Medical raw rubber low molecular removal system

Abstract

The application discloses a medical silicon raw rubber low-molecule removal system and a removal method. The system comprises a raw material tank group, a nitrogen gas feeding module, a heating and conveying module, a wiped-film thin-film evaporation unit, a two-stage condensation recovery module, a low-molecule recovery barrel, a vacuum buffer unit, a vacuum pump and a discharging module, and each module is in closed communication along the material flow direction and the gas flow direction. The evaporation unit is provided with a motor-driven wiped-film mechanism, which spreads the high-viscosity silicon raw rubber into a continuously updated thin liquid film, and cooperates with vacuum negative pressure and interlayer heating to realize efficient removal of low molecules; the two-stage condenser recovers the vaporized low molecules in stages, and the vacuum buffer barrel maintains stable negative pressure. The application can strengthen mass transfer through thin-film evaporation, can deeply remove low molecules in the silicon raw rubber under mild conditions, has the advantages of high cleanliness, stable operation and continuous production, and is suitable for the large-scale production demand of medical implant-grade silicon raw rubber.

Description

Technical Field

[0001] This invention relates to the field of medical polymer material processing technology, and in particular to a medical silicone raw material low molecular weight removal system and removal method. Background Technology

[0002] Medical-grade raw silicone rubber is a core raw material for the manufacture of medical implantable silicone rubber products such as silicone gel breast implants. The residual levels of low-molecular-weight cyclosiloxanes (D3-D20, etc.) and other volatile and migratable small molecules directly affect the biocompatibility and safety of the final product. Medical-grade raw silicone rubber has extremely high requirements for low-molecular-weight residue limits, while batch stability and the cleanliness of the production process must be ensured.

[0003] In existing technologies, polymer devolatilization often employs conventional batch devolatilization and screw extrusion devolatilization equipment. However, these methods have significant technical drawbacks when processing high-viscosity medical-grade silicone raw rubber: Low mass transfer efficiency: High-viscosity raw rubber easily forms a thick layer in batch equipment, requiring low-molecular-weight substances to migrate long distances to the surface before escaping. This results in time-consuming and insufficient removal, failing to meet medical-grade residue requirements. High risk of thermal damage: Uneven heating of the thick layer can lead to localized overheating or prolonged residence time, potentially causing changes in the molecular weight and physical properties of the silicone raw rubber, affecting the quality of the final product. Insufficient cleanliness: Conventional devolatilization equipment has a complex internal structure with many dead corners, making thorough cleaning difficult and prone to batch-to-batch cross-contamination, failing to meet GMP requirements for medical-grade production. Poor operational stability: The volatilized low-molecular-weight siloxanes lack efficient recovery mechanisms and easily enter the vacuum system with the airflow, causing vacuum pump oil contamination and equipment malfunctions. Furthermore, direct emission of low-molecular-weight siloxanes also presents environmental and material waste issues.

