catheter

Abstract

To improve mechanical characteristics of a low-allergic catheter using a synthetic rubber.SOLUTION: A catheter includes a tubular part made of an elastomer. The tubular part contains as the main constituent an elastomer material of a molecular structure having a chain structure 10 constituted by a synthetic rubber, and a cross-linked structure 20 cross-linking the inside of chain structure 10 or between the chain structures 10. The cross-linked structure 20 comprises polyrotaxane having a linear molecule 21, and a cyclic molecule 22 slidable to the linear molecule 21. The chain structure 10 is boned to the cyclic molecule 22 of polyrotaxane.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a catheter. [Background technology]

[0002] Catheters are used for diagnosis and treatment of organs in the digestive system, urinary system, circulatory system, etc. Patent Document 1 discloses a catheter equipped with a balloon made of natural rubber. Patent Document 2 discloses a catheter equipped with a balloon having a multi-layer structure having a layer made of elastomer with low water vapor permeability and an outermost layer made of silicone rubber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3206064 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-186669 Summary of the Invention [Problem to be solved by the invention]

[0004] The elastomer material constituting the catheter is required to provide the catheter with appropriate mechanical properties, such as appropriate flexibility during insertion and strength sufficient to withstand tension and compression without bursting.

[0005] Although catheters using natural rubber as in Patent Document 1 have the above-mentioned excellent mechanical properties, they have the problem of causing allergic symptoms due to the proteins contained in the natural rubber. On the other hand, in the case of the catheter in Patent Document 2, the outermost layer is formed from silicone rubber, so the above-mentioned problem of allergic symptoms can be avoided. However, in this case, the mechanical properties obtained from natural rubber are significantly impaired. [Means for solving the problem]

[0006] A catheter that solves the above problem is a catheter having a tubular portion made of an elastomer, the tubular portion containing as its main component an elastomer material having a chain structure made of synthetic rubber and a crosslinked structure that crosslinks within the chain structure or between the chain structures, the crosslinked structure being a molecular assembly having a first molecule and a second molecule movably combined with the first molecule, and the chain structure is bonded to the second molecule.

[0007] According to the above-mentioned configuration, since the elastomer tubular portion uses an artificially synthesized elastomer material, there is no problem of allergies caused by proteins contained in natural rubber.

[0008] Additionally, in the elastomer material, the second molecules, which are the crosslinking points between the synthetic rubber chain structure and the crosslinked structure, are movable relative to the first molecules of the crosslinked structure. Therefore, when a tensile or compressive force acts on the tubular portion, the second molecules, which are the crosslinking points, move in a direction that weakens the stress acting on the crosslinking points. This suppresses localized stress concentration during tension and compression, resulting in mechanical properties such as low modulus and low hysteresis loss. The mechanical properties of low modulus and low hysteresis loss improve the extensibility and durability of the tubular portion and reduce the resistance generated during deformation. Therefore, the tubular portion having the above configuration exhibits excellent responsiveness and durability during operation.

[0009] The crosslinked structure is, for example, a polyrotaxane having the linear first molecule, the cyclic second molecule that encapsulates the first molecule in a skewered manner, and blocking groups arranged at both ends of the first molecule.

[0010] The synthetic rubber constituting the chain structure is preferably silicone rubber. According to the above configuration, the biocompatibility of the elastomer tubular portion can be further improved. The catheter is preferably a balloon catheter including a shaft and a balloon provided at the tip portion of the shaft, and the tubular portion is preferably the balloon.

