Catheter tip

Abstract

To provide a catheter that is less likely to deteriorate even when stored for a long period of time. [Solution] A catheter tip comprising a catheter tip resin layer containing a resin having ester bonds and / or amide bonds, carbodiimide, and tungsten carbide (WC), wherein the content of the carbodiimide is greater than 0% by mass and less than 0.5% by mass of the total mass of the catheter tip resin layer, and the elongation retention rate is 70% or more.

Description

Technical Field

[0001] The present invention relates to a catheter tip.

Background Art

[0002] When treating or diagnosing a stenosis, a catheter is used to insert a medical device into the living body and introduce it to the target site. When inserting a catheter into the living body, in order to accurately grasp the position of the tip of the catheter, the tip of the catheter (catheter tip) usually contains a radiopaque substance that enables detection by X-rays. For example, metallic tungsten powder is known as an excellent radiopaque substance and is used as a material for the catheter tip (for example, Patent Document 1). In addition, a resin having an amide bond or an ester bond is generally used as the material of the catheter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Catheters are not only used immediately but may also be stored for a long time before use. Resin is usually used for catheter tips for formability and flexibility, but when tungsten is incorporated into the catheter tip as a radiopaque substance, the resin may deteriorate.

[0005] Therefore, an object of the present invention is to provide a catheter tip in which the resin is less likely to deteriorate even after long-term storage, and a catheter including the same.

Means for Solving the Problems

[0006] <着 The present invention has the following configuration: (1) A catheter tip comprising a catheter tip resin layer containing a resin having ester bonds and / or amide bonds, carbodiimide, and tungsten carbide (WC), wherein the content of the carbodiimide is greater than 0% by mass and less than 0.5% by mass with respect to the total mass of the catheter tip resin layer.

[0007] (2) A catheter tip as described in (1), wherein the elongation retention rate expressed by the following formula (1) is 70% or more;

[0008]

number

[0009] Here, in equation (1), A represents the fracture stroke length in the tensile test of the catheter tip resin layer before the load test, and B represents the fracture stroke length in the tensile test of the catheter tip resin layer after the load test. The above load test is performed by leaving a dumbbell-shaped test specimen undisturbed for 30 hours under conditions of 80°C and 95%RH humidity.

[0010] (3) The catheter tip according to (1) or (2), wherein the amount of carbodiimide is greater than 0% by mass and less than or equal to 0.3% by mass with respect to the total mass of the catheter tip resin layer.

[0011] (4) A catheter tip according to any one of (1) to (3), wherein the above carbodiimide consists of only one type.

[0012] (5) The catheter tip according to any one of (1) to (4), wherein the tungsten carbide content is 60% by mass or more relative to the total mass of the catheter tip resin layer.

[0013] (6) The content of the hindered amine light stabilizer (HALS) is more than 0% and not more than 0.1% by mass based on the total mass of the catheter tip resin layer, the catheter tip according to any one of (1) to (5).

[0014] (7) The elongation retention rate is 80% or more, the catheter tip according to any one of (1) to (6).

[0015] (8) The strength retention rate represented by the following formula (2) is 60% or more, the catheter tip according to claim 1;

[0016]

Number

[0017] Here, in formula (2), C represents the breaking strength in the tensile test of the catheter tip resin layer before the load test, and D represents the breaking strength in the tensile test of the catheter tip resin layer after the load test.

[0018] (9) A catheter comprising the catheter tip according to any one of (1) to (8).

[0019] (10) The catheter according to (9), which is used as at least one of a guiding catheter and a guiding sheath.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a catheter tip and a catheter including the same, in which the resin is less likely to deteriorate even after long-term storage.

Brief Description of the Drawings

[0021] [Figure 1] It is a diagram showing the overall configuration of the catheter. [Figure 2] It is a schematic cross-sectional view near the joint of the catheter tip and the catheter body. [Modes for carrying out the invention]

[0022] The present invention provides a catheter tip comprising a catheter tip resin layer containing a resin having ester bonds and / or amide bonds, carbodiimide, and tungsten carbide (WC), wherein the content of the carbodiimide is greater than 0% by mass and less than 0.5% by mass with respect to the total mass of the catheter tip resin layer.

[0023] Metallic tungsten powder is typically used in combination with resins as an X-ray opaque material in catheter tips. The inventors hypothesized that the cause of resin degradation during long-term storage might be the accelerated hydrolysis of ester and / or amide bond sites in the presence of metallic tungsten. That is, when metallic tungsten is present in an air atmosphere containing moisture, the chemical reaction shown in formula 1 below proceeds, resulting in the hydrolysis of hydrogen ions (i.e., "H"). + It releases ions (represented by ").

[0024]

number

[0025] Hydrogen ions promote hydrolysis of ester and / or amide bond sites. Furthermore, as hydrolysis progresses, the terminal carboxyl groups of the decomposition products act as acids, potentially increasing the rate of hydrolysis. Therefore, it is thought that hydrolysis of the resin may gradually progress even under normal temperature and humidity conditions during long-term storage of catheters, potentially leading to the aging and deterioration of the resin.

[0026] Based on these findings, the inventors conducted diligent research and found that using tungsten carbide (WC) instead of metallic tungsten (W) powder as an X-ray opaque material suppresses resin degradation under high temperature and high humidity load conditions. By using tungsten carbide (WC), the formation of tungsten oxide (WO3) as shown in Equation 1 is suppressed, which makes the subsequent hydration reaction of tungsten oxide less likely to proceed. This suppresses the generation of acidic hydrogen ions, thereby preventing a decrease in pH value, and consequently, it is thought that the hydrolysis of ester bonds and / or amide bonds can be suppressed.

[0027] Furthermore, as described above, by using tungsten carbide as an X-ray opaque material and then including carbodiimide as a hydrolysis inhibitor in the layer containing the resin, the progression of hydrolysis is further suppressed, and as a result, the degradation of the resin is significantly suppressed. It should be noted that the above mechanism is based on speculation, and its accuracy does not affect the technical scope of the present invention.

[0028] The catheter according to the present invention will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numeral, and redundant explanations will be omitted. The dimensional ratios in each drawing are exaggerated for illustrative purposes and may differ from the actual ratios.

[0029] Furthermore, any combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention and is deemed to be disclosed herein (i.e., a lawful basis for amendment).

