High-rigidity low-permeability medical polyethylene material and preparation method thereof

Abstract

The application discloses a kind of high rigidity low permeability medical polyethylene material and preparation method thereof, belong to medical polymer material technical field.The material is made of high-density polyethylene, long alkyl chain Si-Al hybrid precursor oligomer, ultra-high molecular weight polyethylene, TEMPO oxidized cellulose nanofiber, compatibilizer and auxiliary agent.Formed rigid inorganic network by Si-Al hybrid precursor, TEMPO oxidized cellulose nanofiber is covalently bridged and anchored in the network by compatibilizer PE-g-MAH, long chain of ultra-high molecular weight polyethylene is topologically constrained by rigid network, and the three cooperatively build stress transfer and molecular chain movement constraint mechanism, while forming dense physical barrier.The rigidity, creep resistance and gas barrier properties of the application are significantly improved while maintaining good toughness of the material, which can meet the medical use requirements.

Description

Technical Field

[0001] This invention relates to the field of medical polymer materials technology, and in particular to a high-rigidity, low-permeability medical polyethylene material and its preparation method. Background Technology

[0002] High-density polyethylene (HDPE) possesses excellent chemical stability, low water absorption, and good processing properties, making it widely used in medical packaging materials and medical devices. However, the non-polar linear molecular chain of HDPE results in inherent defects such as insufficient rigidity and poor creep resistance in its products, limiting its application in high-end medical fields. Furthermore, medical materials require high barrier properties against oxygen and water vapor, and the barrier properties of pure HDPE often fall short of the demands of high-end medical packaging. Therefore, stiffening and barrier modification of HDPE is of significant practical importance.

[0003] Currently, the main modification methods to improve the rigidity and barrier properties of HDPE include inorganic particle filling modification and multilayer composites. Inorganic particle filling modification involves adding inorganic fillers such as talc and nano-silica to the HDPE matrix, utilizing the reinforcing effect of rigid particles on the matrix to improve the flexural modulus and flexural strength of the material. However, the significant polarity difference between inorganic particles and the HDPE matrix leads to poor interfacial compatibility, and filler agglomeration, resulting in stress concentration and material embrittlement, often at the expense of the material's toughness and ductility.

[0004] In terms of toughening modification, ultra-high molecular weight polyethylene (UHMWPE) has been used in the blending modification of HDPE due to its excellent impact resistance. The ultra-long molecular chains of UHMWPE can form a physical entanglement network in the matrix, effectively improving the impact resistance of the material. However, UHMWPE has extremely high melt viscosity, which differs significantly from the processing window of HDPE, making uniform dispersion difficult. More importantly, UHMWPE and HDPE are only bonded by physical entanglement, and under long-term stress or high-temperature conditions, chain segment slippage is prone to occur at the entanglement points, resulting in very limited improvement in the material's creep resistance.

[0005] In terms of barrier modification, multilayer composite technology involves co-extruding HDPE with high-barrier materials such as ethylene-vinyl alcohol copolymer (EVOH) to form a multilayer structure. However, multilayer composite structures suffer from problems such as insufficient interlayer bonding, complex processing technology, and high cost. Furthermore, the barrier properties of EVOH are highly sensitive to humidity, limiting its reliable application in medical packaging in humid environments.

[0006] Therefore, how to simultaneously improve the rigidity, creep resistance and gas barrier properties of HDPE while maintaining its good toughness and processing performance remains a technical challenge that needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a high-rigidity, low-permeability medical polyethylene material and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A high-rigidity, low-permeability medical-grade polyethylene material, made from the following components in parts by weight: High-density polyethylene: 87.5–91.5 parts; Long alkyl chain Si-Al hybrid precursor oligomers: 5-8 parts; Ultra-high molecular weight polyethylene: 3-5 parts; TEMPO oxidized cellulose nanofibers: 1-2 parts; Compatibilizer: 2-3 parts; Light stabilizer: 0.2–0.5 parts; Compound antioxidant: 0.1–0.3 parts; Calcium stearate: 0.1-0.2 parts.

[0009] The density of the high-density polyethylene is 0.948–0.964 g / cm³. 3 The weight-average molecular weight of the ultra-high molecular weight polyethylene is 3.7 × 10⁻⁶. 6 ~4.0×10 6 g / mol; the diameter of the TEMPO oxidized cellulose nanofibers is 5-10 nm; the compatibilizer is maleic anhydride-grafted polyethylene, the base material of the maleic anhydride-grafted polyethylene is high-density polyethylene, and the grafting rate is 0.8-1.0%; the light stabilizer is a hindered amine light stabilizer; the composite antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:(1.0-2.0).

