Thermoplastic polyurethane development composite material, and preparation method and application thereof

Abstract

The application relates to the technical field of biomedical polymer imaging materials, and discloses a thermoplastic polyurethane imaging composite material as well as a preparation method and application thereof.The raw material components of the thermoplastic polyurethane imaging composite material include thermoplastic polyurethane, modified imaging agents and additives; wherein the modified imaging agents are obtained by the reaction of a modifier and an imaging agent; the modifier includes a reactive silane coupling agent and a flexible high-molecular-chain compound, the flexible high-molecular-chain compound contains hydroxyl groups or carboxyl groups on a molecular chain, the hydroxyl groups or the carboxyl groups can chemically react with organic functional groups in a molecular structure of the reactive silane coupling agent or form hydrogen bonds, and the number-average molecular weight of the flexible high-molecular-chain compound is 300-3000.The preparation method is clear in steps and controllable in conditions, and the prepared thermoplastic polyurethane imaging composite material has excellent X-ray imaging properties, a high mechanical property retention rate and good processing fluidity.

Description

Technical Field

[0001] This application relates to the field of biomedical polymer imaging materials technology, and in particular to a thermoplastic polyurethane imaging composite material, its preparation method and application. Background Technology

[0002] Thermoplastic polyurethane (TPU) has become an ideal matrix material for interventional medical devices such as catheters and guidewires due to its excellent biocompatibility, flexibility, abrasion resistance, and chemical resistance, which has positively impacted the performance improvement of medical devices and the convenience of surgical procedures. However, in order to achieve precise positioning during surgery, inorganic contrast agents need to be added to TPU to make the resulting thermoplastic polyurethane contrast-enhancing composite material radiopaque.

[0003] Currently, to obtain clear imaging results, the loading amount of inorganic contrast agents typically needs to reach 30-60 wt%. However, the high loading amount of inorganic contrast agents also brings several technical drawbacks: First, the rigid inorganic contrast agent particles severely disrupt the continuous phase of TPU, leading to a sharp decline in the mechanical properties of the composite material, which cannot meet the flexibility requirements for bending and pushing interventional devices in the body; second, the high surface energy of submicron-sized contrast agent powders makes simple physical blending prone to agglomeration, resulting in rough product surfaces and poor melt flowability, which not only reduces vascular permeability but also makes it difficult to stably process slender, thin-walled catheters; third, the poor interfacial compatibility between the contrast agent and the TPU matrix means that stress cannot be effectively transferred through physical coating alone, easily leading to interfacial debonding and premature material failure; fourth, contrast agent agglomeration causes uneven local concentrations, resulting in artifacts in the imaging images and affecting surgical precision.

[0004] Existing improvement methods mostly use a single stearic acid lubricant or a general-purpose silane coupling agent to treat the developer. While this can improve dispersibility to some extent, it cannot achieve a balance between high developability, excellent mechanical properties, and good processability. Some methods add developer via side feeding to improve dispersibility, but this does not fundamentally solve the interfacial compatibility problem, and the mechanical properties still tend to decline under high filling conditions. Summary of the Invention

[0005] To at least overcome one of the problems existing in the prior art, one objective of this invention is to provide a thermoplastic polyurethane radiopaque composite material. This composite material uses thermoplastic polyurethane, a modified contrast agent, and additives as raw materials. The modified contrast agent is obtained by reacting a modifier and a contrast agent, and a specific modifier is defined to ensure a chemical bond or strong interaction between the modifier and the contrast agent, rather than a simple physical coating. This fundamentally improves the interfacial bonding force between the contrast agent and the TPU matrix, ensuring that the thermoplastic polyurethane radiopaque composite material possesses high radiopigmentability, excellent mechanical properties, and good processing flowability. This meets the requirements of high-end interventional medical devices such as ultra-fine interventional catheters and microguidewires for precise positioning under X-rays and for flexibility and delivery in complex vascular environments. A second objective of this invention is to provide a method for preparing the aforementioned thermoplastic polyurethane radiopaque composite material. A third objective of this application is to provide applications of the aforementioned thermoplastic polyurethane radiopaque composite material.

[0006] Therefore, the present invention adopts the following technical solution: A first aspect of the present invention provides a thermoplastic polyurethane developing composite material, the raw material components of which include thermoplastic polyurethane, a modified developing agent, and an auxiliary agent; wherein the modified developing agent is obtained by reacting a modifier and a developing agent; the modifier includes a reactive silane coupling agent and a flexible polymer segment compound, wherein the molecular chain of the flexible polymer segment compound contains hydroxyl or carboxyl groups, and the hydroxyl or carboxyl groups can chemically react with or form hydrogen bonds with the organic functional groups in the molecular structure of the reactive silane coupling agent; the number average molecular weight of the flexible polymer segment compound is 300-3000.

