Catheter tip

Abstract

Provided is a catheter that is not susceptible to deterioration even if stored for a long period of time. A catheter tip comprising: a resin having an ester bond and / or an amide bond; a tungsten-containing compound; and a hydrolysis inhibitor.

Description

Technical Field

[0001] The present invention relates to catheter tips. Background Art

[0002] When treating or diagnosing stenosis, catheters are used to insert medical devices into a living body and guide them to the target site. To accurately determine the position of the catheter's distal end during insertion, the distal end (catheter tip) of the catheter is typically coated with an X-ray-opaque material that can be detected by X-rays. For example, metallic tungsten powder is known to be an excellent X-ray-opaque material and is used as the material for the distal end of the catheter (e.g., Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent No. 5,584,821 Summary of the Invention

[0006] Catheters are not only used immediately but also stored for long periods of time before use. Resin is often used at the catheter tip for moldability and flexibility. However, when tungsten is added as an X-ray opaque material to the catheter tip, there is a risk of degradation of the resin.

[0007] Therefore, an object of the present invention is to provide a catheter tip having a low possibility of resin degradation even when stored for a long period of time, and a catheter including the same.

[0008] A catheter tip according to one embodiment of the present invention has the following configuration:

[0009] (1) A catheter tip comprising: a resin having an ester bond and / or an amide bond; a tungsten-containing compound; and a hydrolysis inhibitor.

[0010] (2) The catheter tip according to (1), wherein the hydrolysis inhibitor is a carbodiimide group-containing compound.

[0011] (3) The catheter tip according to (1) or (2), wherein the content of the tungsten-containing compound is 10 to 90% by mass relative to the total amount of the resin and the tungsten-containing compound.

[0012] (4) The catheter tip according to any one of (1) to (3), wherein the resin having an ester bond and / or an amide bond comprises a polyamide-based resin.

[0013] (5) The catheter tip according to any one of (1) to (4), wherein the tungsten-containing compound is dispersed in the resin in the form of particles.

[0014] (6) A catheter comprising the catheter tip according to any one of (1) to (5). BRIEF DESCRIPTION OF THE DRAWINGS

[0015] [ Figure 1 ] is a diagram showing the overall structure of the catheter.

[0016] [ Figure 2 ] is a cross-sectional schematic diagram near the junction of the catheter tip and the catheter body. DETAILED DESCRIPTION

[0017] The present invention provides a catheter tip comprising a resin having an ester bond and / or an amide bond, a tungsten-containing compound, and a hydrolysis inhibitor.

[0018] According to the catheter tip and the catheter including the same of the present invention, the possibility of resin deterioration can be reduced even in long-term storage.

[0019] Tungsten-containing compounds are often used in combination with resins. The inventors of this application speculate that the long-term degradation of resins caused by the presence of tungsten-containing compounds may be caused by hydrolysis of ester and / or amide bonds. Based on this research, they discovered that the combined use of a hydrolysis inhibitor can suppress the degradation of resins over time, leading to the completion of the present invention.

[0020] The mechanism of producing such an effect is speculated as follows. It should be noted that the following mechanism does not limit the technical scope of the present invention in any way.

[0021] During the manufacturing process, elemental tungsten metal undergoes oxidation in the presence of oxygen in the air, resulting in a mixture of oxidized tungsten metal (W) and a very small amount of tungsten oxide (WO3) as shown in the following formula. This WO3, when in contact with water, undergoes a hydration reaction to form tungstic acid, promoting the release of acidic hydrogen ions.

