Continuous etching equipment and continuous etching method for PTFE (Polytetrafluoroethylene) tube

Abstract

The invention discloses PTFE pipe continuous etching equipment and a continuous etching method, and relates to the field of surface treatment equipment of plastic pipelines, and the technical scheme is characterized in that the equipment comprises a conveying mechanism, an etching tank, multistage sealing structures arranged at the inlet and outlet ends of the etching tank, a neutralization cleaning unit, a drying unit, a tail gas treatment unit and a control system. The etching groove is filled with sodium-naphthalene etching liquid, and inert gas is introduced to maintain a positive pressure environment; the sealing structure comprises at least three stages of sealing units which are arranged in series, the pressure of each stage of air chamber is positive pressure, neutral pressure and negative pressure in sequence from inside to outside, and poison gas is effectively isolated from the outside. According to the equipment, the leakage risk of toxic gas in the etching process can be remarkably reduced while continuous conveying of the PTFE pipe is realized, and the operation safety and the process stability are improved.

Description

Technical Field

[0001] The invention relates to the field of surface treatment equipment for plastic pipes, and in particular to a PTFE pipe continuous etching device and a continuous etching method. Background Art

[0002] Polytetrafluoroethylene (PTFE) is widely used as a sealing, insulating and fluid transport material in the fields of chemical, electronic, and medical due to its excellent chemical inertness and corrosion resistance. In order to improve the adhesion and activity of the PTFE surface, a sodium-naphthalene complex solution is often used in the prior art to chemically etch its surface. This etching solution is extremely corrosive and forms a carbonized layer rich in active groups on the PTFE surface through defluorination, significantly improving the subsequent coating or bonding performance.

[0003] However, the sodium-naphthalene solution is very easy to react with oxygen or water during the preparation and use process: on the one hand, sodium metal will undergo a violent exothermic reaction when it meets water; on the other hand, the sodium-naphthalene complex will quickly oxidize and fail when it meets oxygen, resulting in unstable etching effect. At the same time, if the toxic gas generated during the etching process leaks, it will pose a serious threat to the operating environment and personnel safety. For this reason, the existing etching device usually adopts a closed tank body, and continuously introduces nitrogen to establish an overpressure environment in the tank, and uses nitrogen punching to remove oxygen and moisture to maintain the activity and stability of the etching solution. However, during the continuous transportation of the PTFE tube, it is difficult to achieve a completely airtight closure at its inlet and outlet, resulting in the leakage of toxic gases from the tube end when the pressure in the tank is greater than that in the outside world, which not only reduces the safety of the system, but also increases the complexity of subsequent waste gas treatment. Summary of the invention

[0004] The purpose of the present invention is to provide a PTFE tube continuous etching device, which has the advantages of significantly improving etching safety and equipment sealing performance.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A PTFE tube continuous etching device, comprising: A conveying mechanism, used for continuously conveying the PTFE tube to be processed; A sealing structure is arranged at the inlet and outlet of the etching tank, each sealing structure includes at least three sealing units arranged in sequence from the inside to the outside along the conveying direction of the PTFE tube, each sealing unit includes a channel section and an air chamber connected thereto, the air chamber is provided with a gas input channel, an exhaust gas outlet, a pressure sensor and a control valve, and the air chamber pressure of each sealing unit is set to positive pressure, neutral pressure and negative pressure in sequence; The neutralization and cleaning unit, the drying unit and the tail gas treatment unit are sequentially connected to the rear end of the etching tank; The control system is used to coordinate the operation of each unit and adjust the air pressure in the etching tank and the working state of the sealing structure.

[0006] Further configuration: at least one primary sealing unit adopts a magnetic fluid sealing structure, wherein the magnetic fluid is composed of magnetic nanoparticles suspended in a carrier liquid, and a ring magnetic field is formed by a magnetic ring arranged outside the channel section, driving the magnetic fluid to adhere to the surface of the PTFE tube to form a dynamic sealing belt.

