Catheters and balloon catheters

Abstract

In the present invention, a catheter having a catheter tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, wherein the first polyamide layer contains more than 10 wt% but no more than 30 wt% of a pressure resistance enhancing agent relative to the total solid content of the first polyamide layer. The present invention provides a catheter having a catheter tube that has superior compressive strength and an inner layer surface with excellent sliding properties.

Description

Technical Field

[0005] ,

[0006]

[0001] The present invention relates to a catheter and a balloon catheter having a catheter tube including a predetermined layer structure.

Background Art

[0002] Conventionally, in order to eliminate and treat the stenosis state of a stenosis in a living body, a balloon catheter is used in which a balloon is introduced into the stenosis generated in a lumen, a body cavity, etc., and the stenosis is expanded from the inside to the outside. For example, a balloon catheter is used in percutaneous transluminal coronary angioplasty (PTCA) that improves blood flow by expanding a stenosis in a coronary artery with a balloon. The balloon catheter is configured by connecting a balloon to the tip of an elongated shaft member extended in the axial direction. ​​​​​​​​​​​​​ Japanese Patent Publication No. 2016-174827 (corresponding to U.S. Patent Application Publication No. 2016 / 0271361) proposes a catheter tube having an inner layer made of modified polyolefin resin, a first polyamide layer formed on the outer surface of the inner layer, and a second polyamide layer formed on the outer surface of the first polyamide layer and containing a coloring agent. [Overview of the project]

[0007] A catheter having a catheter tube disclosed in Japanese Patent Publication No. 2016-174827 (corresponding to U.S. Patent Application Publication No. 2016 / 0271361) has excellent sliding properties of the lumen surface, as well as good flexibility and pressure resistance, resulting in excellent operability.

[0008] On the other hand, the miniaturization and reduction in diameter of medical devices in recent years have been remarkable, and medical procedures that allow medical devices to approach more flexible and narrower lesion sites within the body are becoming more widespread. Therefore, there is a need for catheters that can provide good maneuverability even in complex lesion sites. Specifically, there is a need for catheters that not only have excellent sliding properties for manipulating guidewires, but also maintain the lumen through which the guidewire is inserted and are less prone to kinking.

[0009] Therefore, there is a need for a technology that can further improve the pressure resistance of catheter tubes while maintaining good sliding properties of the inner surface.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a catheter having a catheter tube with good sliding properties on the inner surface and excellent pressure resistance. Another object of the present invention is to provide a balloon catheter equipped with such a catheter.

[0011] The inventors diligently conducted research to solve the above problems. As a result, they discovered that the above problems can be solved by a catheter having a catheter tube, wherein the catheter tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, and the first polyamide layer contains a pressure-resistant agent in an amount of more than 10% by weight and less than or equal to 30% by weight relative to the total solid content of the first polyamide layer, thus completing the present invention. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows a balloon catheter according to one embodiment, where (A) is a simplified diagram showing the overall structure of the balloon catheter, and (B) is an enlarged cross-sectional view showing the tip of the balloon catheter. In Figures 1(A) and (B), reference numeral 410 denotes the balloon; reference numeral 420 denotes the shaft; reference numeral 430 denotes the inner tube; reference numeral 431 denotes the guidewire lumen; reference numeral 440 denotes the outer tube; and reference numeral 450 denotes the hub. [Figure 2] Figure 2 shows a layered structure (cross-sectional view perpendicular to the axis) of a specific example of a catheter tube according to the present invention. In Figure 2, reference numeral 10 denotes the catheter tube; reference numeral 101 denotes the first polyamide layer; and reference numeral 102 denotes the second polyamide layer. [Figure 3] This is a schematic diagram illustrating a jig for evaluating the sliding properties of the tubes obtained in the examples and comparative examples. [Figure 4] This is a schematic diagram illustrating evaluation samples for evaluating the pressure resistance strength of tubes obtained in the examples and comparative examples. In Figure 4, reference numeral 20 denotes the inner tube; reference numeral 30 denotes the outer tube; and reference numeral 40 denotes the intermediate shaft. [Figure 5] This is a photograph of the tube obtained in Example 1-1, observed with a CCD camera. [Modes for carrying out the invention]

[0013] One embodiment of the present invention is a catheter having a catheter tube, wherein the catheter tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, and the first polyamide layer contains a pressure-resistant agent in an amount exceeding 10% by weight and not exceeding 30% by weight relative to the total solid content of the first polyamide layer. Hereinafter, the "catheter tube comprising a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, wherein the first polyamide layer contains a pressure-resistant agent in an amount exceeding 10% by weight and not exceeding 30% by weight relative to the total solid content of the first polyamide layer" will also be simply referred to as the "catheter tube according to the present invention".

[0014] The catheter tube according to the present invention has a first polyamide layer as an inner layer and a second polyamide layer as an outer layer, and the first polyamide layer as the inner layer contains a predetermined amount of a pressure-resistant agent. Surprisingly, the inventors have found that a catheter tube having such a configuration exhibits excellent pressure resistance while maintaining good sliding properties. Although the detailed mechanism is unknown, it is presumed that the pressure resistance is improved not only because both the inner and outer layers of the catheter tube according to the present invention are formed from polyamide resins, resulting in good inter-resin compatibility (adhesion between the inner and outer layers), but also because the rigidity improvement effect can be easily obtained through annealing or fusion treatment. Furthermore, it is presumed that the above effect is obtained due to some factor such as the structure (e.g., particle structure), components, and content of the pressure-resistant agent. It should be noted that the above mechanism is a speculation and does not limit the technical scope of the present invention in any way.

[0015] The embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments described below.

[0016] In this specification, "X~Y" indicating a range means "X or greater and Y or less". Unless otherwise specified, operations and measurements of physical properties are performed under room temperature (20~25°C) / relative humidity of 40~50%RH. Furthermore, "A and / or B" includes A and B individually and all one or more combinations thereof, specifically meaning at least one of A and B, and meaning A, B, and combinations of A and B.

[0017] <Catheter> One embodiment of the present invention is a catheter having a catheter tube, wherein the catheter tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, and the first polyamide layer contains a pressure-resistant agent in an amount of more than 10% by weight and up to 30% by weight relative to the total solid content of the first polyamide layer. According to the present invention, it is possible to provide a catheter having a catheter tube with good sliding properties on the inner surface and excellent pressure resistance.

[0018] The catheter tube according to the present invention is used as the inner and / or outer tube of a balloon catheter, but is particularly preferred as the inner tube. The present invention will be described in more detail below with reference to a specific example of the present invention, a balloon catheter 400, shown in Figure 1, but the following description is not intended to limit the present invention.

[0019] The balloon catheter 400 is a medical device that treats narrowed areas (lesions) by inserting the shaft 420 into a living organ and expanding the balloon 410 located at the tip of the shaft 420 at the narrowed area. For example, it is used as a PTCA catheter. However, the balloon catheter 400 may also be used for other therapeutic purposes, such as a balloon catheter intended for the treatment and improvement of narrowed areas formed in living organs other than coronary arteries, bile ducts, trachea, esophagus, urethra, or other organs.