[0022] [Mathematical formula 1]

[0023] W+(3 / 2)O2→WO3

[0024] WO3+H2O→H2WO4→2H + +WO4 2-

[0025] Due to the presence of these acidic hydrogen ions, the system tends to be acidic, in other words, the pH value decreases. In practice, 1 g of pelletized resin (the resin used in the Examples, resin alone (without tungsten) as shown in Table 1 below), 1 g of a sample of Comparative Example 1 (resin + tungsten powder) subjected to high temperature and high humidity for one week (resin + tungsten (after one week of high temperature and high humidity in Table 1 below), and 1 g of a sample of Comparative Example 1 subjected to high temperature and high humidity in a sealed state for one week (resin + tungsten (after one week of high temperature and high humidity in a sealed state in Table 1 below)) were added to 5 mL of RO water and stirred. After standing at room temperature for 24 hours, the pH was measured using a pH meter (AS ONE AS600, 25°C). As shown in Table 1 below, the pH value of the sample after one week of high temperature and high humidity was lower than that of the resin alone (without tungsten).

[0026] [Table 1]

[0027] condition pH Resin only (no tungsten) 6.82 Resin + tungsten (after 1 week of high temperature and high humidity loading) 5.62 Resin + tungsten (after 1 week of high temperature and high humidity exposure in a sealed state) 6.27

[0028] Under acidic conditions, the ester and / or amide bonds within the resin undergo hydrolysis. Furthermore, as the hydrolysis proceeds, the terminal carboxyl groups of the decomposition products function as carboxylic acids, increasing the rate of the hydrolysis reaction.

[0029] Table 2 below shows the results of molecular weight (PMMA conversion) measurement using GPC for the sample of Comparative Example 1 ((1) sample before loading) and the sample after the sample was left in a high temperature and high humidity environment for a constant period of time ((2) loaded sample).

[0030] [Table 2]

[0031] condition Mn Mw Mz Mw / Mn (1) Sample before loading 9248 40418 102010 4.370 (2) Load sample 4429 12164 22031 2.746

[0032] These results indicate that the presence of a tungsten-containing compound causes the resin to be degraded and decomposed due to high temperature and high humidity loads. This decomposition of the resin is believed to be caused by hydrolysis of the resin.

[0033] It is believed that the progress of such hydrolysis will gradually progress as the catheter is stored for a long time even under normal temperature and humidity environments, and as a result, there is a possibility that the resin will deteriorate over time.

[0034] Here, it is considered that the presence of the hydrolysis inhibitor suppresses the progress of the hydrolysis, and as a result, the deterioration of the resin is suppressed.

[0035] The following describes the catheter according to the present invention using the accompanying drawings. It should be noted that in the description of the accompanying drawings, identical elements are denoted by identical reference numerals, and duplicate descriptions are omitted. For ease of explanation, the dimensional ratios of the various drawings may be exaggerated and differ from the actual ratios.

[0036] Furthermore, combinations of two or more of the preferred embodiments of the present invention described below are also preferred embodiments of the present invention, and are deemed to be disclosed in this specification (ie, to serve as a legal basis for modification).

[0037] Figure 1 This is a diagram showing the overall structure of the catheter 1 of the present invention.

[0038] Figure 1 In the process, the side of the catheter 1 inserted into the living body ( Figure 1 The left side of the catheter 1 is referred to as the distal end side, the side where the hub 30 is arranged in the catheter 1 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 (axially perpendicular cross 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 toward the catheter body 10 is referred to as the "radial direction."

[0039] The catheter 1 includes a catheter body 10 extending in the axial direction, a catheter tip 20 disposed at the distal end of the catheter body 10, a hub 30 disposed at the proximal end of the catheter body 10, and a torsion protector (strain relief) 40 disposed between the catheter body 10 and the hub 30. The catheter body 10 and the catheter tip 20 are joined to each other.

[0040] The catheter body 10 is formed of a flexible hollow tubular member. A lumen 10H is formed in the catheter body 10 over the entire length of the catheter body 10. The lumen 10H opens at the front end of the catheter tip 20.

[0041] like Figure 2 As shown, the catheter body 10 includes an inner layer 11 disposed on the inner surface side, an outer layer 12 disposed on the outer periphery of the inner layer 11, a reinforcing material layer 13 disposed inside the outer layer 12, and a hydrophilic lubricating layer 14. Figure 2 In the embodiment, the inner layer 11 and the hydrophilic lubricating layer 14 are arranged to extend to the front end of the catheter tip 20. Therefore, the inner layer 11 and the hydrophilic lubricating layer 14 are common to the inner layer and the hydrophilic lubricating layer at the catheter tip 20.