[0007] Further configuration: A micro-magnetic array with adjustable magnetic field distribution is arranged on the periphery of the magnetic fluid sealing structure, and the magnetic array includes a plurality of magnetic elements that can independently control the magnetic flux, which is used to dynamically adjust the sealing strength and distribution range of the magnetic fluid under different operating conditions.

[0008] It is further configured that the magnetic fluid of the magnetic fluid sealing structure is composed of 5-15 wt% magnetic nanoparticles suspended in a carrier liquid, and the average particle size of the magnetic nanoparticles is 10-50 nm, and the dynamic viscosity of the magnetic fluid at 20° C. is 50-200 mPa·s.

[0009] It is further configured that at least one primary sealing unit adopts a nitrogen vortex guide structure, the guide structure includes a tangential air inlet hole and a spiral air guide groove, the tangential air inlet hole ejects nitrogen tangentially along the inner wall of the air chamber, and the spiral air guide groove guides the nitrogen to form an annular air curtain around the PTFE tube inside the air chamber.

[0010] It is further configured that the tangential air inlet hole or the spiral air guide groove of the nitrogen vortex guide structure is connected to the control valve through a pipeline, and the control valve is controlled by the control system and is used to adjust the nitrogen flow rate within the range of 0.1-10 L / min to control the vortex intensity of the annular air curtain in real time.

[0011] Further configuration: the third-level sealing unit adopts an annular expansion type sealing layer, which is composed of a high molecular swelling material sensitive to oxygen or water vapor. The annular expansion type sealing layer expands in volume after absorbing oxygen or moisture, and then forms a fitting connection with the inner wall of the channel section of the sealing structure.

[0012] Another object of the present invention is to provide a PTFE tube continuous etching method, using the above-mentioned PTFE tube continuous etching equipment, the method comprises the following steps: Transport: The PTFE tube to be treated is transported to the etching tank through a transport mechanism at a constant speed of 0.5-2 m / min; Etching: The PTFE tube is continuously immersed in a sodium-naphthalene etching solution at a temperature of 20-30°C and a concentration of 5-10% in an etching tank, and nitrogen is introduced into the tank to maintain a positive pressure environment; during the etching process, the PTFE tube passes through the sealing structure provided at the inlet and outlet of the etching tank in turn, and the sealing structure is used to gradedly block oxygen and moisture, and the nitrogen flow rate is maintained at 0.1-10 L / min through a control valve; Neutralization and cleaning: The etched PTFE tube passes through the neutralization tank and multi-stage ultrasonic cleaning tank in sequence to terminate the chemical reaction and remove the residual etching solution; Drying: Dry the cleaned PTFE tube in a hot air drying unit at 80-120℃; Exhaust treatment: The exhaust from all sealing structures and etching tanks is uniformly introduced into the exhaust treatment unit, and is treated by activated carbon adsorption, acid washing or condensation phase transfer adsorption layer before being discharged in compliance with emission standards.

[0013] In summary, the present invention has the following beneficial effects: In the present invention, by respectively setting sealing structures at the inlet and outlet ends of the etching groove, using multiple air chambers arranged in series and the air pressure transitioning step by step, the leakage of toxic gases is greatly reduced without affecting the continuous transportation of the PTFE tube, and oxygen or moisture is prevented from entering. There are air chambers between each level of sealing units of the sealing structure. The first level sealing unit on the outside maintains a slightly negative pressure slightly lower than the atmospheric pressure, which is used to inhale the leaked toxic gas; the second level sealing unit maintains a neutral or slightly positive pressure; the third level sealing unit closest to the etching groove maintains a positive pressure higher than the pressure of the etching groove to ensure that the gas in the groove cannot leak out. Through layer-by-layer isolation and multiple guarantees, the sealing level is improved and dynamic transition is achieved.