[0020] As shown in FIG. 1(A), the balloon catheter 400 includes a flexible elongated shaft 420, an expandable and contractible balloon 410 disposed on the tip side of the shaft 420, and a hub 450 disposed on the proximal end side of the shaft 420. In the description of the balloon catheter 400, the side where the balloon 410 is provided is referred to as the tip side, and the side where the hub 450 is provided is referred to as the proximal end side.

[0021] The balloon catheter 400 is of a so-called rapid exchange type provided with an opening (proximal end opening) 435 through which the guide wire 480 is led out near the tip side of the shaft 420. However, the balloon catheter 400 may be a so-called over-the-wire type balloon catheter formed such that a guide wire lumen 431 (see FIG. 1(B)) extends from the tip to the proximal end of the shaft 420.

[0022] As shown in FIG. 1(B), the shaft 420 includes an inner tube (inner tube shaft) 430 in which a guide wire lumen 431 through which the guide wire 480 is inserted is formed, and an outer tube (outer tube shaft) 440 that forms a pressure medium lumen 441 for supplying a pressure medium for expanding the balloon 410 between the outer peripheral surface of the inner tube 430.

[0023] The shaft 420 is configured with a double tube structure in which the inner tube 430 is inserted into the outer tube 440 and the inner tube 430 and the outer tube 440 are concentrically aligned.

[0024] As shown in FIG. 1(B), the inner tube 430 includes two openings, a tip opening 433 formed at the tip and a proximal end opening 435 formed at the proximal end. Inside the inner tube 430, a guide wire lumen 431 extends in communication with each of the openings 433 and 435.

[0025] The inner tube 430 is composed of a hollow tube material (catheter tube) whose proximal end is curved radially outward. Near the tip of the inner tube 430, the tip portion 413 of the balloon 410 is joined in a liquid-tight and air-tight manner by a known method such as fusion. Also, the vicinity of the proximal end of the inner tube 430 is joined in a liquid-tight and air-tight manner to a connection opening 422 formed at a predetermined position of the outer tube 440. The guide wire 480 is inserted into the guide wire lumen 431 using the tip opening 433 provided at the tip of the inner tube 430 and the proximal end opening 435 provided at the proximal end of the inner tube 430 as an outlet and an inlet, respectively.

[0026] At the tip of the inner tube 430, for example, when the tip of the balloon catheter 400 comes into contact with a living organ (such as the inner wall of a blood vessel), it is possible to attach a tip chip that prevents damage to the living organ. The tip chip can be composed of, for example, a tubular member that is more flexible than the inner tube 430. Incidentally, the tip chip is preferably formed of a polyamide resin, a polyamide elastomer, or a blend thereof. Thereby, when fusing the tip chip and the inner tube, the inner tube 430 according to the present invention can enhance the adhesive force with the tip chip.

[0027] In one embodiment of the present invention, the catheter tube according to the present invention is used as the inner tube 430. Further, in addition to the configuration described in detail below, the catheter tube may be blended with an antithrombotic substance such as heparin, prostaglandin, urokinase, or an arginine derivative.

[0028] The outer tube 440 is composed of a hollow tube material that extends from near the proximal end portion 415 of the balloon 410 to the hub 450 (see FIG. 1(A)). The proximal end portion 415 of the balloon 410 is joined to the tip of the outer tube 440 in a liquid-tight and air-tight manner by a known method such as welding.

[0029] [[ID=As constituent materials for the outer tube 440, for example, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, thermoplastic resins such as soft polyvinyl chloride, various types of rubber such as silicone rubber and latex rubber, various elastomers such as polyurethane elastomer, polyamide elastomer, and polyester elastomer, polyamide resin, crystalline plastics such as crystalline polyethylene and crystalline polypropylene can be used. The outer tube 440 may also be formed from a polyamide resin as described later. In addition, the part of the outer tube 440 that comes into contact with blood (for example, the outer surface of the outer tube 440) may be coated with an antithrombotic substance, or it may be formed from a resin containing an antithrombotic substance.

[0030] The material used to form the balloon 410 is preferably elastic. For example, thermoplastic elastomers such as vinyl chloride, polyurethane elastomer, polystyrene elastomer, styrene-ethylene-butylene-styrene copolymer (SEBS), and styrene-ethylene-propylene-styrene copolymer (SEPS), thermoplastic resins such as PET, rubber, and thermosetting resins such as silicone elastomer, as well as polyamide resins such as polyamide resins, polyamide elastomers, or blends thereof, can be used. The balloon 410 may also be a multilayer balloon with two or more layers. It is preferable that the balloon 410 is formed from a polyamide resin, polyamide elastomer, or a blend thereof. This increases the adhesive strength between the balloon and the inner tube when fusing the balloon and the inner tube together, for example, when using the catheter tube according to the present invention as an inner tube.

[0031] As shown in Figure 1(A), the hub 450 is equipped with a connection portion 451 that can be connected in a liquid-tight and airtight manner to a supply device (not shown), such as an indeflater, for supplying a pressurized medium. The connection portion 451 of the hub 450 can be configured, for example, with a known Luer taper that allows a fluid tube or the like to be connected and disconnected.

[0032] The pressurized medium used to inflate the balloon 410 (e.g., saline solution, contrast agent, etc.) can be introduced into the shaft 420 via the connection part 451 of the hub 450. The pressurized medium is supplied to the balloon 410 via the pressurized medium lumen 441.

[0033] As shown in Figure 1(B), the balloon 410 includes an effective expansion portion (pressure portion) 416 that expands the stenotic portion as it expands, a tip-side tapered portion 413a connected to the tip side of the effective expansion portion 416, and a proximal-side tapered portion 415a connected to the proximal end side of the effective expansion portion 416. The tip portion 413 located on the tip side of the tip-side tapered portion 413a is fixed to the outer surface of the inner tube 430, and the proximal end portion 415 located on the proximal end side of the proximal-side tapered portion 415a is fixed to the outer surface of the outer tube 440. An X-ray contrast marker 460 indicating the central part of the effective expansion portion 416 is provided in the inner tube 430 at the center of the effective expansion portion 416. Alternatively, the X-ray contrast marker 460 may be provided in the inner tube 430 at both ends of the effective expansion portion 416 to indicate both ends of the effective expansion portion 416.

