Thin-wall PTFE medical catheter continuous preparation system and method based on electrostatic adsorption

Abstract

The invention discloses a thin-wall PTFE medical catheter continuous preparation system and method based on electrostatic adsorption, belongs to the technical field of medical catheter preparation, and solves the technical problems of complex process and equipment in the existing PTFE medical catheter preparation process. The device comprises a core wire feeding mechanism, a tensioning mechanism, a sintering mechanism and a traction mechanism which are arranged in sequence, an electrostatic powder spraying mechanism is further arranged between the tensioning mechanism and the sintering mechanism, and the electrostatic powder spraying mechanism is used for coating conduit material powder on the surface of the core wire; a core wire is guided by the traction mechanism to sequentially pass through the tensioning mechanism, the electrostatic powder spraying mechanism and the sintering mechanism. The thin-wall PTFE medical catheter continuous preparation system and method based on electrostatic adsorption can be better used for continuous preparation work of PTFE medical catheters, the cost is controllable, and the working procedures are easy to control.

Description

Technical Field

[0001] The present invention relates to the technical field of medical catheter preparation, and in particular to a system and method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption. Background Art Catheters used to treat lesions inside blood vessels need to be inserted into the body percutaneously, so the catheters are required to have at least linear advancement and operability, and should also have small diameters to facilitate insertion into blood vessels to reduce the burden on patients, and thin walls to increase the flow of fluid in the catheter. Small-diameter, thin-walled catheters made of ordinary materials are difficult to be used as suitable materials for medical catheters because of their poor surface lubricity, easy adhesion of impurities, and easy clogging.

[0002] As for polytetrafluoroethylene (PTFE), since fluorine atoms have a large atomic radius, they can almost completely wrap the main molecular chain composed of carbon atoms, making the carbon-carbon bonds less susceptible to chemical erosion. Therefore, PTFE exhibits excellent chemical corrosion resistance, low friction coefficient, non-adhesion and thermal stability. At the same time, it also makes its molecular chain extremely rigid, and the material has almost no fluidity after heating. However, its excellent physical and chemical properties such as low friction and self-lubrication make it one of the excellent materials for medical catheters.

[0003] Generally speaking, there are two main methods for preparing PTFE medical catheters: paste extrusion and dipping. In the paste extrusion method, the processing aid and PTFE powder are evenly mixed and then extruded using a paste extruder. There are two main processing forms: ① The metal core wire and the PTFE mixture are extruded simultaneously; ② The PTFE tube is first extruded, heated and then stretched to make the tube thin-walled and coated on the surface of the metal core wire before being peeled off to obtain the PTFE medical catheter.

[0004] In the prior art, the PTFE medical tubes prepared by the paste extrusion method have a large diameter and wall thickness. The preparation process requires the addition of additives and then drying to remove the additives. The process flow is complicated, the production process is discontinuous, and the equipment is expensive, resulting in a low cost-effectiveness of the product, which hinders the pace of industrial development.

[0005] The impregnation sintering method requires the volatilization of a large amount of dispersion liquid, which is very likely to cause environmental pollution. The collection of the dispersion liquid will incur a large amount of equipment costs, and the manufactured catheters have micro defects such as pinholes and poor strength. Summary of the invention

[0006] The purpose of the present invention is to provide a system and method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption to solve the technical problems mentioned in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a continuous preparation system for thin-walled PTFE medical catheters based on electrostatic adsorption, comprising a core wire feeding mechanism, a tensioning mechanism, a sintering mechanism and a traction mechanism which are arranged in sequence; An electrostatic powder spraying mechanism is also provided between the tensioning mechanism and the sintering mechanism, and the electrostatic powder spraying mechanism is used to coat the catheter material powder on the surface of the core wire; The core wire passes through the tensioning mechanism, the electrostatic powder spraying mechanism and the sintering mechanism in sequence under the guidance of the traction mechanism.

[0008] Optionally or preferably, the electrostatic powder spraying mechanism comprises a fluidized powder barrel and an electrostatic powder spray gun; The fluidized powder cylinder is used to store catheter material powder, and the electrostatic powder spray gun is used to electrostatically process the catheter material powder and coat the charged catheter material powder onto the surface of the core wire.

[0009] Optionally or preferably, the catheter material powder is a homopolymer of tetrafluoroethylene or modified tetrafluoroethylene; The modified tetrafluoroethylene is a polymer of tetrafluoroethylene and other monomers; The other monomers include chlorotrifluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether.

[0010] Optionally or preferably, the core wire material is silver-plated copper, stainless steel, nickel alloy, iron alloy or silver alloy; The surface roughness of the core wire Ra≤0.4μm, and the diameter error d≤0.005mm.

[0011] A method for continuously preparing a thin-walled PTFE medical catheter based on electrostatic adsorption comprises the following steps: S1, equipment adjustment and core wire layout; S2, catheter material powder processing, processing the catheter material powder, and adding the processed catheter material powder into the fluidized powder cylinder; S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun, and applying the charged catheter material powder to the core wire surface; S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism for sintering to form a core wire with a continuous catheter material coated on the surface; S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

[0012] Optionally or preferably, the method of adjusting the equipment and laying out the core wire in S1 comprises the following steps: S11, adjusting the centers of the tensioning mechanism, the sintering mechanism and the traction mechanism to be located on the same horizontal line, and providing a guide roller between the core wire feeding mechanism and the tensioning mechanism, the guide roller being used to make the center of the unwound metal core wire and the center of the tensioning mechanism located in the same vertical plane; S12, adjusting the distance between the tensioning mechanism and the sintering mechanism and the distance between the sintering mechanism and the traction mechanism, and arranging an electrostatic powder spraying mechanism between the tensioning mechanism and the sintering mechanism; S13, adjust the tensioning force of the tensioning mechanism on the core wire, the adjustment range of the tensioning force is 1N-100N; S14, adjusting the pulling speed of the pulling mechanism on the core wire, the adjustment range of the pulling speed is 0.01m / min-2m / min.