[0004] Currently, there are few dedicated low-molecular-weight removal devices and processes for medical-grade silicone raw materials, and general-purpose equipment cannot simultaneously meet the multiple requirements of removal efficiency, product quality, cleanliness, and operational stability. Therefore, developing a dedicated low-molecular-weight removal system and method for high-viscosity medical-grade silicone raw materials has significant application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a medical silicone raw material low molecular weight removal system and method. By enhancing mass transfer through thin film evaporation, combined with a closed nitrogen feeding system, zoned precise temperature control, two-stage condensation recovery and vacuum pressure stabilization structure, it achieves efficient, gentle, clean and stable deep removal of low molecular weight materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, the present invention provides a medical silicone raw material low molecular weight removal system, including a raw material tank group, a nitrogen feeding module, a heating and conveying module, a scraped film evaporation unit, a condensation and recovery module, a low molecular weight recovery tank, a vacuum buffer unit, a vacuum pump, and a discharge module; The nitrogen feeding module is connected to the top of the raw material tank group and is used to introduce nitrogen into the raw material tank to form a downward pressure. The discharge end of the raw material tank group is connected to the inlet end of the heating and conveying module; The discharge end of the heating and conveying module is connected to the inlet of the scraped film evaporation unit; The top of the scraped film evaporation unit is provided with a steam outlet, which is connected to the air inlet of the condensation recovery module. The liquid outlet of the condensation recovery module is connected to the low molecular weight recovery tank, and the gas outlet of the condensation recovery module is connected to the gas inlet of the vacuum buffer unit. The outlet of the vacuum buffer unit is connected to the inlet of the vacuum pump, which is used to draw negative pressure for the system to form a low-pressure removal environment. The bottom of the scraped film evaporation unit is provided with a material outlet, which is connected to the discharge module for discharging medical silicone raw rubber after the removal of low molecular weight. The scraped film evaporation unit includes an evaporator cylinder, a drive motor, and a scraping mechanism. The drive motor is fixedly installed at the top of the evaporator cylinder, and the scraping mechanism is located inside the evaporator cylinder and is connected to the drive motor for transmission. It is used to spread the material along the inner wall of the evaporator cylinder to form a continuously renewed film. The outer wall of the evaporator cylinder is provided with a heating jacket.

[0007] Furthermore, the raw material tank group includes at least two raw material tanks arranged in parallel. The top of each raw material tank is connected to the nitrogen feeding module, and the bottom outlet of each raw material tank is connected to the feeding end of the heating and conveying module after being merged by the raw material manifold, so as to realize alternating continuous feeding.

[0008] Furthermore, the heating and conveying module includes a jacketed conveying pipe and a conveying power mechanism. The pipe wall of the jacketed conveying pipe is provided with a heating jacket, and a heating medium is introduced into the heating jacket to maintain the material temperature and flowability. The conveying power mechanism is located on the pipe of the jacketed conveying pipe and is used to cooperate with the nitrogen pressure to push the high viscosity silicone raw rubber along the pipe.

[0009] Furthermore, the condensation recovery module includes a primary condenser and a secondary condenser, which are connected in series along the airflow direction. The steam outlet of the scraped film evaporation unit is sequentially connected to the inlet end of the primary condenser, the outlet end of the primary condenser, and the inlet end of the secondary condenser. The outlet end of the secondary condenser is connected to the inlet end of the vacuum buffer unit. The bottom condensate outlets of the primary and secondary condensers are both connected to the low molecular weight recovery tank.

[0010] Furthermore, the vacuum buffer unit includes a vacuum buffer tank, the inlet of which is connected to the outlet of the condensation recovery module, and the outlet of which is connected to the inlet of the vacuum pump, for smoothing system vacuum fluctuations and intercepting liquid droplets carried by the airflow.

[0011] Furthermore, it also includes a zone temperature control module, which is connected to the heating jacket of the scraped film evaporation unit and the heating jacket of the heating conveying module, respectively, and is used to independently control the heating temperature of the evaporation zone and the conveying zone.

[0012] Furthermore, the cylinder of the scraped film evaporation unit is equipped with an observation window, a sampling port, a vacuum gauge, and at least three temperature sensors, which are respectively arranged in the feed section, the middle evaporation zone, and the discharge section of the cylinder.

[0013] Furthermore, all components within the system that come into direct contact with the medical-grade silicone rubber are made of 316 stainless steel.

