Polyimide composite pipes, their preparation methods and applications

Abstract

This invention relates to polyimide composite pipes, their preparation methods, and applications. The polyimide composite pipe includes an inner layer and an outer layer disposed on the inner layer. The inner layer has a surface-modified layer in contact with the outer layer. The surface-modified layer is a modified polyimide modified with a diamine compound. The outer layer is a film layer of other polymer materials besides polyimide. This polyimide composite pipe ensures excellent adhesion between the material layers, avoiding delamination and other problems, while improving the mechanical properties of the composite pipe. Furthermore, the preparation method of this polyimide composite pipe is simple, low-cost, and suitable for large-scale production applications.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to polyimide composite tubing, its preparation method, and its application. Background Technology

[0002] Medical polymer catheters are essential materials in minimally invasive interventional procedures, and their biocompatibility, product size and precision, performance, and quality stability are subject to stringent requirements. Polyimide (PI) 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. PI has become the preferred material for polymer catheters in endovascular therapy, and is widely used in various drug and stent delivery catheters, endoscopes, electrophysiological and diagnostic catheters, neurovascular devices, cardiac ablation devices, varicose vein treatment devices, endovascular pressure sensors, kidney stone removal devices, and ablation equipment for pain management, among others.

[0003] However, the inherent drawbacks of single-material PI tubing limit its application and development. These include a high coefficient of friction, low modulus and tensile strength, leading to problems such as high resistance to entry into the body and sheath elongation and deformation when used in delivery devices. Combining PI with other polymers such as nylon (PA), polyurethane (TPU), and polyether block amide (Pebax) can improve its overall performance and broaden its application scenarios. For example, PA and its copolymers have high strength, wear resistance, high modulus, and fatigue resistance; TPU has high biocompatibility, is elastic, and has excellent low-temperature performance; Pebax provides good weldability, and using different hardnesses of Pebax can create composite tubing with gradual hardness changes. However, PI has a smooth surface, low polarity, low hydrophilicity, and poor interfacial adhesion. Directly combining it with other materials can lead to poor adhesion of the polymer film, causing cracking, blistering, or delamination. Therefore, PI surface modification treatment is required. Common methods include acid and alkali treatment, corona treatment, and plasma treatment. Among them, corona treatment and plasma treatment have high production costs and are not conducive to large-scale production, so they are less commonly used. Acid and alkali treatment is inexpensive, easy to operate, and most widely used. However, acid and alkali solutions are highly corrosive to equipment and will significantly reduce the mechanical properties of PI pipes. Summary of the Invention

[0004] Therefore, it is necessary to provide a polyimide composite pipe, its preparation method, and its application. This polyimide composite pipe can ensure excellent adhesion between the material layers, avoid delamination and other problems, and has superior mechanical properties.

[0005] A polyimide composite pipe includes an inner layer and an outer layer disposed on the inner layer. The inner layer has a surface-modified layer in contact with the outer layer. The surface-modified layer is a modified polyimide modified with a diamine compound. The outer layer is a film layer of other polymer materials besides polyimide.

[0006] In one embodiment, the inner layer further includes a host layer made of unmodified polyimide, and the surface-modified layer is located between the host layer and the outer layer.

[0007] In one embodiment, the diamine compound is NH2-R1-NH2, wherein R1 is ethylene, propylene, butylene, pentylene, or hexylene.

[0008] In one embodiment, the diamine compound is ethylenediamine.

[0009] In one embodiment, the modified polyimide comprises structural units shown in formula (I) and / or formula (II):

[0010]

[0011] R1 represents C with or without substitution. 1-16 Alkylene, or substituted or unsubstituted 5-6 aryl groups;

[0012] R2 is

[0013] A and B are each independently 5-10 aryl groups;

[0014] R3 can be a single bond, -O-, -S-, -SO2-, -NH-, -CO-, or -CH2-.

[0015] In one embodiment, R1 is C 2-6 Alkylene; R2 is

[0016] In one embodiment, the outer layer is made of one or more of nylon, polyurethane, and polyether block amide.

