High-performance and easy-to-process ultra-high molecular weight polyethylene medical material and preparation method thereof

Abstract

The invention relates to the technical field, and particularly discloses a high-performance and easy-to-process ultra-high molecular weight polyethylene medical material and a preparation method of the high-performance and easy-to-process ultra-high molecular weight polyethylene medical material. Carrying out parallel polymerization; mixing the slurry and performing flash evaporation; steam stripping and water washing; performing drying; according to the preparation method, polyethylene with different molecular weights is obtained by adopting a double-kettle parallel polymerization reaction and differential hydrogen regulation and control, and then the polyethylene medical special material (UHMWPE) is obtained through flash evaporation, water washing and drying, so that the prepared UHMWPE medical material has the mechanical property of high molecular weight and the easy processing property of low molecular weight, the cost is reduced, and the UHMWPE medical material is green and environment-friendly, and is suitable for industrial production. The ash content and impurity ion content of the product are far lower than medical standards, safety is guaranteed, and the index requirements of medical special materials are met.

Description

Technical Field

[0001] This invention relates to the field of medical polyethylene materials, specifically to a high-performance, easily processed ultra-high molecular weight polyethylene medical material and its preparation method. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is widely used in medical fields such as artificial joint prostheses, orthopedic implants, and medical catheters due to its excellent biocompatibility, abrasion resistance, and impact resistance. Medical applications place stringent demands on the material's performance. On the one hand, it needs extremely high mechanical properties to ensure the long-term stability and safety of implants under complex stress environments in the human body; on the other hand, it needs good processing performance to enable the fabrication of high-precision, complex-structured medical devices through processes such as injection molding, extrusion, and compression molding, thereby reducing scrap rates and processing costs during production.

[0003] Currently, most existing processes employ single-reactor batch polymerization, which can only generate products with a single molecular weight by controlling the amount of hydrogen used. If a high molecular weight product is generated, although it has excellent mechanical properties, it is difficult to process. If a low molecular weight product is generated, although it is easy to process, its mechanical properties are insufficient. It is difficult to simultaneously meet the dual requirements of medical materials for mechanical and processing properties. Therefore, we propose a high-performance, easy-to-process ultra-high molecular weight polyethylene medical material and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance, easily processable ultra-high molecular weight polyethylene medical material and its preparation method, so as to solve the problem that the single-reactor process mentioned in the background art cannot simultaneously achieve mechanical properties and processing performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-performance, easily processable ultra-high molecular weight polyethylene medical material and its preparation method, comprising the following steps: S1. Catalyst preparation: First, hexane is pressurized into the catalyst preparation vessel using nitrogen gas, and stirring is started. Then, the co-catalyst is pressurized into the catalyst preparation vessel using nitrogen gas. Finally, the weighed main catalyst is added into the catalyst preparation vessel through a sealed reagent bottle and stirred thoroughly to make it evenly mixed. S2, Parallel polymerization: The process adopts a batch polymerization method, with two polymerization reactors used in parallel discharge mode. Hexane is used as the dispersion medium, and ethylene is introduced in the presence of the main catalyst and the co-catalyst to carry out slurry polymerization. The polymerization pressure of one of the polymerization reactors is controlled at 0.2 to 0.8 MPa, the polymerization temperature is controlled at 60 to 90°C, and the viscosity-average molecular weight of the polyethylene generated therein is controlled within the range of 1 million to 3 million by introducing hydrogen gas of a first flow rate into it. Meanwhile, the polymerization pressure of the other polymerization reactor is controlled at 0.2 to 0.8 MPa and the polymerization temperature is controlled at 60 to 90°C. Hydrogen gas with a second flow rate less than the first flow rate is introduced into the reactor to control the viscosity-average molecular weight of the polyethylene generated therein to be within the range of 6 million to 8 million. S3. Slurry mixing and flash evaporation: Polyethylene slurry from two polymerization reactors is pressurized into the same flash evaporator for mixing. The temperature of the flash evaporator is controlled at 50-60℃ and the pressure is 0.01-0.03 MPa. Flash evaporation is performed to remove and recover most of the dissolved ethylene and hexane solvents. S4. Stripping and washing: The flash-distilled slurry is transported to the stripping kettle, softened water is added to the stripping kettle, and steam is introduced. The temperature inside the kettle is controlled at 85-95℃ and the pressure is 2-3 kPa. Stripping and washing are carried out to remove residual solvents and impurities. S5. Drying: The wet polyethylene powder after stripping and washing is dried to obtain high-performance, easy-to-process ultra-high molecular weight polyethylene medical material. After drying, the polyethylene powder is screened and then transported to the mixing silo by a pneumatic conveying system for mixing and packaging.