[0007] This application presents a thermoplastic polyurethane radiopaque composite material using thermoplastic polyurethane as the matrix. Thermoplastic polyurethane itself possesses excellent biocompatibility, flexibility, and processability, laying a solid performance foundation for materials used in interventional medical devices. Building upon this, a modifier composed of a reactive silane coupling agent and a flexible polymer segment compound is used to modify the radiopaque agent. The flexible polymer segment compound contains hydroxyl or carboxyl groups on its molecular chain. These active groups can chemically react with or form hydrogen bonds with the organic functional groups in the reactive silane coupling agent's molecular structure, thereby constructing a flexible interface layer on the radiopaque agent surface connected by chemical bonds or hydrogen bonds. This not only fundamentally improves the interfacial bonding force between the radiopaque agent and the TPU matrix but also effectively alleviates stress concentration problems under high filling conditions, preventing the mechanical properties of the TPU matrix from deteriorating due to the addition of the radiopaque agent. The additives play a supporting role, working synergistically with the thermoplastic polyurethane and the modified radiopaque agent, resulting in a thermoplastic polyurethane radiopaque composite material that combines excellent X-ray radiopaqueness, high mechanical property retention, and good processing fluidity.

[0008] Preferably, the flexible polymer segment compound is selected from at least one of polycaprolactone containing terminal hydroxyl or carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, hydroxyl-terminated polyester polyols, and ethylene-vinyl acetate copolymers. More preferably, the flexible polymer segment compound is selected from at least one of polycaprolactone containing terminal hydroxyl or carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, and ethylene-vinyl acetate copolymers. Even more preferably, the flexible polymer segment compound is selected from a composition of polycaprolactone containing terminal hydroxyl or carboxyl groups and polyethylene glycol containing terminal hydroxyl groups.

[0009] Preferably, the reactive silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and isocyanate propyltriethoxysilane. More preferably, the reactive silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0010] Preferably, the modifier is composed of polycaprolactone containing terminal hydroxyl or terminal carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, and γ-glycidoxypropyltrimethoxysilane in a weight ratio of (1~2):(0.5~1.6):(1~3). More preferably, the modifier is composed of polycaprolactone containing terminal hydroxyl or terminal carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, and γ-glycidoxypropyltrimethoxysilane in a weight ratio of (1.5~2):(0.5~1.6):(2~3).

[0011] In flexible polymer segment compounds, the terminal hydroxyl or carboxyl groups are highly reactive, enabling them to efficiently react chemically with the organic functional groups of reactive silane coupling agents or form hydrogen bonds. This ensures both the efficiency and binding strength of the modification reaction, strengthens the molecular chain entanglement between the modified developer and the TPU matrix, and improves their compatibility. Simultaneously, the siloxane groups of the reactive silane coupling agent can form Si-O-inorganic covalent bonds with the hydroxyl groups on the developer surface, ensuring stable chemical bonding both within the modifier and between the modifier and the developer. This solves the problem of weak bonding and easy detachment of silane coupling agents and developers in existing technologies, ensuring the controllability of the modification reaction and improving the feasibility of industrial preparation.

[0012] Preferably, the mass of the modifier is 0.8-13% of the mass of the developer. More preferably, the mass of the modifier is 4-13% of the mass of the developer. Even more preferably, the mass of the modifier is 5-13% of the mass of the developer.

[0013] In the above technical solution, the mass of the modifier is 0.8~13% of the mass of the developer. This range ensures that the modifier can fully cover the surface of the developer to form a continuous modified layer, avoiding the generation of free phase due to the excessive proportion of modifier, which would reduce the mechanical properties and processing defects of the TPU matrix.

[0014] Preferably, the developer is an inorganic developer with an average particle size of 0.2~3.0 μm. More preferably, the developer is an inorganic developer with an average particle size of 0.5~3.0 μm. Even more preferably, the developer is an inorganic developer with an average particle size of 1.5~3.0 μm.

[0015] Preferably, the inorganic developer is selected from at least one of barium sulfate, bismuth oxide, and basic bismuth carbonate. More preferably, the inorganic developer is selected from at least one of barium sulfate and bismuth oxide.

[0016] The inorganic developer, within the particle size range specified in this application, can ensure sufficient X-ray absorption cross-section to achieve clear development while maintaining good surface smoothness of the product. If the particle size is too small, the specific surface area is too large, making it prone to agglomeration. Even with modifiers, it is difficult to disperse evenly, and the cost is high. If the particle size is too large, individual particles are prone to becoming stress concentration points, and may lead to surface roughness or even protrusions in application.

[0017] Preferably, the method for preparing the modified developer includes the following steps: applying the modifier dissolved in an organic solvent to the surface of the developer in an atomized form, reacting under continuous stirring and heating conditions, removing the solvent, and obtaining the modified developer.