[0017] The preparation method of the above-mentioned polyimide composite pipe includes the following steps:

[0018] Provide core wires;

[0019] A polyimide precursor solution is coated onto the core wire and then imidized to obtain a polyimide layer.

[0020] The surface of the polyimide layer is treated with a treatment solution containing the diamine compound to react the polyimide and diamine compound on the surface of the polyimide layer, thereby generating a surface-modified layer and obtaining the inner layer.

[0021] The outer layer is formed on the surface of the inner layer containing the surface-modified layer, and the surface-modified layer is in contact with the outer layer;

[0022] Core pulling is performed to obtain the polyimide composite pipe.

[0023] In one embodiment, the concentration of the diamine compound in the treatment solution is 5 wt%-30 wt%.

[0024] In one embodiment, the solvent in the treatment liquid is methanol or ethanol.

[0025] In one embodiment, in the step of treating the surface of the polyimide layer with a treatment solution containing the diamine compound, the polyimide layer is passed through the treatment solution at a speed of 1 m / min to 5 m / min.

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

[0027] The present invention has the following beneficial effects:

[0028] This invention modifies the surface of polyimide (PI) using a diamine compound to form a surface-modified layer. The diamine compound reacts with the imide in the polyimide, breaking the imide bonds and generating intermolecular amide bonds. This increases the polarity and hydrophilicity of PI, improves the adhesion between the inner and outer layers, and prevents problems such as cracking, blistering, or delamination. Furthermore, by modifying the molecular structure, the PI chain stacking conformation is altered, resulting in a denser microstructure and improved mechanical properties. This effectively avoids the mechanical property degradation caused by conventional acid / alkali solution modification. Detailed Implementation

[0029] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred 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.

[0030] 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 specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] One embodiment of the present invention provides a polyimide composite pipe, comprising an inner layer and an outer layer disposed on the inner layer. The inner layer has a surface-modified layer in contact with the outer layer. The surface-modified layer is a modified polyimide modified with a diamine compound. The outer layer is a film layer of other polymer materials besides polyimide.

[0032] This invention modifies the surface of polyimide (PI) using a diamine compound to form a surface-modified layer. The diamine compound reacts with the imide in the polyimide, breaking the imide bonds and generating intermolecular amide bonds. This increases the polarity and hydrophilicity of PI, improves the adhesion between the inner and outer layers, and prevents problems such as cracking, blistering, or delamination. Furthermore, by modifying the molecular structure, the PI chain stacking conformation is altered, resulting in a denser microstructure and improved mechanical properties. This effectively avoids the mechanical property degradation caused by conventional acid / alkali solution modification.

[0033] Understandably, in this invention, the inner layer refers to the material layer close to the central axis of the composite pipe, and the outer layer refers to the material layer covering the inner layer and away from the central axis of the composite pipe.

[0034] It is understood that the volume occupied by the surface-modified layer in the inner layer and the area of ​​the surface-modified layer in contact with the outer layer can be adjusted as needed, and are not particularly limited here. They should be understood to be within the protection scope of this invention.

[0035] In some embodiments, the inner layer further includes a host layer made of unmodified polyimide, and a surface-modified layer is located between the host layer and the outer layer.

[0036] In some embodiments, the inner layer is made of modified polyimide.

[0037] In some embodiments, the surfaces of the inner layer that are in contact with the outer layer are both surface-modified layers.

[0038] In some embodiments, the diamine compound is one or more of an aliphatic diamine, an aromatic diamine, or a polymeric diamine.

[0039] In some embodiments, the two amino groups of the diamine compound are primary amines.

[0040] In some embodiments, the diamine compound is NH2-R1-NH2, wherein R1 is C 2-6 The diamine compound is alkylene; further, R1 is ethylene, propyleneene, butylene, pentylene, or hexylene; further, the diamine compound is preferably ethylenediamine (EDA). By selecting a diamine compound with less steric hindrance, it is beneficial for the diamine compound to be inserted into the PI molecule and react with the imide groups in the PI to form amide bonds; it is also beneficial for forming dense molecular chains, further improving the mechanical properties of polyimide composite pipes, among which ethylenediamine has the most significant effect.