[0030] Figure 1 shows the overall configuration of the catheter 1 of the present invention. In Figure 1, the side of the catheter 1 that is inserted into the body (left side of Figure 1) is referred to as the tip side, the side of the catheter 1 where the hub 30 is located is referred to as the proximal end side, and the direction in which the catheter body 10 of the catheter 1 extends is referred to as the axial direction. Furthermore, in a cross-section (orthoaxial section) of the catheter body 10 with the axial direction of the catheter body 10 as the reference axis, the direction moving away from or towards the catheter body 10 is referred to as the "radial direction".

[0031] The catheter 1 comprises a catheter body portion 10 extending in the axial direction, a catheter tip 20 positioned at the tip end of the catheter body portion 10, a hub 30 positioned at the proximal end of the catheter body portion 10, and a kink protector (strain relief) 40 positioned between the catheter body portion 10 and the hub 30. The tip end of the catheter body portion 10 and the catheter tip 20 may be joined to each other, for example, by heat fusion to integrate them.

[0032] Figure 2 is a schematic enlarged cross-sectional view of the tip structure of catheter 1 according to one embodiment of the present invention. As shown in Figure 2, catheter 1 is configured as a flexible tubular member having an axially extending lumen, a tip opening communicating with the lumen, and a proximal opening communicating with the lumen.

[0033] The catheter body 10 may have a layered structure formed by stacking in the radial direction. The catheter body 10 has an inner layer 11 arranged on the inner surface, an outer layer 12 arranged on the outer circumference of the inner layer 11, a reinforcing material layer 13 arranged inside the outer layer 12, and a hydrophilic lubricating layer 14. In the embodiment shown in Figure 2, the inner layer 11 and the hydrophilic lubricating layer 14 are arranged to extend to the tip of the catheter tip 20. Therefore, the inner layer 11 and the hydrophilic lubricating layer 14 are common to the inner layer and hydrophilic lubricating layer of the catheter tip 20. In addition, in the catheter tip, the outer layer 12 may consist of a single layer (without the inner layer 11 and the hydrophilic lubricating layer 14), or the outer layer 12 may consist of a single layer and include a reinforcing material layer (metal reinforcing layer) 13 inside, and the hydrophilic lubricating layer 14 may be absent.

[0034] The inner layer 11 is preferably made of a material that provides low friction, at least in the portion that comes into contact with the device when inserting a treatment catheter or guidewire into the lumen 10H. This configuration allows the device inserted into the catheter body 10 to move longitudinally with less sliding resistance, thereby improving operability. Specifically, the constituent material of the inner layer 11 may be, for example, a fluororesin material such as polytetrafluoroethylene (PTFE).

[0035] The outer layer 12 has a hollow tubular shape that extends axially along the catheter body 10. The hydrophilic lubricating layer 14 has a hollow tubular shape that extends axially along the catheter body 10, similar to the catheter body resin layer 12. The outer layer 12 is preferably made of a material that has kink resistance, good indentation and conformability. Specifically, the constituent material of the outer layer 12 can be polyamide elastomer and / or polyamide (polyamide elastomer, polyamide or a combination thereof), polyester, polyester elastomer, polyurethane elastomer, polyurethane, or a combination thereof.

[0036] The reinforcing layer 13 has multiple reinforcing wires that reinforce the catheter body 10. These reinforcing wires can be, for example, spiral or braided. The reinforcing wires are made of metal such as stainless steel. Specifically, to reduce the radial thickness of the catheter body 10, stainless steel wires can be flattened into plates, and then 8 to 32 of these flattened plates can be used to form a spiral or braided structure. The number of reinforcing wires is preferably a multiple of 8 to provide balanced reinforcement in a tubular shape, but it is not limited to this. Furthermore, by making the reinforcing wires flat, they receive external stresses more evenly compared to an ellipse, resulting in more consistent physical properties.

[0037] The number of layers constituting the catheter body 10 and the materials of each layer may differ along the longitudinal direction of the catheter body 10. For example, to make the tip portion of the catheter body 10 more flexible, the number of layers may be reduced, a more flexible material may be used, reinforcing material may not be placed in that portion, or an inner layer may be provided all the way to the tip.

[0038] When a hydrophilic lubricating layer 14 is present, insertion into the body becomes smoother. The constituent materials of the hydrophilic lubricating layer 14 are not particularly limited, but examples include copolymers of epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, β-methylglycidyl methacrylate, and allyl glycidyl ether with hydrophilic monomers such as N-methylacrylamide, N,N-dimethylacrylamide, and acrylamide; (co)polymers composed of the above hydrophilic monomers; cellulosic polymers such as hydroxypropyl cellulose and carboxymethyl cellulose; polysaccharides, polyvinyl alcohol, methyl vinyl ether-maleic anhydride copolymer, water-soluble polyamide, poly(2-hydroxyethyl (meth)acrylate), polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and copolymers of polyvinylpyrrolidone and polyurethane described in U.S. Patent No. 4,100,309 and Japanese Patent Publication No. 59-19582. These hydrophilic lubricating materials may be used individually or in combination of two or more types.

[0039] A hub 30 is attached (fixed) to the proximal end of the catheter body 10. This hub 30 has a lumen that communicates with the lumen 10H and has a Luer taper.

[0040] The hub 30 allows for the insertion or removal of long objects (linear bodies) such as guidewires, catheters (e.g., balloon catheters, stent transport catheters), endoscopes, ultrasound probes, and temperature sensors, as well as the injection of various liquids such as contrast agents (X-ray contrast agents), medicinal solutions, and saline solution. The hub 30 can also be connected to other devices, such as a Y-shaped branch connector. The hub 30 can be constructed from thermoplastic resins such as polycarbonate, polyamide, polysulfone, and polyarylate.

[0041] The catheter is inserted into the body while confirming its position under X-ray fluoroscopy. In this invention, since the catheter tip 20 contains tungsten carbide, which is an X-ray opaque material, it is not necessarily required that the catheter body 10 contain an X-ray opaque material. However, an X-ray opaque material (X-ray contrast agent) may be incorporated into the constituent material of the catheter body resin layer 12. Examples of X-ray opaque materials that can be used include barium sulfate, bismuth oxide, and tungsten. Furthermore, the X-ray opaque material is not limited to being present throughout the entire length of the catheter body 10, but may be present only in a part of the catheter body 10, for example, only at the tip of the catheter body 10 or only at the catheter tip 20.

[0042] The catheter tip and its constituent materials are described below. In this specification, the range "X~Y" includes X and Y, meaning "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 40~50%RH conditions.