[0034] In a preferred embodiment of the present invention, the catheter tube according to the present invention is used as the inner tube of a balloon catheter. In a preferred embodiment of the balloon catheter according to the present invention, the balloon contains a polyamide resin, and the catheter tube according to the present invention is used as the inner tube of the balloon catheter. That is, in one embodiment of the present invention, a balloon catheter is provided comprising an outer tube having a lumen, an inner tube disposed in the lumen of the outer tube, and a balloon fixed to the tip side of the inner tube and the tip side of the outer tube, wherein the balloon contains a polyamide resin, the inner tube contains a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer, and the first polyamide layer contains a pressure-resistant agent in an amount exceeding 10% by weight and not exceeding 30% by weight relative to the total solid content of the first polyamide layer. The polyamide resin contained in the balloon can be one of those described in the description of the first polyamide layer below. The polyamide resin that forms the balloon may be the same as or different from the polyamide resin that forms the first polyamide layer and the second polyamide layer. In one embodiment of the present invention, the balloon is substantially made of a polyamide resin.

[0035] Figure 2 shows a specific example of a catheter tube according to the present invention, which is a layered structure (cross-sectional view perpendicular to the axis). However, the specific example shown in Figure 2 is not limited to the present invention. In Figure 2, the shape of the cross-sectional view perpendicular to the axis of the catheter tube is circular, but the cross-sectional shape is not limited to polygons, etc. In Figure 2, the catheter tube 10 consists of a first polyamide layer (inner layer) 101 and a second polyamide layer (outer layer) 102 formed on the outer surface of the first polyamide layer 101. In the specific example shown in Figure 2, the catheter tube 10 has a second polyamide layer (outer layer) 102 that is thicker than the first polyamide layer (inner layer) 101. The tensile strength of the catheter tube 10 is improved because the second polyamide layer (outer layer) 102, which does not contain a coloring agent, is thicker than the first polyamide layer (inner layer) 101, which contains a pressure resistance improving agent. As a result, when catheter tube 10 is used as the inner or outer tube in a balloon catheter, the strength of the adhesive joint with resin components containing polyamide resin, polyamide elastomer, or a blend thereof, such as the tip and balloon, is improved. In other words, the apparent adhesion may be improved.

[0036] The catheter tube 10 according to the present invention may optionally include other layers in addition to the first polyamide layer (inner layer) 101 and the second polyamide layer (outer layer) 102. For example, to further improve the sliding properties of the guide wire, the catheter tube according to the present invention may further include a fluororesin layer (not shown) made of a fluororesin such as polytetrafluoroethylene, polyvinylidene fluoride, ethylenetetrafluoroethylene, or perfluoroalkoxy resin on the inner surface of the first polyamide layer (inner layer) 101. However, from the viewpoint of achieving miniaturization and reduction of the diameter of the catheter tube, it is preferable that the catheter tube 10 according to the present invention is composed of a first polyamide layer (inner layer) 101 and a second polyamide layer (outer layer) 102.

[0037] The outer diameter of the catheter tube according to the present invention is set appropriately according to the intended use and is not particularly limited, but when used as the inner tube of the catheter tube 10, it is, for example, 300 to 800 μm, preferably 500 to 600 μm. Similarly, the inner diameter of the catheter tube is not particularly limited, but when used as the inner tube of the catheter tube 10, it is, for example, 250 to 600 μm, preferably 400 to 500 μm.

[0038] The thickness of the catheter tube according to the present invention (the total thickness of the layers, including the first polyamide layer, the second polyamide layer, and any other layers that may be set) is, for example, 50 to 100 μm, and preferably 60 to 80 μm.

[0039] The following provides a more detailed explanation of each layer: the first polyamide layer (inner layer) and the second polyamide layer (outer layer).

[0040] [First polyamide layer] In one embodiment of the present invention, the first polyamide layer (inner layer) comprises a polyamide resin and a predetermined amount of a pressure-resistant enhancer. In a preferred embodiment of the present invention, the first polyamide layer (inner layer) consists of a polyamide resin and a predetermined amount of a pressure-resistant enhancer. Polyamide resins have the advantages of being flexible, having high strength, and having a larger elastic range compared to cases where polyester such as polyethylene terephthalate is used. Furthermore, because polyamide resins have a relatively high melting point, the heating temperature can be increased during annealing and fusion treatments, which has the advantage of easily improving rigidity. Thus, since the catheter tube according to the present invention is formed of a polyamide resin having the above characteristics, it is presumed to have high pressure resistance.

[0041] In this specification, "polyamide resin" means polyamide resin, polyamide elastomer, and / or a blend of these resins.

[0042] The polyamide resin that can be suitably used in the first polyamide layer is not particularly limited as long as it has an acid amide bond (-CO-NH-) in its main chain. Polyamide resins are usually produced by polymerization (homopolymerization) of cyclic lactams or amino acids, or by condensation polymerization of dicarboxylic acids and diamines, in the presence of a suitable catalyst.

[0043] Monomers that can be polymerized on their own include ε-caprolactam, undecanelactam, lauryllactam, aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acid, and piperidone.

[0044] Furthermore, when condensing dicarboxylic acids and diamines, examples of dicarboxylic acids include adipic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, terephthalic acid, 2-methylterephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Examples of diamines include tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, paraphenylenediamine, and metaphenylenediamine.

[0045] As the polyamide resin, a polyamide resin (one that does not have segments other than polyamide) can be used. Examples of polyamide resins include nylon (registered trademark) 4, 6, 7, 8, 11, 12, 6.6, 6.9, 6.10, 6.11, 6.12, 6T, 6 / 6.6, 6 / 12, 6 / 6T, 6T / 6I, etc. Among the above, nylon 11 and nylon 12 are particularly preferred as polyamide resins.

[0046] Polyamide elastomers can also be used as polyamide resins. Examples of polyamide elastomers include block copolymers of polyamide (hard segment) and polyether (soft segment), block copolymers of polyamide (hard segment) and polyester (soft segment), and block copolymers of polyamide (hard segment) and polyether ester (soft segment). More specifically, examples include block copolymers of nylon® 11 and polytetramethylene glycol, and block copolymers of nylon 12 and polytetramethylene glycol.

[0047] The ends of the polyamide resin may be sealed with carboxyl groups, amino groups, etc. The above polyamide resins can be used individually or in combination of two or more types.

[0048] As for the polyamide resins mentioned above, commercially available products may be used, for example, the Diamide® series (L1640, L1840, L1940, L1940W, L2140, L2140W, L2121, etc.), Vestamid® series (all from Daicel-Evonik Corporation); Lilsamide® series, Lilsan® series, Pebax® series (all from Arkema Corporation); Amiran® ​​series (Toray Industries, Inc.); Leona® series (Asahi Kasei Fibers Corporation); UBE Nylon® series (Ube Industries, Ltd.); Lenny® series (Mitsubishi Engineering Plastics Corporation); Zytel® series (DuPont Ltd.); Grilamid® series, Grilflex® series (EBG4530) Examples include NZ, ELG5930, ELG5660, ELG6260, ELG4960, etc. (all from EMS Chemie Japan Co., Ltd.). Furthermore, the above-mentioned commercially available polyamide resins may be used individually or blended with two or more other polyamide resins.

[0049] In a preferred embodiment of the present invention, the polyamide resin constituting the first polyamide layer is a polyamide resin.

