Modified polyimide pipe and preparation method and application thereof

Abstract

The application relates to a modified polyimide pipe and a preparation method and application thereof. The preparation method of the modified polyimide pipe comprises the following steps: modifying graphite oxide powder with an organic amine to obtain graphite oxide powder with amino groups; modifying the graphite oxide powder with amino groups with a silane coupling agent and / or a dianhydride to prepare modified graphite oxide powder; mixing the modified graphite oxide powder with a polyamide acid solution to prepare a mixed solution; coating a core material with the mixed solution, then performing imidization reaction and core extraction to prepare the modified polyimide pipe. The preparation method of the modified polyimide pipe can improve the mechanical properties and lubricating properties of the polyimide, and the outer surface is smooth.

Description

Technical Field

[0001] This invention relates to the field of medical materials, and in particular to a modified polyimide tubing, its preparation method, and its applications. Background Technology

[0002] Polyimide (PI) is a class of high-performance polymers containing an imide ring (-CO-NH-CO-) in its main chain. It possesses excellent thermal stability, good mechanical properties, and dielectric properties, and is widely used in electrical insulation, microelectronics, aerospace, and other fields. The synthesis of polyimide involves dissolving a diamine in a polar solvent, adding a dianhydride monomer, and undergoing a ring-opening addition reaction with the diamine to generate a high-molecular-weight polyamic acid. This polyamic acid is then subjected to high-temperature dehydration and cyclization to obtain the polyimide.

[0003] With the development of minimally invasive interventional therapy techniques, the application of medical interventional tubing is becoming increasingly widespread. Polyimide catheters possess excellent bending resistance, compression resistance, radiation resistance, and chemical stability, and can be manufactured continuously in micron-sized thin-walled, small-diameter tubing. As a minimally invasive interventional therapy catheter, it is now widely used in clinical practice and has become the preferred material for polymer catheters in endovascular therapy. It is widely used in various drug and stent delivery catheters, endoscopes, electrophysiological and diagnostic catheters, neurovascular instruments, cardiac ablation instruments, varicose vein treatment instruments, intravascular pressure sensors, kidney stone removal instruments, and ablation equipment for pain management, etc.

[0004] During interventional therapy, the catheter needs to be safely and effectively delivered to the treatment target. Therefore, interventional therapy has high requirements for the mechanical properties and appearance of the catheter. Mechanical properties include the strength of the tubing and the lubricity of the inner surface. Appearance requirements include the catheter being black and having a smooth outer surface without bumps. However, due to manufacturing processes and other reasons, the mechanical properties of PI tubing have reached their limit, and its color is brown. Therefore, it is necessary to modify PI tubing.

[0005] Graphite oxide powder has the characteristics of high temperature resistance, high strength, good lubricity and good chemical stability, making it an ideal nano-reinforcing material that can improve the mechanical and lubrication properties of polyimide. However, due to the large specific surface area and strong van der Waals forces between the graphite oxide powder, it is very easy to agglomerate, which reduces the load transfer effect and thus reduces the mechanical and lubrication properties of the pipe. Furthermore, the agglomerated outer surface is uneven, resulting in a rough pipe surface. Summary of the Invention

[0006] Therefore, it is necessary to provide a modified polyimide pipe and its preparation method to improve the mechanical and lubrication properties of polyimide and make the outer surface smooth.

[0007] In addition, it is necessary to provide an application for modified polyimide tubing.

[0008] A method for preparing modified polyimide tubing includes the following steps:

[0009] Graphite oxide powder is modified with an organic amine to obtain graphite oxide powder with amino groups; wherein the step of preparing the graphite oxide powder with amino groups includes: dispersing the graphite oxide powder in a first polar solvent, then mixing and reacting it with the organic amine at 10℃~30℃ for 30min~40min, then raising the temperature to 40℃~60℃ and continuing the reaction for 40min~60min, and finally raising the temperature to 70℃~80℃ and reacting for 40min~60min;

[0010] The amino-group-containing graphite powder is modified by using a silane coupling agent and / or dianhydride to prepare modified graphite powder.

[0011] The modified graphene oxide powder was mixed with a polyamic acid solution to prepare a mixture; and

[0012] The core material is coated with the mixture, followed by an imidization reaction and core extraction to prepare a modified polyimide pipe.

[0013] In one embodiment, the imidization reaction is carried out at a temperature of 150°C to 400°C.

[0014] In one embodiment, the step of preparing the graphene oxide powder having amino groups satisfies any one or more of the following conditions:

[0015] (1) The mass ratio of the oxidized graphite powder to the organic amine is 1:(1.5-3);

[0016] (2) The organic amine includes any one or a combination of several of 4-4'-diaminodiphenyl ether, 4-phenylbutylamine, N-butylaniline, 2,6-diethylaniline and 3,4-dimethylaniline; and

[0017] (3) The first polar solvent is selected from any one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

[0018] In one embodiment, the step of modifying the graphite oxide powder with amino groups using the silane coupling agent includes: ultrasonically stirring the graphite oxide powder with amino groups and the silane coupling agent in anhydrous ethanol at 50°C to 60°C for 1 h to 1.5 h, and then washing and drying; wherein the mass ratio of the silane coupling agent to the graphite oxide powder is (1 to 3):100.