[0013] Optionally or preferably, the method for processing the catheter material powder in S2 is: Select the catheter material powder in a specific heat preservation environment, use a sieve to remove the lumps in the powder, and add the sieved catheter material powder into the fluidized powder cylinder; The particle size of the catheter material powder is 0.05 μm-50 μm.

[0014] Optionally or preferably, the method of electrostatically treating the catheter material powder by an electrostatic powder spray gun in S3 is: the charge density of the catheter material powder carrying negative charges should be controlled at 1C / m 3 -5000C / m 3 ; The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun in S3 comprises the following steps; S31, keep the nozzle of the electrostatic powder spray gun 10mm-20mm away from the outer surface of the core wire, and adjust the air pressure of the spray gun to 0.1MPa-0.2MPa; S32, the spray gun adopts fixed-point spraying or rotary spraying on the core wire.

[0015] Optionally or preferably, the method in S4 for sintering the core wire coated with the catheter material powder by the sintering mechanism is: sintering by a sintering furnace at a sintering temperature of 350°C-480°C.

[0016] Optionally or preferably, the method for cooling the core wire whose surface is covered with the continuous conduit material after sintering in S5 is: cooling the core wire whose surface is covered with the continuous conduit material after sintering step by step in an air bath.

[0017] Based on the above technical solution, the present invention can at least produce the following technical effects: The present invention provides a continuous preparation system for thin-walled PTFE medical catheters based on electrostatic adsorption, which has simple equipment and is easy to install. It also optimizes the material system, reduces processing equipment such as removal of processing aids / dispersants, and reduces equipment costs. The continuous preparation method of thin-walled PTFE medical catheters based on the principle of electrostatic adsorption provided by the present invention simplifies the process and improves the molding efficiency, effectively overcoming the defects that the existing paste extrusion method is difficult to prepare small-diameter thin-walled tubes, and the impregnation sintering method is difficult to prepare high-strength medical catheters, and has significant advantages in the industrial development of PTFE medical catheter preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the arrangement structure of the continuous preparation system of thin-walled PTFE medical catheters based on electrostatic adsorption of the present invention; Figure 2 It is the physical model of electrostatic spraying powder in the second embodiment of the present invention; Figure 3 is a voltage distribution diagram within the model area in the second embodiment of the present invention; Figure 4 is a particle motion trajectory diagram in Example 2 of the present invention; Figure 5 is a particle distribution cloud diagram in the second embodiment of the present invention; Figure 6 is a powder deposition thickness cloud map in Example 2 of the present invention; Figure 7 is a curve diagram of force value versus strain of the catheter in the second embodiment of the present invention; Figure 8 is a voltage distribution diagram within the model area in the third embodiment of the present invention; Fig. 9 is a particle motion trajectory diagram in Example 3 of the present invention; Fig.10 is a particle distribution cloud diagram in Example 3 of the present invention; Fig.11 is a powder deposition thickness cloud map in Example 3 of the present invention; Fig.12 is a curve diagram of force value versus strain of the catheter in the third embodiment of the present invention; Fig.13 is a voltage distribution diagram within the model area in the fourth embodiment of the present invention; Fig.14 is a particle motion trajectory diagram in the fourth embodiment of the present invention; Fig.15 is a particle distribution cloud diagram in the fourth embodiment of the present invention; Fig.16 is a powder deposition thickness cloud diagram in the fourth embodiment of the present invention; Fig.17is a curve diagram of force value versus strain of the catheter in the fourth embodiment of the present invention; Fig.18 is a voltage distribution diagram within the model area in the fifth embodiment of the present invention; Fig.19 is a particle motion trajectory diagram in Embodiment 5 of the present invention; Fig. 20 is a particle distribution cloud diagram in Example 5 of the present invention; Fig.21 is a powder deposition thickness cloud map in Example 5 of the present invention; Fig. 22 4 is a curve diagram showing the force value of the catheter as a function of strain in the fifth embodiment of the present invention.

[0019] In the figure: 10, core wire feeding mechanism; 20, tensioning mechanism; 30, electrostatic powder spraying mechanism; 31, fluidized powder cylinder; 32, electrostatic powder spray gun; 40, sintering mechanism; 50, traction mechanism. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work belong to the scope of protection of the present invention.

[0021] Embodiment 1 See also Figure 1 A continuous preparation system for thin-walled PTFE medical catheters based on electrostatic adsorption includes a feeding mechanism 10, a tensioning mechanism 20, an electrostatic powder spraying mechanism 30, a sintering mechanism 40 and a traction mechanism 50 which are arranged in sequence; the core wire passes through the tensioning mechanism 20, the electrostatic powder spraying mechanism 30 and the sintering mechanism 40 in sequence under the guidance of the traction mechanism 50.

[0022] In this embodiment, the feeding mechanism 10 is a core wire feeding rack, which is used to provide metal core wire to the system; the tensioning mechanism 20 is a plurality of continuously arranged tensioning rollers, and an introduction roller is arranged at the end of the tensioning mechanism 20, and the tensioning mechanism 20 is used to provide tensioning force to the metal core wire in the system; the electrostatic powder spraying mechanism 30 is used to coat the catheter material powder on the surface of the core wire; the sintering mechanism 40 is a sintering furnace, which is used to sinter and form the catheter material powder coated on the surface of the core wire; the traction mechanism 50 is used to provide continuous traction force to the metal core wire in the system and keep the metal core wire at a certain traction speed.

[0023] In this embodiment, the electrostatic powder spraying mechanism 30 includes a fluidized powder drum 31 and an electrostatic powder spray gun 32; wherein the fluidized powder drum 31 is used to store the catheter material powder, and the electrostatic powder spray gun 32 is used for electrostatic treatment of the catheter material powder and coating the charged catheter material powder onto the core wire surface.

[0024] In this embodiment, the core wire material is silver-plated copper, stainless steel, nickel alloy, iron alloy or silver alloy, and the surface roughness Ra of the core wire is ≤0.4 μm, and the diameter error d is ≤0.005 mm.