[0018] More preferably, the preparation method of the modified developer includes the following steps: dissolving the modifier in an organic solvent to prepare a modifier solution with a mass fraction of 8%~20%; adding the developer to a high-speed mixer, stirring at 50~100 rpm and preheating to 60~80℃, maintaining this temperature for 10~30 min; increasing the stirring speed of the high-speed mixer to 500~1500 rpm to fluidize the developer; and applying the developer through a dual-fluid atomizing nozzle at a speed of 0.2~ The modified agent solution was uniformly sprayed onto the fluidized developer surface using an atomization pressure of 0.4 MPa and a spray rate of 5-15 mL / min. After spraying, the temperature was raised to 80-100℃, and a vacuum was drawn to a vacuum degree of -0.02--0.06 MPa. The mixture was stirred at a speed of 500-1500 rpm for 15-45 min. After the reaction was completed, the material was transferred to a vacuum drying oven and vacuum dried at 50-70℃ for 2-4 h to obtain the modified developer.

[0019] The above-mentioned method for preparing modified developer is conducive to the uniform dispersion of the modifier on the surface of the developer. The tiny droplets formed by atomization can instantly and uniformly cover the surface of each high-speed moving developer powder particle, avoiding the problems of agglomeration or uneven modification caused by local excess liquid in traditional wet modification. At the same time, continuous high-speed stirring breaks the initial agglomeration of the developer, ensuring that the chemical reaction and physical coating on the surface of the developer powder are carried out efficiently. Heating can promote the modification reaction and accelerate the volatilization of organic solvents.

[0020] Preferably, the Shore hardness of the thermoplastic polyurethane is 75A to 55D. More preferably, the Shore hardness of the thermoplastic polyurethane is 80A to 53D. Even more preferably, the Shore hardness of the thermoplastic polyurethane is 85A to 50D.

[0021] When the Shore hardness value is higher than 90A, the Shore D scale is used.

[0022] Preferably, the additives include antioxidants and lubricants. More preferably, the antioxidant is selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; and the lubricant is selected from at least one of calcium stearate, zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax.

[0023] Preferably, the weight ratio of antioxidant to lubricant in the additive is (1~3):(1~1.6). More preferably, the weight ratio of antioxidant to lubricant in the additive is (1.2~3):(1~1.6).

[0024] Preferably, in the raw materials of the thermoplastic polyurethane developing composite material, the weight ratio of thermoplastic polyurethane, modified developing agent and additives is (40~70):(30.5~60):(0.1~2).

[0025] In this application's thermoplastic polyurethane developing composite material, by rationally controlling the proportions of raw material components, 40-70 parts by weight of thermoplastic polyurethane helps retain the flexibility and biocompatibility of the TPU matrix itself, while avoiding the problem of insufficient modified developer content due to excessive TPU, which would affect developing performance. 30.5-60 parts by weight of modified developer achieves high developability while utilizing its excellent compatibility to avoid a decrease in the mechanical properties and processability of the composite material under high filling conditions, thus achieving a balance between high developing filler content and excellent overall performance. By limiting the amount of additives, migration and precipitation problems caused by excessive additives are avoided. This formulation maximizes the overall performance of the material, synergistically achieving a unity of high developability, excellent mechanical properties, and good processing flowability in the thermoplastic polyurethane developing composite material.

[0026] A second aspect of the present invention provides a method for preparing the thermoplastic polyurethane developing composite material according to the first aspect of the present invention, comprising the following steps: The thermoplastic polyurethane, modified developer, and additives are melt-blended, extruded, and granulated to obtain the thermoplastic polyurethane developer composite material.

[0027] Preferably, the melt blending and extrusion granulation are carried out in a twin-screw extruder; the length-to-diameter ratio L / D of the twin-screw extruder is (40~52):1, the melt blending temperature is 170~210℃, and the screw speed is 200~500rpm.

[0028] A third aspect of this application provides the application of a thermoplastic polyurethane radiopaque composite material in the preparation of ultra-fine interventional catheters, microguidewires, or vascular stent delivery systems. The thermoplastic polyurethane radiopaque composite material is the aforementioned thermoplastic polyurethane radiopaque composite material or is prepared by the aforementioned preparation method.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects: 1) The raw material components of this application include thermoplastic polyurethane, modified developer, and additives; wherein, the modified developer is prepared by reacting a modifier and a developer, the modifier being a compound of a reactive silane coupling agent and a flexible polymer chain compound with a number average molecular weight of 300-3000 and containing hydroxyl or carboxyl groups, the developer being an inorganic developer with an average particle size of 0.2-3.0 μm, and the mass of the modifier being 0.8-13% of the mass of the developer. By forming a flexible interface layer through chemical bonding between the modifier and the developer, and combining the synergistic ratio between thermoplastic polyurethane, modified developer, and additives, the resulting thermoplastic polyurethane developing composite material possesses excellent X-ray developability, high mechanical property retention, and good processing fluidity. Its surface is free of sharkskin and graininess, tensile strength retention is ≥81.1%, elongation at break retention is ≥78.6%, and melt flow rate is significantly improved compared to the unmodified system.