[0050] The weight-average molecular weight of the polyamide resin is preferably 10,000 to 500,000, and more preferably 15,000 to 300,000. In this invention, the "weight-average molecular weight" of the polyamide resin is the value measured by gel permeation chromatography (GPC).

[0051] The first polyamide layer according to the present invention contains a predetermined amount of a pressure-resistant agent. The "pressure-resistant agent" refers to a substance whose addition improves the pressure resistance (pressure strength) of the catheter tube.

[0052] In a preferred embodiment, the pressure resistance improver includes a main component that contributes to improving pressure resistance and a dispersant that improves dispersibility in polyamide resins.

[0053] The main component is not particularly limited, but examples include amorphous carbon such as carbon black; inorganic pigment components such as titanium dioxide, barium sulfate, iron oxide (black iron oxide, yellow iron oxide, red iron oxide), chromium oxide, ultramarine (ultramarine blue, ultramarine violet), nickel titanium yellow, Prussian blue, millery blue, cobalt blue, viridian, molybdenum red, etc. Furthermore, examples of organic pigment components such as quinacridone pigments (e.g., quinacridone red), perylene pigments (e.g., perylene red), anthraquinone pigments (e.g., anthraquinone yellow), azo pigments (e.g., condensed azo yellow organic pigment), and phthalocyanine pigments (e.g., halogenated phthalocyanines such as copper phthalocyanine and high-copper chloride phthalocyanine) can be used as the main component. The main component can be one of the above components alone or in combination of two or more.

[0054] Of these, from the viewpoint of heat resistance during extrusion molding and catheter manufacturing, it is preferable that the pressure resistance improver contains an inorganic pigment-based component as its main component. By improving heat resistance, it becomes possible to process at higher temperatures during annealing and fusion processes during manufacturing, thereby improving the rigidity of the catheter tube and obtaining higher pressure resistance.

[0055] Furthermore, from the viewpoint of further improving pressure resistance and having a high effect in improving the sliding properties of the surface of the first polyamide layer (inner layer), the pressure resistance improver preferably contains amorphous carbon and / or a metal compound as its main component, and more preferably contains amorphous carbon and a metal compound. Herein, "metal compound" refers to the metal compound listed above as an inorganic pigment component. From a similar viewpoint, it is more preferable for the pressure resistance improver to contain carbon black and titanium oxide.

[0056] In other preferred embodiments, the pressure-resistant agent includes at least one selected from the group consisting of carbon black, titanium dioxide, ultramarine, perylene-based pigments, and phthalocyanine-based pigments. Catheter tubes containing these main components have excellent pressure resistance. For example, in a preferred embodiment, the pressure-resistant agent includes carbon black and titanium dioxide. Furthermore, in another preferred embodiment, the pressure-resistant agent includes carbon black, titanium dioxide, and ultramarine. Furthermore, in another preferred embodiment, the pressure-resistant agent includes carbon black, titanium dioxide, ultramarine, and perylene-based pigments. Furthermore, in another preferred embodiment, the pressure-resistant agent includes phthalocyanine-based pigments.

[0057] Furthermore, in another preferred embodiment, the pressure-resistant enhancer includes at least one selected from the group consisting of carbon black, titanium dioxide, and ultramarine. These components are inorganic pigment-based components and have high heat resistance, allowing them to be processed at higher temperatures during annealing and fusion treatments. As a result, the rigidity of the resulting catheter tube is easily improved, and the pressure resistance is further enhanced.

[0058] Preferably, the pressure resistance improver contains a dispersant such as a surfactant in addition to the main component mentioned above. The inclusion of a dispersant in the pressure resistance improver improves the dispersibility of the pressure resistance improver in the first polyamide layer, making it easier for the pressure resistance improver to function.

[0059] Examples of dispersants that may be included in pressure resistance improvers include surfactants such as anionic surfactants (e.g., alkyl sulfates, fatty acid salts, etc.), cationic surfactants (aliphatic amine salts, quaternary ammonium salts, etc.), amphoteric surfactants, and nonionic surfactants (fatty acid esters, polyethylene glycol, etc.); as well as polymeric dispersants such as polycarboxylic acids and their amine salts, polycarboxylic acid esters, polyurethanes, modified polyacrylates, polyesteramides and their amine salts, alginic acid, polyvinyl alcohol, and carboxymethylcellulose.

[0060] In particular, the pressure resistance improver preferably contains an anionic surfactant as a dispersant, and more preferably contains a higher fatty acid metal salt, because it not only has a high effect in dispersing the above main component in polyamide resins but also possesses high safety. Furthermore, from a similar viewpoint, the pressure resistance improver preferably contains at least one selected from the group consisting of calcium laurate, calcium palmitate, calcium stearate, calcium oleate, zinc laurate, zinc palmitate, zinc stearate, and zinc oleate as a dispersant, and the dispersant is particularly preferably calcium stearate and / or zinc stearate. Note that the dispersant can be used with one of the above components alone or in combination of two or more.

[0061] The pressure resistance improver may further contain additives such as stabilizers in addition to the main component and dispersant mentioned above.

[0062] The first polyamide layer according to the present invention contains a pressure-resistant agent in a proportion of more than 10% by weight and up to 30% by weight relative to the total solid content of the first polyamide layer. If the proportion of the pressure-resistant agent contained in the first polyamide layer is 10% by weight or less, the pressure resistance strength of the catheter tube will be insufficient, and the sliding properties of the inner layer surface will decrease. On the other hand, if the proportion of the pressure-resistant agent contained in the first polyamide layer exceeds 30% by weight, the rigidity of the catheter tube will become too high, and sufficient flexibility will not be obtained, potentially reducing operability. In addition, it will become difficult to mold the catheter tube into a tubular shape during manufacturing.

[0063] Furthermore, from the viewpoint of obtaining a catheter (catheter tube) that not only improves pressure resistance while maintaining good sliding properties of the inner layer surface, but also has high flexibility and excellent operability, it is preferable that the first polyamide layer contains 15% to 20% by weight of the pressure resistance improving agent relative to the total solid content of the first polyamide layer.

[0064] As described above, in a preferred embodiment of the present invention, the pressure-resistant agent comprises a main component and a dispersant. In this case, the ratio of the main component to the dispersant in the pressure-resistant agent is not particularly limited, but for example, the pressure-resistant agent consists of 15 to 90% by weight of the main component (total amount if multiple main components are used) and 85 to 10% by weight of the dispersant (total amount if multiple dispersants are used) (however, the total amount of the main component and dispersant is 100% by weight). By using a pressure-resistant agent with such a composition, the dispersibility of the pressure-resistant agent in the layer is improved, and the pressure resistance of the catheter tube is improved. Preferably, the pressure-resistant agent used in the present invention consists of 20 to 70% by weight of the main component (total amount if multiple main components are used) and 80 to 30% by weight of the dispersant (total amount if multiple dispersants are used) (however, the total amount of the main component and dispersant is 100% by weight). More preferably, the pressure resistance improver consists of 40 to 60% by weight of a main component (total amount if multiple main components are used) and 60 to 40% by weight of a dispersant (total amount if multiple dispersants are used) (provided that the total amount of the main component and dispersant is 100% by weight).

