A kind of anticorrosion inner coating spraying device and method for producing medicinal aluminum tube

Abstract

The application discloses an anti-corrosion inner coating spraying device and method for producing medicinal aluminum pipes, and relates to the technical field of packaging material production. Under the condition of setting ultrasonic assistance, the inner wall of the aluminum pipe is treated by low-temperature oxygen plasma to introduce active groups, and then vaporized silane coupling agent is introduced. Under the action of plasma afterglow, an organic-inorganic hybrid transition layer is constructed in situ on the inner surface of the aluminum pipe. Fluorine-containing polymer coating is dissolved to form a coating fluid, which is injected into the aluminum pipe treated by step 1 in the form of pulses, and the coating is wet-spread by using the characteristics of supercritical fluid. The organic-inorganic hybrid transition layer is constructed by ultrasonic-assisted plasma treatment, which enhances the adhesion between the coating and the aluminum pipe substrate and avoids the peeling of the coating. By using the supercritical fluid pulse spraying technology, uniform deposition of the fluorine-containing polymer coating is realized, the coating density is improved, the contact between corrosive substances and the aluminum substrate is effectively blocked, and the anti-corrosion effect is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of packaging material production technology, and in particular to an anti-corrosion inner coating spraying device and method for the production of pharmaceutical aluminum tubes. Background Technology

[0002] Pharmaceutical aluminum tubing is widely used in the packaging of pharmaceutical products such as ointments, gels, and oral liquids due to its excellent barrier properties, ductility, and environmental friendliness. The inner wall of the aluminum tubing comes into direct contact with the medicine, whose complex composition, including some containing corrosive substances such as acids, alkalis, and alcohols, can easily react chemically with the aluminum substrate. This can lead to corrosion and damage to the inner wall of the aluminum tubing, affecting its lifespan and potentially allowing corrosion products to contaminate the medicine, compromising the stability of its components and posing a safety hazard.

[0003] Currently, the corrosion protection of the inner wall of pharmaceutical aluminum tubes mostly adopts conventional spraying processes, which form a protective layer by applying polymer coatings. However, conventional processes have problems such as weak adhesion between the coating and the aluminum substrate, uneven coating, and insufficient coating density. After long-term contact with corrosive drugs, coating peeling and cracking are prone to occur, which cannot meet the high safety and long-term corrosion protection requirements of pharmaceutical packaging. At the same time, existing spraying processes mostly rely on solvent-based coatings, and solvent evaporation can easily cause environmental pollution. Moreover, defects such as bubbles and pinholes are prone to occur during the coating curing process, further reducing the corrosion protection effect and making it difficult to meet the stringent usage standards of pharmaceutical aluminum tubes. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides an anti-corrosion inner coating spraying device and method for the production of pharmaceutical aluminum tubes. The technical solution is as follows:

[0005] A method for applying an anti-corrosion inner coating to pharmaceutical aluminum tubes includes the following steps:

[0006] Step 1: Under the setting of ultrasonic assistance, the inner wall of aluminum tube 1 is treated with low temperature oxygen plasma to introduce active groups. Then, vaporized silane coupling agent is introduced. Under the action of plasma afterglow, an organic-inorganic hybrid transition layer is constructed in situ on the inner surface of the aluminum tube.

[0007] Step 2: Dissolve the fluoropolymer coating to form a coating fluid, and inject the coating fluid into the aluminum tube 1 after step 1 in a pulsed manner. Utilize the characteristics of supercritical fluid to wet and spread the coating. By rapidly depressurizing at a set speed, carbon dioxide is vaporized and separated, and a fluoropolymer coating is uniformly deposited on the organic-inorganic hybrid transition layer.

[0008] Step 3: Place the aluminum tube 1 coated in Step 2 under vacuum conditions and perform a gradient heating program containing at least three temperature levels to sequentially complete degassing, sintering and annealing to form a dense anti-corrosion inner coating.

[0009] Optionally, step 1 includes the following sub-steps:

[0010] Step 101: Clamp the aluminum tube 1 onto the rotating fixture 2, and drive the aluminum tube 1 at a first preset speed. Rotate;

[0011] Step 102: Activate the ultrasonic transducer 3 coupled to the outer wall of the aluminum tube 1, and simultaneously introduce oxygen into the inner cavity of the aluminum tube 1 through the inner spray rod 4. Activate the low-temperature plasma generator 5 to generate an oxygen plasma jet to activate the inner surface for a first preset time. ;

[0012] Step 103: Stop the plasma discharge and heat the silane coupling agent to the vaporization temperature using vaporizer 6. The plasma is carried into the inner cavity of aluminum tube 1 by a carrier gas, and a silanization grafting reaction is carried out for a second preset time using plasma afterglow and activated hydroxyl groups on the surface. This forms an organic-inorganic hybrid transition layer;

[0013] Step 104: Purge with inert gas to remove unreacted residues.

[0014] Optionally, step 2 includes the following sub-steps:

[0015] Step 201: In the supercritical fluid generator 7, the temperature and pressure of carbon dioxide are adjusted to a supercritical state and mixed with fluoropolymer coating to form a homogeneous coating fluid.