[0006] Preferably, in step S1, the main catalyst is a titanium compound selected from one or more mixtures of TiCl4, TiBr4, Ti(OCH3)Cl3, Ti(OCH3)Cl2, and Ti(OCH3)4; The co-catalyst is an organoaluminum compound selected from one or more mixtures of triethylaluminum, diethylaluminum chloride, and triisobutylaluminum.

[0007] Preferably, in step S2, the viscosity-average molecular weight of polyethylene generated in one of the polymerization reactors is controlled within the range of 1.5 million to 2.5 million. The viscosity-average molecular weight of the polyethylene generated in the other polymerization reactor is controlled within the range of 6.5 million to 7.5 million.

[0008] Preferably, in step S3, the ethylene and hexane vapors flashed out are condensed, the liquefied hexane is returned to the flash reactor, and the uncondensed gas is compressed and partially returned to other polymerization reactors for recycling, and partially discharged to the tail gas system.

[0009] Preferably, in step S4, the amount of softened water added to the stripping kettle submerges the inlet of the slurry conveying pipe, forming a liquid seal.

[0010] A high-performance, easy-to-process ultra-high molecular weight polyethylene medical material, which is in powder form with a viscosity-average molecular weight of not less than 5 million and an ash content of not more than 125 mg / kg.

[0011] Preferably, the ash content contains no more than 40 mg / kg of titanium, no more than 5 mg / kg of calcium, no more than 20 mg / kg of aluminum, and no more than 30 mg / kg of chlorine.

[0012] A dual-reactor parallel polymerization system, characterized in that the system comprises: Two sets of discharge systems consisting of two polymerization reactors connected in parallel. One set consists of polymerization reactor 1 and polymerization reactor 2 connected in parallel, and the other set consists of polymerization reactor 3 and polymerization reactor 4 connected in parallel. Each polymerization reactor is equipped with a material inlet, a catalyst inlet, a hydrogen inlet, a slurry outlet, and temperature and pressure detection and control devices. The hydrogen inlets of polymerization reactor 1 and polymerization reactor 2 are respectively connected to a first hydrogen flow controller and a second hydrogen flow controller, and the hydrogen inlets of polymerization reactor 3 and polymerization reactor 4 are respectively connected to a first hydrogen flow controller and a second hydrogen flow controller. It also includes a flash evaporator, the inlet of which is connected to the slurry outlet of polymerization reactor 1 and polymerization reactor 2 via a conveying pipeline, and the inlet of which is connected to the slurry outlet of polymerization reactor 3 and polymerization reactor 4 via a conveying pipeline. It also includes a stripping kettle, the inlet of which is connected to the outlet of the flash evaporator via a conveying pipeline; It also includes a dryer, the inlet of which is connected to the outlet of the stripping kettle via a conveying pipeline.

[0013] Preferably, before the reactions in polymerization reactors 1 and 2 are completed, the same feeding and polymerization reactions are carried out in polymerization reactors 3 and 4 to achieve continuous production.

[0014] This invention has at least the following beneficial effects: It adopts a dual-reactor parallel polymerization reaction and differentiates hydrogen gas control to obtain polyethylene of different molecular weights. Then, through flash evaporation, water washing, and drying, it obtains medical-grade polyethylene material (UHMWPE). The resulting ultra-high molecular weight polyethylene medical material product has both the mechanical properties of high molecular weight and the easy processing properties of low molecular weight, which reduces costs and is environmentally friendly. The ash content and impurity ion content of the product are far lower than the medical standard to ensure safety and meet the requirements of medical-grade material indicators. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0017] A method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material includes the following steps: Catalyst preparation: First, press 100L of hexane into the catalyst preparation vessel using nitrogen gas and start stirring; then press 5.0L of triethylaluminum (co-catalyst) into the vessel using nitrogen gas; finally, add 2.0kg of TiCl4 (main catalyst) through a sealed reagent bottle and stir for 30 minutes until the mixture is homogeneous. Parallel polymerization in two reactors: Reagent reactor 1 and reactor 2 are connected in parallel. 500L of dehydrated hexane (dispersion medium) is added to each reactor, and stirring is started to pressurize the catalyst into both reactors. The polymerization pressure is controlled at 0.5MPa and the temperature at 75℃. Hydrogen is introduced into reactor 1 through a first hydrogen flow controller to maintain the viscosity-average molecular weight of polyethylene at 2 million. Even less hydrogen is introduced into reactor 2 through a second hydrogen flow controller (with a flow rate lower than the first), maintaining the viscosity-average molecular weight of polyethylene at 7 million. Ethylene is introduced for slurry polymerization. One hour before the catalyst has fully reacted, reactors 3 and 4 are started and polymerized using the same operation. After the reaction is complete, reactors 1 and 2 discharge in parallel, completing this batch of polymerization.