[0030] 2) In the preparation method of the thermoplastic polyurethane developing composite material of this application, thermoplastic polyurethane, a modified developing agent obtained by reacting a modifier and a developing agent, and additives are obtained by melt blending and extrusion granulation. In particular, key conditions such as the aspect ratio of the twin-screw extruder, the melt blending temperature, and the screw speed are strictly controlled to obtain the thermoplastic polyurethane developing composite material. This preparation method has clear steps and controllable conditions. The equipment used is all conventional equipment for polymer material processing, and no new special equipment is required. It is suitable for large-scale production and helps to form a thermoplastic polyurethane developing composite material with uniform component dispersion and stable interfacial bonding. Detailed Implementation

[0031] The present invention will be further described in detail below through specific embodiments, comparative examples and tables, but is not limited to all the discussions and data.

[0032] The thermoplastic polyurethane was purchased from Covestro, Germany, model Desmopan® 9390A, medical grade, Shore A hardness 80A; barium sulfate (precipitation method), D50=1.0±0.2μm, purity ≥99%; hydroxyl-terminated polycaprolactone, Mn≈1000; hydroxyl-terminated polyethylene glycol, Mn=400.

[0033] Preparation example: The preparation method of modified barium sulfate in Example 1 includes the following steps: 1.2 g of hydroxyl-terminated polycaprolactone, 1.6 g of hydroxyl-terminated polyethylene glycol, and 1 g of γ-glycidyl etheroxypropyltrimethoxysilane were dissolved in 21.5 g of anhydrous ethanol to prepare a modifier solution with a total mass fraction of 15%. 40 g of barium sulfate was added to a high-speed mixer and preheated to 70 °C with stirring at 80 rpm for 20 min. The stirring speed of the high-speed mixer was increased to 1200 rpm to fluidize the barium sulfate. The modifier solution was uniformly sprayed onto the surface of the barium sulfate through a two-fluid atomizing nozzle at an atomization pressure of 0.3 MPa and a spray rate of 10 mL / min. After spraying, the temperature was raised to 95 °C, and a vacuum was drawn to -0.04 MPa, maintaining stirring at 1200 rpm for 30 min. After the reaction, the material was transferred to a vacuum drying oven and vacuum dried at 60 °C for 3 h to obtain modified barium sulfate (modified developer). The total mass of the modifier was calculated to be 3.8g, accounting for 9.5% of the mass of the barium sulfate developer.

[0034] Preparation of Modified Barium Sulfate (Example 2): The preparation method includes the following steps: 1.5 g of hydroxyl-terminated polycaprolactone, 1 g of hydroxyl-terminated polyethylene glycol, and 1.3 g of γ-glycidyl etheroxypropyltrimethoxysilane were dissolved in 21.5 g of anhydrous ethanol to prepare a modifier solution with a total mass fraction of 15%. 40 g of barium sulfate was added to a high-speed mixer and preheated to 70 °C with stirring at 80 rpm for 20 min. The stirring speed of the high-speed mixer was increased to 1200 rpm to fluidize the barium sulfate. The modifier solution was uniformly sprayed onto the surface of the barium sulfate through a two-fluid atomizing nozzle at an atomization pressure of 0.3 MPa and a spray rate of 10 mL / min. After spraying, the temperature was raised to 95 °C, and a vacuum was drawn to -0.04 MPa, maintaining stirring at 1200 rpm for 30 min. After the reaction, the material was transferred to a vacuum drying oven and vacuum dried at 60 °C for 3 h to obtain modified barium sulfate. The total mass of the modifier was calculated to be 3.8g, accounting for 9.5% of the mass of the barium sulfate developer.

[0035] The preparation method of modified barium sulfate in Example 3 includes the following steps: 2g of hydroxyl-terminated polycaprolactone, 0.5g of hydroxyl-terminated polyethylene glycol, and 2.5g of γ-glycidyl etheroxypropyltrimethoxysilane were dissolved in 28.3g of anhydrous ethanol to prepare a modifier solution with a total mass fraction of 15%. 40g of barium sulfate was added to a high-speed mixer and preheated to 70℃ with stirring at 80rpm for 20min. The stirring speed of the high-speed mixer was increased to 1200rpm to fluidize the barium sulfate. The modifier solution was uniformly sprayed onto the surface of the barium sulfate through a two-fluid atomizing nozzle at an atomization pressure of 0.3MPa and a spray rate of 10mL / min. After spraying, the temperature was raised to 95℃, and a vacuum was drawn to -0.04MPa, maintaining stirring at 1200rpm for 30min. After the reaction, the material was transferred to a vacuum drying oven and vacuum dried at 60℃ for 3h to obtain modified barium sulfate. Calculations show that the total mass of the modifier is 5g, accounting for 12.5% ​​of the mass of the barium sulfate developer.

