】 By biaxially stretching the parison 200 from which the protruding portion 208 has been removed, a balloon 20 can be manufactured having a first part 21 consisting of a first layer 20a and a second layer 20b, and a second part 22 consisting only of the second layer 20b. In this case, a mold 300 as shown in Figure 12 can be used. The mold 300 has a longitudinal axis direction x3, a radial direction y3, and a circumferential direction z3, and has a lumen 305 that extends in the longitudinal axis direction x3 into which the parison 200 is inserted. Preferably, a portion of the parison 200 in the longitudinal axis direction x2 is positioned in the lumen 305 of the mold 300. 【0067】 Preferably, the mold 300 has a mold straight pipe section 300C that forms the straight pipe section 23 of the balloon 20 in the longitudinal axis direction x3, two mold tapered sections 300T that are arranged on both sides of the mold straight pipe section 300C and form the tapered section of the balloon 2, and two mold sleeve sections 300S that are arranged further away from the mold straight pipe section 300C than the mold tapered sections 300T and form the sleeve section of the balloon 20. This allows the mold straight pipe section 300C to form the straight pipe section 23 of the balloon 20, the mold tapered sections 300T to form the proximal tapered section 22 and the distal tapered section 24, and the mold sleeve sections 300S to form the proximal sleeve section 21 and the distal sleeve section 25. 【0068】 The mold 300 may be composed of one component or multiple components. As shown in Figure 12, it may be composed of multiple mold components connected to each other in the longitudinal axis direction x3. For example, the mold straight section 300C, the mold tapered section 300T, and the mold sleeve section 300S may each be different mold components, and these may be connected to each other in the longitudinal axis direction x3. The mold 300 may also be separable in the radial direction y. This makes it easier to insert the parison 200 into the lumen 305 of the mold 300. As shown in Figure 12, each mold component may be joined by engaging adjacent mold components with each other, or, although not shown, adjacent mold components may be joined by magnetic attraction by attaching magnets to each of them. 【0069】 As shown in Figure 13, it is preferable that the lumen 305 of the mold 300 is formed in a substantially circular shape. By placing the parison 200 in such a lumen 305 and introducing fluid into the lumen 205 of the parison 200 and biaxially stretching it, a balloon 20 with a film thickness variation rate of less than or equal to a predetermined value can be manufactured. 【0070】 The material constituting the mold 300 is preferably metal, and more preferably iron, copper, aluminum, or an alloy thereof. For example, stainless steel is an example of an iron alloy, brass is an example of a copper alloy, and duralumin is an example of an aluminum alloy. From the standpoint of having sufficient strength and ease of processing, the mold 300 is preferably made of stainless steel. 【0071】 2. Balloon catheter 【0072】 An embodiment of the present invention provides a balloon catheter 10 equipped with the balloon catheter balloon 20 described above. As described in section 1, "Balloon for balloon catheter," the balloon 20 is connected to the distal end of the shaft 30, as shown in Figure 1. 【0073】 Figure 1 shows a so-called rapid exchange type balloon catheter 10, which has a guidewire port 61 located midway from the distal to the proximal end of the shaft 30, and an inner shaft 60 that functions as a guidewire insertion passage from the guidewire port 61 to the distal end of the shaft 30. Preferably, the balloon catheter 10 has a distal shaft 31 and a proximal shaft 32, and the distal shaft 31 and the proximal shaft 32 are separate components, and the proximal end of the distal shaft 31 is connected to the distal end of the proximal shaft 32, thereby forming a shaft 30 that extends from the balloon 20 to the proximal end of the balloon catheter 10. Alternatively, one shaft 30 may extend from the balloon 20 to the proximal end of the balloon catheter 10, and the distal shaft 31 and the proximal shaft 32 may be composed of multiple tubular members. 【0074】 It is preferable that the shaft 30 has a fluid channel and a guide wire insertion passage inside. To configure the shaft 30 to have a fluid channel and a guide wire insertion passage inside, for example, an inner shaft 60 located inside the shaft 30 can function as a guide wire insertion passage, and the space between the shaft 30 and the inner shaft 60 can function as a fluid channel. In such a configuration, it is preferable that the inner shaft 60 extends from the distal end of the shaft 30 and penetrates the balloon 20, with the distal side of the balloon 20 connected to the inner shaft 60 and the proximal side of the balloon 20 connected to the shaft 30. 【0075】 The shaft 30 is preferably composed of resin, metal, or a combination of resin and metal. Using resin as a constituent material for the shaft makes it easier to impart flexibility and elasticity to the shaft 30. Using metal as a constituent material for the shaft 30 can improve the delivery of the balloon catheter 1. Examples of resins that make up the shaft 30 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluororesins, vinyl chloride resins, silicone resins, natural rubber, and synthetic rubber. These may be used individually or in combination of two or more. Examples of metals that make up the shaft 30 include stainless steel such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloy, Co-Cr alloy, or combinations thereof. When the shaft 30 is composed of a distal shaft 31 and a proximal shaft 32, for example, the distal shaft 31 can be formed from resin and the proximal shaft 32 can be formed from metal. Furthermore, the shaft 30 may have a laminated structure made of different or the same material. 【0076】 The balloon 20 and the shaft 30 can be joined by adhesive bonding, welding, or by attaching a ring-shaped member to the overlapping portion of the balloon 20 and the shaft 30 and crimping it. In particular, it is preferable that the balloon 20 and the shaft 30 are joined by welding. By welding the balloon 20 and the shaft 30, the joint between the balloon 20 and the shaft 30 is less likely to come undone even when the balloon 20 is repeatedly expanded or contracted, thereby improving the joint strength. 【0077】 Preferably, a tip member 70 is provided at the distal end of the balloon catheter 10. The tip member 70 may be provided at the distal end of the balloon catheter 10 by being connected to the distal end of the balloon 20 as a separate component from the inner shaft 60, or the inner shaft 60, which extends distal to the distal end of the balloon 20, may function as the tip member 70. 【0078】 On the inner shaft 60 inside the balloon 20, radiopaque markers 80 may be placed at the location of the balloon 20 in the longitudinal axis direction x1 so that the position of the balloon 20 can be confirmed under X-ray fluoroscopy. Preferably, the radiopaque markers 80 are placed at positions corresponding to both ends of the straight tube portion 23 of the balloon 20, or they may be placed at a position corresponding to the center of the straight tube portion 23 in the longitudinal axis direction x1. 【0079】 A hub 40 may be provided on the proximal side of the shaft 30, and it is preferable that the hub 40 is provided with a fluid injection section 50 that communicates with the fluid flow path supplied to the inside of the balloon 20. 【0080】 The shaft 30 and the hub 40 can be joined by, for example, adhesive bonding or welding. In particular, it is preferable that the shaft 30 and the hub 40 are joined by adhesive bonding. By bonding the shaft 30 and the hub 40, the bonding strength between the shaft 30 and the hub 40 can be increased, improving the durability of the balloon catheter 10, especially when the materials constituting the shaft 30 and the hub 40 are different, for example, when the shaft 30 is made of a highly flexible material and the hub 40 is made of a highly rigid material. 【0081】 Although not shown in the figures, the present invention can also be applied to so-called over-the-wire type balloon catheters, which have a guidewire insertion passage extending from the distal to the proximal end of the shaft. In the case of the over-the-wire type, it is preferable that the inflation lumen and guidewire lumen extend to a hub located on the proximal end, and that the proximal opening of each lumen is provided in a bifurcated hub. 【0082】 In the case of a rapid exchange type catheter, it is preferable that the outer walls of the distal shaft 31 and / or the proximal shaft 32 are appropriately coated, and it is more preferable that both the distal shaft 31 and the proximal shaft 32 are coated. In the case of an over-the-wire type catheter, it is preferable that the outer wall of the outer shaft is appropriately coated. 【0083】 The coating can be hydrophilic or hydrophobic depending on the purpose, and can be applied by immersing the shaft 30 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 30, or covering the outer wall of the shaft 30 with a hydrophilic or hydrophobic coating agent. The coating agent may contain chemicals or additives. 【0084】 Examples of hydrophilic coating agents include 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. 【0085】 Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), ethylene fluoride propylene (FEP), perfluoroalkoxyalkanes (PFA), silicone oil, hydrophobic urethane resins, carbon coatings, diamond coatings, diamond-like carbon (DLC) coatings, ceramic coatings, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups. [Explanation of symbols] 【0086】 10: Balloon catheter 20: Balloon for balloon catheter 20a: 1st layer 20A: First layer rich section 20b: 2nd layer 20B: Second layer rich section 20C: Centroid of the outer edge of the balloon 21: Part 1 22: Part 2 30: Shaft 31: Distal shaft 32: Proximal shaft 40: Hub 50:Fluid injection part 60: Inner shaft 61: Guidewire port 70: Tip component 80: Marker 200: Parison 200a: Inner layer of parison 200b: Outer layer of the parison 201: Parison's First End 202: Parison's second end 205: Parison's lumen 208: Parison projection 210: Daikobu 220: Koatsube 230: Medium thick part 250: Mold for parison 251: First cylindrical member 252: Second cylindrical member 253: Third cylindrical member 300: Mold 300C: Straight pipe section of mold 300S: Mold sleeve section 300T: Mold tapered section 305: Inner cavity of the mold