[0018] Flash evaporation, stripping, and drying: The slurry from both reactors is hydraulically fed into the flash evaporator, where the temperature is controlled at 55℃ and the pressure at 0.02MPa for flash evaporation to remove ethylene and hexane. The flash-evaporated ethylene and hexane vapors are condensed, with the liquefied hexane returned to the flash evaporator, and the uncondensed gas partially returned to polymerization reactors 3 and 4 for recycling, and partially discharged to the tail gas system. The flash-evaporated slurry is then fed into the stripping reactor, where softened water is added to form a liquid seal, and stripping and washing are performed at a controlled temperature of 90℃ and a pressure of 2.5kPa. Finally, the wet powder is dried to a moisture content of 0.2% to obtain high-performance, easily processed ultra-high molecular weight polyethylene medical material. After drying, the powder is sieved and transported to the mixing silo for mixing and packaging via a pneumatic conveying system. Example 2

[0019] A method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material includes the following steps: Catalyst preparation: First, press 120L of hexane into the catalyst preparation vessel using nitrogen gas and start stirring; then press 6.0L of diethylaluminum chloride (co-catalyst) into the vessel using nitrogen gas; finally, add 2.2kg of Ti(OCH3)Cl3 (main catalyst) through a sealed reagent bottle and stir for 40 minutes until the mixture is uniform. Parallel polymerization in two reactors: Polymerization reactor 3 and polymerization reactor 4 are connected in parallel. 550L of dehydrated hexane (dispersion medium) is added to each reactor, and stirring is started to pressurize the catalyst into both reactors. The polymerization pressure is controlled at 0.3MPa and the temperature at 80℃. Hydrogen is introduced into polymerization reactor 3 through a first hydrogen flow controller to control the viscosity-average molecular weight of polyethylene in the reactor at 1.5 million. Even less hydrogen is introduced into polymerization reactor 4 through a second hydrogen flow controller (flow rate less than the first flow rate) to control the viscosity-average molecular weight of polyethylene in the reactor at 6.5 million. Ethylene is introduced for slurry polymerization. One hour before the catalyst has completely reacted, polymerization reactors 1 and 2 are started and polymerized using the same operation. After the reaction is completed, polymerization reactors 3 and 4 are connected in parallel to discharge the polymer, completing this batch of polymerization.

[0020] Flash evaporation, stripping, and drying: The slurry from both reactors is hydraulically fed into the flash evaporator, where the temperature is controlled at 52℃ and the pressure at 0.015MPa for flash evaporation to remove ethylene and hexane. The flash-evaporated ethylene and hexane vapors are condensed, with the liquefied hexane returned to the flash evaporator, and the uncondensed gas partially returned to polymerization reactors 1 and 2 for recycling, and partially discharged to the tail gas system. The flash-evaporated slurry is then fed into the stripping reactor, where softened water is added to form a liquid seal, and stripping and washing are performed at a controlled temperature of 88℃ and a pressure of 2.0kPa. Finally, the wet powder is dried to a moisture content of 0.2% to obtain high-performance, easily processed ultra-high molecular weight polyethylene medical material. After drying, the powder is sieved and transported to the mixing silo for mixing and packaging via a pneumatic conveying system. Example 3

[0021] A method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material includes the following steps: Catalyst preparation: First, press 90L of hexane into the catalyst preparation vessel using nitrogen gas and start stirring; then press 4.5L of triisobutylaluminum (co-catalyst) into the vessel using nitrogen gas; finally, add 1.8kg of Ti(OCH3)4 (main catalyst) through a sealed reagent bottle and stir for 35 minutes until the mixture is homogeneous. Parallel polymerization in two reactors: Refrigerator 1 and Refrigerator 2 are connected in parallel. 480L of dehydrated hexane (dispersion medium) is added to each reactor, and stirring is started to pressurize the catalyst into both reactors. The polymerization pressure is controlled at 0.7MPa and the temperature at 70℃. Hydrogen is introduced into Refrigerator 1 through a first hydrogen flow controller to maintain the viscosity-average molecular weight of polyethylene at 2.5 million. Even less hydrogen is introduced into Refrigerator 2 through a second hydrogen flow controller (with a flow rate lower than the first), maintaining the viscosity-average molecular weight of polyethylene at 7.5 million. Ethylene is introduced for slurry polymerization. One hour before the catalyst has fully reacted, Refrigerators 3 and 4 are started and polymerized using the same operation. After the reaction is complete, Refrigerators 1 and 2 discharge in parallel, completing this batch of polymerization.