[0025] It should be noted that the core material may also be other alloys or surface-plated metals.

[0026] In this embodiment, the catheter material powder is a homopolymer of tetrafluoroethylene or modified tetrafluoroethylene; wherein the modified tetrafluoroethylene is a polymer of tetrafluoroethylene and other monomers; other monomers include chlorotrifluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether.

[0027] Embodiment 2 This embodiment, based on Example 1, provides a method for continuously preparing a thin-walled PTFE medical catheter based on electrostatic adsorption, comprising the following steps; S1, equipment adjustment and core wire layout; In this embodiment, the method for adjusting the equipment and laying out the core wires includes the following steps: S11, adjusting the centers of the tensioning mechanism 20, the sintering mechanism 40 and the traction mechanism 50 to be located on the same horizontal line, and an introduction roller is provided between the core wire feeding mechanism 10 and the tensioning mechanism 20, and the introduction roller is used to make the center of the unwound metal core wire and the center of the tensioning mechanism 20 located in the same vertical plane; S12, adjusting the distances between the tensioning mechanism 20 and the sintering mechanism 40 and between the sintering mechanism 40 and the traction mechanism 50 to be 1 m and 2 m respectively, and arranging an electrostatic powder spraying mechanism between the tensioning mechanism 20 and the sintering mechanism 40; S13, adjusting the tensioning force of the tensioning mechanism 20 on the core wire, the adjustment range of the tensioning force is 1N-100N; In this embodiment, the tensioning force of the tensioning mechanism 20 on the core wire is 10N.

[0028] S14, adjusting the pulling speed of the pulling mechanism 50 on the core wire, the adjustment range of the pulling speed is 0.01m / min-2m / min.

[0029] In this embodiment, the pulling speed of the pulling mechanism 50 on the core wire is 0.2 m / min.

[0030] In this embodiment, the surface roughness Ra of the core wire is 0.2 μm, the diameter d is 0.5 mm, the diameter error is ±0.005 mm, and the material is silver-plated copper.

[0031] S2, catheter material powder processing, the catheter material powder is processed, and the processed catheter material powder is added into the fluidized powder cylinder 31; In this embodiment, the method for processing the catheter material powder is: Select catheter material powder in a specific heat preservation environment of 15° C., use an 800-mesh screen to remove lumps in the powder, obtain fine powder with a maximum particle size of 25 μm, and add the sieved catheter material powder into the fluidized powder cylinder 31; S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun 32, and coating the charged catheter material powder onto the core wire surface; In this embodiment, the electrostatic treatment method of the catheter material powder by the electrostatic powder spray gun 32 is: the charge density of the catheter material powder carrying negative charges should be controlled at 50C / m 3 .

[0032] The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun 32 comprises the following steps; S31, make the nozzle of electrostatic powder spray gun 32 20mm away from the outer surface of the core wire, and adjust the air pressure of the spray gun to 0.15MPa; S32, the spray gun adopts rotary spraying to the core wire, that is, the spray gun nozzle is aligned with the core wire along the radial direction of the metal core wire in a fixed vertical plane and rotates around the axis of the metal core wire.

[0033] S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism 40 for sintering to form a core wire with a continuous catheter material coated on the surface; In this embodiment, the method of sintering the core wire coated with the catheter material powder by the sintering mechanism 40 is: sintering by a sintering furnace, and the sintering temperature is 420°C.

[0034] S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

[0035] In this embodiment, the method for cooling the core wire whose surface is covered with the continuous catheter material after sintering is as follows: cooling the core wire whose surface is covered with the continuous catheter material after sintering step by step in an air bath at 300°C, 250°C, 150°C and 25°C, cutting it to a fixed length according to actual use requirements, and forming a PTFE medical catheter with an inner diameter of 0.5mm±0.005mm and a certain wall thickness after stripping the metal core wire.

[0036] In this embodiment, the PTFE medical catheter obtained by the above method needs to be subjected to a performance test, and the method of the performance test is: Randomly cut 10 PTFE medical catheters with a length of 1000mm for performance testing, find 6 locations as evenly as possible within the entire length of each catheter to measure the outer diameter D0, calculate the average outer diameter D, and calculate the catheter wall thickness T d , the outer diameter standard deviation (square root of the outer diameter variance) is calculated using the outer diameter deviation (outer diameter D0 at the measuring point-outer diameter average value D) and the outer diameter variance (average of the square of the outer diameter deviation), and the outer diameter standard deviation is divided by the average outer diameter D to obtain the outer diameter variation coefficient CVD of a single catheter, and the arithmetic mean of the outer diameter variation coefficients CVD of 10 catheters is calculated as the outer diameter variation coefficient value CV of the catheter in the same embodiment. The outer diameter and wall thickness of the catheter are imaged on a computer using an optical microscope and then calibrated and measured, and the arithmetic mean is calculated.

[0037] The experimental results show that the inner diameter of the PTFE medical catheter prepared in this example is 0.5±0.015 mm, the wall thickness is 0.015±0.005 mm, and the coefficient of variation of the outer diameter is 0.00115 mm / mm.

[0038] The same parameters as those in this embodiment are set to simulate the electrostatic adsorption process. The physical model of the electrostatic spraying powder obtained by modeling is as follows: Figure 2 shown.

[0039] Based on the above model, the electrostatic field voltage is set to -90kV, and the voltage distribution in the model area can be obtained as follows: Figure 3 As shown, it can be seen from the cloud diagram that the farther the distance from the electrostatic generator, the smaller the voltage, and the voltage at the farthest point is reduced to -11.4kv; in addition, this embodiment sets the electrostatic nozzle to be 20mm away from the metal core wire. At this time, the electrostatic field voltage of the metal core wire directly below the electrostatic nozzle is about -27.1kv.