[0014] Second, in the present invention, at least one level of sealing unit adopts a magnetic fluid sealing structure. The magnetic fluid can be used to replace the flexible sealing ring and is applied to the sliding sealing section of each level in the multi-stage channel section structure. The magnetic control seal is introduced into the continuous micro-sealing occasion, and the sealing shape is adjusted in combination with the air pressure feedback. The magnetic fluid sealing belt can achieve non-contact high-pressure sealing without increasing mechanical friction. Furthermore, an adjustable micro-magnetic array is arranged outside the sealing channel to automatically adjust the magnetic field strength and distribution according to the operating state to control the sealing state. Dynamic adaptive sealing strength adjustment is achieved; the sealing layer can be automatically tightened or loosened according to the air pressure feedback.

[0015] Third, in the present invention, at least one level of sealing unit adopts a nitrogen vortex guide structure. On the basis of considering the pressure difference, the airflow morphology is intervened, and a guide cavity structure with a spiral or bevel angle is added in each level of the air chamber. When the nitrogen enters, a directional vortex flow is formed instead of a straight line flow, thereby creating an "air curtain" effect, enhancing the barrier effect, disturbing the gas path, increasing the flow resistance of the leaked gas through the path, and further blocking the diffusion of countercurrent gas.

[0016] The nitrogen vortex guide structure changes the flow direction and shape of nitrogen in the sealing structure, forms a spiral vortex airflow around the channel section or in the air chamber, and establishes a positive turbulence barrier in the micro-gap, so that any reverse leakage gas faces the vortex "reaction zone", increasing the difficulty of leakage.

[0017] Fourth, in the present invention, the third-level sealing unit adopts an annular expansion type sealing layer, which is composed of a high molecular swelling material that is sensitive to oxygen or water vapor. When the system loses pressure, leaks, or encounters moisture, it quickly expands to form an emergency seal to prevent the leakage of toxic gases; it can be used as a passive safety protection layer in the multi-stage channel segment sealing system. Enhance the system's fault tolerance and emergency response capabilities; it is suitable for passive protection under extreme working conditions such as power failure and control failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a PTFE tube continuous etching device; Figure 2 is a schematic diagram of the structure of the sealing unit; Figure 3 It is a structural schematic diagram of a magnetic fluid sealing structure; Figure 4 It is a structural schematic diagram of a nitrogen cyclone guide structure; Figure 5 It is a structural schematic diagram of an annular expansion type sealing layer.

[0019] In the figure, 100, a conveying mechanism; 200, an etching tank; 300, a neutralization and cleaning unit; 400, a drying unit; 500, an exhaust gas treatment unit; 600, sealing structure; 601, channel section; 602, air chamber; 603, gas input channel; 604, exhaust gas outlet; 605, control valve; 606, pressure sensor; 700, magnetic fluid sealing structure; 701, magnetic fluid; 702, magnetic ring; 703, micro magnetic array; 800. Nitrogen vortex guide structure; 801. Tangential air inlet hole; 802. Spiral air guide groove; 900. Annular expansion type sealing layer. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] A PTFE tube continuous etching device, such as Figure 1 and Figure 2 As shown, the device sequentially arranges a conveying mechanism 100, an etching tank 200, a neutralization and cleaning unit 300, a drying unit 400 and an exhaust gas treatment unit 500 along a predetermined transmission path, and also includes a control system for adjusting and monitoring the operating status of the above-mentioned units.

[0023] The conveying mechanism 100 is fixedly arranged at the front end of the equipment, and is used to continuously convey the PTFE tube to be processed to the etching tank 200 at a constant speed; the etching tank 200 is arranged behind the conveying mechanism 100 along the conveying direction, and the tank is filled with sodium-naphthalene etching solution, and inert gas is introduced to maintain a positive pressure environment, thereby ensuring the stability of the etching solution and the etching effect.

[0024] like Figure 1 and Figure 2 As shown, it also includes a sealing structure 600 arranged at both ends of the inlet and outlet of the etching tank 200. The sealing structure 600 is arranged on the conveying path of the PTFE tube, and is respectively located on the front and rear sides of the etching tank 200, and is used to maintain the pressure difference between the inside and the outside of the etching tank 200 during the continuous passage of the PTFE tube, and effectively isolate the etching liquid from the external environment to prevent gas leakage and moisture infiltration.