[0022] Flash evaporation, stripping, and drying: The slurry from both reactors is hydraulically fed into the flash evaporator, where the temperature is controlled at 58℃ and the pressure at 0.025MPa for flash evaporation to remove ethylene and hexane. The flash-evaporated ethylene and hexane vapors are condensed, with the liquefied hexane returned to the flash evaporator, and the uncondensed gas partially returned to polymerization reactors 3 and 4 for recycling, and partially discharged to the tail gas system. The flash-evaporated slurry is then fed into the stripping reactor, where softened water is added to form a liquid seal, and stripping and washing are performed at a controlled temperature of 92℃ and a pressure of 3.0kPa. Finally, the wet powder is dried to a moisture content of 0.2% to obtain high-performance, easily processed ultra-high molecular weight polyethylene medical material. After drying, the powder is sieved and transported to the mixing silo for mixing and packaging via a pneumatic conveying system. Example 4

[0023] The products obtained in Examples 1, 2, and 3 were all in powder form. The samples were prepared as follows: 0.2 g of stearic acid was added to 100 g of polyethylene powder sample and mixed evenly at high speed. The mixture was then pressed into sheets on a flat vulcanizing machine. The temperature was 210°C, the pressure was 20 MPa, the preheating time was 10 minutes, the hot pressing time was 30 minutes, and then the temperature was reduced to room temperature at a rate of 15°C / minute to a sheet thickness of 2 mm.

[0024] The viscosity-average molecular weight of the samples was tested according to the method specified in GB / T1632.3-2010; the viscosity number of the samples was determined according to GB / T1632.3-2010; the simply supported beam double-notched impact strength of the samples was determined according to GB / T 21461.2-2008; the tensile properties of the samples were determined according to GB / T 1040.2-2006; the density of the samples was determined according to GB / T 1033.2-2010; the ash content of the samples was determined according to GB / T 1634.2-2004; the tensile stress of the samples was determined according to GB / T21461.2-2008; the particulate matter of the samples was determined according to GB / T 19701.1-2024; the melt flow rate was determined according to GB / T 3682.1-2018; the basic molding scrap rate and injection molding cycle were determined according to industry-standard methods.

[0025] The Ti content of the samples was determined according to YY / T 1507.1-2016; the Ca content of the samples was determined according to YY / T 1507.3-2016; the Al content of the samples was determined according to YY / T 1507.4-2016; and the Cl content of the samples was determined according to YY / T 1507.2-2016.

[0026] Table 1 Finished Product Inspection Data

[0027] Comparative Example 1 Using the same catalyst and polymerization temperature / pressure as in Example 1, single-pot high molecular weight product (6.5 million) and single-pot low molecular weight product (2 million) were prepared, and the same performance indicators were tested.

[0028] Table 2 Comparison of Finished Product Testing Data

[0029] As shown in Table 3, the dual-reactor product achieves impact strength close to that of the single-reactor high molecular weight product and melt flow rate close to that of the single-reactor low molecular weight product. Example 5

[0030] A method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material includes the following steps: Catalyst preparation: First, pressurize 110L of hexane into the catalyst preparation vessel with nitrogen and start stirring; then pressurize 5.5L of a mixture of triethylaluminum and diethylaluminum chloride (volume ratio 1:1, co-catalyst) into the vessel with nitrogen; finally, add 2.1kg of TiCl4 and TiBr4 mixed powder (mass ratio 2:1, main catalyst) through a sealed reagent bottle and stir for 38min until uniformly mixed.