[0040] PTFE fine powder Figure 3 After being electrostatically treated in the electrostatic field, it is ejected to form Figure 4 The particle motion traces and Figure 5 From the particle distribution cloud diagram shown, it can be seen that the maximum velocity of the particles during the spraying process is 10.4 m / s. However, as the particles leave the spray gun nozzle, the particles are affected by air resistance and their velocity rapidly decreases to 0. They are dispersed in the air to form a group of PTFE dispersed particles with static electricity.

[0041] Under the action of static electricity, as the PTFE particles continue to deposit, they eventually form Figure 6The powder deposition thickness cloud map shown in the figure shows that the maximum thickness of the PTFE powder after electrostatic deposition is 30μm, and the powder deposition thickness in most areas is distributed in the range of 12μm-21μm.

[0042] During the experiment, the PTFE powder was sintered to form a metal core wire with a PTFE tube on the surface. After the metal core wire was peeled off, a PTFE hollow tube was obtained. Samples with a width of 0.5 mm and a thickness of 0.015 mm were cut for mechanical property testing, and the results were as follows: Figure 7 From the force value versus strain curve shown, it can be seen that the maximum tensile force of the sample reaches 0.0326N. Based on this, according to the calculation formula of tensile strength σ=F / S, where F is the maximum tensile force and S is the cross-sectional area of ​​the sample, it can be obtained that the maximum tensile strength of the sample is about 4MPa.

[0043] Embodiment 3 This embodiment, based on Example 1, provides a method for continuously preparing a thin-walled PTFE medical catheter based on electrostatic adsorption, comprising the following steps; S1, equipment adjustment and core wire layout; In this embodiment, the method for adjusting the equipment and laying out the core wires includes the following steps: S11, adjusting the centers of the tensioning mechanism 20, the sintering mechanism 40 and the traction mechanism 50 to be located on the same horizontal line, and an introduction roller is provided between the core wire feeding mechanism 10 and the tensioning mechanism 20, and the introduction roller is used to make the center of the unwound metal core wire and the center of the tensioning mechanism 20 located in the same vertical plane; S12, adjusting the distances between the tensioning mechanism 20 and the sintering mechanism 40 and between the sintering mechanism 40 and the traction mechanism 50 to be 1 m and 2 m respectively, and arranging an electrostatic powder spraying mechanism between the tensioning mechanism 20 and the sintering mechanism 40; S13, adjusting the tensioning force of the tensioning mechanism 20 on the core wire, the adjustment range of the tensioning force is 1N-100N; In this embodiment, the tensioning force of the tensioning mechanism 20 on the core wire is 12N.

[0044] S14, adjusting the pulling speed of the pulling mechanism 50 on the core wire, the adjustment range of the pulling speed is 0.01m / min-2m / min.

[0045] In this embodiment, the pulling speed of the pulling mechanism 50 on the core wire is 0.2 m / min.

[0046] In this embodiment, the surface roughness Ra of the core wire is 0.1 μm, the diameter d is 0.8 mm, the diameter error is ±0.001 mm, and the material is silver-plated copper.

[0047] S2, catheter material powder processing, the catheter material powder is processed, and the processed catheter material powder is added into the fluidized powder cylinder 31; In this embodiment, the method for processing the catheter material powder is: Select catheter material powder in a specific heat preservation environment of 15° C., use a 1250-mesh screen to remove lumps in the powder, obtain fine powder with a maximum particle size of 10 μm, and add the sieved catheter material powder into the fluidized powder cylinder 31; S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun 32, and coating the charged catheter material powder onto the core wire surface; In this embodiment, the method of electrostatically treating the catheter material powder by the electrostatic powder spray gun 32 is: the charge density of the catheter material powder carrying negative charges should be controlled at 89.98C / m 3 .

[0048] The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun 32 comprises the following steps; S31, keep the nozzle of the electrostatic powder spray gun 32 10 mm away from the outer surface of the core wire, and adjust the spray gun air pressure to 0.12 MPa; S32, the spray gun adopts rotary spraying to the core wire, that is, the spray gun nozzle is aligned with the core wire along the radial direction of the metal core wire in a fixed vertical plane and rotates around the axis of the metal core wire.

[0049] S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism 40 for sintering to form a core wire with a continuous catheter material coated on the surface; In this embodiment, the method of sintering the core wire coated with the catheter material powder by the sintering mechanism 40 is: sintering by a sintering furnace, and the sintering temperature is 450°C.

[0050] S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

[0051] In this embodiment, the method for cooling the core wire whose surface is covered with the continuous catheter material after sintering is as follows: the core wire whose surface is covered with the continuous catheter material after sintering is cooled step by step in an air bath at 320°C, 280°C, 180°C and 40°C, and cut to a fixed length according to actual use requirements, and after stripping the metal core wire, a PTFE medical catheter with an inner diameter of 0.8mm±0.001mm and a certain wall thickness is formed.

[0052] In this embodiment, the PTFE medical catheter obtained by the above method needs to be subjected to a performance test, and the method of the performance test is: Randomly cut 10 PTFE medical catheters with a length of 1000mm for performance testing, find 6 locations as evenly as possible within the entire length of each catheter to measure the outer diameter D0, calculate the average outer diameter D, and calculate the catheter wall thickness T d , the outer diameter standard deviation (square root of the outer diameter variance) is calculated using the outer diameter deviation (outer diameter D0 at the measuring point-outer diameter average value D) and the outer diameter variance (average of the square of the outer diameter deviation), and the outer diameter standard deviation is divided by the average outer diameter D to obtain the outer diameter variation coefficient CVD of a single catheter, and the arithmetic mean of the outer diameter variation coefficients CVD of 10 catheters is calculated as the outer diameter variation coefficient value CV of the catheter in the same embodiment. The outer diameter and wall thickness of the catheter are imaged on a computer using an optical microscope and then calibrated and measured, and the arithmetic mean is calculated.

[0053] The experimental results show that the inner diameter of the PTFE medical catheter prepared in this example is 0.8±0.001mm, the wall thickness is 0.012±0.004mm, and the coefficient of variation of the outer diameter is 0.00083mm / mm.