[0014] On the other hand, the present invention provides a method for removing low molecular weight medical silicone raw material, based on the above-mentioned system, comprising the following steps: S1 Raw Material Storage: The medical-grade silicone raw material to be processed is packaged and stored in each raw material tank of the raw material tank group, and sealed in a tight seal. S2 Nitrogen Pressurized Feeding: Clean nitrogen is introduced into the raw material tank in operation, and the silicone raw rubber is forced out from the bottom by the gas pressure inside the tank and flows into the heating and conveying module; S3 Heated and Insulated Conveying: The material enters the conveying pipe with a heating jacket, where it maintains stable viscosity and fluidity under the heating and insulation effect, and is pushed by the conveying power mechanism to be stably conveyed to the scraped film evaporation unit at a set rate. S4 Thin Film Vacuum Evaporation Removal: After the raw silica gel enters the evaporator cylinder, it is scraped along the inner wall of the cylinder by a rotating scraping mechanism to form a continuously renewed liquid film. Under the combined action of the heating jacket and the negative pressure environment of the system, the low molecular weight siloxanes and volatile small molecules in the liquid film are heated and vaporized and escape from the material. S5 Two-Stage Condensation and Recovery: Vaporized low-molecular-weight molecules enter the two-stage condenser sequentially with the airflow, and after staged condensation, they become liquid and are collected in a low-molecular-weight recovery tank. S6 Vacuum Stabilization and Control: The vacuum pump continuously evacuates the system through the vacuum buffer unit to maintain the set negative pressure environment in the evaporation unit. The vacuum buffer unit smooths out vacuum fluctuations and intercepts liquid droplets entrained by the airflow. S7 Finished Product Output: The silicone raw rubber after removing low molecular weight molecules falls along the inner wall of the evaporator cylinder to the bottom and is continuously output through the discharge module.

[0015] Furthermore, in step S4, the heating temperatures of the conveying pipeline and the evaporator cylinder are adjusted separately by the zone temperature control module, wherein the temperature of the evaporation zone is higher than the conveying insulation temperature, and the maximum temperature of the material is lower than the thermal degradation critical temperature of medical silicone rubber.

[0016] Furthermore, in steps S2 and S3, multiple raw material tanks in the raw material tank group alternately switch working states, with one tank supplying material and another preparing or replenishing material, to achieve continuous descaling production of the system.

[0017] Furthermore, during operation, the equipment's operating status is monitored in real time through the observation window, vacuum gauge, and temperature sensor on the evaporator shell, and low molecular weight residue is detected periodically through the sampling port, dynamically adjusting the heating temperature, vacuum degree, and feed rate parameters.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Highly efficient removal and enhanced mass transfer: The scraped film evaporation structure spreads high-viscosity silica raw gum into a micron-level thin liquid film, which greatly shortens the migration path of low molecular weight substances. The continuous renewal of the liquid film ensures the stability of the mass transfer interface. Combined with the vacuum environment to reduce the boiling point of low molecular weight substances, low molecular weight residues can be reduced to medical-grade standards in a short time, and the removal efficiency is significantly improved.

[0019] 2. Gentle processing and controllable quality: Through sandwich heating and zoned temperature control, the heating temperature of the material is precisely controlled. The thin liquid film is heated evenly and the residence time is short, avoiding the deterioration of raw rubber performance caused by local overheating and prolonged heating, and preserving the physical properties and molecular weight distribution of silicone raw rubber to the greatest extent.

[0020] 3. Clean production, suitable for medical use: All material contact parts are made of 316 stainless steel, the flow channel design is simple and without dead corners, and it is easy to clean and disinfect; nitrogen gas closed feeding avoids material contact with the outside world, reduces the risk of contamination, and meets the clean production requirements of medical implant raw materials.

[0021] 4. Stable operation and environmentally friendly recycling: The two-stage series condensation structure condenses low-molecular vapors in stages, resulting in a high recovery rate and significantly reducing the amount of volatiles entering the vacuum system; the vacuum buffer tank smooths out vacuum fluctuations and intercepts droplets, protecting the vacuum pump equipment and extending its service life; the recovered low-molecular vapors can be centrally processed or recycled, reducing environmental pressure.