[0011] The mechanical properties of the elastomer material, such as low modulus and small hysteresis loss, are particularly suitable for balloons, which are inflated and deflated, and in this case, a balloon with a large volume expansion rate and excellent durability can be obtained. [Effects of the Invention]

[0012] According to the present invention, it is possible to improve the mechanical properties of a hypoallergenic catheter made of synthetic rubber. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram of a catheter. [Figure 2] FIG. 2 is an explanatory diagram of the molecular structure of an elastomer material. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described in which the present invention is embodied in a balloon catheter. <Catheter> As shown in FIG. 1, catheter 1 is a balloon catheter comprising a shaft 2 and a balloon 5 provided at the distal end of shaft 2. Shaft 2 is a tubular portion with a double-tube structure having an inner tube 3 and an outer tube 4. Balloon 5 is a tubular portion with a central portion that bulges outward. The distal end of balloon 5 is fixed to the outer peripheral surface of inner tube 3, and the proximal end of balloon 5 is fixed to the outer peripheral surface of outer tube 4.

[0015] The shaft 2 has flexibility that allows it to deform along the shape of the body cavity, and elasticity that allows it to maintain its shape. Examples of materials that can be used to form the shaft 2 include resin, metal, and a combination of resin and metal.

[0016] Examples of resins that can be used to form the shaft 2 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluorine resins, vinyl chloride resins, silicone resins, and combinations thereof.

[0017] Examples of metals that can be used to form the shaft 2 include stainless steel, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloys, Co-Cr alloys, and combinations thereof. The inner tube 3 and the outer tube 4 may be made of the same material, or may be made of different materials.

[0018] The balloon 5 is made of an artificially synthesized elastomer and contains a specific elastomer material as a main component. The content of the specific elastomer material in the balloon 5 is, for example, 50% by mass or more, preferably 80% by mass or more, and more preferably 95% by mass or more.

[0019] Furthermore, the balloon 5 may contain other components in addition to the specific elastomer material, as needed, such as known additives such as plasticizers, inorganic fillers, antioxidants, surfactants, preservatives, antifoaming agents, dispersants, leveling agents, freeze stabilizers, and colorants.

[0020] The space within the inner tube 3 of the shaft 2 functions as an insertion passage for inserting an insertion member such as a wire. The space between the inner tube 3 and outer tube 4 of the shaft 2 functions as a flow path for fluid to be supplied into the balloon 5. The balloon 5 expands when fluid is supplied to the interior through the space between the inner tube 3 and outer tube 4 of the shaft 2. The balloon 5 contracts when the fluid inside it is discharged through the space. The fluid supplied into the balloon 5 is, for example, saline, sterilized purified water, or air. The thickness of the balloon 5 when not inflated is, for example, 10 μm or more and 150 μm or less.

[0021] <Specific elastomer material> As shown in FIG. 2, the specific elastomer material has a molecular structure having a chain structure 10 and a crosslinked structure 20 that crosslinks within the chain structure 10 or between the chain structures 10. The chain structure 10 is made of synthetic rubber. The crosslinked structure 20 is made of polyrotaxane. Note that crosslinking within the chain structure 10 means crosslinking multiple points on the same chain structure 10. Crosslinking between chain structures 10 means crosslinking between multiple chain structures 10.

[0022] (chain structure) Examples of synthetic rubbers that make up the chain structure 10 include silicone rubber, chloroprene rubber, isoprene rubber, ethylene propylene diene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, and combinations thereof. Among these, silicone rubber is particularly preferred because of its high biocompatibility.

[0023] (Crosslinked structure) As shown in Fig. 2, the polyrotaxane as the crosslinked structure 20 is a molecular assembly having a structure including a linear molecule 21, a cyclic molecule 22 that encapsulates the linear molecule 21 in a skewered manner, i.e., that incorporates the linear molecule 21 into a cavity, and blocking groups 23 arranged at both ends of the linear molecule 21. Each cyclic molecule 22 is slidable relative to the linear molecule 21. In this embodiment, the first molecule of the molecular assembly described in the claims is the linear molecule 21, and the second molecule is the cyclic molecule 22.

[0024] Examples of the linear molecule 21 include polyethylene glycol, polylactic acid, polyisoprene, polyisobutylene, polybutadiene, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl methyl ether, and combinations thereof.