[0054] The same parameters as those in this embodiment are set to simulate the electrostatic adsorption process. The physical model of the electrostatic spraying powder obtained by modeling is as follows: Figure 2 shown.

[0055] Based on the above model, the electrostatic field voltage is set to -80kV, and the voltage distribution in the model area can be obtained as follows: Figure 8 As shown, it can be seen from the cloud map that the farther the distance from the electrostatic generator, the smaller the voltage, and the voltage at the farthest point is reduced to -10.7kv; in addition, this embodiment sets the electrostatic nozzle to be 10mm away from the metal core wire. At this time, the electrostatic field voltage of the metal core wire directly below the electrostatic nozzle is about -33.0kv.

[0056] PTFE fine powder Figure 8 After being electrostatically treated in the electrostatic field, it is ejected to form Fig. 9 The particle motion traces and Fig.10 From the particle distribution cloud diagram shown, it can be seen that the maximum speed of the particles during the spraying process is 8.56m / s. However, as the particles leave the spray gun nozzle, the particles are affected by air resistance and their speed rapidly decreases to 0. They are dispersed in the air to form a group of PTFE dispersed particles with static electricity.

[0057] Under the action of static electricity, as the PTFE particles continue to deposit, they eventually form Fig.11 The powder deposition thickness cloud map shown in the figure shows that the maximum thickness of the PTFE powder after electrostatic deposition is 25.6μm, and the powder deposition thickness in most areas is distributed in the range of 10μm-23μm.

[0058] During the experiment, the PTFE powder was sintered to form a metal core wire with a PTFE tube on the surface. After the metal core wire was peeled off, a PTFE hollow tube was obtained. Samples with a width of 0.8 mm and a thickness of 0.012 mm were cut for mechanical property testing, and the results were as follows: Fig.12 From the force value versus strain curve shown, it can be seen that the maximum tensile force of the sample reaches 0.039N. Based on this, according to the calculation formula of tensile strength σ=F / S, where F is the maximum tensile force and S is the cross-sectional area of ​​the sample, it can be obtained that the maximum tensile strength of the sample is about 4.06MPa.

[0059] Embodiment 4 This embodiment, based on Example 1, provides a method for continuously preparing a thin-walled PTFE medical catheter based on electrostatic adsorption, comprising the following steps; S1, equipment adjustment and core wire layout; In this embodiment, the method for adjusting the equipment and laying out the core wires includes the following steps: The centers of the tensioning mechanism 20, the sintering mechanism 40 and the traction mechanism 50 are adjusted to be located on the same horizontal line, and a guide roller is provided between the core wire feeding mechanism 10 and the tensioning mechanism 20, and the guide roller is used to make the center of the unwound metal core wire and the center of the tensioning mechanism 20 located in the same vertical plane; S12, adjusting the distances between the tensioning mechanism 20 and the sintering mechanism 40 and between the sintering mechanism 40 and the traction mechanism 50 to be 1 m and 2 m respectively, and arranging the electrostatic powder spraying mechanism 30 between the tensioning mechanism 20 and the sintering mechanism 40; S13, adjusting the tensioning force of the tensioning mechanism 20 on the core wire, the adjustment range of the tensioning force is 1N-100N; In this embodiment, the tensioning force of the tensioning mechanism 20 on the core wire is 30N.

[0060] S14, adjusting the pulling speed of the pulling mechanism 50 on the core wire, the adjustment range of the pulling speed is 0.01m / min-2m / min.

[0061] In this embodiment, the pulling speed of the pulling mechanism 50 on the core wire is 0.1 m / min.

[0062] In this embodiment, the surface roughness Ra of the core wire is 0.1 μm, the diameter d is 1.2 mm, the diameter error is ±0.001 mm, and the material is silver-plated copper.

[0063] S2, catheter material powder processing, the catheter material powder is processed, and the processed catheter material powder is added into the fluidized powder cylinder 31; In this embodiment, the method for processing the catheter material powder is: Select catheter material powder in a specific heat preservation environment of 10° C., use a 1250-mesh screen to remove lumps in the powder, obtain fine powder with a maximum particle size of 0.5 μm, and add the sieved catheter material powder into the fluidized powder cylinder 31; S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun 32, and coating the charged catheter material powder onto the core wire surface; In this embodiment, the method of electrostatically treating the catheter material powder by the electrostatic powder spray gun 32 is: the charge density of the catheter material powder carrying negative charges should be controlled at 1798.60C / m 3 .

[0064] The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun 32 comprises the following steps; S31, make the nozzle of electrostatic powder spray gun 32 15mm away from the outer surface of the core wire, and adjust the air pressure of the spray gun to 0.2MPa; S32, the spray gun adopts rotary spraying to the core wire, that is, the spray gun nozzle is aligned with the core wire along the radial direction of the metal core wire in a fixed vertical plane and rotates around the axis of the metal core wire.

[0065] S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism 40 for sintering to form a core wire with a continuous catheter material coated on the surface; In this embodiment, the method of sintering the core wire coated with the catheter material powder by the sintering mechanism 40 is: sintering by a sintering furnace, and the sintering temperature is 450°C.

[0066] S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

[0067] In this embodiment, the method for cooling the core wire whose surface is covered with the continuous catheter material after sintering is as follows: cooling the core wire whose surface is covered with the continuous catheter material after sintering step by step in an air bath at 320°C, 280°C, 220°C, 170°C, and 40°C, and cutting it to a fixed length according to actual use requirements, and after stripping the metal core wire, a PTFE medical catheter with an inner diameter of 1.2mm±0.001mm and a certain wall thickness is formed.