[0043] [Catheter tip] The catheter tip 20 is made of a more flexible material than the catheter body 10. The catheter tip 20, also called the tip, has the function of suppressing damage to biological tubular structures such as blood vessels and improving insertability into narrowed areas formed within blood vessels. In Figure 2, the catheter tip 20 has a tapered shape in which the outer diameter decreases towards the tip, but the outer diameter may be approximately the same all the way to the tip.

[0044] The catheter tip has a catheter tip resin layer 21 containing a resin having ester bonds and / or amide bonds, and tungsten carbide. Because the catheter tip contains tungsten carbide, it is radiopaque. The catheter tip resin layer may be a single layer or a multi-layered layer of two or more layers. In the case of multiple layers, the composition (resin type, mixing ratio, etc.) may be different or the same. Furthermore, it is preferable that the tungsten carbide is dispersed as particles within the resin.

[0045] The elongation retention rate of the catheter tip resin layer, represented by formula (1) above, may be 70% or more. By controlling the elongation retention rate to 70% or more, the durability for long-term storage can be further improved. The elongation retention rate of the catheter tip resin layer is preferably 80% or more, and more preferably 85% or more (upper limit 100%). The elongation retention rate of the catheter tip resin layer shall be the value measured by the method described in the following examples. Furthermore, the elongation retention rate can be controlled by appropriately selecting the content and type of carbodiimide added.

[0046] The strength retention rate of the catheter tip resin layer, represented by formula (2) above, may be 60% or more. By controlling the strength retention rate to 60% or more, the durability for long-term storage can be further improved. The strength retention rate of the catheter tip resin layer is preferably 70% or more, and more preferably 75% or more (upper limit 100%). The strength retention rate of the catheter tip resin layer shall be the value measured by the method described in the following examples. Furthermore, the strength retention rate can be controlled by appropriately selecting the amount of carbodiimide added and the type of carbodiimide, etc.

[0047] The catheter tip may consist only of a catheter tip resin layer, or other functional layers (the hydrophilic lubricating layer described above) may be laminated on the inner layer (lumen side) and / or outer layer (surface side) of the catheter tip resin layer. The hydrophilic lubricating layer is as described above.

[0048] (Resin having ester bonds and / or amide bonds) Resins having ester bonds and / or amide bonds (hereinafter also referred to simply as resins having bonds) include polyamides, polyamide elastomers, polyamide-imides, polyesters, polyester elastomers, and the like. These resins may be used individually or two or more may be laminated or blended.

[0049] Of these, the resin having ester bonds and / or amide bonds is preferably polyamide resin because it is highly flexible and has low affinity and hardness differences with adjacent members. In particular, it is more preferably polyamide and polyamide elastomer, and even more preferably polyamide elastomer. The content of polyamide resin is preferably 50% by mass or more (up to 100% by mass), more preferably 80% by mass or more, and even more preferably 100% by mass (consisting of polyamide resin) relative to the total mass of the resin having ester bonds and / or amide bonds. The content of polyamide elastomer is preferably 50% by mass or more (up to 100% by mass), more preferably 80% by mass or more, and even more preferably 100% by mass (consisting of polyamide elastomer) relative to the total mass of the resin having ester bonds and / or amide bonds.

[0050] Furthermore, in the resin constituting the catheter tip, the resin having ester bonds and / or amide bonds is preferably 80% by mass or more (up to 100% by mass) of the total mass of the resin constituting the catheter tip, more preferably 90% by mass or more, and even more preferably 100% by mass (consisting of resin having ester bonds and / or amide bonds).

[0051] Polyamide elastomers, which can be used as resins having ester bonds and / or amide bonds, are thermoplastic resins consisting of copolymers having hard segments derived from crystalline polymers with high melting points and soft segments derived from amorphous polymers with low glass transition temperatures, and which have amide bonds (-CONH-) in the main chain of the polymer forming the hard segments. The constituent units having amide bonds (-CONH-) in the main chain of the polymer forming the hard segments are also called amide units of polyamide elastomers.

[0052] In this specification, "amide unit of polyamide elastomer" refers to a repeating unit derived from an amide bond in the polymer chain of a polyamide elastomer, and the amide unit in the polyamide elastomer is preferably a repeating unit represented by the following chemical formula (1).

[0053] [ka]

[0054] In the above chemical formula (1), n ​​is preferably an integer between 2 and 20, and more preferably an integer between 5 and 11. In the examples described later, n is 11. Also, "*" represents a bond with another repeating unit.

[0055] Examples of polymers that form soft segments include polyesters and polyethers. Furthermore, examples include polyethers such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol (PTMG), and polyester polyols, as well as ABA-type triblock polyetherdiols. The polymers that form soft segments may be used individually or in combination of two or more. Additionally, polyetherdiamines obtained by reacting ammonia or the like with the ends of a polyether can be used; for example, ABA-type triblock polyetherdiamine can be used. Polyethers, which are polymers capable of forming soft segments, can form polyether-blocked amide copolymers by being linked to polyamide blocks, which are hard segments, via ester bonds.

[0056] The content of soft segments in the polyamide elastomer is preferably 1 to 90% by mass, and more preferably 10 to 70% by mass, relative to the total mass of the polyamide elastomer.

[0057] Polyamide elastomers may also include polymers in which the molecular weight has been increased by adding chain extenders such as dicarboxylic acids, in addition to polymers consisting of hard segments and soft segments.

[0058] These polyamide elastomers may be used individually or in combination of two or more.

[0059] The weight-average molecular weight of the polyamide elastomer is preferably 10,000 to 500,000, more preferably 15,000 to 400,000, and even more preferably 20,000 to 300,000. In one embodiment, the weight-average molecular weight of the polyamide elastomer is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more. In one embodiment, the weight-average molecular weight of the polyamide elastomer is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 200,000 or less.

[0060] The Shore D hardness of polyamide elastomers used in catheter tips is preferably 20 to 80, and more preferably 30 to 50, from the viewpoint of flexibility. In this specification, the Shore D hardness according to ISO 868:2003 is used for measuring the hardness of resins, such as polyamide elastomers. When multiple types of polyamide elastomers are used in this specification, the Shore D hardness of the entire polyamide elastomer, taking into account the mass ratio of the content, is used.