[0065] From the viewpoint of improving pressure resistance and the sliding properties of the inner layer surface, the content of the main component relative to the total solid content of the first polyamide layer is preferably 2.5% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, particularly preferably more than 5% by weight, and most preferably 7% by weight or more. On the other hand, from the viewpoint of obtaining a catheter tube with sufficient flexibility and excellent operability, the content of the main component relative to the total solid content of the first polyamide layer is preferably 25% by weight or less, more preferably 20% by weight or less, particularly preferably 15% by weight or less, and most preferably 12% by weight or less. Furthermore, in order to improve pressure resistance, the sliding properties of the inner layer surface, and flexibility in a balanced manner, the content of the main component relative to the total solid content of the first polyamide layer is preferably within the range indicated by any combination of the above lower limit and any of the above upper limit.

[0066] Furthermore, as described above, in a preferred embodiment of the present invention, the pressure-resistant enhancer comprises amorphous carbon and a metal compound as its main components. In this case, the ratio of amorphous carbon to metal compound content is not particularly limited, but for example, the main components contained in the pressure-resistant enhancer consist of 0.1 to 60% by weight of amorphous carbon and 99.9 to 40% by weight of a metal compound (the total amount if multiple metal compounds are used) (however, the total amount of amorphous carbon and metal compound is 100% by weight). By using a pressure-resistant enhancer with such a composition, the sliding properties and pressure resistance of the inner layer surface of the catheter tube are improved. Preferably, the main components contained in the pressure-resistant enhancer used in the present invention consist of 3 to 55% by weight of amorphous carbon and 97 to 45% by weight of a metal compound (the total amount if multiple metal compounds are used) (however, the total amount of amorphous carbon and metal compound is 100% by weight).

[0067] In a form in which the pressure resistance improver contains amorphous carbon and a metal compound as the main components, from the viewpoint of improving pressure resistance and the sliding properties of the inner layer surface, the first polyamide layer preferably contains 0.5% to 10% by weight of amorphous carbon relative to the total solid content of the first polyamide layer. From a similar viewpoint, the first polyamide layer is more preferably containing more than 2.5% to 7.5% by weight of amorphous carbon relative to the total solid content of the first polyamide layer. Furthermore, from a similar viewpoint, the amorphous carbon content in the first polyamide layer is preferably 3% by weight or more, and more preferably 3.5% by weight or more. On the other hand, from the viewpoint of obtaining a catheter tube with sufficient flexibility and excellent operability, the amorphous carbon content relative to the total solid content of the first polyamide layer is preferably 7% by weight or less, more preferably 6% by weight or less, and particularly preferably 5% by weight or less. Furthermore, in order to improve the pressure resistance, sliding properties of the inner layer surface, and flexibility in a balanced manner, it is preferable that the content of amorphous carbon relative to the total solid content of the first polyamide layer be within the range indicated by any combination of the lower limit and the upper limit mentioned above.

[0068] Furthermore, the presence of amorphous carbon in the first polyamide layer can be identified by laser Raman spectroscopy. The carbon content can then be measured by heating the polyamide resin forming the first polyamide layer to a temperature at which it does not carbonize, removing the resin, and measuring the amount of remaining carbon.

[0069] In one embodiment of the present invention, the content of the dispersant in the first polyamide layer is preferably 3% by weight or more, more preferably more than 5% by weight, and particularly preferably 7% by weight or more, relative to the total solid content of the first polyamide layer. On the other hand, from the viewpoint of sufficiently obtaining the effect of improving the pressure resistance strength, the content of the dispersant relative to the total solid content of the first polyamide layer is preferably 25% by weight or less, more preferably 20% by weight or less, particularly preferably 15% by weight or less, and most preferably 12% by weight or less.

[0070] In one embodiment of the present invention, the first polyamide layer comprises a polyamide resin in an amount of 70% to less than 90% by weight (on a solids basis), a main component in an amount of 3 to 25% by weight (on a solids basis), and a dispersant in an amount of 3 to 25% by weight (on a solids basis), with the total weight of the first polyamide layer being 100% by weight. In another embodiment, the first polyamide layer consists of a polyamide resin in an amount of 70% to less than 90% by weight (on a solids basis), a main component in an amount of 3 to 25% by weight (on a solids basis), and a dispersant in an amount of 3 to 25% by weight (on a solids basis) (wherein the total amount of the polyamide resin, main component and dispersant is 100% by weight).

[0071] In a preferred embodiment of the present invention, the first polyamide layer comprises 70% to less than 90% by weight (solids content) of a polyamide resin, 3 to 20% by weight (solids content), and 3 to 20% by weight (solids content) of a dispersant, with the total weight of the first polyamide layer being 100% by weight. In another preferred embodiment, the first polyamide layer consists of 70% to less than 90% by weight (solids content) of a polyamide resin, 3 to 20% by weight (solids content), and 3 to 20% by weight (solids content) of a dispersant (wherein the total amount of the polyamide resin, main component, and dispersant is 100% by weight).

[0072] In a more preferred embodiment, the first polyamide layer comprises 80-85% by weight (solids content) of a polyamide resin, 5-10% by weight (solids content) of a main component, and 5-10% by weight (solids content) of a dispersant, with the total weight of the first polyamide layer being 100% by weight. In another more preferred embodiment, the first polyamide layer consists of 80-85% by weight (solids content) of a polyamide resin, 5-10% by weight (solids content) of a main component, and 5-10% by weight (solids content) of a dispersant (wherein the total amount of the polyamide resin, main component, and dispersant is 100% by weight).

[0073] The shape of the pressure-resistant agent is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular or rectangular prisms, cylindrical shapes, cylindrical shapes where the center of the cylinder is wider than the ends, plate shapes, so-called cocoon shapes with a constriction in the center, so-called aggregate spherical shapes where multiple particles are integrated, rugby ball shapes, and various other shapes. From the viewpoint of improving the sliding properties of the inner layer surface, the shape of the pressure-resistant agent is preferably spherical.

[0074] Furthermore, the structure of the pressure-resistant agent is not particularly limited; for example, it may be hollow or solid. However, it is preferable that it be solid because it has a high effect in improving pressure resistance. Moreover, from the viewpoint of obtaining high pressure resistance while maintaining good sliding properties of the inner layer surface, it is even more preferable that the pressure-resistant agent be solid spherical particles.

[0075] The size of the pressure resistance improver is not particularly limited, but the lower limit of the average particle size of the primary particles of the pressure resistance improver is preferably greater than 2.0 μm, more preferably 3.0 μm or more, and particularly preferably 5.0 μm or more. The upper limit of the average particle size of the primary particles of the pressure resistance improver is preferably 20.0 μm or less, more preferably 15.0 μm or less, and particularly preferably 10.0 μm or less. Within this range, it is possible to improve the pressure resistance strength while maintaining better sliding properties of the inner layer surface. The average particle size (average primary particle diameter) of the primary particles of the pressure resistance improver can be measured, for example, by the conditions described in the examples.