[0068] In this embodiment, the PTFE medical catheter obtained by the above method needs to be subjected to a performance test, and the method of the performance test is: Randomly cut 10 PTFE medical catheters with a length of 1000mm for performance testing, find 6 locations as evenly as possible within the entire length of each catheter to measure the outer diameter D0, calculate the average outer diameter D, and calculate the catheter wall thickness T d, the outer diameter standard deviation (square root of the outer diameter variance) is calculated using the outer diameter deviation (outer diameter D0 at the measuring point-outer diameter average value D) and the outer diameter variance (average of the square of the outer diameter deviation), and the outer diameter standard deviation is divided by the average outer diameter D to obtain the outer diameter variation coefficient CVD of a single catheter, and the arithmetic mean of the outer diameter variation coefficients CVD of 10 catheters is calculated as the outer diameter variation coefficient value CV of the catheter in the same embodiment. The outer diameter and wall thickness of the catheter are imaged on a computer using an optical microscope and then calibrated and measured, and the arithmetic mean is calculated.

[0069] The experimental results show that the inner diameter of the PTFE medical catheter prepared in this example is 1.2±0.001mm, the wall thickness is 0.008±0.004mm, and the coefficient of variation of the outer diameter is 0.00056mm / mm.

[0070] The same parameters as those in this embodiment are set to simulate the electrostatic adsorption process. The physical model of the electrostatic spraying powder obtained by modeling is as follows: Figure 2 shown.

[0071] Based on the above model, the electrostatic field voltage is set to -100kV, and the voltage distribution in the model area can be obtained as follows: Fig.13 As shown, it can be seen from the cloud diagram that the farther the distance from the electrostatic generator, the smaller the voltage, and the voltage at the farthest point is reduced to -12.6kv; in addition, this embodiment sets the electrostatic nozzle to be 15mm away from the metal core wire. At this time, the electrostatic field voltage of the metal core wire directly below the electrostatic nozzle is about -35.3kv.

[0072] PTFE fine powder Fig.13 After being electrostatically treated in the electrostatic field, it is ejected to form Fig.14 The particle motion traces and Fig.15 From the particle distribution cloud diagram shown, it can be seen that the maximum speed of the particles during the spraying process is 9.45m / s. However, as the particles leave the spray gun nozzle, the particles are affected by air resistance and their speed rapidly decreases to 0. They are dispersed in the air to form a group of PTFE dispersed particles with static electricity.

[0073] Under the action of static electricity, as the PTFE particles continue to deposit, they eventually form Fig.16 The powder deposition thickness cloud map shown in the figure shows that the maximum thickness of the PTFE powder after electrostatic deposition is 13.5μm, and the powder deposition thickness in most areas is distributed in the range of 5.4μm-12.1μm.

[0074] During the experiment, the PTFE powder was sintered to form a metal core wire with a PTFE tube on the surface. After the metal core wire was peeled off, a PTFE hollow tube was obtained. Samples with a width of 1.2 mm and a thickness of 0.008 mm were cut for mechanical property testing, and the results were as follows: Fig.17From the force value versus strain curve shown, it can be seen that the maximum tensile force of the sample reaches 0.0615N. Based on this, according to the calculation formula of tensile strength σ=F / S, where F is the maximum tensile force and S is the cross-sectional area of ​​the sample, it can be obtained that the maximum tensile strength of the sample is about 6.40MPa.

[0075] Embodiment 5 This embodiment, based on Example 1, provides a method for continuously preparing a thin-walled PTFE medical catheter based on electrostatic adsorption, comprising the following steps; S1, equipment adjustment and core wire layout; In this embodiment, the method for adjusting the equipment and laying out the core wires includes the following steps: The centers of the tensioning mechanism 20, the sintering mechanism 40 and the traction mechanism 50 are adjusted to be located on the same horizontal line, and a guide roller is provided between the core wire feeding mechanism 10 and the tensioning mechanism 20, and the guide roller is used to make the center of the unwound metal core wire and the center of the tensioning mechanism 20 located in the same vertical plane; S12, adjusting the distances between the tensioning mechanism 20 and the sintering mechanism 40 and between the sintering mechanism 40 and the traction mechanism 50 to be 1 m and 2 m respectively, and arranging the electrostatic powder spraying mechanism 30 between the tensioning mechanism 20 and the sintering mechanism 40; S13, adjusting the tensioning force of the tensioning mechanism 20 on the core wire, the adjustment range of the tensioning force is 1N-100N; In this embodiment, the tensioning force of the tensioning mechanism 20 on the core wire is 5N.

[0076] S14, adjusting the pulling speed of the pulling mechanism 50 on the core wire, the adjustment range of the pulling speed is 0.01m / min-2m / min.

[0077] In this embodiment, the pulling speed of the pulling mechanism 50 on the core wire is 0.5 m / min.

[0078] In this embodiment, the surface roughness Ra of the core wire is 0.2 μm, the diameter d is 0.1 mm, the diameter error is ±0.02 mm, and the material is silver-plated copper.

[0079] S2, catheter material powder processing, the catheter material powder is processed, and the processed catheter material powder is added into the fluidized powder cylinder 31; In this embodiment, the method for processing the catheter material powder is: Select catheter material powder in a specific heat preservation environment of 10° C., use a 1250-mesh screen to remove lumps in the powder, obtain fine powder with a maximum particle size of 10 μm, and add the sieved catheter material powder into the fluidized powder cylinder 31; S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun 32, and coating the charged catheter material powder onto the core wire surface; In this embodiment, the method of electrostatically treating the catheter material powder by the electrostatic powder spray gun 32 is as follows: the charge density of the catheter material powder carrying negative charges should be controlled at 17.99 C / m3.

[0080] The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun 32 comprises the following steps; S31, make the nozzle of electrostatic powder spray gun 32 20mm away from the outer surface of the core wire, and adjust the air pressure of the spray gun to 0.1MPa; S32, the spray gun adopts rotary spraying to the core wire, that is, the spray gun nozzle is aligned with the core wire along the radial direction of the metal core wire in a fixed vertical plane and rotates around the axis of the metal core wire.

[0081] S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism 40 for sintering to form a core wire with a continuous catheter material coated on the surface; In this embodiment, the method of sintering the core wire coated with the catheter material powder by the sintering mechanism 40 is: sintering by a sintering furnace, and the sintering temperature is 400°C.