[0016] Step 202: The control unit 8 calculates the pulse parameters based on the inner diameter D and length L of the aluminum tube 1, and instructs the pulse injection valve 9 to open at a preset frequency f and duty cycle Dc, so that the coating fluid is injected in a pulse form through the micro-atomizing nozzle 10 located at the end of the inner spray rod 4. At this time, the basic negative pressure established by the vacuum system 11 is maintained inside the aluminum tube. ;

[0017] Step 203: During each pulse interval, control the three-way valve to switch instantaneously, causing the internal pressure of aluminum tube 1 to drop sharply from the high pressure during coating fluid injection to the basic negative pressure. This process allows carbon dioxide to be completely vaporized and captured by a carbon dioxide recovery device, while fluoropolymers are released and deposited on the inner wall.

[0018] Step 204: Based on the target coating thickness, repeat steps 202 to 203 to complete the coating process for multiple pulse cycles.

[0019] Optionally, step 3 includes the following sub-steps:

[0020] Step 301: Activate vacuum system 11 to maintain a preset vacuum level inside aluminum tube 1. ;

[0021] Step 302: Control the heating device 14 to heat up to the first temperature. And maintain the third preset duration To remove residual solvents and gases from the coating;

[0022] Step 303, continue heating to the second temperature. And maintain the fourth preset duration ,in The melting point is higher than that of fluoropolymers, allowing the melt to flow level and crosslink with the organic-inorganic hybrid transition layer;

[0023] Step 304, continue heating to the third temperature. And maintain the fifth preset duration The coating is subjected to annealing and densification treatment, wherein ;

[0024] Step 305: After the program is completed, stop heating and allow the furnace to cool slowly to room temperature in a vacuum or inert atmosphere.

[0025] Optionally, the silane coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; the fluoropolymer coating is a nanoscale powder dispersion of one or more of polytetrafluoroethylene, perfluoroethylene propylene, or fusible polytetrafluoroethylene.

[0026] Optionally, the method by which control unit 8 calculates pulse parameters follows a closed-loop feedback control model: based on the actual coating thickness obtained from online monitoring and the preset target thickness. To compensate for the deviation, the pulse frequency f and the number of cycles N are dynamically adjusted.

[0027] Optionally, the organic-inorganic hybrid transition layer constructed in step 1 has a thickness of 50nm-200nm. One end of the organic-inorganic hybrid transition layer is anchored to the aluminum substrate by chemical bonds, and the other end has active functional groups that can react or strongly interact with fluoropolymers.

[0028] A corrosion-resistant inner coating spraying device for the production of pharmaceutical aluminum tubes is used to realize a method for spraying a corrosion-resistant inner coating for the production of pharmaceutical aluminum tubes. The device includes a rotary clamping fixture 2, an inner spray bar 4, a micro-atomizing nozzle 10, a spraying integrated module, an ultrasonic transducer 3, a vacuum and recovery system, a heating device 14, and a control unit 8. The rotary clamping fixture 2 is used to fix and drive the aluminum tube 1 to rotate.

[0029] The micro-atomizing nozzle 10 is installed at the end of the inner spray rod 4, and the inner spray rod 4 extends coaxially into the interior of the aluminum tube 1.

[0030] The spraying integrated module is connected to the inner spray bar 4 and includes a low-temperature plasma generator 5, a silane coupling agent vaporizer 6, a supercritical fluid generator 7, and a pulse jet valve 9.

[0031] The ultrasonic transducer 3 is used to provide vibration for the aluminum tube 1;

[0032] The vacuum and recovery system is connected to the other end of aluminum tube 1 via a three-way valve. The vacuum and recovery system includes a vacuum system 11 and a carbon dioxide recovery device.

[0033] Heating device 14 is installed around aluminum tube 1 to control the temperature of aluminum tube 1;

[0034] The control unit 8 is electrically connected to each of the above-mentioned components and is used to coordinate the execution of each step of a method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes.

[0035] Optionally, the supercritical fluid generator 7 has an independent temperature and pressure control module, and its outlet is connected to the pulse jet valve 9; the opening frequency f, duty cycle Dc, and number of openings of the pulse jet valve 9 can all be independently programmed and controlled by the control unit 8.

[0036] Optionally, the control unit 8 has a built-in process parameter database and adaptive control algorithm, used to automatically call and fine-tune at least one of the following parameters according to different specifications of aluminum tubes 1: plasma treatment time. Silanization treatment time Pulse frequency f, number of pulse cycles N, curing temperature of each segment , , And its corresponding duration.

[0037] In summary, the present invention has at least one of the following beneficial technical effects:

[0038] This invention provides a method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes. An organic-inorganic hybrid transition layer is constructed through ultrasonic-assisted plasma treatment, enhancing the adhesion between the coating and the aluminum tube substrate and preventing coating peeling. Supercritical fluid pulse spraying technology achieves uniform deposition of the fluoropolymer coating, improving coating density and effectively preventing corrosive substances from contacting the aluminum substrate, thus significantly improving the anti-corrosion effect.

[0039] The gradient temperature vacuum curing process can remove residual impurities in the coating, promote cross-linking and densification of the coating, further optimize the coating performance, and ensure compliance with pharmaceutical packaging safety standards.