[0042] The inner layer 11 is preferably made of a material that provides low friction at least in the portion contacting the device, such as a treatment catheter or guidewire, when inserted into the lumen 10H. This configuration allows the device inserted into the catheter body 10 to move longitudinally with reduced sliding resistance, thereby improving operability. Specifically, examples of materials for the inner layer 11 include fluororesins such as polytetrafluoroethylene (PTFE).

[0043] The outer layer 12 is preferably made of a material having torsion resistance, suitable pushability, and followability. Specifically, the outer layer 12 can be made of a polyamide elastomer and / or polyamide (polyamide elastomer, polyamide, or a combination thereof), polyester, polyester elastomer, polyurethane elastomer, polyurethane resin, or a combination thereof.

[0044] The reinforcing material layer 13 comprises a plurality of reinforcing wires that reinforce the catheter body 10. Examples of these reinforcing wires include spiral or braided wires. The reinforcing wires are made of a metal such as stainless steel. Specifically, a stainless steel wire is flattened into a flat plate to reduce the radial wall thickness of the catheter body 10, and then a plurality of such wires, approximately 8 to 32 in number, are used to form a spiral or braid (a braided structure). To achieve balanced tubular reinforcement, the number of reinforcing wires is preferably a multiple of 8, but is not limited thereto.

[0045] By forming the reinforcing wire into a flat plate, the external stress is evenly applied compared to an elliptical shape, and thus the physical properties are constant.

[0046] It should be noted that the number of layers constituting the catheter body 10 and the materials constituting each layer may vary along the length of the catheter body 10. For example, in order to increase flexibility in the distal end portion of the catheter body 10, the number of layers may be reduced, a softer material may be used, reinforcement material may be omitted only in this portion, and an inner layer may be provided up to the distal end.

[0047] Insertion of the catheter into the body is performed while confirming its position under X-ray fluoroscopy. In the present invention, the catheter tip 20 contains a tungsten-containing compound as an X-ray opaque substance. Therefore, it is not necessary for the catheter body 10 to contain an X-ray opaque substance. However, an X-ray opaque substance (X-ray contrast agent) may be incorporated into the material constituting the outer layer 12. Examples of X-ray opaque substances include barium sulfate, bismuth oxide, and tungsten. Furthermore, the X-ray opaque substance is not limited to being present throughout the entire length of the catheter body 10 and may also be present in a portion of the catheter body 10, for example, only at the distal end or only at the catheter tip 20.

[0048] The constituent materials of the hydrophilic lubricating layer 14 are not particularly limited, and examples thereof include copolymers of monomers containing epoxy groups such as glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, β-methyl glycidyl methacrylate, and allyl glycidyl ether with hydrophilic monomers such as N-methylacrylamide, N,N-dimethylacrylamide, and acrylamide; (co)polymers composed of the above-mentioned hydrophilic monomers; cellulose-based 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, polyvinyl pyrrolidone, and copolymers of polyvinyl pyrrolidone and polyurethane described in U.S. Patent No. 4100309 and Japanese Patent Application Publication No. 59-19582. These hydrophilic lubricating materials may be used alone or in combination of two or more.

[0049] A hub 30 is attached (fixed) to the proximal end of the catheter body 10. The hub 30 has an inner cavity that communicates with the inner cavity 10H and has a Luer connector.

[0050] The distal end portion of the catheter body 10 and the catheter tip 20 can be integrated by being joined together, for example, by heat welding.

[0051] Long objects (linear bodies) such as guidewires, catheters (e.g., balloon catheters, stent delivery catheters), endoscopes, ultrasonic probes, and temperature sensors can be inserted or removed from hub 30, or various liquids such as contrast agents (X-ray contrast agents), medical solutions, and saline solutions can be injected. Hub 30 can also be connected to other devices, such as a Y-shaped branch connector. Hub 30 can be formed of thermoplastic resins such as polycarbonate, polyamide, polysulfone, and polyarylate.