[0061] Polyamides that can be used as resins having ester bonds and / or amide bonds are not particularly limited as long as they are polymers having amide bonds (-CO-NH-) in the main chain, and are usually produced by polymerization of cyclic lactams or amino acids, or by condensation polymerization of dicarboxylic acids and diamines. Homopolyamides are preferred as polyamides. Monomers that can be polymerized on their own include ε-caprolactam, ω-laurolactam, 6-aminocaproic acid, enantractam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acid, and piperidone.

[0062] 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.

[0063] Examples of polyamides include nylon 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. Polyamides can be used individually or in combination of two or more types.

[0064] The ends of the polyamide may be sealed with carboxylic acids, amines, etc. Examples of carboxylic acids include aliphatic monocarboxylic acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. Examples of amines include aliphatic primary amines such as hexylamine, octylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, and behenylamine.

[0065] The weight-average molecular weight of the polyamide is preferably 10,000 to 500,000, more preferably 15,000 to 400,000, and even more preferably 20,000 to 300,000.

[0066] The resin content in the catheter tip resin layer is set appropriately considering factors such as radiopaqueness, flexibility, and moldability. For example, if the tungsten carbide content is 60% by mass or more of the total catheter tip resin layer, the resin content in the catheter tip resin layer may be, for example, 10 to 40% by mass, or 20 to 35% by mass. In one embodiment, the resin content in the catheter tip resin layer is preferably 10% by mass or more, and more preferably 20% by mass or more. In another embodiment, the resin content in the catheter tip resin layer is preferably 40% by mass or less, and more preferably 35% by mass or less.

[0067] As another example, if the tungsten carbide content is less than 40% by mass of the entire catheter tip resin layer, the resin content in the catheter tip resin layer may be, for example, 60-99% by mass, or 80-95% by mass.

[0068] In this specification, when a catheter tip resin layer consists of multiple layers, the content of a certain component in the catheter tip resin layer means the ratio of the total mass of that component contained in all catheter tip resin layers to the total mass of all catheter tip resin layers.

[0069] (X-ray opaque substance) The catheter tip resin layer also contains tungsten carbide as an X-ray opaque material. While metallic tungsten powder, commonly used as an X-ray opaque material, can release acid upon oxidation and subsequent hydration, as described above, tungsten carbide is superior because it exhibits virtually no such effect, thereby reducing the risk of resin degradation.

[0070] In one embodiment, only tungsten carbide is used as the radiopaque material. In one embodiment, the catheter tip resin layer contains elemental metallic tungsten (W) powder as the radiopaque material. In one embodiment, the catheter tip resin layer does not contain elemental metallic tungsten (W). In one embodiment, the catheter tip contains elemental metallic tungsten (W) powder as the radiopaque material. In one embodiment, the catheter tip does not contain elemental metallic tungsten (W). In this specification, the term "does not contain" means, for example, not intentionally added as a raw material, and also means "does not contain" if it is included due to unintentional contamination, for example, due to decomposition over time. Specifically, the content of metallic tungsten (W) powder in the catheter tip resin layer is preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

[0071] The particle size of tungsten carbide can be 1 to 10 μm. When the particle size of tungsten carbide is 1 μm or larger, the surface area is sufficiently small, and the area exposed to air is reduced, making it difficult for the decomposition, oxidation, and hydration reactions of tungsten carbide to proceed, and as a result, the release of acid is sufficiently suppressed. Also, when the particle size of tungsten carbide is 10 μm or smaller, the system is more likely to become uniform when mixed with the resin, contributing to improved operability during manufacturing and enabling the maintenance of high quality of the catheter tip resin layer. The particle size of tungsten carbide is preferably 2 to 5 μm, and more preferably 3 to 4.5 μm. In one embodiment, the particle size of tungsten carbide is 1 μm or larger, preferably 2 μm or larger, and more preferably 3 μm or larger. In one embodiment, the particle size of tungsten carbide is 10 μm or smaller, preferably 5 μm or smaller, and more preferably 4.5 μm or smaller. Herein, in this specification, particle diameter refers to the volume-average particle diameter, which can be measured, for example, by dynamic light scattering, but is not limited to this method.

[0072] Furthermore, various types of tungsten carbide are commercially available, and these commercially available products can be preferably used in the present invention.

[0073] Tungsten carbide may be present in the total catheter tip resin layer at a concentration of 60% by mass or more. When the tungsten carbide content is 60% by mass or more of the total catheter tip resin layer, sufficient visibility of the catheter tip 20 can be ensured when X-ray transmission occurs. In one embodiment, tungsten carbide is preferably present in the total catheter tip resin layer at a concentration of 60-80% by mass, more preferably at 65-80% by mass, and even more preferably at 70-80% by mass, but 60-70% by mass may also be suitable. In one embodiment, tungsten carbide may be present in the total catheter tip resin layer at a concentration of 65% by mass or more, or 70% by mass or more. In one embodiment, tungsten carbide may be present in the total catheter tip resin layer at a concentration of 80% by mass or less, or 70% by mass or less.

[0074] Furthermore, depending on the shape and fragility of the object to which the catheter tip is used, a more flexible catheter tip may be required. In such catheter tips, it is preferable that the tungsten carbide content be lower. Therefore, in one embodiment, the tungsten carbide content may be greater than 0% by mass and less than 40% by mass of the entire catheter tip resin layer. When the tungsten carbide content exceeds 0% by mass of the entire catheter tip resin layer, the catheter tip 20 is visualized when X-rayed. Also, when the tungsten carbide content is less than 40% by mass, the catheter tip may have even greater flexibility. In one embodiment, it is preferable that the tungsten carbide content be 1 to 20% by mass of the entire catheter tip resin layer.

[0075] (Carbodiimide) Carbodiimides are compounds that contain a carbodiimide group (-N=C=N-) within their molecule. It is preferable that carbodiimide-containing compounds are polyfunctional (having two or more carbodiimide groups within their molecule).

[0076] Furthermore, the polyfunctional carbodiimide group-containing compound is preferably a cyclic carbodiimide or a polycarbodiimide. In particular, the polyfunctional carbodiimide group-containing compound is preferably a polycarbodiimide because it enhances the effects of the present invention.