[0040] The entire process is environmentally friendly and efficient, adaptable to the production of pharmaceutical aluminum tubes of different specifications. The equipment has a compact structure and precise control, enabling automated continuous production and improving production efficiency and product consistency. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the anti-corrosion inner coating spraying device for the production of pharmaceutical aluminum tubes according to the present invention;

[0042] Figure 2 This is a schematic diagram of the electrical component connection principle of an anti-corrosion inner coating spraying device for the production of pharmaceutical aluminum tubes according to the present invention;

[0043] Figure 3 This is a schematic flowchart of a method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to the present invention.

[0044] Explanation of reference numerals in the attached drawings: 1. Aluminum tube; 2. Rotary clamping fixture; 3. Ultrasonic transducer; 4. Inner spray bar; 5. Low-temperature plasma generator; 6. Silane coupling agent vaporizer; 7. Supercritical fluid generator; 8. Control unit; 9. Pulse jet valve; 10. Micro-atomizing nozzle; 11. Vacuum system. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the accompanying drawings.

[0046] This invention discloses an anti-corrosion inner coating spraying device and method for the production of pharmaceutical aluminum tubes.

[0047] Reference Figures 1-3 Example 1: A method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes, comprising the following steps:

[0048] Step 1: Under the setting of ultrasonic assistance, the inner wall of aluminum tube 1 is treated with low temperature oxygen plasma to introduce active groups. Then, vaporized silane coupling agent is introduced. Under the action of plasma afterglow, an organic-inorganic hybrid transition layer is constructed in situ on the inner surface of the aluminum tube.

[0049] Step 2: Dissolve the fluoropolymer coating to form a coating fluid, and inject the coating fluid into the aluminum tube 1 after step 1 in a pulsed manner. Utilize the characteristics of supercritical fluid to wet and spread the coating. By rapidly depressurizing at a set speed, carbon dioxide is vaporized and separated, and a fluoropolymer coating is uniformly deposited on the organic-inorganic hybrid transition layer.

[0050] Step 3: Place the aluminum tube 1 coated in Step 2 under vacuum conditions and perform a gradient heating program containing at least three temperature levels to sequentially complete degassing, sintering and annealing to form a dense anti-corrosion inner coating.

[0051] By adopting the above technical solution, in step 1, the rotating clamping fixture 2 clamps the aluminum tube 1, and the ultrasonic transducer 3 applies ultrasonic vibration with a frequency of 20kHz to 40kHz to the outer wall of the aluminum tube 1. The inner spray rod 4 extends into the interior of the aluminum tube 1, and the low-temperature plasma generator 5 introduces oxygen with a purity of 99.9% into the inner cavity of the aluminum tube 1 through the inner spray rod 4. The discharge power is set to 200W to 500W to generate an oxygen plasma jet that treats the inner wall of the aluminum tube 1 for 30 to 120 seconds, causing hydroxyl active groups to be generated on the surface. Subsequently, the plasma discharge is stopped, and the silane coupling agent vaporizer 6 heats γ-aminopropyltriethoxysilane to a vaporization temperature Tvap of 160°C to 200°C. Using high-purity nitrogen as the carrier gas, the vaporized silane coupling agent is sent into the inner cavity of the aluminum tube 1, where it reacts for 60 to 180 seconds under the plasma afterglow and the action of hydroxyl groups, thus constructing an organic-inorganic hybrid transition layer in situ.

[0052] In step 2, the supercritical fluid generator 7 heats carbon dioxide to 40°C to 60°C and pressurizes it to 8MPa to 15MPa to bring it into a supercritical state. Then, a dispersion of polytetrafluoroethylene nanoparticles is added and stirred to form a homogeneous coating fluid. The control unit 8 calculates the opening frequency f of the pulse jet valve 9 to be 2Hz to 5Hz and the duty cycle Dc to be 30% to 60% based on the inner diameter D and length L of the aluminum tube 1. When the pulse jet valve 9 is open, the coating fluid is injected into the aluminum tube 1 in a pulsed manner through the micro-atomizing nozzle 10 at the end of the inner spray rod 4. At this time, the vacuum system 11 maintains a basic negative pressure inside the aluminum tube 1. The pressure ranges from 0.01 MPa to 0.05 MPa. At the end of each pulse, control unit 8 commands the three-way valve to switch, causing the internal pressure of aluminum tube 1 to drop rapidly from above 8 MPa to a basic negative pressure within 0.5 seconds. Carbon dioxide is vaporized and captured by a carbon dioxide recovery device, and polytetrafluoroethylene is precipitated and deposited.

[0053] In step 3, the vacuum system 11 is activated to create a vacuum inside the aluminum tube 1. The pressure reaches 10 Pa to 100 Pa. Heating device 14 raises the temperature to the first temperature at a rate of 3 °C / min. Degas at 120°C to 150°C for 20 to 40 minutes; then increase the temperature to the second temperature at a rate of 2°C / min. Sintering and leveling are carried out at 300℃ to 340℃ for 15 to 30 minutes; then the temperature is increased to the third temperature at a rate of 1.5℃ / min. Annealing and densification are carried out at 360°C to 400°C for 10 to 20 minutes, then heating is stopped and the product is slowly cooled to below 50°C under vacuum before being removed.