[0019] In one embodiment, the silane coupling agent is selected from any one or a combination of several of epoxy silane coupling agents, amino silane coupling agents, and methacryloyloxy silane coupling agents; or, the silane coupling agent is selected from any one or a combination of several of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

[0020] In one embodiment, the step of modifying the graphite oxide powder with amino groups using the dianhydride includes: mixing the graphite oxide powder with amino groups with a second polar solvent, then adding the dianhydride, and reacting at 40°C to 60°C for 2 to 3 hours; wherein the mass ratio of the dianhydride to the graphite oxide powder is (2.01 to 2.06):1.

[0021] In one embodiment, the second polar solvent is selected from any one or a combination of several of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; and / or,

[0022] The dianhydride is selected from any one or a combination of several of the following: 3,3,4',4'-diphenyl ether tetracarboxylic acid dianhydride, 3,3,4',4'-benzophenone tetracarboxylic acid dianhydride, 3,3,4',4'-biphenyl tetracarboxylic acid dianhydride, and pyromellitic dianhydride.

[0023] In one embodiment, the mass ratio of the modified graphite oxide powder to the polyamic acid solution is (0.5-5):100, and the mass percentage concentration of the polyamic acid solution is 13%-17%.

[0024] A modified polyimide pipe is prepared by the above-described method for preparing modified polyimide pipes.

[0025] The above-mentioned application of modified polyimide tubing in the manufacture of medical devices.

[0026] A medical device comprising the aforementioned modified polyimide tubing.

[0027] The above-mentioned method for preparing modified polyimide tubing first involves amino-modifying graphite oxide powder to obtain graphite oxide powder with amino groups. The graphite oxide powder with amino groups is then added to a polar solvent, followed by the addition of one or more of a silane coupling agent and dianhydrides. Adding the dianhydride later prevents a complexation reaction between the dianhydride and the polar solvent, thus inhibiting polymerization. In the system with added dianhydride, the dianhydride and amino groups undergo a ring-opening condensation reaction; in the system with added silane coupling agent, the silane coupling agent and amino groups undergo a coupling reaction. Therefore, the addition of the silane coupling agent and dianhydride improves the dispersibility of the graphite oxide powder. Finally, the mixture is thoroughly stirred with a polyamic acid solution. When the dianhydride raw material ratio reaches a certain value, high-molecular-weight, organic solvent-soluble graphite oxide-modified polyamic acid is generated. The modified graphite oxide powder can be well dispersed in the polyamic acid solution, achieving uniform dispersion and exhibiting the excellent properties of the graphite oxide powder. The modified mixture is used to coat the core material, followed by an imidization reaction. This allows the modified graphene oxide powder to be uniformly coated within the polyimide matrix, resulting in a smooth surface and improved interfacial adhesion between the graphene oxide powder and the polyimide matrix. Finally, the core material is removed, yielding a modified polyimide tubing. This method significantly improves the mechanical and lubrication properties of polyimide tubing, resulting in a smooth surface and greatly enhancing its applications in interventional medical fields. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the preparation method of the modified polyimide pipe according to the first embodiment of the present invention;

[0029] Figure 2 This is a process flow diagram of the preparation method of the modified polyimide pipe according to the second embodiment of the present invention. Detailed Implementation

[0030] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0032] Unless otherwise stated or in case of contradiction, the terms or phrases used in this invention shall have the following meanings:

[0033] In this invention, terms such as "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with terms such as "first," "second," etc., may explicitly or implicitly include at least one of those features.

[0034] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this invention, "one or several" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more. "One or several" has a similar meaning.

[0036] When a numerical range is disclosed in this invention, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed in this invention should be understood to include any and all subranges to which they are incorporated.

[0037] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0038] The terms "comprising" and "having," and any variations thereof, used in embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0039] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0040] In interventional procedures, medical tubing is crucial for safely and effectively delivering catheters to the target treatment location. Polyimide (PI) tubing, due to its temperature resistance and high rigidity, is often used in extreme interventional conditions, such as inserting nickel-titanium guidewires, requiring excellent tensile strength. Furthermore, lubrication is a critical parameter for medical PI tubing during intervention to ensure smooth operation and improve surgical safety. High-temperature welding is an essential step in assembling medical PI tubing into interventional catheters; therefore, heat resistance is also an important performance indicator.

[0041] During the modification of PI tubing using graphite oxide powder, the inventors discovered that graphite oxide powder, due to its large specific surface area and strong van der Waals forces, is prone to agglomeration, leading to reduced load transfer efficiency and consequently lower mechanical properties of the PI tubing. Furthermore, the uneven outer surface results in rough tubing, failing to meet the requirements for high tensile strength, high lubricity, and good heat resistance in medical tubing. Therefore, this invention provides a method for preparing modified polyimide tubing, comprising the following steps:

[0042] The graphite oxide powder was modified with an organic amine to obtain graphite oxide powder with amino groups. The steps for preparing graphite oxide powder with amino groups include: dispersing graphite oxide powder in a first polar solvent, then mixing and reacting it with an organic amine at 10℃~30℃ for 30min~40min, then raising the temperature to 40℃~60℃ and continuing the reaction for 40min~60min, and finally raising the temperature to 70℃~80℃ and reacting for 40min~60min.

[0043] Modified graphite oxide powder with amino groups is prepared by modifying graphite oxide powder with silane coupling agent and / or dianhydride; wherein the mass ratio of silane coupling agent to graphite oxide powder is (1-3):100, or the mass ratio of dianhydride to graphite oxide powder is (2.01-2.06):1.