[0077] Examples of polycarbodiimides include aromatic polycarbodiimides, aliphatic polycarbodiimides, and alicyclic polycarbodiimides. Aromatic polycarbodiimides are polycarbodiimides that have an aromatic ring in their molecule and may or may not have an aliphatic ring. Aliphatic polycarbodiimides are polycarbodiimides that do not have an aromatic ring or an aliphatic ring in their molecule. Alicyclic polycarbodiimides are polycarbodiimides that have an aliphatic ring in their molecule but no aromatic ring. Among these, aromatic polycarbodiimides and / or alicyclic polycarbodiimides are preferred from the viewpoint of storage stability, alicyclic polycarbodiimides are more preferred, and polycarbodiimides that are cyclic are also acceptable.

[0078] Polycarbodiimides can be specifically obtained by decarboxylating and condensing diisocyanates. Diisocyanates can be, for example, linear or alicyclic aliphatic diisocyanate compounds, aromatic diisocyanate compounds, or heterocyclic diisocyanate compounds. These may be used individually or in combination of two or more. Specifically, examples include linear aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate; and alicyclic diisocyanates such as 1,4-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatocyclohexyl)propane, isophorone diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate. Examples include diisocyanates; aliphatic diisocyanates containing aromatic rings such as 1,3-bis(2-isocyanato-2-propyl)benzene; and aromatic isocyanates such as toluene-2,4-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and 2,4,6-triisopropylbenzene-1,3-diyldiisocyanate. These may be used individually or in combination of two or more.

[0079] Polycarbodiimides in which the terminal isocyanate groups are encapsulated by a encapsulant are preferred in terms of storage stability. Examples of encapsulants include compounds having active hydrogen that reacts with isocyanate groups, or compounds having isocyanate groups. Examples include monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates having one substituent selected from carboxyl groups, amino groups, and isocyanate groups.

[0080] Cyclic carbodiimides may include molecules having a macrocyclic structure in whole or in part of a branch, and in particular, molecules in which a carbodiimide group (-N=C=N-) is introduced into the macrocyclic structure. Here, a macrocyclic structure may mean, for example, a ring with 8 or more members, 10 or more members, or 12 or more members. Furthermore, a cyclic carbodiimide molecule may have one, two, or three or more macrocyclic structures. Examples of cyclic carbodiimides include the cyclic carbodiimide represented by formula (i) disclosed in International Publication No. 2010 / 071211 (specifically, the cyclic carbodiimide described on pages 13-15) and the cyclic carbodiimide represented by formula (i) described in Japanese Patent Application Publication No. 2016-65001 (specifically, the cyclic carbodiimide described on pages 10-11).

[0081] In one embodiment, there may be two or more types of carbodiimides. When two or more types are used, it may be possible to achieve both improved hydrolysis inhibition and resistance to temperature and humidity. In particular, when two or more types of carbodiimides are included, it is preferable to include at least one of polycarbodiimides and cyclic carbodiimides, and more preferable to include both polycarbodiimides and cyclic carbodiimides.

[0082] In other embodiments, only one type of carbodiimide may be used. When only one type is used, the ease of the manufacturing process is improved, and the durability to temperature and humidity may be further improved compared to when two or more types are mixed. In particular, when only one type of carbodiimide is used, the carbodiimide is preferably a polycarbodiimide or a cyclic carbodiimide, and may be only a polycarbodiimide or only a cyclic carbodiimide.

[0083] There are no particular limitations on the method of adding and mixing carbodiimide to the resin; it may be mixed by dry blending, or the resin may be in a solution or molten state and the carbodiimide may be kneaded in. A solvent may also be used during kneading. Examples of solvents that can be used include hydrocarbon solvents, ketone solvents, ester solvents, ether solvents, halogen solvents, amide solvents, etc.

[0084] The carbodiimide content is greater than 0% by mass and less than or equal to 0.5% by mass relative to the total mass of the catheter tip resin layer. Preferably, the carbodiimide content is greater than 0% by mass and less than or equal to 0.3% by mass, more preferably between 0.01 and 0.3% by mass, and even more preferably between 0.05 and 0.3% by mass, relative to the total mass of the catheter tip. By having the amount of hydrolysis inhibitor added within the above range, resin degradation is effectively suppressed and the properties of the resin are not significantly affected. Furthermore, the carbodiimide content may be, for example, greater than 0% by mass and less than or equal to 0.25% by mass, more preferably between 0.001 and 0.15% by mass, and even more preferably between 0.005 and 0.15% by mass, relative to the total mass of the resin in the catheter tip resin layer. When two or more types of carbodiimide are included, the carbodiimide content represents the sum of these values.

[0085] In addition to carbodiimide, other hydrolysis inhibitors may be added. Conventional hydrolysis inhibitors can be used, for example, compounds that react with and bond to the carboxyl group terminus of the decomposition product. Specifically, examples include compounds containing functional groups such as epoxy groups (e.g., glycidyl ester compounds, glycidyl ether compounds, etc.) and oxazoline groups (e.g., bisoxazoline compounds, etc.).

[0086] (HALS (Hindered Amine Light Stabilizer)) In many cases, HALS (hindered amine-based light stabilizers) are added to the catheter tip resin layer to ensure long-term stability. However, the addition of HALS degrades the quality of the resin during long-term storage, so it is preferable to use as little as possible. The configuration of the present invention ensures long-term stability while minimizing the HALS content.

[0087] Examples of HALS (hindered amine light stabilizers) include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (mixture), bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, and bis(2,2,6,6- decandioate Tetramethyl-1(octyloxy)-4-piperidyl) ester and reaction products of 1,1-dimethylethyl hydroperoxide and octane, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, ester mixture of 2,2,6,6-tetramethyl-4-piperidinol and higher fatty acids, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2 ,3,4-butanetetracarboxylate, polycondensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, poly[{(6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl){(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}}], dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6, Examples of HALS include, but are not limited to, polycondensates of 6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, and N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidine-4-yl)amino)-triazine-2-yl)-4,7-diazadecane-1,10-diamine. These HALS may be used individually or in combination of two or more.

[0088] The HALS content may be greater than 0% by mass and less than or equal to 0.1% by mass relative to the total mass of the catheter tip resin layer. When the HALS content is greater than 0% by mass, degradation of the resin caused by light can be effectively suppressed, and when it is 0.1% by mass or less, the HALS can be prevented from rising to the surface of the resin. Furthermore, the catheter tip according to the present invention contains carbodiimide, which effectively captures the generated acid (hydrogen ions). Therefore, the generation of acid (hydrogen ions) due to light can be sufficiently suppressed, and even if the HALS content is 0.1% by mass or less, degradation of the resin can be sufficiently suppressed. In one embodiment, the HALS content is preferably greater than 0% by mass and less than 0.1% by mass, more preferably greater than 0% by mass and less than 0.05% by mass, and even more preferably 0.001% by mass or more and 0.025% by mass or less, relative to the total mass of the catheter tip resin layer.