[0022] 5. Continuous operation and adjustable process: The alternating feeding of dual raw material tanks combined with continuous evaporation discharge enables large-scale continuous production; multiple monitoring devices can provide real-time feedback on operating parameters, making it easy to adjust process parameters such as temperature, vacuum, and feed rate according to the characteristics of raw materials and removal requirements, adapting to the processing needs of different specifications of raw silicone rubber. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the overall structure of the medical silicone raw material low molecular weight removal system described in this invention; Figure 2 This is a schematic diagram of the main structure of the scraped film thin-film evaporation unit described in this invention; Figure 3 This is a schematic diagram showing the connection of the raw material tank group, nitrogen feeding module and heating conveying module described in this invention; Figure 4 This is a schematic diagram showing the connection between the condensation recovery module, the vacuum buffer unit, and the vacuum pump described in this invention; Figure 5 This is a schematic diagram showing the arrangement of the auxiliary monitoring structure on the evaporator shell according to the present invention; Figure 6 This is a schematic diagram of the process flow of the removal method described in this invention.

[0024] As shown in the figure: 1-Raw material tank A, 2-Raw material tank B, 3-Nitrogen feeding module, 4-Heating conveying module, 41-Jacketed conveying pipe, 42-Transmission power mechanism, 5-Scraped film evaporation unit, 51-Evaporator cylinder, 52-Drive motor, 53-Scraped film mechanism, 54-Heating jacket, 55-Inlet, 56-Steam outlet, 57-Outlet, 6-Condensation recovery module, 61-First-stage condenser, 62-Second-stage condenser, 7-Vacuum buffer unit, 71-Vacuum buffer tank, 8-Vacuum pump, 9-Low molecular weight recovery tank, 10-Outlet module, 11-Observation window, 12-Sampling port, 13-Vacuum gauge, 14-Temperature sensor, 15-Raw material manifold. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] Example 1: Medical Silicone Raw Gum Low Molecular Weight Removal System like Figures 1 to 5 As shown, this embodiment provides a medical silicone raw material low molecular weight removal system, which is specifically designed for the deep removal of low molecular weight from high-viscosity medical addition-type silicone raw material. The system is arranged in sequence along the material processing flow direction as a raw material supply unit, a scraped film evaporation unit and a discharge module, and along the gas phase flow direction as a condensation recovery module, a vacuum buffer unit and a vacuum pump. Each unit is connected to the corresponding unit through a closed pipeline to form a fully closed continuous processing system.

[0027] The raw material supply unit includes a raw material tank group, a nitrogen feeding module 3, and a heating and conveying module 4, which are used to realize the closed storage of materials, shear-free pressure stabilization feeding, and constant temperature conveying.

[0028] The raw material tank assembly includes two 150L vertical stainless steel raw material tanks, namely raw material tank A1 and raw material tank B2, which are arranged in parallel. Each raw material tank is equipped with a nitrogen interface, a feed inlet and a pressure monitoring point on its top. The nitrogen interface is uniformly connected to the nitrogen feed module 3, which can introduce purified medical-grade nitrogen. The nitrogen feed module 3 fills the tank with nitrogen to form a stable downward pressure, which drives the high-viscosity material to be discharged from the bottom. The entire process is without shearing and without contact with the external environment, avoiding damage to the material properties and external contamination.

[0029] Each raw material tank has a conical discharge structure at the bottom. The two discharge ports are connected to the raw material manifold 15 through pipelines. After the raw material manifold 15 is connected to the feed end of the heating and conveying module 4, the parallel structure of the two tanks can realize uninterrupted alternating feeding. When one tank is being replenished, the other tank maintains normal feeding, ensuring the system can operate continuously for a long time.

[0030] The heating and conveying module 4 includes a jacketed conveying pipe 41 and a conveying power mechanism 42. The jacketed conveying pipe 41 is a double-layered jacketed pipe, with the inner layer being the material flow channel and the outer layer being the heating medium flow channel. Circulating heat transfer oil is introduced into the jacket to continuously keep the material in the pipe warm and stabilize the material viscosity within a suitable conveying range. The conveying power mechanism 42 adopts a high-viscosity special screw conveying pump, which is installed in series on the jacketed conveying pipe 41. It works in conjunction with the nitrogen pressure to accurately adjust the feed flow rate and smoothly convey the material to the downstream evaporation unit.