[0054] Example 2, step 1 includes the following sub-steps:

[0055] Step 101: Clamp the aluminum tube 1 onto the rotating fixture 2, and drive the aluminum tube 1 at a first preset speed. Rotate;

[0056] Step 102: Activate the ultrasonic transducer 3 coupled to the outer wall of the aluminum tube 1, and simultaneously introduce oxygen into the inner cavity of the aluminum tube 1 through the inner spray rod 4. Activate the low-temperature plasma generator 5 to generate an oxygen plasma jet to activate the inner surface for a first preset time. ;

[0057] Step 103: Stop the plasma discharge and heat the silane coupling agent to the vaporization temperature using vaporizer 6. The plasma is carried into the inner cavity of aluminum tube 1 by a carrier gas, and a silanization grafting reaction is carried out for a second preset time using plasma afterglow and activated hydroxyl groups on the surface. This forms an organic-inorganic hybrid transition layer;

[0058] Step 104: Purge with inert gas to remove unreacted residues.

[0059] By adopting the above technical solution, after the aluminum tube 1 is clamped in the rotating fixture 2, the control unit 8 sets the first preset rotational speed ω1 to 20 rpm to 80 rpm, so that the aluminum tube 1 rotates at a uniform speed. The ultrasonic power of the ultrasonic transducer 3 is 100W to 300W, which acts on the outer wall of the aluminum tube 1 through air coupling. The oxygen flow rate of the low-temperature plasma generator 5 is 0.5L / min to 2L / min, and the first preset duration is... The optimal time is 60 to 90 seconds to ensure full activation of the inner surface. After the plasma discharge stops, vaporizer 6 heats the silane coupling agent to its vaporization temperature. The temperature is 170℃ to 190℃, the carrier gas flow rate is 1L / min to 3L / min, and the second preset time is... The duration is 90 to 150 seconds. The plasma afterglow extends the lifetime of active groups and promotes the self-assembly of silane molecules into a film on the inner wall. Afterwards, pure nitrogen gas is introduced for 120 seconds at a flow rate of 5 L / min to completely remove unreacted silane and the byproduct ethanol.

[0060] Example 3, step 2 includes the following sub-steps:

[0061] Step 201: In the supercritical fluid generator 7, the temperature and pressure of carbon dioxide are adjusted to a supercritical state and mixed with fluoropolymer coating to form a homogeneous coating fluid.

[0062] Step 202: The control unit 8 calculates the pulse parameters based on the inner diameter D and length L of the aluminum tube 1, and instructs the pulse injection valve 9 to open at a preset frequency f and duty cycle Dc, so that the coating fluid is injected in a pulse form through the micro-atomizing nozzle 10 located at the end of the inner spray rod 4. At this time, the basic negative pressure established by the vacuum system 11 is maintained inside the aluminum tube. ;

[0063] Step 203: During each pulse interval, control the three-way valve to switch instantaneously, causing the internal pressure of aluminum tube 1 to drop sharply from the high pressure during coating fluid injection to the basic negative pressure. This process allows carbon dioxide to be completely vaporized and captured by a carbon dioxide recovery device, while fluoropolymers are released and deposited on the inner wall.

[0064] Step 204: Based on the target coating thickness, repeat steps 202 to 203 to complete the coating process for multiple pulse cycles.

[0065] By adopting the above technical solution, the stirrer in the supercritical fluid generator 7 mixes at a speed of 500 rpm to 1000 rpm to ensure uniform dispersion of polytetrafluoroethylene propylene nanoparticles. The pulse injection valve 9 is a fast-response solenoid valve with an opening response time of less than 10 milliseconds. The micro-atomizing nozzle 10 has an orifice diameter of 0.1 mm to 0.3 mm, which is beneficial for the instantaneous atomization of supercritical fluid. In step 202, the control unit 8 calculates according to the model that the volume of coating fluid injected in a single pulse is 10% to 20% of the internal volume of the aluminum tube 1, and combines this with the target coating thickness. The estimated initial frequency f is 3Hz, and the number of pulse cycles N is 5 to 15. In step 203, the switching of the three-way valve is driven by a pneumatic actuator, with a switching time of less than 0.2 seconds, ensuring rapid pressure reduction and separation. The carbon dioxide recovery device contains a cooler and a gas-liquid separator, which condenses and recovers the vaporized carbon dioxide, ensuring that the uniformity deviation of the coating precipitation layer thickness is less than 5%.

[0066] Example 4, step 3 includes the following sub-steps:

[0067] Step 301: Activate vacuum system 11 to maintain a preset vacuum level inside aluminum tube 1. ;

[0068] Step 302: Control the heating device 14 to heat up to the first temperature. And maintain the third preset duration To remove residual solvents and gases from the coating;

[0069] Step 303, continue heating to the second temperature. And maintain the fourth preset duration ,in The melting point is higher than that of fluoropolymers, allowing the melt to flow level and crosslink with the organic-inorganic hybrid transition layer;

[0070] Step 304, continue heating to the third temperature. And maintain the fifth preset duration The coating is subjected to annealing and densification treatment, wherein ;

[0071] Step 305: After the program is completed, stop heating and allow the furnace to cool slowly to room temperature in a vacuum or inert atmosphere.