[0082] S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

[0083] In this embodiment, the method for cooling the core wire whose surface is covered with the continuous catheter material after sintering is as follows: cooling the core wire whose surface is covered with the continuous catheter material after sintering step by step in an air bath at 300°C, 250°C, 150°C and 25°C, cutting it to a fixed length according to actual use requirements, and forming a PTFE medical catheter with an inner diameter of 0.1mm±0.02mm and a certain wall thickness after stripping the metal core wire.

[0084] In this embodiment, the PTFE medical catheter obtained by the above method needs to be subjected to a performance test, and the method of the performance test is: Randomly intercept 10 PTFE medical catheters with a length of 1000 mm for performance testing, find 6 points as evenly as possible within the entire length of each catheter to measure the outer diameter D0, calculate the average outer diameter D, and calculate the catheter wall thickness Td, use the outer diameter deviation (outer diameter D0 at the measuring point-outer diameter average value D) and the outer diameter variance (the average of the square of the outer diameter deviation) to calculate the outer diameter standard deviation (the square root of the outer diameter variance), divide the outer diameter standard deviation by the average outer diameter D to obtain the outer diameter variation coefficient CVD of a single catheter, and calculate the arithmetic mean of the outer diameter variation coefficient CVD of the 10 catheters as the outer diameter variation coefficient value CV of the catheter in the same embodiment. The outer diameter and wall thickness of the catheter are imaged on a computer using an optical microscope for calibration measurement, and the arithmetic mean is calculated.

[0085] The experimental results show that the inner diameter of the PTFE medical catheter prepared in this example is 0.1±0.02 mm, the wall thickness is 0.05±0.008 mm, and the coefficient of variation of the outer diameter is 0.00154 mm / mm.

[0086] The same parameters as those in this embodiment are set to simulate the electrostatic adsorption process. The physical model of the electrostatic spraying powder obtained by modeling is as follows: Figure 2 shown.

[0087] Based on the above model, the electrostatic field voltage is set to -85kv, and the voltage distribution in the model area can be obtained as follows: Fig.18 As shown, it can be seen from the cloud diagram that the farther the distance from the electrostatic generator, the smaller the voltage, and the voltage at the farthest point is reduced to -10.1kv; in addition, this embodiment sets the electrostatic nozzle to be 20mm away from the metal core wire. At this time, the electrostatic field voltage of the metal core wire directly below the electrostatic nozzle is about -24.1kv.

[0088] PTFE fine powder Fig.18 After being electrostatically treated in the electrostatic field, it is ejected to form Fig.19 The particle motion traces and Fig. 20 From the particle distribution cloud diagram shown, it can be seen that the maximum speed of the particles during the spraying process is 7.16m / s. However, as the particles leave the spray gun nozzle, the particles are affected by air resistance and their speed rapidly decreases to 0. They are dispersed in the air to form a group of PTFE dispersed particles with static electricity.

[0089] Under the action of static electricity, as the PTFE particles continue to deposit, they eventually form Fig.21 The powder deposition thickness cloud map shown in the figure shows that the maximum thickness of the PTFE powder after electrostatic deposition is 78.9μm, and the powder deposition thickness in most areas is distributed in the range of 23.7μm-71.0μm.

[0090] During the experiment, the PTFE powder was sintered to form a metal core wire with a PTFE tube on the surface. After the metal core wire was peeled off, a PTFE hollow tube was obtained. Samples with a width of 0.1 mm and a thickness of 0.05 mm were cut for mechanical property testing, and the results were as follows: Fig. 22 From the force value versus strain curve shown, it can be seen that the maximum tensile force of the sample reaches 0.0125N. Based on this, according to the calculation formula of tensile strength σ=F / S, where F is the maximum tensile force and S is the cross-sectional area of ​​the sample, it can be obtained that the maximum tensile strength of the sample is about 2.5MPa.

[0091] The continuous preparation method of thin-walled PTFE medical catheter based on the electrostatic adsorption principle provided by the present invention has at least the following beneficial effects: (1) No dispersion liquid or processing aid is required: The processing aid in the paste extrusion method is generally a petroleum-based organic solvent with an initial boiling point of 150℃-250℃. Its main purpose is to increase the adhesion between PTFE powders and make the powders easier to compress into preforms; while the dispersion liquid used in the impregnation method is a solution with a lower boiling point, which is mainly used to disperse PTFE powders to form a suspension, making it easier to adhere to the surface of the metal core wire. Whether it is a dispersion liquid or a processing aid, it needs to be evaporated / volatized by using drying equipment in the subsequent processing process, which not only increases the equipment cost, but also increases the preparation process and creates the risk of environmental pollution. One of the advantages of the present invention is that it does not require dispersion liquid and processing aids, but uses an electrostatic powder spraying device to make the PTFE powder carry negative charge. After being sprayed out by a spray gun, it is adsorbed on the surface of the metal core wire based on the principle of electrostatic adsorption. The powder adsorption thickness can be controlled by the amount of charge carried by the powder, the distance between the spray gun and the metal core wire, the position of the spray gun, and the travel speed of the metal core wire. This method is convenient for thickness control. At the same time, since no dispersion liquid is used, the problem of defects such as pinholes in the process of removing the dispersion liquid is effectively avoided, and the prepared medical catheter has better surface quality and better performance.

[0092] (2) Simple equipment, low cost, short process flow, and easy control: The method used in the present invention does not require the removal of processing aids and dispersion liquids, so there is no need for a drying process and its equipment cost investment. At the same time, compared with the paste extrusion method, there is no need for a step-by-step molding process of first extruding a preform and then extruding a thin-walled tube for a second time. Instead, during the tensioning and pulling process of the metal core wire, the PTFE powder is electrostatically adsorbed and then sintered, and then multi-stage cooled for continuous molding. There are fewer molding steps. During the molding process, only process parameters such as the metal core wire travel speed and the amount of charge carried by the powder need to be controlled to adjust the wall thickness of the medical catheter. The catheter wall thickness is easy to control and the process is simpler.