[0025] Each sealing structure 600 is sequentially provided with at least three levels of sealing units along the conveying direction of the PTFE tube, and each sealing unit is sequentially arranged in the axial direction from the etching groove 200 to the outside, and is respectively a first-level sealing unit, a second-level sealing unit and a third-level sealing unit. Each sealing unit includes a cylindrical channel section 601 and an air chamber 602 connected thereto. Each air chamber 602 is respectively provided with a gas input channel 603, an exhaust gas outlet 604, a pressure sensor 606 and a control valve 605, which are used to control the flow and pressure state of the gas in different sealing units. In order to form a stable pressure gradient, the working gas pressure of the air chamber 602 is sequentially set to positive pressure, neutral pressure and negative pressure from the side close to the etching groove 200 to the outside, that is, the first-level sealing unit corresponding to the air chamber 602 is set to positive pressure to prevent the leakage of etching gas; the second level is set to neutral pressure to reduce the pressure difference shock; the third level is set to negative pressure to adsorb the gas that may escape and guide it to the exhaust gas treatment system, thereby realizing the multi-level dynamic isolation and safe transition sealing of the gas. By setting the above-mentioned graded sealing structure 600, even when the PTFE tube is in a state of continuous movement, efficient sealing isolation between the etching area and the external environment can still be achieved.

[0026] The neutralization and cleaning unit 300 is connected to the rear end of the etching tank 200, and is used to remove the etching solution and acidic substances remaining on the tube surface; the drying unit 400 is arranged after the neutralization and cleaning unit 300, and is used to dry the moisture on the surface of the cleaned PTFE tube; the exhaust gas treatment unit 500 is further connected to the drying unit 400, and is used to collect and purify the exhaust gas discharged from the above units to meet environmental protection requirements.

[0027] The control system is electrically connected to the driving device of the conveying mechanism 100, the inert gas supply system of the etching tank 200, the pressure sensors 606 and control valves 605 of the sealing structures at various levels, the neutralization and cleaning unit 300, the drying unit 400 and the exhaust gas treatment unit 500. It coordinates the start and stop sequence of each unit through a programmed logic controller, and automatically adjusts the air pressure in the etching tank 200 and the pressure of the air chambers 602 at various levels of the sealing structure 600 according to the real-time monitored pressure and temperature parameters, so as to achieve stable, efficient and safe operation of the entire process.

[0028] In the sealing structure 600, the "positive pressure level", "neutral pressure level" and "negative pressure level" of the three-level sealing unit are all gauge pressures relative to the external ambient atmospheric pressure, and the specific numerical ranges are preferably as follows: The positive pressure level air chamber 602 preferably maintains the pressure in the air chamber 602 within the range of (+50 Pa to +200 Pa) to form a pressure gradient pointing outward to prevent external air and moisture from entering the etching area. The neutral pressure level air chamber 602 preferably controls the pressure in the air chamber 602 within the range of (–10 Pa to +10 Pa) to make it basically balanced with the ambient pressure, thereby reducing the lateral pressure effect on the magnetic fluid 701 seal and the expansion sealing layer. The negative pressure level air chamber 602 preferably maintains the pressure in the air chamber 602 within the range of (–50 Pa to –200 Pa) to generate a negative pressure gradient pointing inward, further attracting and removing possible overflowing gas, and ensuring that all leaked gas is safely directed to the exhaust gas treatment unit 500.

[0029] On the basis of the above implementation manner, as a further limited implementation manner, Figure 2 and Figure 3 As shown, at least one primary sealing unit adopts a magnetic fluid sealing structure 700 to achieve non-contact flexible sealing of the PTFE tube. The magnetic fluid sealing structure 700 is arranged in the channel section 601 of the sealing unit. The magnetic fluid 701 is composed of 5 to 15 wt% magnetic nanoparticles suspended in a carrier liquid. The average particle size of the magnetic nanoparticles is 10 to 50 nm. The dynamic viscosity range of the magnetic fluid 701 at room temperature (20°C) is 50 to 200 mPa·s, so that it has good fluidity and magnetic response performance.