[0041] In some embodiments, the modified polyimide comprises structural units shown in formula (I) and / or formula (II):

[0042]

[0043]

[0044] R1 represents C with or without substitution. 1-16 Alkylene or substituted or unsubstituted 5-6 aryl groups;

[0045] R2 is

[0046] A and B are each independently 5-10 aryl groups;

[0047] R3 can be a single bond, -O-, -S-, -SO2-, -NH-, -CO-, or -CH2-.

[0048] Understandably, in this invention, "*" indicates a connection site.

[0049] In some embodiments, R1 is C 2-12 Alkylene, phenyl, pyridyl, pyrimidinyl, or triazine; further, R1 is C 2-8 Alkylene; further, R1 is C 2-6 Alkylene; further, R1 is C 2-4 Alkylene; further, R1 is ethylene, propyleneene, butylene, pentylene, or hexylene.

[0050] In some embodiments, R1 is -(CR a R b ) m - where m is an integer from 2 to 16; further, m is 2, 3, 4, 5, 6, 7, or 8; further, m is 2; m CRs a R b Whether they are the same or different, R a and R b Each is independently selected from: H or C 1-4 Alkyl; further, Ra and R b Each is independently selected from H, methyl, ethyl, 1-propyl (-CH2CH2CH3), 2-propyl (-CH(CH3)2), 1-butyl (-CH2CH2CH2CH3), 2-methyl-1-propyl (-CH2CH(CH3)2), 2-butyl (-CH(CH3)CH2CH3), 2-methyl-2-propyl (-C(CH3)3); further, R a and R b Each is independently selected from H, methyl, or ethyl.

[0051] In some embodiments, A is phenyl; in some embodiments, R2 is...

[0052] In some embodiments, A is phenyl, and B is phenyl; in some embodiments, R2 is...

[0053] It is understood that the material of the outer layer in this invention can be any of the polymer materials commonly used in the art to improve the performance of polyimide composite pipes, such as nylon (PA) to improve the strength and wear resistance of composite pipes, polyurethane (TPU) to improve the biocompatibility of composite pipes, and polyether block amide (Pebax) to improve the welding performance or hardness of composite pipes. No particular limitation is made here, and it should be understood that they are all within the protection scope of this invention.

[0054] It is understood that there is no particular limitation on the number of inner and outer layers in the above-mentioned polyimide composite pipes, and they can be selected according to actual needs (such as pipe thickness), and should be understood as being within the protection scope of this invention.

[0055] An embodiment of the present invention also provides a method for preparing the above-mentioned polyimide composite pipe, comprising the following steps:

[0056] S101: Provides core wire.

[0057] The type of core wire in step S101 is not particularly limited and can be a core wire commonly used in the art, such as a metal core wire, a plastic core wire, or a rubber core wire. In some embodiments, the core wire is a stainless steel wire, a silver-plated copper wire, or a pure copper wire; further, the core wire is a pure copper wire.

[0058] S102: Clean and dry the core wire.

[0059] Understandably, step S102 can be omitted when there is no need to clean the core wires.

[0060] In some embodiments, in step S102, the core wire is cleaned by passing it through a cleaning tank at a predetermined speed (e.g., 0.2 m / min - 10 m / min). In some embodiments, water and / or ethanol are used to wash the core wire.

[0061] S103: Coat the core wire with a polyimide precursor solution and perform imidization treatment to obtain a polyimide layer.

[0062] Understandably, one or more polyimide layers can be formed by simply repeating step S103, which involves first coating the core wire with a precursor solution, then performing an imidization treatment to form a polyimide layer, then coating the formed polyimide layer with a precursor solution, and then performing an imidization treatment. This process is repeated to obtain the desired number of polyimide layers.

[0063] In some embodiments, in step S103, the precursor solution is loaded onto the core wire using methods such as impregnation, coating, or spraying.