[0031] The scraped film thin-film evaporation unit 5 is the core removal unit of the system, including an evaporator cylinder 51, a drive motor 52, a scraping film mechanism 53 and a heating jacket 54, which is used to spread high-viscosity materials into a continuously renewing thin liquid film, and achieve low-molecular-weight low-temperature vaporization removal in conjunction with a negative pressure environment.

[0032] The drive motor 52 is an explosion-proof geared motor, which is fixed to the center of the top of the cylinder by a mounting bracket; the film scraping mechanism 53 is set inside the cylinder and includes a central rotating shaft and multiple sets of film scraping assemblies arranged axially. The upper end of the rotating shaft is connected to the motor output shaft by a coupling, and the scraper blades of the film scraping assembly are set close to the inner wall of the cylinder.

[0033] When the motor drives the shaft to rotate at a constant speed, the scraper will evenly scrape the high-viscosity material falling on the cylinder wall, forming a thin liquid film of uniform thickness that is continuously renewed downwards, which greatly shortens the diffusion and migration path of low molecular weight substances and significantly improves mass transfer efficiency.

[0034] The heating jacket 54 is wrapped around the outer wall of the evaporator cylinder 51, and circulating heat transfer oil is introduced into it to provide the heat required for evaporation of the liquid film inside the cylinder. With the help of the system's vacuum negative pressure environment, low molecular weight substances in the liquid film can vaporize and escape at temperatures far below the boiling point of atmospheric pressure, achieving low-temperature and efficient removal.

[0035] An inlet 55 is provided on the upper side wall of the evaporator cylinder 51, which is connected to the outlet end of the jacketed conveying pipe 41. The material enters the cylinder through the inlet 55 and falls onto the inner wall. A steam outlet 56 is provided at the center of the top of the cylinder. The vaporized low-molecular-weight steam is discharged from the outlet under the action of negative pressure suction. The bottom of the cylinder is a conical receiving section, and a material outlet 57 is provided at the lowest point, which is connected to the discharge module 10 for outputting the finished material after the removal of low-molecular-weight components.

[0036] The condensation recovery module 6 and the vacuum buffer unit 7 are connected in series along the gas phase flow direction, and are respectively responsible for low molecular weight fractional recovery and system negative pressure stability maintenance.

[0037] The condensation recovery module 6 adopts a two-stage series condensation structure, including a primary condenser 61 and a secondary condenser 62, both of which are shell-and-tube condensers. The steam outlet 56 of the evaporator cylinder 51 is connected to the upper air inlet of the primary condenser 61 through an insulated steam pipeline, and the lower air outlet of the primary condenser 61 is connected to the upper air inlet of the secondary condenser 62. The bottom of the two condensers is provided with condensate outlets, which are connected to the low molecular weight recovery tank 9 through a collecting pipeline.

[0038] The first-stage condenser uses circulating water at 40-60℃ to remove most of the high-boiling-point low-molecular-weight components; the second-stage condenser uses low-temperature coolant at 5-15℃ to deeply remove low-boiling-point components. Through staged condensation, a high recovery rate is achieved, significantly reducing the amount of volatiles entering the downstream vacuum system.

[0039] The vacuum buffer unit 7 is a vertical vacuum buffer tank 71. An air inlet and an air outlet are provided on the upper part of the tank. The air inlet is connected to the air outlet of the secondary condenser 62, and the air outlet is connected to the air inlet of the vacuum pump 8. The vacuum pump 8 is a dry vacuum pump, which provides stable negative pressure to the system, so that the evaporator is kept in a high vacuum environment of 100-500Pa. The vacuum buffer tank 71, on the one hand, uses the volume expansion buffering effect to smooth the vacuum pulsation generated by the operation of the vacuum pump and maintain the vacuum degree in the evaporation chamber. On the other hand, it uses gravity settling to intercept the tiny droplets entrained in the airflow, preventing droplets from entering the vacuum pump and causing equipment corrosion and failure.