[0044] The modified graphene oxide powder was mixed with a polyamic acid solution to prepare a mixture; and

[0045] The core material is coated with a mixture, then imidized and core-pulled to prepare modified polyimide tubing.

[0046] The above-mentioned method for preparing modified polyimide tubing involves modifying graphite oxide powder to enhance the interfacial adhesion between the modified graphite oxide powder and the resin matrix, thereby improving the dispersion ability of the modified graphite oxide powder in the resin. The modified graphite oxide powder is then added to a polyamic acid solution, and the core material is coated, imidized, and cored to obtain the modified polyimide tubing. Because the modified graphite oxide powder has good dispersion ability in the resin matrix and is not prone to agglomeration, it can effectively improve mechanical properties, lubrication properties, and high-temperature resistance.

[0047] The following sections will elaborate on different modification methods for graphite oxide powder.

[0048] Please see Figure 1 The method for preparing the modified polyimide pipe according to the first embodiment of the present invention includes the following steps:

[0049] Step S110: Modify graphite oxide powder with organic amine to obtain graphite oxide powder with amino groups.

[0050] The step of preparing graphite oxide powder with amino groups includes: dispersing graphite oxide powder in a first polar solvent, then mixing and reacting it with an organic amine at 10℃~30℃ for 30min~40min, then raising the temperature to 40℃~60℃ and continuing the reaction for 40min~60min, and finally raising the temperature to 70℃~80℃ and reacting for 40min~60min.

[0051] In some embodiments, the organic amine includes, but is not limited to, any one or a combination of several of 4,4'-diaminodiphenyl ether (ODA), 4-phenylbutylamine, N-butylaniline, 2,6-diethylaniline, and 3,4-dimethylaniline. It is understood that only a few commonly used organic amines have been given above, but the invention is not limited thereto; other organic amines, such as alkylamines, may also be used.

[0052] In some embodiments, the mass ratio of graphite oxide powder to organic amine is 1:(1.5–3). In a specific example, the mass ratio of graphite oxide powder to organic amine may be, but is not limited to, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, or any range of two of these values. Within the above mass ratio range, the performance of the prepared modified polyimide tubing can be further improved.

[0053] In some embodiments, the particle size of the graphite oxide powder is 2000 mesh to 3000 mesh. In a specific example, the particle size of the graphite oxide powder is 2000 mesh, 2200 mesh, 2400 mesh, 2500 mesh, 2800 mesh, 3000 mesh, or any combination of these values.

[0054] In some embodiments, the first polar solvent includes, but is not limited to, any one or a combination of several of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP).

[0055] In one embodiment, the step of dispersing graphite oxide powder in a first polar solvent includes: mixing and stirring the graphite oxide powder with the first polar solvent at room temperature for 2 hours, and then sonicating at 0°C for 30 minutes. The room temperature can be between 10°C and 30°C. It is understood that the above only provides one method for dispersing graphite oxide powder in a first polar solvent, but is not limited to this method; any method that achieves uniform dispersion is acceptable.

[0056] In some embodiments, a purification step is also included. After the reaction is complete, the first polar solvent and unreacted organic amine are removed, followed by washing and drying. In one specific example, after the reaction is complete, the first polar solvent is removed by vacuum filtration, then unreacted organic amine is removed by rinsing with the first polar solvent, followed by washing with ethanol and water, and finally vacuum drying at 40°C for 36 hours.

[0057] The amino group of the organic amine reacts with the carboxyl group on the graphite oxide powder to generate an amide group (CONH-), which is loaded onto the graphite oxide powder through chemical bonds. As the amount of organic amine increases, the effective loading on the support can be increased, and the presence of -NH2 can be observed, thus giving the graphite oxide powder an amino group.

[0058] Step S120: Modify the graphite oxide powder with amino groups using a silane coupling agent to prepare the modified graphite oxide powder.

[0059] First, amine-modified graphite oxide powder is obtained to form graphite oxide powder with amino groups. Then, a silane coupling agent is added. Because graphite oxide powder has a high specific surface energy and is prone to agglomeration, amine modification can reduce its activated state. Further coupling reaction between the silane coupling agent and the amino groups further reduces the specific surface energy of the graphite oxide powder, increases its contact area, improves its compatibility, and prevents agglomeration, thereby improving the dispersibility of the modified graphite oxide powder. In addition, the silane coupling agent also reacts with the graphite oxide powder, further enhancing its dispersibility.

[0060] In some embodiments, the silane coupling agent may be selected from one or a combination of several of vinyl silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, and methacryloxysilane coupling agents. For example, in a specific example, the silane coupling agent includes, but is not limited to, one or a combination of several of vinyltriethoxysilane (A151), vinyltrimethoxysilane (A171), vinyltris(β-methoxyethoxy)silane (A172), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), and γ-methacryloyloxypropyltrimethoxysilane (KH570).

[0061] Furthermore, the silane coupling agent is selected from any one or a combination of several of epoxy silane coupling agents, amino silane coupling agents, and methacryloxy silane coupling agents. Even further, the silane coupling agent is selected from any one or a combination of several of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH550), and γ-methacryloyloxypropyltrimethoxysilane (KH570). More preferably, the silane coupling agent includes at least KH560. Experiments have shown that the above-mentioned silane coupling agents have a better performance improvement effect on the prepared modified polyimide pipes.