[0064] Understandably, a take-up and untake-down device can also be used to allow the core wire to pass through an impregnation tank containing a coating solution at a certain speed. In some embodiments, in step S103, the core wire is passed through a precursor solution at a predetermined speed and then enters a sintering furnace at a predetermined speed for imidization treatment.

[0065] In some embodiments, in step S103, the core wire passes through the precursor solution at a speed of 0.2 m / min-10 m / min and passes through the sintering furnace at a speed of 0.2 m / min-10 m / min; further, the moving speed is 1 m / min-6 m / min.

[0066] In some embodiments, in step S103, the precursor solution is coated onto the surface of the core wire using an impregnation method. Further, the coating in step S103 is a diameter-controlled coating. Specifically, the core wire coated with the coating solution can be passed through the inner cavity of a mold to control the amount of liquid on the core wire, thereby controlling the thickness of the coating layer. In one embodiment, the thickness of the coating layer is 20 μm-100 μm. In another embodiment, the total thickness of the coating layer is 30 μm-80 μm; further, the total thickness of the coating layer is 40 μm-60 μm.

[0067] In step S103, "imidization treatment" refers to the process of imidizing and curing the precursor (polyamic acid, PAA) in the precursor solution on the surface of the core wire to obtain a cross-linked polyimide layer.

[0068] In some embodiments, the polyimide precursor solution includes polyamic acid and a solvent, wherein the polyamic acid is an oligomer obtained after the polymerization reaction of polyimide monomers; further, the polyimide monomers include diamine monomers and dianhydride monomers.

[0069] In some embodiments, the diamine monomer is an aryl diamine compound, and the dianhydride monomer is an aryl dianhydride compound. Further, the diamine monomer is one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, bis(3-aminophenoxy)benzophenone, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl sulfone, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2-(4-aminophenyl)-5-aminobenzimidazole. Further, the dianhydride monomer is one or more of 3,3,4',4'-diphenyl ether tetracarboxylic dianhydride (BTDA), 3,3,4',4'-benzophenone tetracarboxylic dianhydride, 3,3,4',4'-biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride.

[0070] In some embodiments, the molar ratio of dianhydride monomer to diamine monomer is 1:(0.5-1); further, the molar ratio of dianhydride monomer to diamine monomer is 1:0.8, 1:0.9 or 1:1.

[0071] In some embodiments, in step S103, after adding the monomer used to prepare the polyimide, the mixture is first reacted at 15°C-45°C for 1-5 hours, and then the temperature is raised to 100°C-120°C for 1-5 hours to obtain a precursor solution with a suitable degree of polymerization.

[0072] In some embodiments, the mass percentage concentration of polyamic acid (PAA) in the precursor solution is 5%-35%; further, the mass percentage concentration is 10%-25%; further, the mass percentage concentration is 12%-23%; and even further, the mass percentage concentration is 20%.

[0073] In some embodiments, the viscosity of the precursor solution is 10 Pa·s-100 Pa·s; further, the viscosity of the precursor solution is 20 Pa·s-80 Pa·s; further, the viscosity of the precursor solution is 30 Pa·s-60 Pa·s; and even further, the viscosity of the precursor solution is 50 Pa·s.

[0074] S104: The surface of the polyimide layer is treated with a treatment solution containing a diamine compound to react the polyimide and diamine compound on the surface of the polyimide layer to generate a surface-modified layer, thus obtaining the inner layer.

[0075] By reacting a diamine compound with a polyimide, the imide bond is broken to form an amide bond, for example:

[0076]

[0077] The process involves the reaction of a diamine compound with the imide groups at the ends of the polyimide chains to form intermolecular amide groups. This cross-linking of the two polymer chains facilitates the composite bonding of the material layers, preventing problems such as cracking, blistering, or delamination, and improving the mechanical properties of the polyimide composite pipe. Furthermore, this method only requires contact between the polyimide and a treatment liquid containing the diamine compound; the reaction conditions are mild, requiring no complex equipment, resulting in low production costs and enabling continuous production of composite pipes, making it suitable for industrial applications.