[0036] Preparation of Example 4: The method for preparing modified barium sulfate includes the following steps: 1.2 g of hydroxyl-terminated polycaprolactone, 1.6 g of hydroxyl-terminated polyethylene glycol, and 1 g of γ-glycidyl etheroxypropyltrimethoxysilane were dissolved in 21.5 g of anhydrous ethanol to prepare a modifier solution with a total mass fraction of 15%. 40 g of barium sulfate was added to a high-speed mixer and preheated to 70 °C with stirring at 80 rpm for 20 min. The stirring speed of the high-speed mixer was increased to 900 rpm to fluidize the barium sulfate. The modifier solution was uniformly sprayed onto the surface of the barium sulfate through a two-fluid atomizing nozzle at an atomization pressure of 0.3 MPa and a spray rate of 12 mL / min. After spraying, the temperature was raised to 95 °C, and a vacuum was drawn to -0.04 MPa, maintaining stirring at 900 rpm for 30 min. After the reaction, the material was transferred to a vacuum drying oven and vacuum dried at 60 °C for 3 h to obtain modified barium sulfate. The total mass of the modifier was calculated to be 3.8g, accounting for 9.5% of the mass of the barium sulfate developer.

[0037] Preparation of comparative examples: The preparation method for the modified barium sulfate of Comparative Example 1 includes the following steps: Dissolve 3.8g of γ-glycidoxypropyltrimethoxysilane in 21.5g of anhydrous ethanol to prepare a modifier solution with a total mass fraction of 15%; the remaining steps and dosages are the same as those for the preparation of modified barium sulfate in Example 1.

[0038] The preparation method for the modified barium sulfate of Comparative Example 2 includes the following steps: Add 40g of barium sulfate to a high-speed mixer and preheat it to 80℃ at a stirring speed of 80rpm for 10min. Weigh 0.4g of stearic acid (1% of the mass of barium sulfate) and add it to the high-speed mixer. Increase the stirring speed of the high-speed mixer to 1200rpm and continue stirring at 90℃ for 20min to allow the stearic acid to melt and uniformly coat the surface of the barium sulfate particles. Stop heating, reduce the stirring speed to 80rpm and cool to below 40℃. Discharge the material to obtain barium sulfate modified by dry method with stearic acid.

[0039] It is particularly important to emphasize that, unless otherwise specified, the raw materials, reagents, or apparatus used in this invention can be obtained through conventional commercial channels. In this invention, unless otherwise specified, all quantities are parts by weight.

[0040] Examples of thermoplastic polyurethane developing composite materials: A thermoplastic polyurethane developing composite material is prepared by the following steps: 40-70 parts of thermoplastic polyurethane, 30.5-60 parts of modified developer, and 0.1-2 parts of additives are added to a low-speed mixer and mixed at room temperature for 10 minutes to obtain a premix. The premix is ​​then melt-blended and extruded in a twin-screw extruder with an L / D ratio of (40-52):1, a screw speed of 200-500 rpm, and temperatures set to 170℃ in zone 1, 180℃ in zone 2, 190℃ in zone 3, 200℃ in zone 4, 195℃ in zone 5, and 190℃ at the die head. The extruded strip is then water-cooled, air-dried, pelletized, and dried at 80℃ for 4 hours to obtain the thermoplastic polyurethane developer composite material.