[0030] A magnetic ring 702 is disposed on the periphery of the magnetic fluid sealing structure 700, and the magnetic ring 702 is disposed around the outer wall of the channel section 601 to form a stable annular magnetic field. The magnetic field acts on the magnetic fluid 701, so that it is driven by magnetic force to fit closely to the outer surface of the PTFE tube, thereby forming a continuous dynamic sealing belt along its circumference to effectively block the leakage of gas and liquid inside the etching tank 200.

[0031] In order to further improve the sealing effect of the magnetic fluid 701 and adapt to the sealing requirements under different operating conditions, a micro magnetic array 703 with adjustable magnetic field distribution is also provided on the outside of the magnetic ring 702. The magnetic array includes a plurality of magnetic elements arranged at intervals along the sealing direction, and each magnetic element can independently adjust its magnetic flux intensity. Through the fine control of each magnetic element, the magnetic field distribution of the magnetic fluid sealing structure 700 can be dynamically adjusted under different working conditions, thereby realizing the precise control of the sealing strength and the sealing area range, and further improving the adaptability of the sealing unit to the PTFE tube and the stability of the sealing performance.

[0032] In this embodiment, the magnetic fluid sealing structure 700 is located in the first-stage sealing unit. As an alternative embodiment, the magnetic fluid sealing structure 700 is located in the second-stage sealing unit.

[0033] On the basis of the above implementation manner, as a further limited implementation manner, Figure 2 and Figure 4 As shown, at least one primary sealing unit adopts a nitrogen vortex guide structure 800, which is arranged in a coordinated manner along the radial and circumferential directions: a tangential air inlet hole 801 is opened on the side wall of the air chamber 602, and its nozzle is tangentially toward the inner wall of the air chamber 602, which is used to eject the nitrogen introduced through the pipeline at a high speed in a tangential direction; a spiral air guide groove 802 is arranged to extend in a spiral shape along the inner wall of the air chamber 602, and its opening faces the center of the air chamber 602, which is used to receive and guide the tangentially ejected nitrogen, so that the nitrogen forms a circle of continuous annular air curtain along the outer surface of the PTFE tube inside the air chamber 602, thereby enhancing the gas isolation effect on the circumference of the pipeline under the action of the vortex.

[0034] The tangential air inlet hole 801 and the spiral air guide groove 802 are respectively connected to the control valve 605 located outside the sealing structure through pipelines. The control valve 605 is controlled by the control system and connected to the control system through electrical or signal lines. The control system adjusts the control valve 605 according to the real-time monitored pressure and flow parameters of the air chamber 602 to stably adjust the nitrogen flow rate within the range of 0.1 to 10 L / min, thereby accurately controlling the vortex intensity and distribution range of the annular air curtain to meet the sealing requirements of the sealing structure for gas and liquid leakage under different working conditions.

[0035] In this embodiment, the nitrogen cyclone guide structure 800 is located in the first-stage sealing unit. As an alternative embodiment, the nitrogen cyclone guide structure 800 is located in the second-stage sealing unit.

[0036] On the basis of the above implementation manner, as a further limited implementation manner, Figure 2 and Figure 5 As shown, the third-level sealing unit adopts an annular expansion type sealing layer 900, which is continuously arranged along the outer wall of the outer sealing unit and fixedly connected to the outer surface of the outer sealing unit by directly fitting. The expansion type sealing layer is composed of a high molecular swelling material that is highly sensitive to oxygen or water vapor; when it absorbs oxygen or water vapor in the external environment, the volume of the material expands rapidly, causing the sealing layer to be pressed inward against the outer wall of the outer sealing unit, forming a tightly fitting connection interface, thereby further improving the sealing structure's barrier performance against gas and liquid leakage.