[0078] The diamine compound in step S104 is as described above and will not be repeated here.

[0079] In some embodiments, the solvent in the treatment solution is a polar solvent; further, the solvent is water or an alcohol solvent; further still, the solvent is methanol or ethanol, preferably methanol. Through extensive experimentation, those skilled in the art have discovered that using alcohol solvents can promote a certain degree of swelling in the film, thereby promoting the modification of polyimide and making it easier for polyimide to undergo crosslinking reactions with diamine compounds, with methanol being particularly effective.

[0080] In some embodiments, the concentration of the diamine compound in the treatment solution is 5 wt%-30 wt%; further, the concentration of the diamine compound is 10 wt%-25 wt%; further still, the concentration of the diamine compound is 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, 15 wt%, 16 wt%, 18 wt%, 20 wt%, 22 wt%, 24 wt%, 26 wt%, or 28 wt% to obtain better modification effects.

[0081] In some embodiments, in step S104, the polyimide layer is passed through the treatment liquid at a speed of 1 m / min-5 m / min; further, the concentration of the diamine compound in the treatment liquid is 5 wt%-30 wt%, and the polyimide layer is passed through the treatment liquid at a speed of 1 m / min-5 m / min; further, the speed is 2 m / min, 3 m / min or 4 m / min, so as to generate a suitable proportion of modified polyimide in the inner layer, so as to ensure that the polyimide composite pipe obtains excellent mechanical properties.

[0082] In some embodiments, step S104, after modification is completed, further includes a cleaning step to remove residual treatment liquid and avoid affecting subsequent steps.

[0083] In some embodiments, after modification, the sample is passed through a cleaning solution (such as alcohol or water) at a speed of 1 m / min to 5 m / min, and then dried.

[0084] S105: An outer layer is formed on the surface of the inner layer containing the surface-modified layer, and the surface-modified layer is in contact with the outer layer.

[0085] In some embodiments, in step S105, a coating liquid containing an outer layer material is coated onto the surface modified layer obtained in step S104, sintered, and cored to obtain a polyimide composite pipe.

[0086] The outer layer material in step S105 is as described above and will not be repeated here.

[0087] It should be noted that the number of outer layers is not particularly limited and can be adjusted as needed, and should be understood that all of them are within the protection scope of this invention. In the sintering step, a sintering furnace can be used, and the specific parameters are mainly set based on the characteristics of the material in the solution bath.

[0088] In some embodiments, in step S105, the inner layer containing the surface-modified layer is passed through the coating liquid at a predetermined speed; further, the predetermined speed is 1 m / min-5 m / min.

[0089] In some embodiments, polyimide composite pipes are prepared using a continuous dip-coating process.

[0090] An embodiment of the present invention also provides the application of the above-mentioned polyimide composite tubing in medical devices.

[0091] One embodiment of the present invention also provides a medical device comprising the above-mentioned polyimide composite tubing.

[0092] The present invention is illustrated below with specific examples. It should be noted that the following examples are merely illustrations and should not be construed as limiting the present invention.

[0093] Example 1

[0094] The precursor solution of polyimide (PAA, wherein the dianhydride forming PAA is 3,3,4',4'-biphenyltetracarboxylic dianhydride, the diamine is 1,4-phenylenediamine, the molar ratio of dianhydride monomer to diamine monomer is 1:0.8, and the mass percentage concentration of PAA in the precursor solution is 20%) is added to the solution tank of the coating area. A stainless steel wire core is passed through the solution tank at a speed of 1 m / min, then enters a sintering furnace to evaporate the solvent and solidify, resulting in a PI coating with a thickness of 5-10 μm. The core wire, after the first coating, passes through the solution tank and sintering furnace again for a second coating, repeating this process to achieve the target outer diameter. The tube is finished through a winding and cutting device, and finally soaked in water and cored to obtain the PI tube.