[0076] The thickness of the first polyamide layer (the radial wall thickness of the inner tube of the first polyamide layer) is preferably thinner than the thickness of the second polyamide layer (the radial wall thickness of the inner tube of the second polyamide layer), which will be described later. In one embodiment of the present invention, a balloon catheter is provided in which the thickness of the first polyamide layer is thinner than the thickness of the second polyamide layer. The ratio of the thickness of the first polyamide layer to the thickness of the second polyamide layer is, for example, 1:2 to 1:50 (thickness of the first polyamide layer:thickness of the second polyamide layer), and preferably 1:3 to 1:8. The thickness of the first polyamide layer is preferably 5 to 30 μm, and more preferably 7 to 20 μm. By making the thickness of the first polyamide layer 5 μm or more, the operability of the catheter (catheter tube) can be improved, and by making it 30 μm or less, a catheter tube with a narrow diameter can be made.

[0077] To form a first polyamide layer containing a polyamide resin and a pressure-resistant agent, for example, a pellet can be prepared by kneading the polyamide resin and the pressure-resistant agent in any proportion according to a known method, and then using the pellet as the raw material for the first polyamide layer in the co-extrusion molding of the catheter tube.

[0078] [Second polyamide layer] In one embodiment of the present invention, the second polyamide layer (outer layer) contains a polyamide resin. In a preferred embodiment of the present invention, the second polyamide layer (outer layer) is made of a polyamide resin. Because polyamide resins are flexible and have high strength, they are used as materials for the outer tube and balloon of catheters. By forming the outer layer of the inner tube, which is a catheter tube, with a polyamide resin that is also used in other components, the compatibility between components is improved during fusion, and the breakage of the catheter can be effectively prevented. Furthermore, by using a polyamide resin as the resin that forms the outer layer of the inner tube, the catheter can be smoothly inserted into the lumen without kinking, even in lumens with large bends.

[0079] The description of the first polyamide layer above applies to the polyamide resin and its molecular weight that can be suitably used in the second polyamide layer. From the viewpoint of obtaining a catheter (catheter tube) that has good sliding properties and pressure resistance, as well as high flexibility and excellent operability, it is preferable that the second polyamide layer contains a polyamide resin and a polyamide elastomer. In particular, from the viewpoint of improving pressure resistance and operability (flexibility) in a well-balanced manner, it is preferable that the first polyamide layer contains a polyamide resin, and the second polyamide layer contains a polyamide resin and a polyamide elastomer (i.e., the second polyamide layer contains a blend of polyamide resin and polyamide elastomer). In this form, the mixing ratio (weight ratio) of the polyamide resin and polyamide elastomer is not particularly limited, but it is preferably 50:50 to 95:5 (polyamide resin: polyamide elastomer, the same applies hereinafter), more preferably 60:40 to 90:10, and particularly preferably 70:30 to 85:15. Furthermore, from the viewpoint of interlayer adhesion, it is preferable that the same polyamide resin be used for the first polyamide layer and the second polyamide layer.

[0080] The thickness of the second polyamide layer is preferably greater than that of the first polyamide layer. A thicker second polyamide layer can improve adhesion to the tip and balloon when the catheter tube is used as the inner tube of a balloon catheter. More specifically, the thickness of the second polyamide layer is preferably 30 to 75 μm, and more preferably 35 to 70 μm.

[0081] The catheter tube according to the present invention can be formed by co-extrusion molding using polyamide resin fine powder, coating dispersion, or pellets (and a pressure resistance improver for the first polyamide layer) as raw materials. The manufacturing conditions during extrusion molding can be arbitrarily set by those skilled in the art, but for example, the melting temperature is set to 100 to 250°C. Furthermore, in order to improve the pressure resistance, it is preferable to perform annealing treatment after extrusion molding. The annealing conditions are not particularly limited, but for example, it is preferable to perform annealing at 80 to 140°C for 1 to 3 hours. [Examples]

[0082] The effects of the present invention will be explained using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, the operations were carried out at room temperature (25°C).

[0083] [Example 1-1] (1) Preparation of composite material pellets Polyamide resin (Nylon 12; Diamide L1940W; manufactured by Daicel-Evonik Corporation) was compounded at a ratio of 80% by weight and pressure-resistant enhancer 1 (containing 25% by weight of carbon black, 25% by weight of titanium dioxide, 25% by weight of calcium stearate, and 25% by weight of zinc stearate (total of all components is 100% by weight); DAIREN Black PPB-0491 (DIC Corporation)) at a ratio of 20% by weight (total of polyamide resin and pressure-resistant enhancer 1 is 100% by weight) using a twin-screw compounder. The compounding was performed twice to ensure thorough mixing of the polyamide resin and pressure-resistant enhancer 1. Subsequently, extrusion and cutting were performed to obtain pellets of composite material 1 with a pressure-resistant enhancer 1 content of 20% by weight.

[0084] The pressure-resistant agent 1 described above consists of solid particles, and the average particle size of the primary particles was 6.2 μm. The average particle size of the primary particles of the pressure-resistant agent 1 was determined by the following method.

[0085] A sample of 0.005 g of pressure-resistant agent was mixed with 30 mL of 2-propanol as a dispersion medium, and the average particle size was measured using a laser diffraction particle size distribution analyzer (batch cell). The analyzer used was an LA-960S (manufactured by Horiba, Ltd.), with a refractive index of 1.810 for the sample and 1.378 for the dispersion medium.

[0086] (2) Preparation of tubes A two-layer tube having an inner layer (a first polyamide layer made of the above composite material 1; film thickness 17.5 μm) and an outer layer (a second polyamide layer; film thickness 57.5 μm) was coated onto a copper wire and co-extruded. After that, the copper wire was removed and the tube was annealed at 130°C for 2 hours to obtain tube 1-1 (inner diameter 0.43 mm × middle diameter 0.465 mm × outer diameter 0.58 mm). Polyamide resin (nylon 12; diamide L1940W (Daicel-Evonik Corporation)) was used as the material for the second polyamide layer.

[0087] [Comparative Example 1-1] Comparative tube 1-1 was obtained by the same method as in Example 3 described in Japanese Patent Publication No. 2016-174827 (corresponding to U.S. Patent Application Publication No. 2016 / 0271361).

[0088] [Example 2-1] (1) Preparation of composite material pellets Pellet of composite material 1 was obtained in the same manner as in (1) of Example 1-1 above.