[0062] In some embodiments, the mass ratio of silane coupling agent to graphite oxide powder is (1–3):100. In a specific example, the mass ratio of silane coupling agent to graphite oxide powder may be, but is not limited to, 1:100, 1.2:100, 1.5:100, 1.8:100, 2:100, 2.2:100, 2.5:100, 2.8:100, 3:100, or any range of two of these values. Within the above-mentioned range of proportions, the modified graphite oxide powder exhibits better dispersibility.

[0063] In some embodiments, step S120 includes: ultrasonically stirring graphite powder with amino groups and a silane coupling agent in anhydrous ethanol at 50°C–60°C for 1–1.5 h. Then washing and drying. In one specific example, washing is performed with deionized water and acetone.

[0064] Step S130: Mix the modified graphite oxide powder with a polyamic acid solution to prepare a mixture.

[0065] In some embodiments, the mass ratio of modified graphite oxide powder to polyamic acid solution is (0.5–5):100. In a specific example, the mass ratio of modified graphite oxide powder to polyamic acid solution is 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, or any range of two of these values. Further, the mass ratio of modified graphite oxide powder to polyamic acid solution is (0.5–3):100.

[0066] Furthermore, the mass percentage concentration of the polyamic acid solution is 13% to 17%. In a specific example, the mass percentage concentration of the polyamic acid solution may be, but is not limited to, 13%, 14%, 15%, 16%, 17%, or any combination of these values.

[0067] In some embodiments, the solvent for the polyamic acid solution is a polar solvent, such as DMF, DMAc, NMP, etc.

[0068] Step S140: Coat the core material with the mixture, then perform an imidization reaction and core extraction to prepare modified polyimide tubing.

[0069] In some embodiments, the step of coating the core material with the mixture includes: coating the core material at a rate of 2 cm / min to 10 cm / min through an immersion tank containing the mixture. In a specific example, the core material is stainless steel wire. It is understood that the core material is not limited to stainless steel wire, but may also be other core materials commonly used in the art, such as silver-plated copper wire.

[0070] In some embodiments, the temperature during the imidization reaction is 80°C to 400°C. Further, the temperature during the imidization reaction is 150°C to 400°C. It is understood that the above only describes one imidization reaction process, but it is not limited to this; other commonly used imidization reaction processes in the art can also be described, which will not be elaborated upon here.

[0071] The above-mentioned method for preparing modified polyimide tubing has at least the following advantages:

[0072] (1) The above method first modifies graphite oxide powder with amino groups to obtain graphite oxide powder with amino groups. Then, a silane coupling agent is added. The silane coupling agent will undergo a coupling reaction with the amino groups, improving the dispersibility of the modified graphite oxide powder. Finally, it is thoroughly stirred with a polyamic acid solution. The modified graphite oxide powder can be well dispersed in the polyamic acid solution, achieving uniform dispersion and giving full play to the excellent properties of the graphite oxide powder. The modified mixture is used to coat the core material. After an imidization reaction, the modified graphite oxide powder is also uniformly coated in the polyimide matrix, resulting in a smooth surface and improved interfacial adhesion between the graphite oxide powder and the PI resin matrix. Finally, the core material is removed, resulting in an irregular cross-sectional morphology when the tube is stretched, thus obtaining a modified PI tube. This method can significantly improve the mechanical properties, lubrication properties, and heat resistance of polyimide tubes, thereby greatly enhancing the application of PI tubes in the field of medical intervention.

[0073] (2) The above preparation method is simple, low in cost, and easy to mass-produce and continuously produce products.

[0074] (3) The above preparation method is applicable to reinforced polyimide composite pipe materials with various diameters and wall thicknesses.

[0075] Please see Figure 2 The preparation method of the modified polyimide pipe according to the second embodiment of the present invention includes the following steps:

[0076] Step S210: Modify graphite oxide powder with organic amine to obtain graphite oxide powder with amino groups.

[0077] The step of preparing graphite oxide powder with amino groups includes: dispersing graphite oxide powder in a first polar solvent, then mixing and reacting it with an organic amine at 10℃~30℃ for 30min~40min, then raising the temperature to 40℃~60℃ and continuing the reaction for 40min~60min, and finally raising the temperature to 70℃~80℃ and reacting for 40min~60min.

[0078] Specifically, step S210 is the same as step S110 of the method for preparing modified polyimide tubing in the first embodiment, and will not be described again.

[0079] Step S220: Modify the graphite oxide powder with amino groups using dianhydride to prepare the modified graphite oxide powder.

[0080] In some embodiments, the mass ratio of dianhydride to graphite oxide powder is (2.01 to 2.06):1. In a specific example, the mass ratio of dianhydride to graphite oxide powder may be, but is not limited to, 2.01:1, 2.02:1, 2.03:1, 2.04:1, 2.05:1, 2.06:1, or any range of two of these values.

[0081] In some embodiments, step S220 includes: mixing graphite powder with amino groups with a second polar solvent, then adding dianhydride, and reacting at 40°C to 60°C for 2 to 3 hours.