[0037] Furthermore, the polymer swelling material used in the annular expansion sealing layer 900 preferably has the following characteristics: under the conditions of 20-25°C room temperature and relative humidity of about 50%, the water absorption or oxygen absorption rate is less than 5 min, the swelling ratio can reach 10-100 times, and it can still maintain a certain mechanical strength and chemical corrosion resistance under saturated state. The polymer swelling material can preferably be: sodium polyacrylate-acrylamide copolymer super absorbent resin: it is copolymerized with sodium acrylate and acrylamide in a molar ratio of 1:0.1-1, and cross-linked with N,N′-ethylenebisacrylamide, and has a high water absorption ratio of more than 50 times and good chemical stability. As an alternative embodiment, the polymer swelling material is a cross-linked polyvinyl alcohol (PVA) hydrogel, which is mainly composed of PVA, and is cross-linked by a cross-linking agent such as boric acid or glutaraldehyde to form a three-dimensional network structure, which is sensitive to water vapor and can maintain a certain elasticity after swelling. As an alternative embodiment, the polymer swelling material is modified bentonite, and natural bentonite is modified with organic cations to improve the adsorption and swelling capacity of polar molecules, and can further fill tiny gaps in a wet state. As an alternative embodiment, the polymer swelling material is a sodium alginate-based water-absorbing material: sodium alginate and calcium salt ions are cross-linked to construct a Joule network, which has both biodegradability and good swelling properties. As an alternative embodiment, the polymer swelling material is silane-modified silica, and hydrophilic groups are introduced on the surface of silica through a silane coupling agent to form nano-scale water-absorbing particles that can expand rapidly in a trace moisture environment.

[0038] This embodiment also provides a PTFE tube continuous etching method, using the above-mentioned PTFE tube continuous etching equipment, the method comprises the following steps: Transport: The PTFE tube to be processed is transported to the etching tank 200 through the transport mechanism 100 at a constant speed of 0.5-2 m / min; Etching: The PTFE tube is continuously immersed in a sodium-naphthalene etching solution at a temperature of 20-30°C and a concentration of 5-10% in the etching tank 200, and nitrogen is introduced into the tank to maintain a positive pressure environment; during the etching process, the PTFE tube passes through the sealing structure provided at the inlet and outlet of the etching tank 200 in turn, and the sealing structure is used to gradedly block oxygen and moisture, and the nitrogen flow rate is maintained at 0.1-10 L / min through the control valve 605; Neutralization and cleaning: The etched PTFE tube passes through the neutralization tank and multi-stage ultrasonic cleaning tank in sequence to terminate the chemical reaction and remove the residual etching solution; Drying: Dry the cleaned PTFE tube in a hot air drying unit at 80~120℃; Tail gas treatment: The tail gas from all sealing structures and etching tanks 200 is uniformly introduced into the tail gas treatment unit, and is discharged after being treated by activated carbon adsorption, acid washing or condensation phase transfer adsorption layer to meet the emission standards.

[0039] The above-mentioned embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A PTFE tube continuous etching device, characterized in that: include: A conveying mechanism (100) is used to continuously convey the PTFE tube to be processed; The etching tank (200) is located on the transmission path of the PTFE tube, and the etching tank (200) is filled with sodium-naphthalene etching solution and an inert gas is introduced to maintain a positive pressure environment; A sealing structure (600) is arranged at the inlet and outlet of the etching tank (200), each sealing structure (600) comprises at least three levels of sealing units arranged in sequence from the inside to the outside along the conveying direction of the PTFE tube, each sealing unit comprises a channel section (601) and an air chamber (602) connected thereto, the air chamber (602) is provided with a gas input channel (603), an exhaust gas outlet (604), a pressure sensor (606) and a control valve (605), and the air chamber pressure of each sealing unit is set to positive pressure, neutral pressure and negative pressure in sequence; A neutralization and cleaning unit (300), a drying unit (400) and an exhaust gas treatment unit (500) are sequentially connected to the rear end of the etching tank (200); The control system is used to coordinate the operation of each unit and adjust the air pressure in the etching tank (200) and the working state of the sealing structure.