[0089] (2) Preparation of tubes In Example 1-1(2) above, tube 2-1 was obtained in the same manner as in Example 1-1, except that the material of the outer layer (second polyamide layer) was changed to a polyamide resin containing polyamide resin (nylon 12; diamide L1940W (Daicel Evonik Co., Ltd.)) and polyamide elastomer (Grillflex ELG6260 (EMS Chemie Japan Co., Ltd.)) in a weight ratio of 80:20 (inner diameter 0.43 mm × middle diameter 0.46 mm × outer diameter 0.58 mm).

[0090] [Example 2-2] (1) Preparation of composite material pellets Pellet of composite material 2 was obtained in the same manner as in Example 1-1(1), except that the polyamide resin content was changed to 85% by weight and the pressure resistance improver 1 content to 15% by weight.

[0091] (2) Preparation of tubes Tube 2-2 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 2 were used instead of pellets of composite material 1.

[0092] [Comparative Example 2-1] (1) Preparation of composite material pellets A pellet of comparative composite material 1 was obtained in the same manner as in Example 1-1(1), except that the polyamide resin content was changed to 90% by weight and the pressure resistance improver 1 content to 10% by weight.

[0093] (2) Preparation of tubes In Example 2-1(2) above, comparative tube 2-1 was obtained in the same manner as in Example 2-1(2), except that pellets of comparative composite material 1 were used instead of pellets of composite material 1.

[0094] [Example 3-1] (1) Preparation of composite material pellets In Example 1-1(1) above, a pellet of composite material 3 was obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 2 (containing 33.4% by weight of carbon black, 33.3% by weight of calcium stearate, and 33.3% by weight of zinc stearate (total of all components is 100% by weight); DIC Corporation).

[0095] Furthermore, the pressure resistance improver 2 mentioned above was in the form of solid particles.

[0096] (2) Preparation of tubes Tube 3-1 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 3 were used instead of pellets of composite material 1.

[0097] [Example 3-2] (1) Preparation of composite material pellets In Example 1-1(1) above, a pellet of composite material 4 was obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 3 (containing 33.4% by weight of titanium dioxide, 33.3% by weight of calcium stearate, and 33.3% by weight of zinc stearate (total of all components is 100% by weight); DIC Corporation).

[0098] Furthermore, the pressure-resistant agent 3 mentioned above was in the form of solid particles.

[0099] (2) Preparation of tubes Tube 3-2 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 4 were used instead of pellets of composite material 1.

[0100] [Example 3-3] (1) Preparation of composite material pellets In Example 1-1(1) above, pellets of composite material 5 were obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 4 (containing 13.1% by weight of carbon black, 8.2% by weight of titanium dioxide, 41% by weight of ultramarine, 4.9% by weight of perylene red, 16.4% by weight of calcium stearate, and 16.4% by weight of zinc stearate (total of all components is 100% by weight); DIC Corporation).

[0101] The pressure resistance improver 4 described above was a solid particle, and the average particle size of the primary particles was 2.8 μm.

[0102] (2) Preparation of tubes Tube 3-3 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 5 were used instead of pellets of composite material 1.

[0103] [Examples 3-4] (1) Preparation of composite material pellets In Example 1-1(1) above, a pellet of composite material 6 was obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 5 (containing 2.5 wt% carbon black, 35 wt% titanium dioxide, 12.5 wt% ultramarine, 25 wt% calcium stearate, and 25 wt% zinc stearate (total of all components is 100 wt%); DIC Corporation).

[0104] Furthermore, the pressure resistance improver 5 mentioned above was in the form of solid particles.

[0105] (2) Preparation of tubes Tube 3-4 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 6 were used instead of pellets of composite material 1.

[0106] [Examples 3-5] (1) Preparation of composite material pellets In Example 1-1(1) above, a pellet of composite material 7 was obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 6 (containing 0.3 wt% carbon black, 66.5 wt% titanium dioxide, 16.6 wt% calcium stearate, and 16.6 wt% zinc stearate (total of all components is 100 wt%); DIC Corporation).

[0107] Furthermore, the pressure-resistant agent 6 mentioned above was in the form of solid particles.

[0108] (2) Preparation of tubes Tube 3-5 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 7 were used instead of pellets of composite material 1.

[0109] [Examples 3-6] (1) Preparation of composite material pellets In Example 1-1(1) above, a pellet of composite material 8 was obtained in the same manner as in Example 1-1(1), except that the type of pressure-resistant agent was changed to pressure-resistant agent 7 (containing 16.7 wt% copper phthalocyanine compound (Pigment Blue 15:3), 6.7 wt% copper phthalocyanine compound (Pigment Green 7), 25 wt% calcium stearate, and 51.6 wt% zinc stearate (total of all components is 100 wt%); DIC Corporation).

[0110] Furthermore, the pressure-resistant agent 7 mentioned above was in the form of solid particles.

[0111] (2) Preparation of tubes Tube 3-6 was obtained in the same manner as in Example 2-1(2), except that pellets of composite material 8 were used instead of pellets of composite material 1.

[0112] [Sliding performance evaluation] The individual tubes obtained in Example 1-1 and Comparative Example 1-1 were set in the jig shown in Figure 3. The tubes were filled with water. The length of each tube was 34 cm. A Ni-Ti alloy wire (φ0.34 mm) was inserted through the tube, and the resistance value when it was pulled out was measured. To ignore the effect of the wire end shape, the average resistance value when the wire end passed through the straight section (length: 5 cm) was used as the measurement value. The measuring instrument used was AUTOGRAPH® AG-X plus (Shimadzu Corporation). The evaluation results are shown in Table 1 below.

[0113] [Table 1]

[0114] As shown in Table 1, the tube (catheter tube) according to the present invention has good sliding properties equivalent to those of a tube having an inner layer made of modified polyolefin. In other words, according to the present invention, a catheter tube with good sliding properties of the inner tube (inner surface) can be obtained. Similar results were also obtained for the tubes (catheter tubes) of Examples 2-1 to 2-2.

[0115] Furthermore, while the tube of Comparative Example 1-1 required the application of a release agent to the copper wire in order to remove it after co-extrusion molding, the tube of Example 1-1 did not require this. Therefore, the catheter tube according to the present invention can be said to have excellent sliding properties from a manufacturing standpoint as well.

[0116] [Pressure resistance strength evaluation] (1) Preparation of evaluation samples Evaluation samples simulating balloon catheters were prepared using the tubes obtained in the above examples and comparative examples as inner tubes. A schematic of the evaluation samples is shown in Figure 4. In these evaluation samples, the inner tube 20 (tube from the examples and comparative examples) is inserted into the outer tube 30 (outer tube shaft made of polyamide resin), and one end of the intermediate shaft 40 (made of polyamide resin) is heat-sealed to one end (base end) of the outer tube 30. The other end (tip end) of the outer tube 30 is heat-sealed to the inner tube 20 and the outer tube 30 to ensure airtightness. The intermediate shaft 40 is equipped with a pressurized lumen (cavity), and pressure is applied from the intermediate shaft 40 side to the outside of the inner tube 20 via the outer tube 30 by water pressure. Note that evaluation samples without balloons were made because proper evaluation cannot be performed if the balloon bursts.