[0052] The following describes the catheter tip and its constituent materials. It should be noted that, in this specification, the range "X to Y" includes both X and Y and refers to "X or greater and Y or less." Unless otherwise specified, operations and measurements of physical properties were performed at room temperature (20-25°C) and a relative humidity of 40-50%.

[0053] (Catheter tip)

[0054] The catheter tip 20 is formed of a material softer than the catheter body 10. The catheter tip 20, also called a distal tip, has the function of suppressing damage to a living lumen such as a blood vessel and improving insertability into a stenosis formed in a blood vessel. Figure 2In the embodiment, the catheter tip 20 has a tapered shape with the outer diameter decreasing toward the distal end, but the outer diameter may be substantially the same up to the distal end.

[0055] The catheter tip comprises: a resin having an ester bond and / or an amide bond (a resin having an ester bond, an amide bond, or a combination thereof), a tungsten-containing compound, and a hydrolysis inhibitor. Since the catheter tip contains the tungsten-containing compound, it has X-ray contrast properties. The resin having an ester bond and / or an amide bond, the tungsten-containing compound, and the hydrolysis inhibitor are preferably present in the same layer (the tungsten-containing layer (at the catheter tip, the layer containing the tungsten-containing compound is also referred to as the tungsten-containing layer)). Furthermore, the tungsten-containing layer may be a single layer or a multilayer 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, the tungsten-containing compound is preferably dispersed in the resin in the form of particles.

[0056] The catheter tip may be composed only of the tungsten-containing layer, or other functional layers (such as the aforementioned hydrophilic lubricating layer) may be laminated on the inner layer side (lumen side) and / or outer layer side (surface side) of the tungsten-containing layer.

[0057] Examples of the resin having an ester bond and / or an amide bond (hereinafter also referred to as a resin having a bond) include ethylene-vinyl acetate copolymers, polyamides, polyamide elastomers, polyurethane elastomers, polyamide-imides, etc. These resins may be used alone or in combination of two or more.

[0058] Wherein, the flexibility of the resin with key is high, and the affinity with adjacent parts, hardness difference are little, therefore preferably comprises polyamide-based resin, more preferably comprises polyamide and / or polyamide elastomer (polyamide, polyamide elastomer or their combination), further more preferably comprises polyamide elastomer.In the resin with key, polyamide-based resin is preferably more than 50 mass % (upper limit 100 mass %), more preferably more than 80 mass % (upper limit 100 mass %), further preferably 100 mass % (being formed by polyamide-based resin).In addition, in the resin with key, polyamide elastomer is preferably more than 50 mass % (upper limit 100 mass %), more preferably more than 80 mass % (upper limit 100 mass %), further preferably 100 mass % (being formed by polyamide elastomer).

[0059] It should be noted that, of the resin constituting the catheter tip, the proportion of the resin containing bonds is preferably 80% by mass or more (upper limit 100% by mass), more preferably 90% by mass or more (upper limit 100% by mass), and even more preferably 100% by mass (formed from the resin containing bonds). Furthermore, of the resin in the tungsten-containing layer, the proportion of the resin containing bonds is preferably 80% by mass or more (upper limit 100% by mass), more preferably 90% by mass or more (upper limit 100% by mass), and even more preferably 100% by mass (formed from the resin containing bonds).

[0060] A polyamide elastomer is a thermoplastic resin formed from a copolymer comprising a hard segment derived from a crystalline polymer with a high melting point and a soft segment derived from an amorphous polymer with a low glass transition temperature. The polymer backbone of the hard segment has an amide bond (-CONH-). Structural units containing an amide bond (-CONH-) in the backbone of the polymer backbone of the hard segment are also referred to as amide units of the polyamide elastomer.

[0061] In the present specification, the "amide unit of the polyamide elastomer" refers to a repeating unit derived from an amide bond in the high molecular weight chain of the polyamide elastomer. The amide unit in the polyamide elastomer is preferably a repeating unit represented by the following formula (1).