[0093] (3) Wider applicability and a wider range of formed catheter wall thickness: The paste extrusion method is difficult to prepare small-diameter thin-walled catheters (minimum wall thickness is about 0.03 mm); the impregnation sintering method is affected by the volatile dispersion liquid, and pinhole defects are very likely to appear on the catheter surface and the catheter strength is low. The present invention uses a method of electrostatically adsorbing PTFE powder on the surface of a metal core wire and then sintering it: the outer diameter of the metal core wire determines the inner diameter of the catheter, and the process parameters such as the charge carried by the powder and the travel speed of the metal core wire determine the thickness of the sprayed powder and the wall thickness of the formed catheter. The method described in the present invention can be used to form a PTFE medical catheter with an inner diameter of 0.2 mm to 8 mm and a wall thickness of 0.005 mm to 0.15 mm, with no pinhole defects on the surface and high strength.

[0094] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0095] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A continuous preparation system for thin-walled PTFE medical catheters based on electrostatic adsorption, characterized in that: It comprises a core wire feeding mechanism (10), a tensioning mechanism (20), a sintering mechanism (40) and a pulling mechanism (50) which are arranged in sequence; An electrostatic powder spraying mechanism (30) is also provided between the tensioning mechanism (20) and the sintering mechanism (40), and the electrostatic powder spraying mechanism (30) is used to coat the catheter material powder on the surface of the core wire; Under the guidance of the traction mechanism (50), the core wire passes through the tensioning mechanism (20), the electrostatic powder spraying mechanism (30) and the sintering mechanism (40) in sequence.

2. The continuous preparation system of thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 1, characterized in that: The electrostatic powder spraying mechanism (30) comprises a fluidized powder barrel (31) and an electrostatic powder spray gun (32); The fluidized powder cylinder (31) is used to store catheter material powder, and the electrostatic powder spray gun (32) is used to electrostatically process the catheter material powder and to coat the charged catheter material powder onto the surface of the core wire.

3. The continuous preparation system of thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 1, characterized in that: The catheter material powder is a homopolymer of tetrafluoroethylene or modified tetrafluoroethylene; The modified tetrafluoroethylene is a polymer of tetrafluoroethylene and other monomers; The other monomers include chlorotrifluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether.

4. The continuous preparation system of thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 1, characterized in that: The core wire material is silver-plated copper, stainless steel, nickel alloy, iron alloy or silver alloy; The surface roughness of the core wire Ra≤0.4μm, and the diameter error d≤0.005mm.

5. A method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption, characterized in that: The continuous preparation system according to any one of claims 1 to 4 is used to continuously prepare thin-walled PTFE medical catheters, comprising the following steps: S1, equipment adjustment and core wire layout; S2, treating the catheter material powder, treating the catheter material powder, and adding the treated catheter material powder into the fluidized powder cylinder (31); S3, electrostatic spraying, electrostatically treating the catheter material powder by an electrostatic powder spray gun (32), and coating the charged catheter material powder onto the core wire surface; S4, sintering and forming, the core wire coated with the catheter material powder enters the sintering mechanism (40) for sintering to form a core wire with a surface coated with a continuous catheter material; S5, cooling and cutting, cooling the core wire whose surface is covered with the continuous catheter material after sintering, cutting it to a fixed length after cooling, stripping the core wire, and forming a catheter.

6. The method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 5, characterized in that: The method for adjusting the equipment and laying out the core wire in S1 includes the following steps: S11, adjusting the centers of the tensioning mechanism (20), the sintering mechanism (40) and the traction mechanism (50) to be located on the same horizontal line, and providing an introduction roller between the core wire feeding mechanism and the tensioning mechanism (20), the introduction roller being used to ensure that the center of the unwound metal core wire and the center of the tensioning mechanism (20) are located on the same vertical plane; S12, adjusting the distance between the tensioning mechanism (20) and the sintering mechanism (40) and the distance between the sintering mechanism (40) and the traction mechanism (50), and arranging an electrostatic powder spraying mechanism (30) between the tensioning mechanism (20) and the sintering mechanism (40); S13, adjusting the tensioning force of the tensioning mechanism (20) on the core wire, wherein the adjustment range of the tensioning force is 1N-100N; S14, adjusting the pulling speed of the pulling mechanism (50) on the core wire, wherein the adjustment range of the pulling speed is 0.01 m / min-2 m / min.

7. The method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 5, characterized in that: The method for processing the catheter material powder in S2 is: Selecting catheter material powder in a specific heat preservation environment, using a screen to remove lumps in the powder, and adding the sieved catheter material powder into a fluidized powder cylinder (31); The particle size of the catheter material powder is 0.05 μm-50 μm.

8. The method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 5, characterized in that: The method of electrostatically treating the catheter material powder by the electrostatic powder spray gun (32) in S3 is as follows: the charge density of the catheter material powder carrying negative charges should be controlled at 1C / m 3 -5000C / m 3 ; The method of applying charged catheter material powder to the core wire surface by an electrostatic powder spray gun (32) in S3 comprises the following steps; S31, the distance between the nozzle of the electrostatic powder spray gun (32) and the outer surface of the core wire is 10 mm-20 mm, and the air pressure of the spray gun is adjusted to 0.1 MPa-0.2 MPa; S32, the spray gun adopts fixed-point spraying or rotary spraying on the core wire.

9. The method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 5, characterized in that: In S4, the sintering mechanism (40) sintered the core wire coated with the catheter material powder by using a sintering furnace at a sintering temperature of 350° C. to 480° C.

10. The method for continuously preparing thin-walled PTFE medical catheters based on electrostatic adsorption according to claim 5, characterized in that: The method for cooling the core wire of the continuous conduit material covered on the surface after sintering in S5 is: cooling the core wire of the continuous conduit material covered on the surface after sintering step by step in an air bath.

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