[0041] In some specific embodiments, the Shore A hardness of the thermoplastic polyurethane can be 75A, 80A, 85A, 90A, 30D, or 55D. The modified developer is obtained by reacting a modifier and a developer. The modifier includes a reactive silane coupling agent and a flexible polymer segment compound. The flexible polymer segment compound contains hydroxyl or carboxyl groups on its molecular chain. These hydroxyl or carboxyl groups can chemically react with or form hydrogen bonds with the organic functional groups in the molecular structure of the reactive silane coupling agent. The number average molecular weight of the flexible polymer segment compound can be 300, 400, 1000, 1300, 1600, 2100, 2500, or 3000. The flexible polymer segment compound can be selected from at least one of polycaprolactone containing terminal hydroxyl or terminal carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, hydroxyl-terminated polyester polyols, and ethylene-vinyl acetate copolymers. The modifier may consist of polycaprolactone containing terminal hydroxyl or carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, or γ-glycidoxypropyltrimethoxysilane in a weight ratio of 1.2:1.6:1, 1.5:1:1.3, 2:0.5:2.5, or 1:1:3. The reactive silane coupling agent may be selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and isocyanate propyltriethoxysilane. The mass of the modifier is 0.8%, 1%, 4%, 6%, 9%, 11%, or 13% of the developer's mass. The developer is an inorganic developer, and the average particle size of the inorganic developer may be 0.2 μm, 0.8 μm, 1.2 μm, 1.8 μm, 2.5 μm, or 3.0 μm. The inorganic developer may be selected from at least one of barium sulfate, bismuth oxide, and basic bismuth carbonate. The amount of thermoplastic polyurethane can be 40, 50, 60, or 70 parts; the amount of modified developer can be 30.5, 40, 50, or 60 parts; and the amount of additives can be 0.1, 0.3, 0.8, or 2 parts. Additives include antioxidants and lubricants. Antioxidants can be selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; lubricants can be selected from at least one of calcium stearate, zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax. The weight ratio of antioxidants to lubricants in the additives can be 1:1, 1:1.2, 1:1.6, 2:1, or 3:1.

[0042] In some specific embodiments, the preparation method of the modified developer includes the following steps: dissolving the modifier in an organic solvent to prepare a modifier solution with a mass fraction of 8%, 10%, 15%, or 20%; adding the developer to a high-speed mixer, stirring at 50 rpm, 70 rpm, 80 rpm, or 100 rpm and preheating to 60°C, 70°C, or 80°C, and maintaining the temperature for 10 min, 20 min, or 30 min; increasing the stirring speed of the high-speed mixer to 500 rpm, 800 rpm, 1200 rpm, or 1500 rpm to fluidize the developer; and applying the developer through a dual-fluid atomizing nozzle at a pressure of 0.2 MPa, 0.3 MPa, or 0.4 MPa. The modified agent solution was uniformly sprayed onto the fluidized developer surface using an atomization pressure of Pa and a spray rate of 5 mL / min, 10 mL / min, or 15 mL / min. After spraying, the temperature was raised to 80℃, 90℃, or 100℃, and a vacuum was drawn to a vacuum degree of -0.02MPa, -0.04MPa, or -0.06MPa. The mixture was stirred at a speed of 500 rpm, 800 rpm, 1200 rpm, or 1500 rpm for 15 min, 20 min, 30 min, or 45 min, respectively. After the reaction was completed, the material was transferred to a vacuum drying oven and vacuum dried at 50℃, 60℃, or 70℃ for 2 h, 3 h, or 4 h, respectively, to obtain the modified developer. Example 1

[0043] A thermoplastic polyurethane developing composite material is prepared by the following steps: 50g of thermoplastic polyurethane, 40g of modified barium sulfate from Preparation Example 1, and 1g of additives (composed of 0.5g antioxidant 1010 and 0.5g calcium stearate) were added to a low-speed mixer and mixed at room temperature for 10 minutes to obtain a premix. The premix was then melt-blended and extruded in a twin-screw extruder with an L / D ratio of 40:1, a screw speed of 350 rpm, and temperatures set to 170℃ in zone 1, 180℃ in zone 2, 190℃ in zone 3, 200℃ in zone 4, 195℃ in zone 5, and 190℃ at the die head. The extruded strip was water-cooled, air-dried, pelletized, and dried at 80℃ for 4 hours to obtain the thermoplastic polyurethane developing composite material. Example 2

[0044] The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in Example 1 is replaced with an equal amount of modified barium sulfate in Example 2. Example 3

[0045] The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in Example 1 is replaced with an equal amount of modified barium sulfate in Example 3. Example 4

[0046] The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in Example 1 is replaced with an equal amount of modified barium sulfate in Example 4.

[0047] Comparative Example 1: The preparation method of a thermoplastic polyurethane developing composite material is the same as that of Example 1, except that Comparative Example 1 does not add the modified barium sulfate and additives of Preparation Example 1, but instead adds 91g of thermoplastic polyurethane.

[0048] Comparative Example 2: The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in Preparation Example 1 in Comparative Example 2 is replaced with an equal amount of unmodified barium sulfate.

[0049] Comparative Example 3: The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in the preparation of Example 1 in Comparative Example 3 is replaced with an equal amount of modified barium sulfate prepared in Comparative Example 1.

[0050] Comparative Example 4: The preparation method of a thermoplastic polyurethane developing composite material is the same as that of Example 1, except that the modified barium sulfate in the preparation of Example 1 in Comparative Example 4 is replaced with an equal amount of modified barium sulfate in the preparation of Comparative Example 2.