[0072] By adopting the above technical solution, the preset vacuum degree is achieved. Maintain at 30 Pa to 50 Pa. First temperature. Set to 130℃, third preset duration The treatment lasts for 30 minutes, during which time the main process is to expel trace amounts of carbon dioxide and moisture adsorbed inside the coating. The second temperature... The temperature is set to approximately 310°C to 330°C above the melting point of fusible polytetrafluoroethylene, with a fourth preset duration. For 25 minutes, the coating particles melt and undergo interfacial cross-linking under the action of amino or epoxy groups in the organic-inorganic hybrid transition layer. The third temperature... Set to 380℃ to 400℃, fifth preset duration The cooling period is 15 minutes, which allows the polymer molecular chains to fully relax and densify. During the slow cooling phase in the furnace, the vacuum level is maintained, and the cooling rate is controlled below 2℃ / min until the temperature drops below 80℃ before the vacuum is broken.

[0073] Example 5: The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; the fluoropolymer coating is a nanoscale powder dispersion of one or more of polytetrafluoroethylene, perfluoroethylene propylene, or fusible polytetrafluoroethylene.

[0074] By adopting the above technical solutions, when γ-aminopropyltriethoxysilane is used as the silane coupling agent, its amino groups can form hydrogen bonds or covalent bonds with the carboxyl or sulfonyl fluoride groups in the fluoropolymer coating; when γ-glycidoxypropyltrimethoxysilane is used, its epoxy groups can undergo ring-opening crosslinking during curing. The fluoropolymer coating uses polytetrafluoroethylene nanodispersion with an average particle size of 50 nm to 200 nm and a solid content of 10 wt% to 30 wt%; or perfluoroethylene propylene with a melt index of 10 g / 10 min to 30 g / 10 min; or fusible polytetrafluoroethylene with a melting point of 300 °C to 315 °C. 0.5 wt% to 2 wt% of high-temperature resistant pigments can be added to the coating.

[0075] Example 6: The method by which control unit 8 calculates pulse parameters follows a closed-loop feedback control model: based on the actual coating thickness obtained from online monitoring and the preset target thickness. To compensate for the deviation, the pulse frequency f and the number of cycles N are dynamically adjusted.

[0076] By adopting the above technical solution, the closed-loop feedback control model, relying on a laser confocal displacement sensor installed downstream of the spraying station, can monitor the actual thickness of the coating on the inner wall of the aluminum tube 1 after deposition online. The control unit 8 compares the measured thickness with the preset target thickness. If the deviation exceeds ±2μm, the pulse frequency f is adjusted in 0.5Hz increments. If the upper limit of the pulse frequency adjustment is still not met, the number of pulse cycles N is adjusted by increasing or decreasing it by 1 to 3 cycles. This model uses a PID control algorithm with a sampling period of once per second to ensure that the final coating thickness deviation is within ±3μm.

[0077] Example 7: The organic-inorganic hybrid transition layer constructed in step 1 has a thickness of 50nm-200nm. One end of the organic-inorganic hybrid transition layer is anchored to the aluminum substrate by chemical bonds, and the other end has active functional groups that can react or strongly interact with fluoropolymers.

[0078] By adopting the above technical solution, the thickness of the constructed organic-inorganic hybrid transition layer is controlled between 50nm and 200nm. The bottom layer of this transition layer is chemically anchored to the aluminum substrate through Al-O-Si covalent bonds, while the top layer, with its exposed amino or epoxy groups, reacts chemically with the fluorinated polymer side groups or forms strong intermolecular forces during the sintering stage in step 3. This results in a coating adhesion rating of 5B in the cross-cut adhesion test and no rust or blistering after 1000 hours of salt spray testing.

[0079] Example 8: A corrosion-resistant inner coating spraying device for pharmaceutical aluminum tube production, used to implement a corrosion-resistant inner coating spraying method for pharmaceutical aluminum tube production. The device includes a rotary clamping fixture 2, an inner spray bar 4, a micro-atomizing nozzle 10, a spraying integrated module, an ultrasonic transducer 3, a vacuum and recovery system, a heating device 14, and a control unit 8. The rotary clamping fixture 2 is used to fix and drive the aluminum tube 1 to rotate.

[0080] The micro-atomizing nozzle 10 is installed at the end of the inner spray rod 4, and the inner spray rod 4 extends coaxially into the interior of the aluminum tube 1.

[0081] The spraying integrated module is connected to the inner spray bar 4 and includes a low-temperature plasma generator 5, a silane coupling agent vaporizer 6, a supercritical fluid generator 7, and a pulse jet valve 9.

[0082] The ultrasonic transducer 3 is used to provide vibration for the aluminum tube 1;

[0083] The vacuum and recovery system is connected to the other end of aluminum tube 1 via a three-way valve. The vacuum and recovery system includes a vacuum system 11 and a carbon dioxide recovery device.