[0082] In some embodiments, the second polar solvent may be a polar solvent commonly used in the art for the preparation of polyamic acids. For example, the second polar solvent may include, but is not limited to, any one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

[0083] In some embodiments, the dianhydride is not particularly limited and can be any dianhydride commonly used in the art for preparing polyamic acids, such as 3,3,4',4'-diphenyl ether tetracarboxylic acid dianhydride, 3,3,4',4'-benzophenone tetracarboxylic acid dianhydride, 3,3,4',4'-biphenyl tetracarboxylic acid dianhydride, and pyromellitic dianhydride.

[0084] Dimethyl dianhydride can undergo ring-opening condensation with amino groups to graft high-molecular-weight polyamic acid onto graphene oxide powder, thereby improving the dispersibility of the graphene oxide powder. Furthermore, adding graphene oxide powder with amino groups to a polar solvent, followed by the addition of dianhydride, prevents complexation reactions between the dianhydride and the polar solvent, thus inhibiting polymerization. When the dianhydride raw material ratio reaches a certain value, high-molecular-weight polyamic acid modified with graphene oxide powder and soluble in organic solvents can be generated.

[0085] Step S230: Mix the modified graphite oxide powder with a polyamic acid solution to prepare a mixture.

[0086] In some embodiments, the mass ratio of modified graphite oxide powder to polyamic acid solution is (0.5–5):100. In a specific example, the mass ratio of modified graphite oxide powder to polyamic acid solution is 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, or any range of two of these values. Further, the mass ratio of modified graphite oxide powder to polyamic acid solution is (0.5–3):100.

[0087] Furthermore, the mass percentage concentration of the polyamic acid solution is 13% to 17%. In a specific example, the mass percentage concentration of the polyamic acid solution may be, but is not limited to, 13%, 14%, 15%, 16%, 17%, or any combination of these values.

[0088] In some embodiments, the solvent for the polyamic acid solution is a polar solvent, such as DMF, DMAc, NMP, etc.

[0089] Step S240: Coat the core material with the mixture, then perform an imidization reaction and core extraction to prepare modified polyimide tubing.

[0090] Specifically, step S240 is the same as step S140 of the method for preparing modified polyimide tubing in the first embodiment, and will not be described again.

[0091] The above-mentioned method for preparing modified polyimide tubing has at least the following advantages:

[0092] (1) The above method first modifies graphite oxide powder with amino groups to obtain graphite oxide powder with amino groups. Then, dianhydride is added. Adding dianhydride last can prevent complexation reaction between dianhydride and polar solvent, thus inhibiting polymerization. Moreover, dianhydride will undergo ring-opening condensation reaction with amino groups, improving the dispersibility of modified graphite oxide powder. Finally, it is thoroughly stirred with polyamic acid solution, and the modified graphite oxide powder can be well dispersed in polyamic acid solution, achieving uniform dispersion and exerting the excellent properties of graphite oxide powder. The modified mixture is used to coat the core material. After imidization reaction, the modified graphite oxide powder is also uniformly coated in polyimide matrix, improving the interfacial adhesion between graphite oxide powder and PI resin matrix. Finally, the core material is removed, resulting in an irregular cross-sectional morphology of the tube when stretched, obtaining a modified PI tube. This method can significantly improve the mechanical properties, lubrication properties and heat resistance of polyimide tubes, thereby greatly enhancing the application of PI tubes in the field of medical intervention.

[0093] (2) The above preparation method is simple, low in cost, and easy to mass-produce and continuously produce products.

[0094] (3) The above preparation method is applicable to reinforced polyimide composite pipe materials with various diameters and wall thicknesses.

[0095] The present invention also provides a modified polyimide pipe according to one embodiment, which is prepared by the preparation method of the modified polyimide pipe according to the first embodiment, or by the preparation method of the modified polyimide pipe according to the second embodiment.

[0096] The modified polyimide tubing described above has good mechanical properties, lubrication properties and heat resistance properties, and has wide applications in the field of interventional medicine.

[0097] The present invention also provides an embodiment of the application of modified polyimide tubing in the manufacture of medical devices.

[0098] The present invention also provides a medical device according to one embodiment, comprising the above-described modified polyimide tubing.

[0099] To make the objectives and advantages of the present invention clearer, the modified polyimide tubing and its effects of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and should not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions were implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0100] Example 1

[0101] This embodiment provides a modified polyimide pipe, the specific preparation process of which is as follows:

[0102] (1) Graphite oxide powder (IGO) with a particle size of 2000 mesh was dissolved in the polar solvent DMF and stirred at room temperature for 2 h. Then, under sealed conditions, it was sonicated in an ice bath for 30 min to ensure complete dissolution of IGO. Subsequently, the organic amine 4,4'-diaminodiphenyl ether was weighed and added to the above IGO solution, with a mass ratio of organic amine to graphite oxide powder of 2:1. Under nitrogen protection, the mixture was stirred at room temperature for 30 min, then the temperature was adjusted to 40℃ and the reaction was continued for 40 min, and then the temperature was adjusted to 70℃ and the reaction was continued for 40 min. The reaction liquid was cooled to room temperature, filtered under reduced pressure, and washed with the above polar solvent to remove unreacted organic amine. Then it was washed with ethanol and water, and then placed in a vacuum oven and vacuum dried at 40℃ for 36 h to obtain graphite oxide powder with amino groups.