Claims

[Claim 1] A balloon for a balloon catheter having longitudinal axis direction, radial direction and circumferential direction, and comprising a first layer and a second layer made of a material with a higher Shore D hardness than the first layer, The second layer is arranged over the entire 360° in the circumferential direction, The first layer is located radially inward from the second layer, A balloon for a balloon catheter, having in a cross section perpendicular to the longitudinal axis direction at least one first part consisting of the first layer and the second layer, and at least one second part consisting only of the second layer, wherein the range in the circumferential direction in which the second part is arranged is 90° or less out of 360° in the circumferential direction. [Claim 2] The balloon for a balloon catheter according to claim 1, wherein the second part extends in the longitudinal direction. [Claim 3] A balloon for a balloon catheter according to claim 2, comprising a plurality of first parts and a plurality of second parts, wherein the second parts are spaced apart in the circumferential direction such that the circumferential outer length of each first part is at least twice the circumferential outer length of each second part. [Claim 4] The balloon for a balloon catheter according to claim 3, wherein, in the first part, when the radial thickness of the first layer is T1, the radial thickness of the second layer is T2, and the sum of T1 and T2 is T, the balloon further comprises a portion P1 in which T1 is greater than 50% of T and a portion P2 in which T2 is greater than 50% of T. [Claim 5] The balloon for a balloon catheter according to claim 4, wherein the first part further comprises a first layer rich portion in which the circumferential outer length of the portion P1 is 15% or more of the circumferential outer length of each of the first parts, and two or more second layer rich portions in which the circumferential outer length of the portion P2 is 15% or more of the circumferential outer length of each of the first parts, and the first layer rich portion is sandwiched between the second layer rich portions in the circumferential direction. [Claim 6] A balloon catheter comprising a balloon for a balloon catheter as described in any one of claims 1 to 5.

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