[0062] [Chemical Formula 1]

[0063] Formula (1)

[0064]

[0065] In the above formula (1), n ​​is preferably an integer of 2 to 20, and more preferably an integer of 5 to 11. In addition, in the examples described below, n is 11.

[0066] As the polymer forming the soft segment, for example, polyester and polyether can be mentioned. In addition, for example, polyethers such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol (PTMG), polyester polyols, ABA type triblock polyether diols, etc. can be mentioned. The polymer forming the soft segment can be used alone or in combination with more than two kinds. In addition, polyether diamines obtained by reacting the end of the polyether with ammonia, etc. can be used, for example, ABA type triblock polyether diamines can be used. With regard to the polyether as a polymer that can form a soft segment, it can form a polyether block amide copolymer formed by bonding the polyamide block as a hard segment via an ester bond.

[0067] The content of the soft segment of the polyamide elastomer is preferably 1 to 50% by mass, more preferably 10 to 30% by mass.

[0068] In addition to hard segments and soft segments, polyamide elastomers can also use chain extenders such as dicarboxylic acids.

[0069] These polyamide elastomers may be used alone or in combination of two or more.

[0070] 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.

[0071] It should be noted that the molecular weight of the polymer involved in the present invention can be measured by known methods such as MS mass spectrometry, light scattering, liquid chromatography, gas chromatography, gel filtration chromatography (GPC), etc., and in this specification, it refers to the molecular weight measured by GPC.

[0072] As measurement conditions in the GPC method, for example, the following conditions can be mentioned.

[0073] (1) Pretreatment: Filter using a 0.45 μm PTFE cartridge filter

[0074] (2) Equipment: HLC-8420GPC (manufactured by TOSOH)

[0075] (3) Separation column: TSKgel Super AWM-H (6.0 mm I.D. × 15 cm)

[0076] (4) Measurement temperature: 40°C

[0077] (5) Mobile phase: Hexafluoroisopropanol (+10mM CF3COONa)

[0078] (6) Flow rate: 0.3 mL / min

[0079] (7) Injection volume: 20 μL

[0080] (8) Detector: Differential refractometer (RI detector), polarity = (+)

[0081] (9) Concentration: 1 mg / mL

[0082] (10) Molecular weight standard substance: standard polymethyl methacrylate.

[0083] From the perspective of flexibility, the Shore D hardness of the polyamide elastomer that can be used in the catheter tip is preferably 20 to 80, more preferably 30 to 50. The hardness of the polyamide elastomer is measured using the Shore D hardness according to ISO 868:2003. When multiple polyamide elastomers are used, the Shore D hardness of the entire polyamide elastomer, taking into account the mass ratio of the polyamide elastomers, is used.

[0084] Polyamides are polymers having an amide bond (-CO-NH-) in the main chain, and are not particularly limited. Polyamides are generally produced by polymerization of lactams or amino acids with a ring structure, or by polycondensation of dicarboxylic acids and diamines. Homopolyamides are preferably used as polyamides. Monomers that can be polymerized independently include ε-caprolactam, ω-laurolactam, 6-aminocaproic acid, enantholactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 9-aminononanoic acid, and piperidone.

[0085] In addition, examples of the dicarboxylic acid used in the polycondensation of dicarboxylic acids and diamines include adipic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, terephthalic acid, 2-methylterephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Examples of the diamines include tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, p-phenylenediamine, and m-phenylenediamine.

[0086] Examples of the polyamide 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, and 6T / 6I. The polyamide may be used alone or in combination of two or more.

[0087] It should be noted that the ends of the polyamide can be capped 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, palmitamine, stearylamine, and behenylamine.

[0088] 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.

[0089] The content of the bonded resin relative to 100% by mass of the total amount of the bonded resin, the tungsten-containing compound, and the hydrolysis inhibitor is appropriately set in consideration of X-ray contrast properties, flexibility, moldability, etc., and is, for example, 10 to 90% by mass, or 20 to 70% by mass.