[0089] (Additives) In the present invention, the catheter tip resin layer may contain other additives. Additives that may be included in the catheter tip resin layer are not particularly limited, but include ultraviolet absorbers and antioxidants.

[0090] (UV absorber) Examples of UV absorbers include 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2-hydroxy-3-t-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole, 2-(2-hydroxy-5-t-octylphenyl)benzotriazole, 2-(2-hydroxy-octoxyphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3, Examples of UV absorbers include, but are not limited to, benzotriazole-based UV absorbers such as 3-tetramethylbutyl)phenol, 2-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-(octyloxy)phenol, and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-(hexyloxy)phenol; benzophenone-based UV absorbers such as 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone; and benzoate-based UV absorbers such as 2,4-di-t-butylphenyl 3,5-di-t-butyl-4-hydroxybenzoate and n-hexadecyl 3,5-di-t-butyl-4-hydroxybenzoate. These UV absorbers may be used individually or in combination of two or more.

[0091] The amount of UV absorber can be 0% by mass or more and less than 1.0% by mass relative to the total mass of the catheter tip resin layer. When the amount of UV absorber is less than 1.0% by mass, it is possible to suppress the UV absorber from rising to the surface of the resin. In one embodiment, the amount of UV absorber is preferably 0% by mass or more and 0.5% by mass or less, more preferably greater than 0% by mass and 0.1% by mass or less, and even more preferably 0.001% by mass or more and 0.025% by mass or less, relative to the total mass of the catheter tip resin layer.

[0092] (Antioxidant) In this specification, antioxidants can prevent deterioration such as modification or decomposition caused by oxidation of the resin. Examples of antioxidants in this specification include phosphorus-based antioxidants, sulfur-based antioxidants, and phenol-based antioxidants. Specific examples of phosphorus-based antioxidants include tris(nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis(2,4-di-t-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl) pentaerythritol didiphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-diphenylenediphosphonite, and 2,2'-methylenebis(4,6-di-t-butylphenyl Examples include, but are not limited to, 2-ethylhexyl phosphite, 2,2'-ethylidenebis(4,6-di-t-butylphenyl)fluorophosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, 2-(2,4,6-tri-t-butylphenyl)-5-ethyl-5-butyl-1,3,2-oxaphospholinane, 2,2',2''-nitrilotriethyl-tris(3,3',5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diyl)phosphite, and 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine. Specific examples of sulfur-based antioxidants include, but are not limited to, dilauryl-3,3'-thiopropionate, dimyristyl-3,3'-thiodipropionate, disteary-3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate), ditridecyl-3,3'-thiodipropionate, and 1,3,5-tris-β-stearylthiopropionyloxyethyl isocyanurate.Specific examples of the above-mentioned phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 4,4'-butylidenebis(3-methyl-6-t-butylphenol), ethylenebis(oxyethylene)bis[3-(5-t-butyl-4-hydroxy-m-tolyl)propionate], 4,4'-thiobis(3-methyl-6-t-butylphenol), and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydro Examples of antioxidants include, but are not limited to, xybenzyl)benzene, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 3,9-bis-{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), and 2,2'-dihydroxy-3,3'-di(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane. These antioxidants may be used individually or in combination of two or more.

[0093] The antioxidant content may be 0% by mass or more and 1% by mass or less relative to the total mass of the catheter resin layer. When the total antioxidant content is within the above range, it is possible to suppress the antioxidant from rising to the surface of the resin. In one embodiment, the total content of antioxidants and light stabilizers is preferably 0% by mass or more and less than 1% by mass, more preferably greater than 0% by mass and 0.5% by mass or less, even more preferably 0.001% by mass or more and 0.3% by mass or less, and even more preferably 0.001% by mass or more and 0.1% by mass or less, relative to the total mass of the catheter tip resin layer.

[0094] Furthermore, the total content of antioxidants and light stabilizers may be greater than 0% by mass and less than or equal to 3% by mass relative to the total mass of the catheter resin layer. When the total content of antioxidants and light stabilizers is within the above range, it is possible to suppress the antioxidants and light stabilizers from rising to the surface of the resin. In one embodiment, the total content of antioxidants and light stabilizers may be less than or equal to 3% by mass, less than or equal to 1% by mass, less than or equal to 0.5% by mass, less than or equal to 0.1% by mass, less than or equal to 0.05% by mass, less than or equal to 0.02% by mass, or less than or equal to 0.01% by mass, relative to the total mass of the catheter resin layer.

[0095] (Other additives) Furthermore, the catheter tip resin layer may also contain additives other than antioxidants and light stabilizers. Such additives may impart advantageous physical properties to the catheter tip, such as its operability. Examples of other additives used herein include, but are not limited to, plasticizers, lubricants, surfactants, antistatic agents, fillers, diluents, coupling agents, colorants, flame retardants, and foaming agents.

[0096] Examples of plasticizers include benzoic acid esters such as diethylene glycol dibenzoate, phthalate esters such as dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), ditridecyl phthalate (DTDP), bis(2-ethylhexyl) terephthalate (DOTP), bis(2-ethylhexyl) isophthalate (DOIP), di-2-ethylhexyl adipate (DOA), and adipate. Aliphatic dibasic acid esters such as diisononyl pirate (DINA), diisodecyl adipate (DIDA), di-2-ethylhexyl sebacate (DOS), diisononyl sebacate (DINS), trimellitic acid esters such as tri-2-ethylhexyl trimellitic acid (TOTM), triisononyl trimellitic acid (TINTM), triisodecyl trimellitic acid (TIDTM), pyromellitic acid esters such as tetra-2-ethylhexyl pyromellitic acid (TOPM), tri-2-ethylhexyl phosphate (TOP ), phosphate esters such as tricresyl phosphate (TCP), alkyl esters of polyhydric alcohols such as pentaerythritol, epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil, epoxy esters such as 4,5-epoxy-1,2-cyclohexanedicarboxylate di-2-ethylhexyl ester, alicyclic dibasic acid esters such as 1,2-cyclohexanedicarboxylate diisononyl (DINCH) and 4-cyclohexene-1,2-dicarboxylate di-2-ethylhexyl ester, 1,4-buta dicapric acid Examples include, but are not limited to, fatty acid glycol esters such as smeardiol, tributyl acetyl citrate (ATBC), trihexyl acetyl citrate (ATHC), triethylhexyl acetyl citrate (ATEHC), trihexyl butyryl citrate (BTHC), isosorbide diesters, chlorinated paraffins obtained by chlorinating paraffin wax or n-paraffin, chlorinated fatty acid esters such as chlorinated stearate, and higher fatty acid esters such as butyl oleate.