[0025] Examples of the cyclic molecule 22 include cyclodextrin, crown ether, cyclophane, calixarene, cucurbituril, cyclic amide, and combinations thereof. Examples of the cyclodextrin include α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The cyclodextrin may have some of its hydroxyl groups substituted with other groups, or may have a substituent having a graft chain to make it soluble in various organic solvents. Examples of the other groups include "-SH," "-NH," "-COOH," "-SOH," and "-POH." Examples of the graft chain include a graft chain formed by ring-opening polymerization of a lactone monomer. Specific examples of the cyclic molecule 22 include cyclodextrin having 20 or more graft chains of polycaprolactone. The number of cyclic molecules 22 included in one linear molecule 21 may be one or more.

[0026] Examples of blocking groups for polyrotaxanes include dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, substituted benzenes, optionally substituted polynuclear aromatics, steroids, and combinations thereof. Examples of substituents contained in the substituted benzenes and polynuclear aromatics include alkyl groups, alkyloxy groups, hydroxy groups, halogen groups, cyano groups, sulfonyl groups, carboxyl groups, amino groups, and phenyl groups. The above substituents may be singular or plural.

[0027] An example of the polyrotaxane is a polyrotaxane in which the linear molecule 21 is polyethylene glycol, the cyclic molecule 22 is cyclodextrin, and the blocking group 23 is an adamantane group.

[0028] In the polyrotaxane as the crosslinked structure 20, the cyclic molecule 22 portion is chemically bonded to the chain structure 10. Examples of the bond between the cyclic molecule 22 and the chain structure 10 include a carbon-carbon bond and a carbon-silicon bond.

[0029] <Balloon manufacturing method> Next, an example of a method for manufacturing the balloon 5 will be described. First, polyrotaxane is synthesized by a known method. At this time, a cyclic molecule having a functional group capable of bonding to the chain structure 10 is used as the cyclic molecule 22. Examples of the functional group capable of bonding include a hydrosilyl group and a phenolic hydroxyl group. Note that examples of methods for synthesizing polyrotaxane include the method disclosed in International Publication No. 2005-080469.

[0030] A latex compound liquid is prepared by mixing polyrotaxane, synthetic rubber polymer latex, an emulsifier, and an aqueous solvent. Examples of the emulsifier include anionic surfactants and nonionic surfactants. Examples of the aqueous solvent include water and a mixed solvent of water and an organic solvent. The amount of polyrotaxane in the latex compound liquid is, for example, 0.5 to 10 parts by mass per 100 parts by mass of the solid content of the synthetic rubber polymer latex. The solid content of the latex compound liquid is, for example, 5 to 30% by mass. In the latex compound liquid, the emulsifier forms micelles, and the synthetic rubber polymer and polyrotaxane are encapsulated in the micelles.

[0031] Next, the rod-shaped mold with the calcium-based coagulation liquid adhered to its surface is immersed in a latex compound liquid to uniformly adhere the latex compound liquid to the surface of the mold, and then the adhered latex compound liquid is dried. This is followed by a water-washing treatment to remove water-soluble components, and a heat treatment to form a crosslinked structure 20. The heat treatment temperature is, for example, 60 to 150°C, and the heat treatment time is, for example, 30 to 120 minutes. After the heat treatment, the target balloon 5 is obtained by demolding from the mold.

[0032] Next, the operation and effects of this embodiment will be described. (1) The catheter 1 has a tubular portion made of an elastomer. The tubular portion contains, as a main component, an elastomer material having a molecular structure including a chain structure 10 made of synthetic rubber and a crosslinked structure 20 that crosslinks within the chain structure 10 or between the chain structures 10. The crosslinked structure 20 is a polyrotaxane having a linear molecule 21 and a cyclic molecule 22 that can slide relative to the linear molecule 21. The chain structure 10 is bonded to the cyclic molecule 22 of the polyrotaxane.