2. The PTFE tube continuous etching equipment according to claim 1, characterized in that: At least one primary sealing unit adopts a magnetic fluid sealing structure (700), wherein the magnetic fluid (701) is composed of magnetic nanoparticles suspended in a carrier liquid, and a magnetic ring (702) arranged outside the channel section (601) forms an annular magnetic field, driving the magnetic fluid (701) to adhere to the surface of the PTFE tube to form a dynamic sealing belt.

3. The PTFE tube continuous etching equipment according to claim 2, characterized in that: A micro-magnetic array (703) capable of adjusting magnetic field distribution is disposed on the periphery of the magnetic fluid sealing structure (700); the magnetic array comprises a plurality of magnetic elements capable of independently controlling magnetic flux, and is used to dynamically adjust the sealing strength and distribution range of the magnetic fluid (701) under different operating conditions.

4. The PTFE tube continuous etching equipment according to claim 2, characterized in that: The magnetic fluid (701) of the magnetic fluid sealing structure (700) is composed of 5-15 wt% of magnetic nanoparticles suspended in a carrier liquid, and the average particle size of the magnetic nanoparticles is 10-50 nm. The dynamic viscosity of the magnetic fluid (701) at 20° C. is 50-200 mPa·s.

5. The PTFE tube continuous etching equipment according to claim 1, characterized in that: At least one primary sealing unit adopts a nitrogen vortex guide structure (800), wherein the guide structure comprises a tangential air inlet hole (801) and a spiral air guide groove (802), wherein the tangential air inlet hole (801) ejects nitrogen tangentially along the inner wall of the air chamber (602), and the spiral air guide groove (802) guides the nitrogen to form an annular air curtain surrounding the PTFE tube inside the air chamber (602).

6. The PTFE tube continuous etching equipment according to claim 5, characterized in that: The tangential air inlet (801) or the spiral air guide groove (802) of the nitrogen vortex guide structure (800) is connected to the control valve (605) through a pipeline. The control valve (605) is controlled by the control system and is used to adjust the nitrogen flow rate within the range of 0.1-10 L / min to control the vortex intensity of the annular air curtain in real time.

7. The PTFE tube continuous etching equipment according to claim 1, characterized in that: The third-level sealing unit adopts an annular expansion type sealing layer (900), which is composed of a high molecular swelling material that is sensitive to oxygen or water vapor. After absorbing oxygen or water, the annular expansion type sealing layer (900) expands in volume, thereby forming a fitting connection with the inner wall of the channel section (601) of the sealing structure (600).

8. A PTFE tube continuous etching method, characterized in that: Using the PTFE tube continuous etching device according to any one of claims 1 to 7, the method comprises the following steps: Transport: The PTFE tube to be processed is transported to the etching tank (200) through the transport mechanism (100) at a constant speed of 0.5-2 m / min; Etching: the PTFE tube is continuously immersed in a sodium-naphthalene etching solution at a temperature of 20-30° C. and a concentration of 5-10% in an etching tank (200), and nitrogen is introduced into the tank to maintain a positive pressure environment; wherein, during the etching process, the PTFE tube successively passes through the sealing structures provided at the inlet and outlet of the etching tank (200), and the sealing structures are used to gradedly block oxygen and moisture, and the nitrogen flow rate is maintained at 0.1-10 L / min through a control valve (605); Neutralization and cleaning: The etched PTFE tube passes through the neutralization tank and multi-stage ultrasonic cleaning tank in sequence to terminate the chemical reaction and remove the residual etching solution; Drying: Dry the cleaned PTFE tube in a hot air drying unit at 80-120℃; Tail gas treatment: Tail gases from all sealing structures and etching tanks (200) are uniformly introduced into the tail gas treatment unit, and are treated by activated carbon adsorption, acid washing or condensation phase transfer adsorption layer before being discharged in compliance with the emission standards.

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