[0103] (2) The above-mentioned graphite oxide powder with amino groups was mixed with the polar solvent DMF, and then 3,3,4',4'-diphenyl ether tetracarboxylic acid dianhydride was added. The mixture was reacted for 2 hours to obtain the modified graphite oxide powder. The mass ratio of dianhydride to graphite oxide powder was 2.03:1.

[0104] (3) Add the modified graphite oxide powder, which accounts for 0.5% of the mass of the polyamic acid solution, to the polyamic acid solution. After stirring thoroughly, perform ultrasonic treatment to disperse it evenly and obtain a mixture, wherein the mass percentage concentration of the polyimide solution is 15%.

[0105] (4) Pour the mixture into the impregnation tank, fix the mandrel with a certain tension using a take-up and unwinding machine, and pass it through the impregnation tank at a speed of 10 cm / min. The mandrel is made of stainless steel wire. Then, pull it through the mandrel and cure it in a sintering furnace at a temperature of 300℃. After passing through the sintering furnace, the solvent evaporates completely, and the coating is cured, resulting in a modified polyimide inner tube with a mandrel. After removing the mandrel, the modified polyimide tube is obtained.

[0106] Example 2

[0107] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1, except that the amount of dianhydride used in step (2) is different. In step (2) of this embodiment, the mass ratio of dianhydride to graphite oxide powder is 2.04:1.

[0108] Example 3

[0109] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1, except that the amount of dianhydride used in step (2) is different. In step (2) of this embodiment, the mass ratio of dianhydride to graphite oxide powder is 2.05:1.

[0110] Example 4

[0111] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1. The difference is that the organic amine in step (1) is different. In step (1) of this embodiment, the organic amine is N-butylaniline.

[0112] Example 5

[0113] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1, except that step (2) is different. Step (2) of this embodiment is as follows:

[0114] Graphite oxide powder with amino groups was ultrasonically stirred with silane coupling agent KH560 in anhydrous ethanol at 50°C for 1 hour. The mixture was then washed with deionized water and acetone and dried to obtain modified graphite oxide powder. The silane coupling agent accounted for 1% of the mass of the graphite oxide powder.

[0115] Example 6

[0116] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the amount of silane coupling agent added in step (2) is different. In step (2) of this embodiment, the silane coupling agent accounts for 2% of the mass percentage of the graphite oxide powder.

[0117] Example 7

[0118] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the amount of silane coupling agent added in step (2) is different. In step (2) of this embodiment, the silane coupling agent accounts for 3% of the mass percentage of the graphite oxide powder.

[0119] Example 8

[0120] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5. The difference is that the amount of organic amine used in step (1) is different. In step (1) of this embodiment, the mass ratio of organic amine to graphite oxide powder is 1:1.

[0121] Example 9

[0122] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5. The difference is that the amount of organic amine used in step (1) is different. In step (1) of this embodiment, the mass ratio of organic amine to graphite oxide powder is 5:1.

[0123] Example 10

[0124] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5. The difference is that the organic amine used in step (1) is different. In step (1) of this embodiment, the organic amine is 4-phenylbutylamine.

[0125] Example 11

[0126] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the silane coupling agent is different in step (2). In step (2) of this embodiment, the silane coupling agent is KH570.

[0127] Example 12

[0128] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the silane coupling agent is different in step (2). In step (2) of this embodiment, the silane coupling agent is KH550.

[0129] Example 13

[0130] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the amount of modified graphite oxide powder added in step (3) is different. In step (3) of this embodiment, the modified graphite oxide powder accounts for 3% of the mass percentage of the polyimide solution.

[0131] Example 14

[0132] This embodiment provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that the amount of modified graphite oxide powder added in step (3) is different. In step (3) of this embodiment, the modified graphite oxide powder accounts for 5% of the mass percentage of the polyimide solution.

[0133] Comparative Example 1

[0134] Comparative Example 1 provides a method for preparing a modified polyimide pipe, comprising the following steps:

[0135] (1) Dissolve 1200 mesh graphite oxide powder (IGO) in polar solvent DMF and stir at room temperature for 2 hours. Then, under sealed conditions, sonicate in an ice bath for 30 minutes to ensure that the IGO is fully dissolved.

[0136] (2) Add 0.5% graphite powder (by mass percentage) of the polyamic acid solution to the polyamic acid solution, stir thoroughly, and then perform ultrasonic treatment to disperse evenly to obtain a mixture.

[0137] (3) Pour the mixture into the impregnation tank, fix the mandrel with a certain tension using a take-up and unwinding machine, and pass it through the impregnation tank at a speed of 10 cm / min. The mandrel is made of stainless steel wire. Then, pull it through the mandrel and cure it in a sintering furnace at a temperature of 300℃. After passing through the sintering furnace, the solvent evaporates completely, and a modified polyimide inner tube with a mandrel is obtained. After removing the mandrel, the modified polyimide tube is obtained.

[0138] Comparative Example 2

[0139] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1. The difference is that step (2) is not performed, and graphite oxide powder with amino groups is directly added to the polyamic acid solution. The modified graphite oxide powder accounts for 0.5% of the mass of the polyamic acid solution.