[0097] Examples of lubricants include, but are not limited to, silicones, liquid paraffin, paraffin wax, fatty acid metal salts such as metal stearate and metal laurate, fatty acid amides, fatty acid waxes, and higher fatty acid waxes.

[0098] Examples of surfactants include, but are not limited to, fatty acid esters of glycerin such as glycerin monostearate, glycerin monolaurate, glycerin monooleate, and glycerin monopalmitate; fatty acid esters of propylene glycol such as propylene glycol monolaurate, propylene glycol monostearate, propylene glycol monooleate, and propylene glycol monopalmitate; and fatty acid esters of sorbitan such as sorbitan monolaurate, sorbitan monostearate, sorbitan monooleate, and sorbitan monopalmitate.

[0099] Examples of antistatic agents include, but are not limited to, anionic antistatic agents of the alkyl sulfonate, alkyl ether carboxylic acid, or dialkyl sulfosuccinate type; nonionic antistatic agents such as polyethylene glycol derivatives, sorbitan derivatives, and diethanolamine derivatives; cationic antistatic agents such as quaternary ammonium salts of the alkylamidoamine type and alkyldimethylbenzyl type, organic acid salts or hydrochlorides of the alkylpyridinium type; and amphoteric antistatic agents such as alkyl betaine type and alkylimidazoline type.

[0100] Examples of diluents include, but are not limited to, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate and low-boiling-point aliphatic and aromatic hydrocarbons.

[0101] Examples of fillers include, but are not limited to, calcium carbonate, silica, alumina, clay, talc, diatomaceous earth, metal oxides such as ferrite, glass, carbon, metal fibers and powders, glass spheres, graphite, aluminum hydroxide, barium sulfate, magnesium oxide, magnesium carbonate, magnesium silicate, and calcium silicate.

[0102] Examples of colorants include, but are not limited to, carbon black, lead sulfide, white carbon, titanium white, lithopone, red ochre, antimony sulfide, chromium yellow, chromium green, phthalocyanine green, cobalt blue, phthalocyanine blue, and molybdenum orange.

[0103] Examples of flame retardants include, but are not limited to, inorganic compounds such as aluminum hydroxide, antimony trioxide, magnesium hydroxide, and zinc borate; phosphorus compounds such as cresyl diphenyl phosphate, trischloroethyl phosphate, trischloropropyl phosphate, and trisdichloropropyl phosphate; and halogen compounds such as chlorinated paraffin.

[0104] Examples of foaming agents include, but are not limited to, organic foaming agents such as azodicarbonamide and oxybisbenzenesulfonyl hydrazide, and inorganic foaming agents such as sodium bicarbonate.

[0105] Furthermore, in addition to the catheter tip resin layer, the catheter tip may be provided with an inner layer (inner layer 11 in Figure 2) to ensure low friction at least in the portion that comes into contact with devices such as treatment catheters and guidewires when inserting these devices into the lumen 10H. The inner layer is as described above.

[0106] (catheter) The catheter 1 of the present invention is a long medical device that can be inserted into a living organ and used for the treatment and improvement of stenosis, or for the purpose of delivering medical devices such as stents within the body. Examples of living organs include, but are not limited to, blood vessels, bile ducts, trachea, esophagus, other parts of the digestive tract, urethra, ear, nose and throat lumen, and other organs. In one embodiment, the living organ is a blood vessel, which may be, for example, a coronary artery.

[0107] The catheter 1 of the present invention contains an X-ray opaque material. This allows the catheter 1 to be visualized during X-ray irradiation using contrast imaging techniques such as X-ray fluoroscopy when guiding it through a blood vessel to a target location. The X-ray opaque material may be included in the catheter tip 20 in particular.

[0108] In one embodiment, the catheter 1 is used together with an introducer sheath. In another embodiment, the catheter 1 is used together with an introducer sheath and a guidewire. Here, the introducer sheath is a tubular medical device that is passed through the inside of a blood vessel from outside the body in advance in order to insert the catheter into the blood vessel, and the guidewire is a medical device that is introduced before the catheter is inserted in order to help guide the catheter to a desired location in the blood vessel. For example, after passing through the introducer sheath, the guidewire is passed through the introducer sheath and the catheter 1 is inserted through the blood vessel to the vicinity of the site where it is to be introduced. Then the catheter 1 is introduced into the blood vessel by passing the guidewire through the internal hole of the introducer sheath, and then guided through the blood vessel along the guidewire to the target location. After that, by removing the guidewire, the catheter 1 can guide the medical device to the target location.

[0109] Furthermore, the catheters relating to this embodiment may also include catheters used as guiding catheters and guiding sheaths. [Examples]

[0110] 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. In the following examples, unless otherwise specified, each operation was performed at room temperature (20°C to 25°C) and 40 to 50% RH.

[0111] [Preparation of dumbbell-shaped test specimens] [Example 1] 29.9 parts by mass of polyamide elastomer (Shore D hardness 40), 69.8 parts by mass of tungsten carbide particles (average particle size 3.0-4.19 μm), 0.3 parts by mass of an alicyclic polycarbodiimide compound containing a carbodiimide group as a hydrolysis inhibitor, and 0.019 parts by mass of a hindered amine-based light stabilizer (HALS; Tinuvin 770) as a light stabilizer were weighed and mixed. The resulting mixture was press-molded using a 20t manual hydraulic heating press at a set temperature of 200°C. The thickness of the molded product was set to 1.9-2.1 mm. The molded press sheet was punched out to produce dumbbell-shaped test specimens according to JIS K 7161-2:2014 5A.

[0112] [Example 2] The dumbbell-shaped test specimens of this example were prepared in the same manner as in Example 1, except that the polyamide elastomer content was 29.8 parts by mass, the tungsten carbide particle content was 70 parts by mass, and the carbodiimide group-containing compound (alicyclic polycarbodiimide compound) content was 0.2 parts by mass.