[0031] Parallel polymerization in two reactors: Refrigerator 1 and Refrigerator 2 are connected in parallel. 520L of dehydrated hexane is added to each reactor, and stirring is started. The catalyst is then pressurized into both reactors. The polymerization pressure is controlled at 0.4MPa and the temperature at 78℃. Hydrogen gas is introduced into Refrigerator 1 to control the viscosity-average molecular weight of polyethylene at 1.8 million; less hydrogen gas is introduced into Refrigerator 2 to control the viscosity-average molecular weight of polyethylene at 6.8 million. Ethylene polymerization is then introduced. Before the reaction ends, Refrigerators 3 and 4 are started for feeding, while Refrigerators 1 and 2 discharge in parallel. Flash evaporation, stripping, and drying: The slurry is pumped into a flash evaporator, where the temperature is controlled at 54℃ and the pressure at 0.018MPa for flash evaporation. The ethylene and hexane vapors produced by flash evaporation are condensed, and the liquefied hexane is returned to the flash evaporator. The uncondensed gas is compressed, and part of it is returned to other polymerization reactors for recycling, while part is discharged to the tail gas system. The slurry after flash evaporation is sent to a stripping reactor, where softened water is added to form a liquid seal. The temperature is controlled at 91℃ and the pressure at 2.2kPa for stripping and water washing. After drying, the powder has a moisture content of 0.2%, is sieved, and then pneumatically mixed and packaged.

[0032] The polymerization process is a batch operation, while other processes can be continuous or intermittent. The main raw materials are sourced from outside the plant area, and the recovered solvent hexane is sent outside the plant area for treatment. Tail gas is also discharged outside the plant area for recovery and treatment.

[0033] In this process, steam is introduced into the jacket of the polymerization reactor to raise the temperature. Once the reaction temperature is reached, ethylene gas is gradually introduced to initiate the polymerization reaction. During the polymerization reaction, the reaction pressure is controlled by adjusting the ethylene flow rate, the reaction temperature is controlled by controlling the amount of circulating water in the polymerization reactor jacket to remove heat, and the molecular weight of the polymer in the two polymerization reactors is controlled by adjusting the amount of hydrogen added. A predetermined amount of ethylene is introduced within a certain time period, and the batch reaction is complete when all the catalyst in the polymerization reactor has reacted. Example 6

[0034] A method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material includes the following steps: Catalyst preparation: First, press 95L of hexane into the catalyst preparation vessel using nitrogen gas and start stirring; then press 4.8L of a mixture of diethylaluminum chloride and triisobutylaluminum (volume ratio of 3:2, co-catalyst) into the vessel using nitrogen gas; finally, add 1.9kg of Ti(OCH3)Cl2 (main catalyst) through a sealed reagent bottle and stir for 32min until the mixture is homogeneous. Parallel polymerization in two reactors: Refrigerator 1 and Refrigerator 2 are connected in parallel. 490L of dehydrated hexane is added to each reactor, stirring is started, and the catalyst is pressurized into both reactors. The polymerization pressure is controlled at 0.6MPa and the temperature at 72℃. Hydrogen gas is introduced into Refrigerator 1 to control the viscosity-average molecular weight of polyethylene at 2.2 million; less hydrogen gas is introduced into Refrigerator 2 to control the viscosity-average molecular weight of polyethylene at 7.2 million. Ethylene polymerization is then introduced. Before the reaction ends, Refrigerators 3 and 4, which were not involved in the current batch reaction, are started to feed the product for continuous production. Refrigerators 1 and 2 discharge the product in parallel.

[0035] Flash evaporation, stripping, and drying: The slurry is pumped into a flash evaporator, where the temperature is controlled at 56℃ and the pressure at 0.022MPa for flash evaporation. The ethylene and hexane vapors produced by flash evaporation are condensed, and the liquefied hexane is returned to the flash evaporator. The uncondensed gas is compressed, and part of it is returned to other polymerization reactors for recycling, while part is discharged to the tail gas system. The slurry after flash evaporation is sent to a stripping reactor, where softened water is added to form a liquid seal. The temperature is controlled at 89℃ and the pressure at 2.8kPa for stripping and water washing. After drying, the powder has a moisture content of 0.2%, is sieved, and then pneumatically mixed and packaged. Example 7

[0036] The products provided in Examples 5 and 6 were tested according to the method described in Example 4, and the results are shown in the table below.