[0090] (Containing tungsten compounds)

[0091] The catheter tip contains a tungsten-containing compound as an X-ray opaque substance. Examples of the tungsten-containing compound include elemental metallic tungsten and tungsten carbide. The tungsten-containing compound may be used alone or in combination of two or more.

[0092] The tungsten-containing compound is preferably a particle. Here, for example, the so-called tungsten carbide particle refers to tungsten carbide as the main component (the largest component) of the particle (the main component is preferably 80 mass % or more, 90 mass % or more, 95 mass % or more, 98 mass % or more), and usually, the tungsten carbide contains uncarburized tungsten.

[0093] As the tungsten-containing compound, tungsten powder (particles) is preferred. It should be noted that, generally, as tungsten powder, in addition to tungsten (W) as the main component (the main component is preferably 80% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more), it also contains oxygen (forming a trace amount of tungsten oxide (WO X’ (X’≈2), WO X (2 < X < 3))), iron (Fe), molybdenum (Mo), etc.

[0094] As the average particle diameter of the tungsten powder, it is preferably 0.5 to 30 μm, more preferably 1 to 10 μm, and further preferably 2 to 4 μm. This average particle diameter is the volume average particle diameter measured by the dynamic light scattering method, but is not limited thereto.

[0095] In addition, various tungsten powders are commercially available, and those commercially available products can be preferably used in the present invention.

[0096] Relative to the total amount of the resin having a bond and the tungsten-containing compound, the content of the tungsten-containing compound is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, further more preferably 50 to 80% by mass, can be greater than 50% by mass and 80% by mass or less, and can be 60 to 80% by mass. By making the content of the tungsten-containing compound within the above range, the imaging property and flexibility are excellent.

[0097] (Hydrolysis inhibitor)

[0098] As the above hydrolysis inhibitor, conventionally known hydrolysis inhibitors can be used. For example, compounds that react with the carboxyl terminal of the decomposition product and bond can be cited. Specifically, for example, compounds containing functional groups such as carbodiimide group, epoxy group (for example, glycidyl ester compound, glycidyl ether compound, etc.), oxazoline group (for example, bisoxazoline compound, etc.) can be cited. Among them, from the viewpoint of the hydrolysis inhibition effect, the hydrolysis inhibitor is preferably a compound containing a carbodiimide group.

[0099] The compound containing a carbodiimide group is a compound having a carbodiimide group (-N = C = N-) in the molecule. The compound containing a carbodiimide group is preferably polyfunctional (having 2 or more carbodiimide groups in the molecule).

[0100] In addition, as the compound containing a carbodiimide group, cyclic carbodiimide and polycarbodiimide are preferred. Among them, in order to further exert the effects of the present invention, the compound containing a carbodiimide group is preferably polycarbodiimide.

[0101] Polycarbodiimide can include, for example, aromatic (Aromatic) polycarbodiimide compounds, aliphatic (Aliphatic) polycarbodiimide compounds, and alicyclic (Alicyclic) polycarbodiimide compounds. Here, polycarbodiimide is generally linear. Aromatic polycarbodiimide compounds refer to polycarbodiimide compounds having an aromatic ring in the molecule and may or may not have an aliphatic ring. Aliphatic polycarbodiimide compounds refer to polycarbodiimide compounds that do not have an aromatic ring and an aliphatic ring in the molecule. Alicyclic polycarbodiimide compounds refer to polycarbodiimide compounds that have an aliphatic ring in the molecule but do not have an aromatic ring. Among them, from the viewpoints of storage stability, preferably aromatic polycarbodiimide compounds and / or alicyclic polycarbodiimide compounds, more preferably alicyclic polycarbodiimide compounds, polycarbodiimide compounds can also be cyclic.

[0102] As polycarbodiimide, specifically, can be mentioned the material obtained by making diisocyanate carry out decarbonation condensation reaction.As diisocyanate, for example, can be any compound among chain or alicyclic aliphatic diisocyanate compound, aromatic diisocyanate compound or heterocyclic diisocyanate compound, among these, can use 1 kind alone, can also use 2 or more kinds in combination. Specifically, examples include chain aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as 1,4-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatocyclohexyl)propane, isophorone diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate; aliphatic diisocyanates containing an aromatic ring 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-diyl diisocyanate. These may be used alone or in combination of two or more.