[0040] The system is equipped with an independent zone temperature control module, with separate conveying temperature control loops and evaporation temperature control loops. It independently controls the heating temperature of the jacketed conveying pipe 41 and the heating jacket 54, achieving precise temperature control in each zone. This ensures the fluidity of the conveying process while preventing excessively high evaporation temperatures from damaging the material properties.

[0041] The evaporator cylinder 51 is equipped with a complete monitoring system: a visual observation window 11 is provided on the side wall of the cylinder to directly observe the internal film formation state and material flow; a sealable sampling port 12 is provided to take samples in real time to detect low molecular weight residues without stopping the machine; a vacuum gauge 13 is installed on the top to monitor the vacuum degree of the chamber in real time; and temperature sensors 14 are installed at the top, middle and bottom along the cylinder axis to monitor the material temperature distribution in real time, corresponding to the feeding section, evaporation section and discharge section.

[0042] All components in this system that come into direct contact with medical-grade silicone rubber are made of 316L stainless steel with mirror-polished inner surfaces. The flow channels are smooth with no dead corners or stagnant areas, allowing for CIP cleaning and steam sterilization, meeting the cleanliness requirements of medical-grade production.

[0043] Example 2: Method for removing low molecular weight medical silicone raw material This embodiment provides a method for removing low-molecular-weight silicone raw material from medical devices, based on the system described in Embodiment 1. The process flow is as follows: Figure 6 As shown, the specific steps are as follows: S1 Raw Material Storage Process: The medical addition-type silicone raw material to be processed is packaged into raw material tanks A1 and B2 in a clean environment, the tank openings are sealed, and the pipeline connection and sealing performance are confirmed to be qualified.

[0044] S2 Nitrogen Pressurized Feeding Process: Open the nitrogen inlet valve of raw material tank A1 and introduce clean nitrogen at 0.15MPa into the tank. Under stable pressure, the high-viscosity silicone raw rubber in the tank is forced out from the bottom outlet, flows into the raw material manifold 15 and then into the jacketed conveying pipeline 41. During operation, the two raw material tanks of the raw material tank group alternately switch working states, with one tank supplying material and the other tank preparing or replenishing material, so as to realize continuous descaling production of the system.

[0045] S3 Heating and Insulation Conveying Process: Start the heat transfer oil circulation in the heating jacket of the conveying pipeline, control the conveying and insulation temperature to 70℃, and maintain the stability of the material viscosity; start the conveying power mechanism 42, adjust the screw speed, control the feeding rate to 10L / h, and smoothly convey the material to the feed port 55 of the evaporator cylinder 51.

[0046] S4 Thin Film Vacuum Evaporation Removal Process: Start the drive motor 52, set the speed to 80 rpm, and drive the scraping mechanism 53 to rotate at a uniform speed; after the material enters the cylinder from the feed port 55, it falls onto the inner wall and is evenly scraped by the rotating scraping component to form a continuously renewing liquid film with a thickness of about 1 mm; turn on the heat transfer oil circulation of the evaporator heating jacket 54 and control the wall temperature of the evaporation zone to 140℃; at the same time, start the vacuum pump 8 and adjust the system vacuum to 200 Pa absolute pressure; under the combined action of heating and high vacuum, the low molecular weight cyclosiloxanes and volatile small molecules in the liquid film are rapidly vaporized and escaped, and the material with removed low molecular weight flows slowly downward along the cylinder wall; in this step, the heating temperature of the conveying pipeline and the evaporator cylinder are separately controlled by the zone temperature control module. The temperature of the evaporation zone is higher than the conveying insulation temperature, and the maximum temperature of the material is lower than the thermal degradation critical temperature of medical silicone raw rubber to avoid damage to the material properties.

[0047] S5 Two-Stage Condensation and Recovery Process: Vaporized low-molecular-weight vapor flows out from the top steam outlet 56 under negative pressure suction and first enters the first-stage condenser 61, where the first-stage condensation temperature is controlled at 50℃. Most of the high-boiling-point low molecules condense into liquid here. The remaining uncondensed low-boiling-point components enter the second-stage condenser 62 with the airflow, where the second-stage condensation temperature is controlled at 10℃. The remaining low molecules are fully condensed here. The liquid low molecules produced by the two-stage condensers flow into the low-molecular-weight recovery tank 9 through pipelines for centralized collection.