[0084] Heating device 14 is installed around aluminum tube 1 to control the temperature of aluminum tube 1;

[0085] The control unit 8 is electrically connected to each of the above-mentioned components and is used to coordinate the execution of each step of a method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes.

[0086] By adopting the above technical solution, the rotary clamping fixture 2 includes a servo motor drive with stepless speed adjustment. The inner spray bar 4 is a stainless steel capillary tube with an outer diameter of 1 / 5 to 1 / 3 of the inner diameter of the aluminum tube 1, and its end is equipped with a micro-atomizing nozzle 10 that can spray radially in 360 degrees. The spraying integrated module integrates the radio frequency power supply of the low-temperature plasma generator 5, the heating jacket of the silane coupling agent vaporizer 6, and the plunger pump of the supercritical fluid generator 7. The ultrasonic transducer 3 is attached to the outer wall of the middle part of the aluminum tube 1 by a bracket. In the vacuum and recovery system, the vacuum system 11 is a rotary vane vacuum pump, and the carbon dioxide recovery device includes a condenser and a storage tank. The heating device 14 is a segmented ceramic infrared heater, uniformly arranged along the axial direction of the aluminum tube 1. The control unit 8 can be a PLC controller with a touch screen.

[0087] Example 9: The supercritical fluid generator 7 has an independent temperature and pressure control module, and its outlet is connected to the pulse jet valve 9; the opening frequency f, duty cycle Dc and opening times of the pulse jet valve 9 can all be independently programmed and controlled by the control unit 8.

[0088] By adopting the above technical solutions, the temperature control module of the supercritical fluid generator 7 uses PID control, and the pressure control module achieves pressure fluctuations of less than ±0.2MPa through a back pressure valve. The pulse jet valve 9 is a piezoelectric ceramic driven type. The control unit 8 can be programmed to set the opening frequency f continuously adjustable from 0.5Hz to 20Hz, the duty cycle Dc adjustable from 10% to 90%, and the number of openings, i.e., the number of pulse cycles N, adjustable from 1 to 100. The inner surface of the valve body flow channel is polished to prevent paint adhesion.

[0089] Example 10: The control unit 8 has a built-in process parameter database and adaptive control algorithm, used to automatically call and fine-tune at least one of the following parameters according to different specifications of aluminum tubes 1: plasma treatment time. Silanization treatment time Pulse frequency f, number of pulse cycles N, curing temperature of each segment , , And its corresponding duration.

[0090] By adopting the above technical solution, the process parameter database built into the control unit 8 stores initial parameter sets corresponding to aluminum tubes 1 with different inner diameters D from 10mm to 40mm and lengths L from 50mm to 200mm. The adaptive control algorithm adopts a combination of case-based reasoning and fuzzy logic: after inputting the specifications of aluminum tube 1, it retrieves the closest case in the database and extracts the plasma treatment duration t1, silanization treatment duration t2, pulse frequency f, pulse cycle count N, and first temperature. Second temperature Third temperature And the duration of its application; then, after a test spray on an aluminum tube 1, based on the feedback of coating thickness and adhesion detected online, fine-tuning is performed using fuzzy rules. , The addition of f and N allows the process to adapt to batch differences in incoming materials, ensuring consistent film quality.

[0091] The following specific embodiments illustrate the implementation principle of the present invention:

[0092] A corrosion-resistant inner coating spraying device for pharmaceutical aluminum tube production was used. The device includes a rotating clamping fixture 2, an inner spray bar 4, a micro-atomizing nozzle 10, a spraying integrated module, an ultrasonic transducer 3, a vacuum and recovery system, a heating device 14, and a control unit 8. The aluminum tube 1 used is made of 1060 industrial pure aluminum, with an inner diameter D of 22 mm, a length L of 120 mm, and a wall thickness of 1.5 mm. The method steps are as follows:

[0093] Step 1, Low-temperature plasma-silanization synergistic pretreatment. The aluminum tube 1 is clamped in the rotating fixture 2, and the control unit 8 sets the first preset rotation speed. The speed is 60 rpm. The ultrasonic transducer 3, operating at a frequency of 28 kHz and a power of 250 W, acts on the outer wall of the aluminum tube 1 via air coupling. The low-temperature plasma generator 5 introduces 99.9% pure oxygen into the inner cavity of the aluminum tube 1 through the inner nozzle 4 at a flow rate of 1.2 L / min and a discharge power of 350 W, performing oxygen plasma jet treatment on the inner wall of the aluminum tube 1 for a first preset duration. For 80 seconds, a large number of hydroxyl groups are generated on the inner surface. After the plasma discharge is stopped, the silane coupling agent vaporizer 6 heats the γ-aminopropyltriethoxysilane to its vaporization temperature. At 185℃, using high-purity nitrogen gas at a flow rate of 2.5 L / min as the carrier gas, the vaporized silane coupling agent is introduced into the inner cavity of aluminum tube 1. A silanization grafting reaction is then carried out using plasma afterglow and hydroxyl groups, for a second preset duration. An organic-inorganic hybrid transition layer was constructed in situ for 120 seconds. Then, pure nitrogen gas was introduced at a rate of 5 L / min for 120 seconds to remove unreacted substances. The thickness of the organic-inorganic hybrid transition layer was measured to be 120 nm.