[0103] From the perspective of storage stability, polycarbodiimides are preferably those whose terminal isocyanate groups are blocked with a blocking agent. Examples of blocking agents 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 the group consisting of a carboxyl group, an amino group, and an isocyanate group.

[0104] Examples of the cyclic carbodiimide include the cyclic carbodiimide compound represented by formula (i) disclosed in International Publication No. 2010 / 071211 (specifically, the cyclic carbodiimide compound described on pages 13 to 15, the cyclic carbodiimide compound represented by formula (i) disclosed in U.S. Patent Application Publication No. 2011 / 251384 (pages 4 to 6), which is incorporated by reference), and the cyclic carbodiimide compound represented by formula (i) described in Japanese Patent Application Laid-Open No. 2016-65001 (specifically, the cyclic carbodiimide compound described on pages 10 to 11).

[0105] The method for adding and mixing the hydrolysis inhibitor into the resin is not particularly limited. Mixing can be performed by dry blending, or the resin can be dissolved or molten and then mixed with the hydrolysis inhibitor (e.g., a carbodiimide-containing compound). A solvent can also be used during mixing. Examples of the solvent include hydrocarbon solvents, ketone solvents, ester solvents, ether solvents, halogen solvents, and amide solvents.

[0106] The amount of the hydrolysis inhibitor added is preferably 2 parts by mass or less, more preferably 0.01 to 2 parts by mass, and even more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the bonded resin. By adjusting the amount of the hydrolysis inhibitor added within the above range, resin degradation can be effectively suppressed, and the effect on the resin properties is minimal.

[0107] The catheter tip 20 may be provided with a hydrophilic lubricating layer ( Figure 2 The hydrophilic lubricating layer 14 in the embodiment of the present invention is arranged radially outside the tungsten-containing layer, which provides surface lubricity when wet.

[0108] The constituent materials of the hydrophilic lubricating layer are not particularly limited, and examples thereof include copolymers of monomers containing epoxy groups 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-mentioned hydrophilic monomers; cellulose-based 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, polyvinyl pyrrolidone, and copolymers of polyvinyl pyrrolidone and polyurethane described in U.S. Patent No. 4100309 and Japanese Patent Application Publication No. 59-19582. These hydrophilic lubricating materials may be used alone or in combination of two or more.

[0109] In addition, in order to reduce friction at least in the portion in contact with the treatment instrument such as a catheter or a guide wire when the treatment instrument is inserted into the lumen 10H, the catheter tip 20 may be provided with an inner layer ( Figure 2 The inner layer 11 is preferably made of a material that provides low friction at least in the portion contacting the device when a treatment catheter, guidewire, or other device is inserted into the lumen 10H. Specifically, the inner layer can be made of a fluorine-based resin material such as polytetrafluoroethylene (PTFE).

[0110] The catheter tip may contain pigments or dyes that exhibit white, black, blue, red, or yellow, or mixtures thereof. Examples of such pigments or dyes include carbon black, activated carbon, graphite, carbon nanotubes, fullerenes; titanium oxide; and condensed polycyclic organic pigments such as cyanine pigments, nickel disulfide pigments, squarylium pigments, naphthoquinone pigments, diimide pigments, azo organic pigments, phthalocyanine pigments, naphthalocyanine pigments, and azulenocyanine pigments.

[0111] Furthermore, the catheter tip may be provided with a reinforcement body made of SUS or the like in the above-mentioned material. Examples of the reinforcement body include a coil shape and a blade shape.

[0112] Example

[0113] The effects of the present invention are illustrated using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. It should be noted that, in the following examples, unless otherwise specified, the operation is carried out at room temperature (25°C). In addition, unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts", respectively.