[0051] Comparative Example 5: The preparation method of a thermoplastic polyurethane developing composite material is the same as that in Example 1, except that the modified barium sulfate in Preparation Example 1 in Comparative Example 5 is replaced with 1.2g of hydroxyl-terminated polycaprolactone, 1.6g of hydroxyl-terminated polyethylene glycol, and 1g of γ-glycidyl etheroxypropyltrimethoxysilane. Instead of undergoing a pre-reaction, it is directly added to a low-speed mixer along with the thermoplastic polyurethane and additives and mixed at room temperature.

[0052] Material performance testing: The thermoplastic polyurethane developing composite materials obtained in Examples 1-4 and Comparative Examples 1-5 were subjected to various performance tests, and the test methods are as follows: 1. Tensile strength and elongation at break: tested in accordance with GB / T 1040.2-2022 standard.

[0053] 2. Melt Flow Rate (MFR): Tested according to GB / T 3682.1-2018 standard (test conditions are 190℃ / 2.16kg).

[0054] 3. Surface finish: Referring to the GB / T 3246.2-2022 standard, a surface roughness tester is used. The sampling length is 0.8 mm, the test range is 0-10 μm. The roughness of 3 different positions on the surface of the test sample is measured, and the average value is taken, denoted as Ra. The rating is carried out according to the following criteria: Excellent: Ra ≤ 0.8 μm, the surface has no particle feeling and shark skin; Good: 0.8 μm < Ra ≤ 1.5 μm, the surface has slight particle feeling and no shark skin; Poor: Ra > 1.5 μm, the surface has obvious particle feeling, shark skin or protrusions.

[0055] 4. X-ray imaging property: The test sample is made into a 0.2-mm-thick film and placed under an X-ray imager (tube voltage 60 kV, tube current 10 mA, exposure time 0.1 s) for imaging. The analysis and rating are carried out according to the following criteria: Excellent: The imaging profile is clear, there are no dot-like and linear artifacts, and the gray value is uniform; Good: The imaging profile is relatively clear, there are a small number of tiny artifacts, and the gray value is basically uniform; Poor: The imaging profile is blurred, there are a large number of artifacts, and the gray value has significant differences; None: There is no imaging effect, and there is no gray difference from the background.

[0056] The test performances of the thermoplastic polyurethane imaging composite materials of Examples 1-4 and Comparative Examples 1-5 are shown in Table 1 below:

[0057] Note: Tensile strength retention rate (%) = (tensile strength of the composite material ÷ tensile strength of pure TPU in Comparative Example 1) × 100%; The calculation method of elongation at break retention rate is the same.

[0058] For the thermoplastic polyurethane imaging composite materials of Examples 1-4, a modifier composed of a reactive silane coupling agent and a flexible polymer chain segment compound is used to pre-chemically modify the imaging agent, and a flexible interfacial layer with strong interaction with the TPU matrix is constructed. The prepared composite materials successfully overcome the problems of traditional highly filled imaging materials with low mechanical properties, poor dispersion, and weak interfacial bonding force, and achieve the unity of high imaging property, excellent mechanical properties and good processing fluidity. The test results show that the tensile strength retention rate of the thermoplastic polyurethane imaging composite material of this application ≥ 81.1%, the elongation at break retention rate ≥ 78.6%, the melt flow rate is significantly improved, the surface roughness Ra ≤ 0.38 μm, and the surface finish and X-ray imaging property are both excellent grades, which can meet the strict requirements of high-end interventional medical devices such as ultra-fine interventional catheters and micro-guidewires for smooth pushing and accurate imaging and positioning in complex blood vessels.

[0059] Compared with Example 1, in Comparative Example 1, the preparation method and the dosage of each raw material are the same as those in Example 1 except that no imaging agent and additives are added. The results show that although the pure TPU material in Comparative Example 1 has excellent mechanical properties and surface finish, it does not have X-ray imaging property and cannot be used for interventional devices that require precise intraoperative positioning.

[0060] Compared with Example 1, Comparative Example 2 used the same preparation method and raw material amounts, except that modified barium sulfate was replaced with unmodified barium sulfate in equal amounts. The results showed that the composite material of Comparative Example 2 exhibited a significant decrease in various properties: tensile strength retention decreased to 49.0%, elongation at break retention was only 37.8%, melt flow rate was as low as 3.9 g / 10 min, surface roughness was as high as 2.15 μm, and X-ray reproducibility was poor. This may be because the unmodified barium sulfate has poor interfacial compatibility with the TPU matrix, severely disrupting the continuous phase of the matrix at high filler content, and is prone to agglomeration, leading to problems such as stress concentration, processing difficulties, and uneven development.