[0140] Comparative Example 3

[0141] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that step (1) is different and step (2) is not included. Step (1) of this comparative example is as follows: graphite oxide powder and silane coupling agent KH560 are ultrasonically stirred in anhydrous ethanol at 50°C for 1 hour. Then, the mixture is washed and dried with deionized water and acetone to obtain modified graphite oxide powder. The silane coupling agent accounts for 1% of the mass percentage of the graphite oxide powder. The modified graphite oxide powder obtained in step (1) is directly mixed with a polyamic acid solution. The modified graphite oxide powder accounts for 0.5% of the mass percentage of the polyamic acid solution.

[0142] Comparative Example 4

[0143] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 1, except that step (1) is different and step (2) is not included. The step (1) of this comparative example is as follows:

[0144] (1) Graphite oxide powder (IGO) with a particle size of 1200 mesh was dissolved in the polar solvent DMF and stirred at room temperature for 2 h. Then, under sealed conditions, it was sonicated in an ice bath for 30 min to ensure complete dissolution of IGO. Subsequently, organic amine 4,4'-diaminodiphenyl ether and silane coupling agent KH550 were weighed and added to the above IGO solution. The mass ratio of organic amine to graphite oxide powder was 2:1, and the mass ratio of dianhydride to graphite oxide powder was 2.03:1. Under nitrogen protection, the mixture was stirred at room temperature for 30 min, then the temperature was adjusted to 40℃ and the reaction was continued for 40 min, and then the temperature was adjusted to 70℃ and the reaction was continued for 40 min. The reaction liquid was cooled to room temperature, filtered under reduced pressure, and washed with the above polar solvent to remove unreacted organic amine. Then it was washed with ethanol and water, and then placed in a vacuum oven and vacuum dried at 40℃ for 36 h to obtain modified graphite oxide powder.

[0145] Comparative Example 5

[0146] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that steps (1) and (2) are different. Steps (1) and (2) of this comparative example are as follows:

[0147] (1) Graphite oxide powder with a particle size of 1200 mesh was dissolved in anhydrous ethanol and stirred at room temperature for 2 hours. Then, under sealed conditions, it was sonicated in an ice bath for 30 minutes to ensure complete dissolution of IGO. Next, silane coupling agent KH560 was added, and the mixture was sonicated in anhydrous ethanol for another 1 hour. The powder was then washed with deionized water and acetone and dried to obtain silane coupling agent-modified graphite oxide powder. The silane coupling agent accounted for 1% of the mass of the graphite oxide powder.

[0148] (2) The silane coupling agent-modified graphite oxide powder was dispersed in the polar solvent DMF, and then the organic amine 4-4'-diaminodiphenyl ether was added. The mass ratio of organic amine to graphite oxide powder was 2:1. Under nitrogen protection, the mixture was stirred at room temperature for 30 min, then the temperature was adjusted to 40℃ and the reaction was continued for 40 min, and then the temperature was adjusted to 70℃ and the reaction was continued for 40 min. The reaction liquid was cooled to room temperature, filtered under reduced pressure, and washed with the above-mentioned polar solvent to remove unreacted organic amine. Then it was washed with ethanol and water, and then placed in a vacuum oven and vacuum dried at 40℃ for 36 h to obtain the modified graphite oxide powder.

[0149] Comparative Example 6

[0150] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 3, except that step (1) is different and step (2) is not included. The step (1) of this comparative example is as follows:

[0151] (1) Graphite oxide powder (IGO) with a particle size of 1200 mesh was dissolved in the polar solvent DMF and stirred at room temperature for 2 h. Then, under sealed conditions, it was sonicated in an ice bath for 30 min to ensure complete dissolution of IGO. Subsequently, organic amine 4,4'-diaminodiphenyl ether and silane coupling agent KH560 were weighed and added to the above IGO solution. The mass ratio of organic amine to graphite oxide powder was 2:1, and the mass percentage of silane coupling agent to graphite oxide powder was 1%. Under nitrogen protection, the mixture was stirred at room temperature for 30 min, then the temperature was adjusted to 40℃ and the reaction was continued for 40 min, and then the temperature was adjusted to 70℃ and the reaction was continued for 40 min. The reaction liquid was cooled to room temperature, filtered under reduced pressure, and washed with the above polar solvent to remove unreacted organic amine. Then it was washed with ethanol and water, and then placed in a vacuum oven and vacuum dried at 40℃ for 36 h to obtain modified graphite oxide powder.

[0152] Comparative Example 7

[0153] This comparative example provides a modified polyimide pipe, the preparation process of which is similar to that of Example 5, except that step (1) is different. Step (1) of this example is as follows: Graphite oxide powder (IGO) with a particle size of 1200 mesh is dissolved in the polar solvent DMF and stirred at room temperature for 2 hours. Then, under sealed conditions, it is subjected to low-temperature ultrasonication in an ice bath for 30 minutes to ensure that the IGO is fully dissolved. Subsequently, the organic amine 4-4'-diaminodiphenyl ether is weighed and added to the above IGO solution, with a mass ratio of organic amine to graphite oxide powder of 2:1. Under nitrogen protection, the reaction is stirred at 60°C for 6 hours. The reaction liquid is cooled to room temperature, filtered under reduced pressure, and washed with the above polar solvent to remove unreacted organic amine. Then, it is washed with ethanol and water, and then placed in a vacuum oven and vacuum dried at 40°C for 36 hours to obtain amino-modified graphite oxide powder.