[0033] The elastomer material constituting the tubular portion of the above structure is an artificially synthesized elastomer material, so there is no problem of allergies caused by proteins contained in natural rubber. Additionally, in the elastomer material, the cyclic molecules 22, which are the crosslinking points between the synthetic rubber chain structure 10 and the crosslinked structure 20, are movable relative to the linear molecules 21 of the crosslinked structure 20. Therefore, when a tensile or compressive force acts on the tubular portion, the second molecules, which are the crosslinking points, move in a direction that weakens the stress acting on the crosslinking points. This suppresses localized stress concentration during tension and compression, resulting in mechanical properties such as low modulus and low hysteresis loss. The mechanical properties of low modulus and low hysteresis loss improve the extensibility and durability of the tubular portion and reduce the resistance generated during deformation. Therefore, the tubular portion having the above configuration exhibits excellent responsiveness and durability during operation.

[0034] (2) The catheter 1 is a balloon catheter including a shaft 2 and a balloon 5 provided at the distal end of the shaft 2. The tubular portion made of elastomer is the balloon 5.

[0035] The low modulus and small hysteresis loss mechanical properties of the specific elastomer material are particularly suitable for the balloon 5, which is the portion that is inflated and deflated. In this case, the balloon 5 has a large volume expansion rate and excellent durability.

[0036] (3) The synthetic rubber that constitutes the chain structure 10 is silicone rubber. According to the above configuration, the biocompatibility of the elastomer tubular portion can be further improved. This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0037] The crosslinked structure 20 is not limited to polyrotaxane, but may be any molecular assembly having a structure including a first molecule and a second molecule movably combined with the first molecule. The type and specific shape of the catheter 1 are not limited to those described in the above embodiment. For example, the catheter 1 may not include a balloon 5, or may include a shaft 2 with a multi-tube structure of three or more, or a shaft 2 with a single tube structure.

[0038] In the catheter 1, the portion corresponding to the elastomeric tubular portion is not limited to the balloon 5. For example, a portion of the shaft 2, such as the inner tube 3 and outer tube 4, or the entire shaft 2 may be made of a specific elastomer material to form the elastomeric tubular portion. When a portion of or the entire shaft 2 is made of an elastomeric tubular portion, the Young's modulus of the specific elastomer material is made higher than that of the balloon 5 in order to ensure the strength required for the shaft 2. The Young's modulus of the specific elastomer material can be adjusted, for example, by changing the number of crosslinking points between the chain structure 10 and the crosslinked structure 20 to adjust the crosslinking density.

[0039] The elastomer tubular portion may have other layers provided that the mechanical properties of the specific elastomer material are not impaired. Examples of other layers include a coating layer provided on the outer or inner surface.

[0040] The method for manufacturing the elastomer tubular portion is not limited to the manufacturing method of the above embodiment, and may be any known method used for molding a tubular elastomer member from a resin material, such as extrusion molding.

[0041] Next, the technical ideas that can be understood from the above-described embodiment and modified examples will be described below. (i) The catheter, wherein the first linear molecule is polyethylene glycol and the second cyclic molecule is cyclodextrin. [Explanation of symbols]

[0042] 1. Catheter 2...Shaft 3…Inner pipe 4…Outer tube 5. Balloon 10…chain structure 20…Crosslinked structure 21…Linear molecule 22...Cyclic molecule 23...blocking group

Claims

1. A catheter comprising an elastomeric tubular portion, the tubular portion contains, as a main component, an elastomer material having a chain structure constituted by synthetic rubber and a crosslinked structure that crosslinks within the chain structure or between the chain structures; the crosslinked structure is a molecular assembly having a structure including a first molecule and a second molecule movably combined with the first molecule, the chain structure is bound to the second molecule; the crosslinked structure is a polyrotaxane having the linear first molecule, the cyclic second molecule that encapsulates the first molecule in a skewered manner so as to be slidable relative to the first molecule, and blocking groups arranged at both ends of the first molecule, A catheter characterized in that the synthetic rubber constituting the chain structure is silicone rubber.

2. the catheter is a balloon catheter including a shaft and a balloon provided at a distal end portion of the shaft; The catheter according to claim 1 , wherein the tubular portion is the balloon.

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