[0117] (2) Evaluation A guidewire (ASAHI SION® Blue, Asahi Intecc Co., Ltd.) was inserted into the inner tube in 37°C warm water. At this time, the guidewire was positioned so that it protruded 50-70 mm from the tip. The evaluation sample in this state was pressurized at 1 atm (1 atm = 101325 Pa) for 30 seconds using an intermediate shaft, and then depressurized. Subsequently, the pressure was held at 2 atm for 30 seconds and then depressurized, and then held at 3 atm for 30 seconds and then depressurized, and so on, with the pressure being increased in increments of 1 atm. At each depressurization, the catheter (evaluation sample) was moved while the guidewire was fixed, and the pressure at which the guidewire could no longer pass through the inner tube at the proximal end was measured. Note that proper evaluation (comparison) of pressure resistance strength cannot be performed unless minute conditions such as the flatness of the tube are standardized, so it is necessary to compare the example with the comparative example under these standardized conditions. Therefore, Example 1-1 was compared with Comparative Example 1-1, which had the same conditions as above, and similarly, Examples 2-1 and 2-2 were compared with Comparative Example 2-2.

[0118] As a result, in a comparison between Example 1-1 and Comparative Example 1-1, when the pressure resistance of the Comparative Example tube was set to 1.00, the pressure resistance ratio of the tube in Example 1-1 was found to be 1.18. These results indicate that the tube (catheter tube) according to the present invention has further improved pressure resistance compared to a tube having an inner layer made of modified polyolefin. In other words, according to the present invention, a catheter tube with excellent pressure resistance can be obtained. It should be noted that the tube of Comparative Example 1-1 also achieves sufficient pressure resistance during actual use.

[0119] Furthermore, a comparison was made between Examples 2-1 to 2-2 and Comparative Example 2-1. Table 2 below shows the pressure resistance ratio of the tubes in the examples, when the pressure resistance of the tubes in the comparative example is set to 1.00, along with the pressure resistance values ​​obtained by the evaluation method described above.

[0120] [Table 2]

[0121] As shown in Table 2, when the pressure-resistant agent content relative to the total solid content of the first polyamide layer was 10% by weight, a tendency for the pressure resistance to decrease was observed. Therefore, it can be said that good pressure resistance can be obtained by increasing the pressure-resistant agent content in the first polyamide layer to more than 10% by weight.

[0122] [Observation of the tube surface] When the surface of the tube obtained in Example 1-1 was observed using a CCD camera (Figure 5), many microstructures (the white areas in the photograph in Figure 5) were observed. Such microstructures suggest that the copper wire is not in close contact with the surface, and are presumed to contribute to good sliding properties.

[0123] This application is based on Japanese Patent Application No. 2021-039903, filed on March 12, 2021, and its disclosures are referenced and incorporated as a whole.

Claims

1. A catheter having a catheter tube, The catheter tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer. The first polyamide layer contains a pressure-resistant agent in an amount exceeding 10% by weight and not exceeding 30% by weight, relative to the total solid content of the first polyamide layer. The pressure-resistant agent comprises 15 to 90% by weight of a main component and 85 to 10% by weight of a dispersant (where the total amount of the main component and the dispersant is 100% by weight). The main component is two or more selected from the group consisting of carbon black; titanium dioxide, barium sulfate, iron oxide, chromium oxide, ultramarine, nickel titanium yellow, Prussian blue, millery blue, cobalt blue, viridian, molybdenum red; quinacridone pigments, perylene pigments, anthraquinone pigments, azo pigments, and phthalocyanine pigments, and comprises at least carbon black and titanium dioxide. The aforementioned dispersant is a higher fatty acid metal salt, in the catheter.

2. The catheter according to claim 1, wherein the dispersant is at least one selected from the group consisting of calcium laurate, calcium palmitate, calcium stearate, calcium oleate, zinc laurate, zinc palmitate, zinc stearate, and zinc oleate.

3. The catheter according to claim 1 or 2, wherein the first polyamide layer contains 15% to 20% by weight of the pressure-resistant agent with respect to the total solid content of the first polyamide layer.

4. The catheter according to any one of claims 1 to 3, wherein the first polyamide layer contains carbon black in an amount exceeding 2.5% by weight and not exceeding 7.5% by weight, relative to the total solid content of the first polyamide layer.

5. The catheter according to any one of claims 1 to 4, wherein the average particle size of the primary particles of the pressure-resistant agent is 3.0 μm or more.

6. The catheter according to any one of claims 1 to 5, wherein the second polyamide layer comprises a polyamide resin and a polyamide elastomer.

7. The catheter according to any one of claims 1 to 6, wherein the pressure-resistant agent is a solid spherical particle.

8. The device comprises an outer tube having a lumen, an inner tube positioned within the lumen of the outer tube, and balloons fixed to the tip of the inner tube and the tip of the outer tube. The balloon contains a polyamide resin, The inner tube comprises a first polyamide layer and a second polyamide layer disposed on the outer surface of the first polyamide layer. The first polyamide layer contains a pressure-resistant agent in an amount exceeding 10% by weight and not exceeding 30% by weight, relative to the total solid content of the first polyamide layer. The pressure-resistant agent comprises 15 to 90% by weight of a main component and 85 to 10% by weight of a dispersant (where the total amount of the main component and the dispersant is 100% by weight). The main component is two or more selected from the group consisting of carbon black; titanium dioxide, barium sulfate, iron oxide, chromium oxide, ultramarine, nickel titanium yellow, Prussian blue, millery blue, cobalt blue, viridian, molybdenum red; quinacridone pigments, perylene pigments, anthraquinone pigments, azo pigments, and phthalocyanine pigments, and comprises at least carbon black and titanium dioxide. The aforementioned dispersant is a higher fatty acid metal salt, in a balloon catheter.

9. The balloon catheter according to claim 8, wherein the dispersant is at least one selected from the group consisting of calcium laurate, calcium palmitate, calcium stearate, calcium oleate, zinc laurate, zinc palmitate, zinc stearate, and zinc oleate.

10. The balloon catheter according to claim 8 or 9, wherein the first polyamide layer contains 15% to 20% by weight of the pressure-resistant agent with respect to the total solid content of the first polyamide layer.

11. The balloon catheter according to any one of claims 8 to 10, wherein the first polyamide layer contains carbon black in an amount exceeding 2.5% by weight and not exceeding 7.5% by weight, relative to the total solid content of the first polyamide layer.

12. The balloon catheter according to any one of claims 8 to 11, wherein the average particle size of the primary particles of the pressure-resistant agent is 3.0 μm or more.

13. The balloon catheter according to any one of claims 8 to 12, wherein the second polyamide layer comprises a polyamide resin and a polyamide elastomer.

14. The balloon catheter according to any one of claims 8 to 13, wherein the pressure-resistant agent is a solid spherical particle.

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