[0113] [Example 3] The dumbbell-shaped test specimens of this example were prepared in the same manner as in Example 1, except that the polyamide elastomer content was 29.95 parts by mass, the tungsten carbide particle content was 69.9 parts by mass, and a cyclic carbodiimide compound was used as the carbodiimide group-containing compound, with the carbodiimide group-containing compound content being 0.15 parts by mass.

[0114] [Example 4] The dumbbell-shaped test specimens of this example were prepared in the same manner as in Example 1, except that the polyamide elastomer content was 29.7 parts by mass, the tungsten carbide particle content was 70 parts by mass, and an alicyclic polycarbodiimide compound and a cyclic carbodiimide compound were used as the carbodiimide group-containing compounds, with the alicyclic polycarbodiimide compound content being 0.15 parts by mass and the cyclic carbodiimide compound content being 0.15 parts by mass.

[0115] [Comparative Example 1] The dumbbell-shaped test specimens of this example were prepared in the same manner as in Example 1, except that the polyamide elastomer content was 30 parts by mass, the tungsten carbide particle content was 70 parts by mass, and no carbodiimide group-containing compound was added.

[0116] [Comparative Example 2] The dumbbell-shaped test specimens for this example were prepared in the same manner as in Example 1, except that the polyamide elastomer content was 29.9 parts by mass and 69.8 parts by mass of metallic tungsten were added instead of tungsten carbide particles.

[0117] [Comparative Example 3] The dumbbell-shaped test specimens for this example were prepared in the same manner as in Comparative Example 2, except that the polyamide elastomer content was 29.9 parts by mass, the metallic tungsten content was 69.8 parts by mass, and a cyclic carbodiimide compound (0.3 parts by mass) was used as the carbodiimide group-containing compound.

[0118] [Comparative Example 4] The dumbbell-shaped test specimens for this example were prepared in the same manner as in Comparative Example 2, except that the polyamide elastomer content was 30 parts by mass, the metallic tungsten content was 70 parts by mass, and no carbodiimide group-containing compound was added.

[0119] [Load test] To examine the long-term durability of the dumbbell-shaped test specimens prepared in the examples and comparative examples, load tests were conducted by subjecting them to high temperature and high humidity conditions. Specifically, the dumbbell test specimens were left standing at a temperature of 80°C and a humidity of 95% RH. For Examples 1-4 and Comparative Example 1, the standing time was 30 hours. For Comparative Examples 2-4, the standing time was 21 hours.

[0120] [Tensile test] In accordance with JIS K 7161-1:2014, tensile tests were performed on dumbbell-shaped test specimens of Examples 1-4 and Comparative Examples 1-4 before and after the load test.

[0121] <Test Conditions> Distance between gripping parts: 50mm Distance between gauge lines: 20mm Test speed: 100 mm / min As values ​​indicating durability, the elongation retention rate shown in equation (1) and the strength retention rate shown in equation (2) below were calculated. Higher elongation retention rates and strength retention rates indicate higher durability. Here, the fracture stroke length refers to the value obtained by subtracting the gauge length before the test from the gauge length after fracture. The results of the elongation retention rates for Examples 1 to 4 and Comparative Example 1 are shown in Table 1, and the results of the elongation retention rates for Comparative Examples 2 to 4 are shown in Table 2.

[0122]

number

[0123]

number

[0124] [Table 1]

[0125] [Table 2]

[0126] Furthermore, when the strength retention rates of Examples 1-4 and Comparative Examples 1-4 were measured, the strength retention rates of Examples 1-4 were all 60% or higher, while those of Comparative Examples 1-4 were all less than 60%. As a result of these tensile tests, the dumbbell-shaped test specimens of Examples 1-4 showed higher elongation retention rates and strength retention rates before and after the load test compared with the dumbbell-shaped test specimen of Comparative Example 1, which did not contain carbodiimide. In addition, Comparative Examples 2-4, which contained metallic tungsten instead of tungsten carbide, showed lower elongation retention rates and strength retention rates before and after the load test compared with the dumbbell-shaped test specimens of Examples 1-4, despite shorter load times. From these results, it was confirmed that the dumbbell-shaped test specimens of Examples 1-4 have high durability against load testing.

[0127] Furthermore, regarding the type of carbodiimide used, Example 1, which used only one type of carbodiimide, showed a higher elongation retention rate compared to Example 4, which used a combination of two types of carbodiimide. [Explanation of Symbols]

[0128] 1. Catheter, 10 Catheter body, 20 catheter tips, 21 Catheter tip resin layer, 30 hubs, 40 Kink-resistant protector (strain relief).

Claims

1. A catheter tip comprising a catheter tip resin layer containing a resin having ester bonds and / or amide bonds, carbodiimide, and tungsten carbide (WC), A catheter tip in which the content of the carbodiimide is greater than 0% by mass and less than 0.5% by mass with respect to the total mass of the catheter tip resin layer.

2. A catheter tip according to claim 1, wherein the elongation retention rate represented by the following formula (1) is 70% or more; [Math 1] Here, in equation (1), A represents the fracture stroke length in the tensile test of the catheter tip resin layer before the load test, and B represents the fracture stroke length in the tensile test of the catheter tip resin layer after the load test. The aforementioned load test is performed by leaving a dumbbell-shaped test specimen undisturbed for 30 hours under conditions of 80°C and 95% RH humidity.

3. The catheter tip according to claim 1, wherein the amount of carbodiimide is greater than 0% by mass and less than or equal to 0.3% by mass with respect to the total mass of the catheter tip resin layer.

4. The catheter tip according to claim 3, wherein the carbodiimide comprises only one type.

5. The catheter tip according to claim 1, wherein the tungsten carbide content is 60% by mass or more with respect to the total mass of the catheter tip resin layer.

6. The catheter tip according to claim 1, wherein the content of the hindered amine-based light stabilizer (HALS) is greater than 0% by mass and less than or equal to 0.1% by mass, relative to the total mass of the catheter tip resin layer.

7. The catheter tip according to claim 1, wherein the elongation retention rate is 80% or more.

8. The catheter tip according to claim 1, wherein the strength retention rate expressed by the following formula (2) is 60% or more; [Math 2] Here, in equation (2), C represents the breaking strength of the catheter tip resin layer in the tensile test before the load test, and D represents the breaking strength of the catheter tip resin layer in the tensile test after the load test.

9. A catheter comprising the catheter tip described in claim 1.

10. The catheter according to claim 9, which is used as at least one of a guiding catheter and a guiding sheath.

Images