[0095] The PI tube is fed out through a feeding device, and the core wire pulls the PI tube (including the mandrel) through tank 1 and tank 2 (tank 1 contains a 10wt% ethylenediamine methanol solution, and tank 2 contains pure water) at a speed of 3m / min. After the surface moisture of the PI tube is removed by a drying device, the modified PI tube is obtained. It is then wound up by a winding device for later use. The modified PI tube contains the following structural units:

[0096] (R1 is ethylene, R3 is a single bond)

[0097] PI composite pipes were prepared using a continuous dip-coating process. Specifically, the modified PI pipe was drawn through a Pebax solution bath and a sintering furnace, and then re-entered into the coating area for the next coating layer. After the film thickness increased by 50 μm, the pipe was wound up and the core was pulled out. The surface and mechanical properties of the modified PI pipes and PI composite pipes were sampled and tested. Please refer to Table 1 for details.

[0098] Example 2

[0099] PI tubes (prepared using the same method as in Example 1) were fed out using a feeding device. The core wire pulled the PI tube (including the mandrel) through tanks 1 and 2 (tank 1 contained a 10 wt% ethylenediamine methanol solution, and tank 2 contained pure water) at a speed of 2 m / min. After removing surface moisture using a drying device, the modified PI tube was obtained and wound up for later use. A continuous dip-coating process was used to prepare the PI composite tube. The core wire pulled the modified PI tube through a Pebax solution tank and a sintering furnace, then re-entered the coating area for the next coating layer. After the film thickness increased by 50 μm, the tube was wound up and the core was pulled out. The surface and mechanical properties of the modified PI tubes and PI composite tubes were sampled and tested; please refer to Table 1 for details.

[0100] Example 3

[0101] The PI tube (prepared using the same method as in Example 1) was fed out using a feeding device. The core wire pulled the PI tube (including the mandrel) through tank 1 and tank 2 (tank 1 contained a 20wt% ethylenediamine methanol solution, and tank 2 contained pure water) at a speed of 3 m / min. After removing surface moisture using a drying device, the modified PI tube was obtained and wound up for later use. A continuous dip-coating process was used to prepare the PI composite tube. Specifically, the core wire pulled the modified PI tube through a Pebax solution tank and a sintering furnace, and then it re-entered the coating area for the next coating layer. After the film thickness increased by 50 μm, it was wound up and the core was pulled out. The surface and mechanical properties of the modified PI tube and the PI composite tube were sampled and tested; please refer to Table 1 for details.

[0102] Example 4

[0103] It is basically the same as Example 1, except that p-phenylenediamine is used instead of ethylenediamine in Example 1.

[0104] Example 5

[0105] It is basically the same as Example 1, except that water is used instead of methanol solvent in the treatment solution of Example 1.

[0106] Comparative Example 1

[0107] The PI tube (prepared using the same method as in Example 1) was fed out using a feeding device. The core wire pulled the PI tube (including the mandrel) through tank 1 and tank 2 (tank 1 containing methanol solution and tank 2 containing pure water) at a speed of 3 m / min. After removing surface moisture using a drying device, the tube was wound up using a winding device for later use. A continuous dip-coating process was used to prepare the PI composite tube. Specifically, the modified PI tube was pulled through a Pebax solution tank and a sintering furnace, and then re-entered into the coating area for the next coating layer. After the film thickness increased by 50 μm, the tube was wound up and the core was pulled out. The surface and mechanical properties of the modified PI tube and the PI composite tube were sampled and tested; please refer to Table 1 for details.

[0108] Comparative Example 2

[0109] It is basically the same as Example 1, except that tank 1 contains a sodium hydroxide solution with a concentration of 10 wt%.