[0114] [Preparation of dumbbell-shaped test pieces]

[0115] [Example 1]

[0116] 30 parts by mass of a polyamide elastomer (Shore D hardness 40, weight average molecular weight (Mw) approximately 40,000) was mixed with 70 parts by mass of tungsten particles (average particle size 3.0 μm, W 99.9% or more) and 0.3 parts by mass of an alicyclic polycarbodiimide compound (a carbodiimide group-containing compound serving as a hydrolysis inhibitor). A 20-ton manual hydraulic heating press was used for press molding at a set temperature of 200°C. The thickness of the molded product was set to 1.9 to 2.1 mm. The molded pressed sheet was punched out according to JISK 7161-2:2014 5A to produce a dumbbell-shaped test piece.

[0117] [Example 2]

[0118] A dumbbell-shaped test piece was prepared in the same manner as in Example 1 except that a cyclic carbodiimide compound, which is a carbodiimide group-containing compound, was used as the hydrolysis inhibitor instead of the alicyclic polycarbodiimide compound.

[0119] [Comparative Example 1]

[0120] A dumbbell-shaped test piece was prepared in the same manner as in Example 1 except that the carbodiimide group-containing compound was not used as the hydrolysis inhibitor.

[0121] [Load test]

[0122] The dumbbell-shaped test pieces prepared in the Examples and Comparative Examples were subjected to high temperature and high humidity conditions. Specifically, the dumbbell test pieces were subjected to a load test for a total of 7 cycles (1 week) using the conditions listed in Table 3 below as one cycle (24 hours).

[0123] [Table 3]

[0124] Table 3: Cyclic loading conditions (1 cycle is 24 hours (excluding transfer time))

[0125]

[0126] [Tensile test]

[0127] According to JIS K 7161-1:2014, a tensile test was performed on the dumbbell-shaped test pieces of Examples 1 and 2 and Comparative Example 1 before and after the load test.

[0128] <Test conditions>

[0129] Distance between fixtures: 50mm

[0130] Distance between marking lines: 20mm

[0131] Test speed: 100mm / min.

[0132] The durability value is calculated using the following formula: the survival rate. A higher survival rate indicates higher durability. The fracture stroke length is the value obtained by subtracting the distance between markings before the test from the distance between markings after fracture.

[0133] [Mathematical formula 2]

[0134] Residual rate (%) = (B / A) × 100

[0135] A: Breaking stroke length before load test (mm)

[0136] B: Breaking stroke length after load test (mm).

[0137] [Table 4]

[0138] Table 4: Tensile test results of Example 1, Example 2 and Comparative Example 1 before and after load test

[0139]

[0140] The tensile test results showed that the dumbbell-shaped test piece of Comparative Example 1 had a survival rate of approximately 7% before and after the load test. In contrast, the dumbbell-shaped test pieces of Examples 1 and 2 had survival rates of 10% or more before and after the load test, which were higher than those of Comparative Example 1. These results confirm that the dumbbell-shaped test piece of Example 1 has higher durability than that of the dumbbell-shaped test piece of Comparative Example 1.

[0141] This application is based on Japanese patent application No. 2023-081659 filed on May 17, 2023, the disclosure of which is incorporated herein in its entirety.

[0142] Description of Reference Numerals

[0143] 1 catheter,

[0144] 10 catheter body,

[0145] 30 hub,

[0146] 20 catheter tip,

[0147] 40 anti-torsion protection parts (strain relief parts).

Claims

1. A catheter tip comprising: a resin having an ester bond and / or an amide bond; a tungsten-containing compound; and a hydrolysis inhibitor.

2. The catheter tip of claim 1, wherein: The hydrolysis inhibitor is a compound containing a carbodiimide group.

3. The catheter tip according to claim 1 or 2, wherein: The content of the tungsten-containing compound is 10 to 90% by mass relative to the total amount of the resin and the tungsten-containing compound.

4. The catheter tip according to claim 1 or 2, wherein: The resin having an ester bond and / or an amide bond includes a polyamide-based resin.

5. The catheter tip according to claim 1 or 2, wherein: The tungsten-containing compound is dispersed in the resin in the form of particles.

6. A catheter comprising the catheter tip according to claim 1 or 2.

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