[0048] S6 Vacuum stabilization and control process: Non-condensable gas enters the vacuum buffer tank 71 after passing through the secondary condenser 62. After being buffered and stabilized, it is discharged by the vacuum pump 8. The vacuum buffer tank 71 smooths out vacuum fluctuations in real time, maintains the vacuum level inside the tank within ±10Pa, and intercepts tiny droplets entrained in the gas flow to protect the vacuum pump.

[0049] S7 Finished Product Output Process: After removing the low molecular weight silicone raw rubber, it slides down the inner wall of the cylinder to the bottom conical receiving section, and is continuously output through the material outlet 57 and the discharge module 10 to obtain the finished silicone raw rubber.

[0050] During system operation, the internal film-forming state is monitored through observation window 11, and real-time operating parameters are read through temperature sensor 14 and vacuum gauge 13. Samples are taken from sampling port 12 every 2 hours, and the total residual amount of low molecular weight D3-D20 is detected by gas chromatography. The feed rate, heating temperature and vacuum parameters are dynamically adjusted according to the detection results to ensure stable removal effect.

[0051] The total residual amount of low molecular weight cyclosiloxanes in medical raw silicone treated by this method can be stably reduced to below 0.1%, and the viscosity, molecular weight, cross-linking properties and other properties of the raw silicone do not change significantly, fully meeting the quality requirements of medical implant-grade raw materials.

[0052] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A medical-grade raw rubber low-molecular-weight removal system, characterized in that: It includes raw material tank group, nitrogen feeding module, heating and conveying module, scraped film thin film evaporation unit, condensation recovery module, low molecular weight recovery tank, vacuum buffer unit, vacuum pump and discharge module; The nitrogen feeding module is connected to the top of the raw material tank group and is used to introduce nitrogen into the raw material tank to form a downward pressure. The discharge end of the raw material tank group is connected to the inlet end of the heating and conveying module; The discharge end of the heating and conveying module is connected to the inlet of the scraped film evaporation unit; The top of the scraped film evaporation unit is provided with a steam outlet, which is connected to the air inlet of the condensation recovery module. The liquid outlet of the condensation recovery module is connected to the low molecular weight recovery tank, and the gas outlet of the condensation recovery module is connected to the gas inlet of the vacuum buffer unit. The outlet of the vacuum buffer unit is connected to the inlet of the vacuum pump, which is used to draw negative pressure for the system to form a low-pressure removal environment. The bottom of the scraped film evaporation unit is provided with a material outlet, which is connected to the discharge module for discharging medical silicone raw rubber after the removal of low molecular weight. The scraped film evaporation unit includes an evaporator cylinder, a drive mechanism, and a scraping mechanism. The drive mechanism is fixedly installed at the top of the evaporator cylinder, and the scraping mechanism is located inside the evaporator cylinder and is connected to the drive mechanism for transmission. It is used to spread the material along the inner wall of the evaporator cylinder to form a continuously renewed film. The outer wall of the evaporator cylinder is provided with a heating jacket.

2. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: The raw material tank group includes at least two raw material tanks arranged in parallel. The top of each raw material tank is connected to the nitrogen feeding module, and the bottom outlet of each raw material tank is connected to the feeding end of the heating and conveying module after being merged by the raw material manifold, so as to realize alternating continuous feeding.

3. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: The heating and conveying module includes a jacketed conveying pipe and a conveying power mechanism. The pipe wall of the jacketed conveying pipe is provided with a heating jacket, and a heating medium is introduced into the heating jacket to maintain the temperature and flowability of the material. The conveying power mechanism is located on the pipe of the jacketed conveying pipe and is used to cooperate with the downward pressure of nitrogen to push the high viscosity silicone raw rubber along the pipe.

4. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: The condensation recovery module includes a primary condenser and a secondary condenser, which are connected in series along the airflow direction. The steam outlet of the scraped film evaporation unit is sequentially connected to the air inlet of the primary condenser, the air outlet of the primary condenser, and the air inlet of the secondary condenser. The air outlet of the secondary condenser is connected to the air inlet of the vacuum buffer unit. The bottom condensate outlets of the primary and secondary condensers are both connected to the low molecular weight recovery tank.

5. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: The vacuum buffer unit includes a vacuum buffer tank, the air inlet of which is connected to the air outlet of the condensation recovery module, and the air outlet of which is connected to the air inlet of the vacuum pump. It is used to smooth out system vacuum fluctuations and intercept liquid droplets carried by the airflow.

6. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: It also includes a zone temperature control module, which is connected to the heating jacket of the scraped film evaporation unit and the heating jacket of the heating conveying module, respectively, and is used to independently control the heating temperature of the evaporation zone and the conveying zone.

7. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: The tube of the scraped film evaporation unit is equipped with an observation window, a sampling port, a vacuum gauge, and at least three temperature sensors, which are respectively arranged in the feed section, the middle evaporation zone, and the discharge section of the tube.

8. The medical raw rubber low molecular weight removal system according to claim 1, characterized in that: All components in the system that come into direct contact with medical-grade silicone rubber are made of 316 stainless steel.

9. A method for removing low molecular weight medical silicone raw material, implemented based on the medical silicone raw material low molecular weight removal system according to any one of claims 1-8, characterized in that: Includes the following steps: S1 Raw Material Storage: The medical-grade silicone raw material to be processed is packaged and stored in each raw material tank of the raw material tank group, and sealed in a tight seal. S2 Nitrogen Pressurized Feeding: Clean nitrogen is introduced into the raw material tank in operation, and the silicone raw rubber is forced out from the bottom by the gas pressure inside the tank and flows into the heating and conveying module; S3 Heated and Insulated Conveying: The material enters the conveying pipe with a heating jacket, where it maintains stable viscosity and fluidity under the heating and insulation effect, and is pushed by the conveying power mechanism to be stably conveyed to the scraped film evaporation unit at a set rate. S4 Thin Film Vacuum Evaporation Removal: After the raw silica gel enters the evaporator cylinder, it is scraped along the inner wall of the cylinder by a rotating scraping mechanism to form a continuously renewed liquid film. Under the combined action of the heating jacket and the negative pressure environment of the system, the low molecular weight siloxanes and volatile small molecules in the liquid film are heated and vaporized and escape from the material. S5 Two-Stage Condensation and Recovery: Vaporized low-molecular-weight molecules enter the two-stage condenser sequentially with the airflow, and after staged condensation, they become liquid and are collected in a low-molecular-weight recovery tank. S6 Vacuum Stabilization and Control: The vacuum pump continuously evacuates the system through the vacuum buffer unit to maintain the set negative pressure environment in the evaporation unit. The vacuum buffer unit smooths out vacuum fluctuations and intercepts liquid droplets entrained by the airflow. S7 Finished Product Output: The silicone raw rubber after removing low molecular weight molecules falls along the inner wall of the evaporator cylinder to the bottom and is continuously output through the discharge module.

10. The method for removing low molecular weight medical silicone rubber according to claim 9, characterized in that: In step S4, the heating temperature of the conveying pipeline and the evaporator cylinder is adjusted by the zone temperature control module respectively. The temperature of the evaporation zone is higher than the conveying insulation temperature, and the highest temperature of the material is lower than the thermal degradation critical temperature of medical silicone rubber. In steps S2 and S3, multiple raw material tanks in the raw material tank group alternately switch working states, with one tank supplying material and another preparing or replenishing material, to achieve continuous descaling production in the system. During operation, the equipment's operating status is monitored in real time through the observation window, vacuum gauge, and temperature sensor on the evaporator cylinder. Low molecular weight residue is detected periodically through the sampling port, and the heating temperature, vacuum degree, and feed rate parameters are dynamically adjusted.

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