[0110] Performance testing

[0111] The polyimide composite pipes of Examples 1-5, Comparative Example 1, and Comparative Example 2 were subjected to performance tests, as detailed in Table 1. The testing instruments for each indicator are as follows:

[0112] Water contact angle of modified PI pipe: SL200K contact angle tester;

[0113] Surface tension of modified PI tubes: dyne pen;

[0114] Breaking force of modified PI tube (N): Instron 3365 universal testing machine;

[0115] The coating adhesion of modified PI tubes (adhesion is defined as the difference between the average friction force value of the 3rd-5th tests and the average friction force value of the 23rd-25th tests in a linear reciprocating test): MCJ-01A linear reciprocating friction testing machine; specific operation is as follows: 1) Check whether the silicone sheet of the MCJ-01A linear reciprocating friction testing machine is damaged; if damaged, it needs to be replaced; lower the pull-down arm to completely immerse the silicone sheet in water, and set the temperature to 25±1℃; 2) Adjust the limit rod to bring the pull-up arm to the designated position according to the test requirements; 3) Place the clamp on the force gauge and use the clamp to hold the sample to be tested; 4) Click the test software, set the gauge length to 15cm, the clamping force value g / f to 300, the test speed to 10mm / min, and perform 25 cycles of testing, with 3 samples tested in each group. After the test is completed, click the "Stop / Reset" button.

[0116] Breaking force of PI composite pipe (N): Instron 3365 universal testing machine;

[0117] Layering details: XTZ-D microscope.

[0118] Table 1

[0119]

[0120] As shown in Table 1, the breaking force and surface tension of the modified PI tubes in Examples 1-5 are significantly greater than those in Comparative Example 1, and the water contact angle is significantly smaller than that in Comparative Example 1. This indicates that by using diamine compounds to modify the surface of polyimide, not only can the hydrophilicity and wettability of the modified PI tubes be improved, but also the mechanical properties can be improved.

[0121] As shown in Table 1, the polyimide composite pipes of Examples 1-5 have lower coating strength values ​​compared to Comparative Example 1, indicating greater stability between the material layers. Furthermore, no delamination was observed in Examples 1-5, demonstrating that modifying the polyimide with a diamine compound effectively improves the adhesion between the material layers and prevents delamination. In summary, Table 1 shows that the mechanical properties of the polyimide composite pipes of Examples 1-5 are significantly better than those of Comparative Example 1. This indicates that the modification method of the present invention can ensure superior adhesion between the material layers, avoid delamination, and improve the mechanical properties of the polyimide composite pipe.

[0122] Comparing Example 1 and Example 2, the difference lies in the core wire speed during the polyimide modification step. It can be seen that the core wire speed will affect the coating firmness and breaking force of the PI composite pipe to a certain extent. When the ethylenediamine concentration in the treatment solution is 10wt%, it is preferable for the core wire to pass through the treatment solution at a speed of 2m / min to obtain a suitable degree of modification.

[0123] Comparing Example 1 and Example 3, the difference lies in the different concentrations of ethylenediamine in the treatment solution. It can be seen that the concentration of the treatment solution will affect the coating firmness and breaking strength of the PI composite pipe to a certain extent. When the core wire passes through the treatment solution at a speed of 3 m / min, the preferred concentration of ethylenediamine in the treatment solution is 20 wt% to obtain a suitable degree of modification.

[0124] Comparing Example 1 and Example 4, the difference lies in the different types of diamine compounds in the treatment solution. It can be seen that the type of diamine compound will affect the coating firmness and breaking strength of the PI composite pipe to a certain extent. It is preferable to use ethylenediamine containing chain groups with small steric hindrance to ensure the modification effect of the PI composite pipe.

[0125] Comparing Example 1 and Example 5, the difference lies in the different solvents in the treatment solution. It can be seen that the type of solvent will affect the coating strength and breaking strength of the PI composite pipe to a certain extent. Methanol is preferred as a solvent, mainly because methanol can promote the film to a certain extent to swell, thereby promoting surface modification.

[0126] Comparative Example 1 and Comparative Example 2 differ in that Comparative Example 2 uses a traditional acid-base treatment method, namely, surface modification using alkaline solution treatment. As can be seen from Table 1, although acid-base treatment can modify the surface of polyimide materials to a certain extent, it will cause a loss of the mechanical properties of the polyimide composite pipe itself. In contrast, the solution of Example 1 can improve the above-mentioned problems without sacrificing the mechanical properties of the polyimide composite pipe itself, and can improve the mechanical properties of the polyimide composite pipe while ensuring better adhesion between the material layers.