[0061] Compared with Example 1, Comparative Example 3 was prepared using the same method and with the same amount of raw materials. The difference was that the modified barium sulfate from Example 1 was replaced with an equal amount of the modified barium sulfate from Comparative Example 1. The results showed that the tensile strength retention rate of the composite material in Comparative Example 3 was 62.5%, the elongation at break retention rate was 51.9%, and the melt flow rate was 8.0 g / 10 min, all significantly lower than that of Example 1. Furthermore, the surface roughness Ra = 0.86 μm, and the developability was only "good". This indicates that while small molecule coupling agents can improve the dispersibility of the system, they cannot form a flexible interface layer, resulting in low interfacial stress transfer efficiency and limited effectiveness in maintaining mechanical properties.

[0062] Compared with Example 1, Comparative Example 4 was prepared using the same method and with the same amount of raw materials. The difference was that the modified barium sulfate from Example 1 was replaced with an equal amount of the modified barium sulfate from Comparative Example 2. The results showed that the tensile strength retention rate of the composite material in Comparative Example 4 was 58.7%, the elongation at break retention rate was 47.9%, and the melt flow rate was 7.2 g / 10 min, all significantly lower than the corresponding results in Example 1. This may be because the stearic acid only undergoes physical adsorption or weak interaction with the developer and TPU matrix, making it prone to desorption during high-shear processing and unable to provide a stable and strong interfacial bond.

[0063] Compared with Example 1, Comparative Example 5 used the same preparation method and the same amount of raw materials. The difference was that in Comparative Example 5, the three raw materials constituting the composite modifier (hydroxyl-terminated polycaprolactone, hydroxyl-terminated polyethylene glycol, and silane coupling agent) were not pre-treated with the developer, but were directly added together with TPU and additives for melt blending. The results showed that the tensile strength retention rate was only 68.7%, and the elongation at break retention rate was only 59.7%. This indicates that simple in-situ blending cannot form a uniform and stable chemical bonding interface on the developer surface, making it difficult for the modifier to exert a synergistic effect. The dispersibility and interfacial bonding effect were far inferior to the pre-atomization modification process, thus the performance improvement effect on the composite material was limited.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A thermoplastic polyurethane developing composite material, characterized in that, Its raw material components include thermoplastic polyurethane, modified developer, and additives; The modified developer is obtained by reacting a modifier and a developer. The modifier includes a reactive silane coupling agent and a flexible polymer segment compound. The flexible polymer segment compound contains hydroxyl or carboxyl groups on its molecular chain. The hydroxyl or carboxyl groups can chemically react with or form hydrogen bonds with the organic functional groups in the molecular structure of the reactive silane coupling agent. The number-average molecular weight of the flexible polymer segment compound is 300-3000.

2. The thermoplastic polyurethane developing composite material according to claim 1, characterized in that, The flexible polymer segment compound is selected from at least one of polycaprolactone containing terminal hydroxyl or terminal carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, hydroxyl-terminated polyester polyols, and ethylene-vinyl acetate copolymers. And / or, the reactive silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and isocyanate propyltriethoxysilane.

3. The thermoplastic polyurethane developing composite material according to claim 2, characterized in that, The modifier is composed of polycaprolactone containing terminal hydroxyl or terminal carboxyl groups, polyethylene glycol containing terminal hydroxyl groups, and γ-glycidoxypropyltrimethoxysilane in a weight ratio of (1~2):(0.5~1.6):(1~3).

4. The thermoplastic polyurethane developing composite material according to claim 1, characterized in that, The mass of the modifier is 0.8 to 13% of the mass of the developer.

5. The thermoplastic polyurethane developing composite material according to claim 1, characterized in that, The developer is an inorganic developer with an average particle size of 0.2~3.0 μm.

6. The thermoplastic polyurethane developing composite material according to claim 1, characterized in that, The method for preparing the modified developer includes the following steps: applying the modifier dissolved in an organic solvent to the surface of the developer in an atomized form, reacting under continuous stirring and heating conditions, removing the solvent, and obtaining the modified developer.

7. The thermoplastic polyurethane developing composite material according to claim 1, characterized in that, The thermoplastic polyurethane has a Shore hardness of 75A to 55D.

8. The thermoplastic polyurethane developing composite material according to any one of claims 1 to 7, characterized in that, Its raw materials include the following components in parts by weight: 40-70 parts of thermoplastic polyurethane; Modified developer 30.5~60 parts; Additives: 0.1-2 parts.

9. A method for preparing a thermoplastic polyurethane developing composite material as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The thermoplastic polyurethane, modified developer, and additives are melt-blended, extruded, and granulated to obtain the thermoplastic polyurethane developer composite material.

10. The application of a thermoplastic polyurethane radiopaque composite material as described in any one of claims 1 to 8 or a thermoplastic polyurethane radiopaque composite material prepared by the preparation method as described in claim 9 in the preparation of ultra-fine interventional catheters, microguidewires or vascular stent delivery systems.

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