[0094] Step 2, supercritical fluid pulse spraying. The supercritical fluid generator 7 heats carbon dioxide to 52°C and pressurizes it to 12 MPa, bringing it to a supercritical state. A polytetrafluoroethylene (PTFE) nano-dispersion with an average particle size of 150 nm and a solid content of 25 wt% is added, and the mixture is stirred at 800 rpm to form a homogeneous coating fluid. The control unit 8 calculates the single pulse injection volume as 18% of the internal volume of the aluminum tube 1 based on its inner diameter D and length L, and sets the opening frequency f of the pulse injection valve 9 to 4 Hz, the duty cycle Dc to 45%, and the initial pulse cycle number N to 12. The vacuum system 11 maintains a basic negative pressure inside the aluminum tube 1. The pressure is 0.03 MPa. When the pulse injection valve 9 opens, the coating fluid is injected into the aluminum tube 1 in a pulsed manner through the micro-atomizing nozzle 10 at the end of the inner spray rod 4. At the moment each pulse ends, the three-way valve switches within 0.2 seconds, and the pressure inside the aluminum tube 1 drops sharply from 12 MPa to the basic negative pressure. Carbon dioxide is vaporized and condensed and recovered by a carbon dioxide recovery device, while polytetrafluoroethylene is uniformly precipitated and deposited on the organic-inorganic hybrid transition layer. Control unit 8 adjusts the frequency f to 3.5 Hz based on the actual coating thickness monitored online by the laser confocal displacement sensor, resulting in a final cycle count N of 13 times, thus obtaining a wet film of the deposited coating.

[0095] Step 3, gradient vacuum curing. Vacuum system 11 maintains a preset vacuum level inside aluminum tube 1. The pressure is 40 Pa. Heating device 14 raises the temperature to the first temperature at a rate of 3°C / min. Set the temperature to 135℃ and maintain the third preset time. For 35 minutes, remove residual carbon dioxide and moisture from the coating. Increase the temperature to the second temperature at a rate of 2°C / min. Set the temperature to 325℃ and maintain it for the fourth preset time. For 25 minutes, the PTFE particles melted and leveled, undergoing strong interfacial crosslinking with the amino groups exposed in the organic-inorganic hybrid transition layer. The temperature was increased to the third temperature at a rate of 1.5 °C / min. Maintain the temperature at 390℃ for the fifth preset duration. The coating is annealed for 18 minutes to densify it. After heating is stopped, it is slowly cooled to 55°C under vacuum at a rate of 1.8°C / min, and then removed to obtain the finished product.

[0096] The comparative example uses a traditional solvent-based coating spraying and curing process. An aluminum tube of the same specification (1) is degreased with alkaline oil, washed with deionized water, and dried. Then, a commercially available polytetrafluoroethylene (PTFE) solvent-based coating is sprayed onto it using an air spray gun at room temperature. The wet film is allowed to stand and level for 10 minutes, then placed in a normal pressure hot air oven and baked at 150°C for 20 minutes to remove the solvent. The temperature is then raised to 360°C for sintering for 35 minutes, and the tube is cooled to room temperature in the oven. This process does not use plasma pretreatment, supercritical fluids, or vacuum curing.

[0097] The performance of the finished products obtained from the specific embodiments and the comparative embodiments were compared, and the comparison results are shown in Table 1:

[0098] Table 1

[0099]

[0100] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes, characterized in that: Includes the following steps: Step 1: Under the setting of ultrasonic assistance, the inner wall of the aluminum tube (1) is treated with low temperature oxygen plasma to introduce active groups. Then, vaporized silane coupling agent is introduced. Under the action of plasma afterglow, an organic-inorganic hybrid transition layer is constructed in situ on the inner surface of the aluminum tube. Step 2: Dissolve the fluoropolymer coating to form a coating fluid, and inject the coating fluid into the aluminum tube (1) after step 1 in a pulsed manner. Utilize the characteristics of supercritical fluid to wet and spread the coating. Separate carbon dioxide by rapidly depressurizing at a set speed, and uniformly deposit the fluoropolymer coating on the organic-inorganic hybrid transition layer. Step 3: The aluminum tube (1) after being sprayed in step 2 is placed under vacuum conditions and a gradient heating program including at least three temperature levels is performed to complete degassing, sintering and annealing in sequence to form a dense anti-corrosion inner coating.

2. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 1, characterized in that, Step 1 includes the following sub-steps: Step 101: Clamp the aluminum tube (1) onto the rotating fixture (2), and drive the aluminum tube (1) at a first preset speed. Rotate; Step 102: Start the ultrasonic transducer (3) coupled to the outer wall of the aluminum tube (1), and simultaneously introduce oxygen into the inner cavity of the aluminum tube (1) through the inner spray rod (4), start the low-temperature plasma generator (5) to generate an oxygen plasma jet, and perform activation treatment on the inner surface for a first preset time. ; Step 103: Stop the plasma discharge and heat the silane coupling agent to the vaporization temperature using the vaporizer (6). The plasma is carried into the inner cavity of the aluminum tube (1) by the carrier gas, and the silanization grafting reaction is carried out using the plasma afterglow and the activated hydroxyl groups on the surface for a second preset time. This forms an organic-inorganic hybrid transition layer; Step 104: Purge with inert gas to remove unreacted residues.

3. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 2, characterized in that, Step 2 includes the following sub-steps: Step 201: In the supercritical fluid generator (7), the temperature and pressure of carbon dioxide are adjusted to the supercritical state and mixed with fluoropolymer coating to form a homogeneous coating fluid. Step 202: The control unit (8) calculates the pulse parameters based on the inner diameter D and length L of the aluminum tube (1), and instructs the pulse injection valve (9) to open at a preset frequency f and duty cycle Dc, so that the coating fluid is injected in a pulse form through the micro-atomizing nozzle (10) located at the end of the inner spray rod (4). At this time, the basic negative pressure established by the vacuum system (11) is maintained inside the aluminum tube. ; Step 203: During each pulse interval, control the three-way valve to switch instantaneously, causing the internal pressure of the aluminum tube (1) to drop sharply from the high pressure during the injection of the coating fluid to the basic negative pressure. This process allows carbon dioxide to be completely vaporized and captured by a carbon dioxide recovery device, while fluoropolymers are released and deposited on the inner wall. Step 204: Based on the target coating thickness, repeat steps 202 to 203 to complete the coating process for multiple pulse cycles.

4. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 3, characterized in that, Step 3 includes the following sub-steps: Step 301: Start the vacuum system (11) to maintain the preset vacuum level inside the aluminum tube (1). ; Step 302: Control the heating device (14) to heat up to the first temperature. And maintain the third preset duration To remove residual solvents and gases from the coating; Step 303, continue heating to the second temperature. And maintain the fourth preset duration ,in The melting point is higher than that of fluoropolymers, allowing the melt to flow level and crosslink with the organic-inorganic hybrid transition layer; Step 304, continue heating to the third temperature. And maintain the fifth preset duration The coating is subjected to annealing and densification treatment, wherein ; Step 305: After the program is completed, stop heating and allow the furnace to cool slowly to room temperature in a vacuum or inert atmosphere.

5. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 4, characterized in that, The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; the fluoropolymer coating is a nanoscale powder dispersion of one or more of polytetrafluoroethylene, perfluoroethylene propylene, or fusible polytetrafluoroethylene.

6. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 5, characterized in that, The method for calculating pulse parameters in control unit (8) follows a closed-loop feedback control model: based on the actual coating thickness obtained from online monitoring and the preset target thickness. To compensate for the deviation, the pulse frequency f and the number of cycles N are dynamically adjusted.

7. The method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes according to claim 6, characterized in that, The organic-inorganic hybrid transition layer constructed in step 1 has a thickness of 50nm-200nm. One end of the organic-inorganic hybrid transition layer is anchored to the aluminum substrate by chemical bonds, and the other end has active functional groups that can react or strongly interact with fluoropolymers.

8. A corrosion-resistant inner coating spraying device for the production of pharmaceutical aluminum tubes, characterized in that: The apparatus for implementing the anti-corrosion inner coating spraying method for pharmaceutical aluminum tube production as described in claim 7 includes a rotary clamping fixture (2), an inner spray bar (4), a micro-atomizing nozzle (10), a spraying integrated module, an ultrasonic transducer (3), a vacuum and recovery system, a heating device (14), and a control unit (8). The rotary clamping fixture (2) is used to fix and drive the aluminum tube (1) to rotate. The micro-atomizing nozzle (10) is installed at the end of the inner spray rod (4), and the inner spray rod (4) extends coaxially into the interior of the aluminum tube (1); The spraying integrated module is connected to the inner spray bar (4) and includes a low-temperature plasma generator (5), a silane coupling agent vaporizer (6), a supercritical fluid generator (7) and a pulse jet valve (9). The ultrasonic transducer (3) is used to provide vibration for the aluminum tube (1); The vacuum and recovery system is connected to the other end of the aluminum tube (1) via a three-way valve. The vacuum and recovery system includes a vacuum system (11) and a carbon dioxide recovery device. The heating device (14) is installed around the aluminum tube (1) to control the temperature of the aluminum tube (1); The control unit (8) is electrically connected to each electrical component to coordinate the execution of each step of a method for spraying an anti-corrosion inner coating for the production of pharmaceutical aluminum tubes.

9. The anti-corrosion inner coating spraying device for the production of pharmaceutical aluminum tubes according to claim 8, characterized in that: The supercritical fluid generator (7) has an independent temperature and pressure control module, and its outlet is connected to the pulse jet valve (9). The opening frequency f, duty cycle Dc and number of openings of the pulse jet valve (9) can be independently programmed and controlled by the control unit (8).

10. The anti-corrosion inner coating spraying device for the production of pharmaceutical aluminum tubes according to claim 8, characterized in that: The control unit (8) has a built-in process parameter database and adaptive control algorithm, which is used to automatically call and fine-tune at least one of the following parameters according to different specifications of aluminum tubes (1): plasma treatment time Silanization treatment time Pulse frequency f, number of pulse cycles N, curing temperature of each segment , , And its corresponding duration.

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