[0127] 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.

[0128] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope 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 protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A polyimide composite pipe, characterized in that, The device includes an inner layer and an outer layer disposed on the inner layer; the inner layer has a surface-modified layer in contact with the outer layer, the surface-modified layer being a modified polyimide modified with a diamine compound, wherein the process of modifying with the diamine compound forms intermolecular amide groups and crosslinks the two polymer chains in the modified polyimide; wherein the diamine compound is NH2-R1-NH2, and R1 is ethylene, propylene, butylene, pentylene, or hexylene; The outer layer is made of polyether block amide; The preparation method of the polyimide composite pipe includes the following steps: Provide core wires; A polyimide precursor solution is coated onto the core wire and then imidized to obtain a polyimide layer. The surface of the polyimide layer is treated with a treatment solution containing the diamine compound to react the polyimide and the diamine compound on the surface of the polyimide layer, generating a surface-modified layer to obtain the inner layer; wherein the concentration of the diamine compound in the treatment solution is 5wt%-30wt%; in the step of treating the surface of the polyimide layer with the treatment solution containing the diamine compound, the polyimide layer is passed through the treatment solution at a speed of 1m / min-5m / min; after the imidization modification is completed, it is passed through a cleaning solution at a speed of 1m / min-5m / min and then dried, wherein the cleaning solution is alcohol or water; The outer layer is formed on the surface of the inner layer containing the surface-modified layer using a continuous dip-coating process, wherein the surface-modified layer is in contact with the outer layer; Core pulling is performed to obtain the polyimide composite pipe.

2. The polyimide composite pipe according to claim 1, characterized in that, The inner layer also includes a main body layer, the main body layer being made of unmodified polyimide, and the surface-modified layer being located between the main body layer and the outer layer.

3. The polyimide composite pipe according to claim 1, characterized in that, The diamine compound is ethylenediamine.

4. The polyimide composite pipe according to claim 1, characterized in that, The modified polyimide comprises structural units shown in formula (I) and / or formula (II): （I） (II) R1 is C with or without substitution. 1-16 Alkylene or substituted or unsubstituted 5-6 aryl groups; R2 is or ; A and B are each independently 5-10 aryl groups; R3 can be a single bond, -O-, -S-, -SO2-, -NH-, -CO-, or -CH2-.

5. The polyimide composite pipe according to claim 4, characterized in that, R1 is C 2-6 Alkylene; R2 is or .

6. A method for preparing a polyimide composite pipe, characterized in that, The method for preparing the polyimide composite pipe according to any one of claims 1-5 includes the following steps: Provide core wires; A polyimide precursor solution is coated onto the core wire and then imidized to obtain a polyimide layer. The surface of the polyimide layer is treated with a treatment solution containing the diamine compound to react the polyimide and the diamine compound on the surface of the polyimide layer, generating a surface-modified layer to obtain the inner layer; wherein the diamine compound is NH2-R1-NH2, and R1 is ethylidene, propyleneide, butylidene, pentylidene, or hexylidene; the concentration of the diamine compound in the treatment solution is 5wt%-30wt%; in the step of treating the surface of the polyimide layer with the treatment solution containing the diamine compound, the polyimide layer is passed through the treatment solution at a speed of 1m / min-5m / min; after the imidization modification is completed, it is passed through a cleaning solution at a speed of 1m / min-5m / min, and then dried, wherein the cleaning solution is alcohol or water; The outer layer is formed on the surface of the inner layer containing the surface-modified layer using a continuous dip-coating process, wherein the surface-modified layer is in contact with the outer layer; wherein the outer layer is made of polyether block amide. Core pulling is performed to obtain the polyimide composite pipe.

7. The preparation method according to claim 6, characterized in that, The solvent in the treatment solution is methanol or ethanol.

8. A medical device, characterized in that, The product comprises the polyimide composite pipe according to any one of claims 1-5.

9. The use of the polyimide composite tubing according to any one of claims 1-5 in the preparation of endovascular therapeutic polymer catheters.

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