[0154] The following is the specific test section:

[0155] The modified polyimide pipes prepared according to the above embodiments and comparative examples were subjected to the following tests:

[0156] With a diameter of 0.13*0.18mm 2 Taking the mechanical test of the pipe as an example, a 50mm long modified PI pipe was cut, the sample was connected to a tensile tester, the tensile speed was 400mm / min, the gauge length was 20mm, and the pipe was stretched until it broke.

[0157] Heat resistance testing was conducted using a thermogravimetric (TG) analyzer under a nitrogen atmosphere at a heating rate of 10 °C / min. Thermogravimetric analysis yielded the temperature (T0) corresponding to a 5% weight loss. 5％ (as the initial thermal decomposition temperature);

[0158] Internal friction force test: 1. Pass the PI tube through a fixture with a 1.4mm aperture, with the proximal end of the PI tube protruding approximately 50mm from the fixture. Secure the distal end of the fixture to the PI tube using epoxy resin. 2. After securing the fixture, insert the mandrel into the PI tube from the proximal end until the distal end of the mandrel extends approximately 2mm beyond the distal end of the PI tube. Insert the distal portion of the PI tube with the mandrel through the side channel of the bending fixture until the PI tube protrudes approximately 10mm from the bending channel. Then push the proximal mandrel to extend it approximately 10mm beyond the PI tube. 3. Fix the fixture to the lower jaw of the stretching machine, and then fix the mandrel to the upper jaw. The distance between the upper and lower jaws is 100mm. The stretching speed is 50mm / min, and the end condition is set to stop when the stretch reaches 150mm. 4. Record the maximum force after the stretching is completed.

[0159] The measurement results are shown in Table 1 below.

[0160] Table 1. Performance comparison of modified polyimide pipes in each embodiment and comparative example.

[0161]

[0162]

[0163] The experimental data above show that the addition of modified graphite oxide powder increases the fracture strength compared to the addition of unmodified graphite oxide powder. The method of first modifying with organic amine and then with silane coupling agent can further improve the mechanical properties of the prepared modified polyimide pipe compared to other methods of modifying graphite oxide powder.

[0164] Thermogravimetric analysis shows that the addition of modified graphite oxide powder introduces heat-resistant graphite powder material, which can effectively improve the heat resistance of polyimide pipes.

[0165] Friction tests show that the friction of modified PI pipes decreases, thus improving the lubricity of PI pipes.

[0166] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0167] The above-described embodiments are merely illustrative of several implementation methods of the present invention, facilitating a detailed understanding of the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing modified polyimide tubing, characterized in that, Includes the following steps: Graphite oxide powder is modified with an organic amine to obtain graphite oxide powder with amino groups; wherein the particle size of the graphite oxide powder is 2000 mesh to 3000 mesh, and the steps for preparing the graphite oxide powder with amino groups include: dispersing the graphite oxide powder in a first polar solvent, then mixing and reacting it with the organic amine at 10℃ to 30℃ for 30 min to 40 min, then raising the temperature to 40℃ to 60℃ and continuing the reaction for 40 min to 60 min, and finally raising the temperature to 70℃ to 80℃ and reacting for 40 min to 60 min; The amino-group-containing graphite oxide powder was modified with a silane coupling agent to prepare modified graphite oxide powder. The modified graphene oxide powder was mixed with a polyamic acid solution to prepare a mixture; and The core material is coated with the mixture, followed by an imidization reaction and core extraction to prepare a modified polyimide pipe.

2. The method for preparing the modified polyimide pipe according to claim 1, characterized in that, The step of preparing the amino-group-containing graphite oxide powder satisfies any one or more of the following conditions: (1) The mass ratio of the graphite oxide powder to the organic amine is 1:(1.5~3). (2) The organic amine comprises any one or more combinations of 4-4'-diaminodiphenyl ether, 4-phenylbutylamine, N-butylaniline, 2,6-diethylaniline and 3,4-dimethylaniline; and (3) The first polar solvent is selected from any one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

3. The method for preparing the modified polyimide pipe according to claim 1, characterized in that, The step of modifying the graphite oxide powder with amino groups using the silane coupling agent includes: ultrasonically stirring the graphite oxide powder with amino groups and the silane coupling agent in anhydrous ethanol at 50°C to 60°C for 1 h to 1.5 h, and then washing and drying; wherein the mass ratio of the silane coupling agent to the graphite oxide powder is (1 to 3):

100.

4. The method for preparing the modified polyimide pipe according to claim 3, characterized in that, The silane coupling agent is selected from any one or more combinations of epoxy silane coupling agents, amino silane coupling agents, and methacryloyloxy silane coupling agents; or, the silane coupling agent is selected from any one or more combinations of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

5. The method for preparing the modified polyimide pipe according to claim 1, characterized in that, The silane coupling agent includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

6. The method for preparing the modified polyimide pipe according to claim 1, characterized in that, During the imidization reaction, the temperature is 80℃~400℃.

7. The method for preparing the modified polyimide pipe according to claim 1, characterized in that, The mass ratio of the modified graphite oxide powder to the polyamic acid solution is (0.5~5):100, and the mass percentage concentration of the polyamic acid solution is 13%~17%.

8. A modified polyimide pipe, characterized in that, It is prepared by the method for preparing modified polyimide tubing according to any one of claims 1 to 7.

9. The application of the modified polyimide tubing as described in claim 8 in the manufacture of medical devices.

10. A medical device, characterized in that, Includes the modified polyimide tubing as described in claim 8.

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