[0037] Table 3 Finished Product Inspection Data

[0038] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of a high performance, easy processable ultra high molecular weight polyethylene medical grade material, characterized in that, The method comprises the following steps: S1, catalyst configuration: nitrogen is used to send hexane to a preparation kettle, a promoter is first added, then a main catalyst is added, and stirring is performed to uniformly mix the components; S2, parallel polymerization: in a batch polymerization mode, two polymerization kettles are used in a parallel discharge mode, hexane is used as a dispersion medium, and polymerization is performed by introducing ethylene in the presence of the main catalyst and the promoter; The polymerization pressure and the polymerization temperature of one of the polymerization kettles are controlled, and the viscosity average molecular weight of polyethylene generated in the polymerization kettle is controlled to be in the range of 10-30 million by introducing hydrogen with a first flow rate into the polymerization kettle; Meanwhile, the polymerization pressure and the polymerization temperature of the other polymerization kettle are controlled, and the viscosity average molecular weight of polyethylene generated in the polymerization kettle is controlled to be in the range of 6-8 million by introducing hydrogen with a second flow rate into the polymerization kettle, and the second flow rate is less than the first flow rate; S3, slurry mixing and flashing: the polyethylene slurries from the two polymerization kettles are mixed in the same flash kettle by pressure feeding, and the solvent is preliminarily removed; S4, stripping and water washing: the slurry after flashing is transported to a stripping kettle to remove residual solvents and impurities; S5, drying: the wet polyethylene powder after stripping and water washing is dried to obtain high-performance, easy-to-process ultrahigh molecular weight polyethylene medical material.

2. The process for the preparation of high performance, easy processable ultra high molecular weight polyethylene medical grade material as claimed in claim 1, wherein: In step S1, the main catalyst is a titanium compound selected from one or more mixtures of TiCl4, TiBr4, Ti(OCH3)Cl3, Ti(OCH3)Cl2 and Ti(OCH3)4; The promoter is an organic aluminum compound selected from one or more mixtures of triethylaluminum, diethylaluminum chloride and triisobutylaluminum.

3. The method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material according to claim 1, characterized in that: In step S2, the viscosity average molecular weight of polyethylene generated in one of the polymerization kettles is controlled to be in the range of 15-25 million; The viscosity average molecular weight of polyethylene generated in the other polymerization kettle is controlled to be in the range of 6.5-7.5 million.

4. The method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material according to claim 1, characterized in that: In step S3, the ethylene and hexane vapor flashed out are condensed, the liquefied hexane is returned to the flash kettle, and the uncondensed gas is compressed and partially returned to other polymerization kettles for recycling or partially discharged to a tail gas system.

5. The method for preparing high-performance, easily processable ultra-high molecular weight polyethylene medical material according to claim 1, characterized in that: In step S4, the amount of soft water added to the stripping kettle is sufficient to cover the pipe opening of the slurry conveying pipe to form a liquid seal.

6. A high performance, easy processable ultra high molecular weight polyethylene medical grade material prepared by the process of any one of claims 1 to 5, characterized by: It is a powdery particle with a viscosity average molecular weight of not less than 5 million and an ash content of not more than 125 mg / kg.

7. The high performance, easy-to-process UHMWPE medical grade material according to claim 6, characterized in that: In the ash, the titanium element content is not more than 40 mg / kg, the calcium element content is not more than 5 mg / kg, the aluminum element content is not more than 20 mg / kg, and the chlorine element content is not more than 30 mg / kg.

8. A two-kettle parallel polymerization system for carrying out the process of claim 1, wherein, The system comprises: 2 groups of discharge systems provided by two polymerization kettles in parallel, one group being polymerization kettle 1 and polymerization kettle 2 arranged in parallel, and the other group being polymerization kettle 3 and polymerization kettle 4 arranged in parallel, and the polymerization kettles are each provided with a material inlet, a catalyst inlet, a hydrogen inlet, a slurry outlet and a temperature and pressure detection and control device; The first hydrogen flow controller and the second hydrogen flow controller are connected with the hydrogen inlets of the polymerization kettle 1 and the polymerization kettle 2 respectively, and the first hydrogen flow controller and the second hydrogen flow controller are connected with the hydrogen inlets of the polymerization kettle 3 and the polymerization kettle 4 respectively; The flash kettle is further provided with a feeding port connected with the slurry outlet of the polymerization kettle through a conveying pipeline; The stripping kettle is further provided with a feeding port connected with the discharge port of the flash kettle through a conveying pipeline; The dryer is further provided with a feeding port connected with the discharge port of the stripping kettle through a conveying pipeline.

9. The twin-kettle parallel polymerization system of claim 8, wherein: Before the reaction in the polymerization kettle 1 and the polymerization kettle 2 ends, the feeding and the polymerization reaction are started in the polymerization kettle 3 and the polymerization kettle 4 in the same operation mode, and the continuous production is carried out.

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