[0010] Preferably, the method for preparing the long alkyl chain Si-Al hybrid precursor oligomer includes the following steps: S1: Under an inert atmosphere, the aluminum source is dissolved in anhydrous isopropanol, followed by the addition of ethyl acetoacetate. The mixture is stirred at 40–60 °C for 30–60 min to form a coordination complex, thus obtaining the aluminum source solution.

[0011] S2: Under an inert atmosphere, add tetraethyl orthosilicate and glycerol (pharmaceutical grade) and long alkyltriethoxysilane to the reactor, stir at 30-50°C for 10-20 minutes to mix them completely, then slowly add the aluminum source solution from step S1, followed by adding acetic acid as an acid catalyst to control the pH of the system at 3-4.

[0012] S3: Slowly heat the system obtained in step S2 to 60-80℃ and maintain it for 1-2 hours, then cool it down to 40-60℃ and remove the low molecular weight alcohol under reduced pressure at a vacuum of -0.08 to -0.1 MPa. Collect the product to obtain the long alkyl chain Si-Al hybrid precursor oligomer.

[0013] Preferably, in step S1, the aluminum source is aluminum isopropoxide or aluminum sec-butoxide.

[0014] Preferably, in step S2, the long alkyltriethoxysilane is selected from one of n-octyltriethoxysilane, n-decyltriethoxysilane, and octadecyltriethoxysilane.

[0015] Preferably, in step S2, the molar ratio of tetraethyl orthosilicate to glycerol is 1:(0.2-0.5); the molar ratio of tetraethyl orthosilicate to aluminum source is 1:(0.3-0.7); and the molar ratio of long alkyltriethoxysilane to tetraethyl orthosilicate is 1:(0.5-1.0).

[0016] In the above scheme, in S1, ethyl acetoacetate acts as a chelating ligand to undergo a coordination substitution reaction with aluminum alkoxide, forming a stable aluminum complex. The aim is to reduce the hydrolysis reactivity of the aluminum source and match its hydrolysis rate with that of tetraethyl orthosilicate. In S2, tetraethyl orthosilicate, long alkyltriethoxysilane, and stabilized aluminum source undergo co-hydrolysis under acetic acid catalysis. Alkoxy groups are converted into silanols (Si-OH) and aluminum hydroxyl groups (Al-OH) as active species. Glycerol acts as a stabilizer to inhibit excessive polycondensation of hydrolysis products. In S3, heating promotes the removal of water molecules from these active species through condensation reactions, gradually forming an inorganic network framework composed of Si-O-Si, Si-O-Al, and Al-O-Al bonds. At the same time, long alkyl side chains are stably connected to the network through Si-C bonds. Vacuum removal of low-molecular-weight alcohols can remove condensation byproducts, promote reaction equilibrium, and prevent runaway condensation from forming highly cross-linked gels. The resulting long-alkyl chain Si-Al hybrid precursor oligomer has an inorganic network that provides rigidity and thermal stability, while the long alkyl side chains impart good compatibility with the polyethylene matrix.

[0017] A method for preparing a high-rigidity, low-permeability medical polyethylene material includes the following steps: Step 1: Dry high-density polyethylene, ultra-high molecular weight polyethylene, and maleic anhydride-grafted polyethylene separately to control the moisture content ≤0.05%; freeze-dry or spray-dry TEMPO oxidized cellulose nanofibers to control the moisture content ≤0.5%.

[0018] Step 2: Weigh out the dried high-density polyethylene, ultra-high molecular weight polyethylene, maleic anhydride-grafted polyethylene, long alkyl chain Si-Al hybrid precursor oligomer, TEMPO oxidized cellulose nanofiber, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, and put them into a high-speed mixer to mix to obtain a premix.

[0019] Step 3: The premixed material is fed into a twin-screw extruder for melt blending and extrusion. The twin-screw extruder has a vacuum exhaust port in the middle section of the barrel, and the vacuum degree is controlled at -0.06 to -0.08 MPa. The screw speed of the twin-screw extruder is 200 to 400 r / min. The temperature from zone 1 to the die head is set as follows: zone 1 150 to 170℃, zone 2 180 to 200℃, zone 3 200 to 220℃, zone 4 200 to 220℃, zone 5 190 to 210℃, and die head 190 to 210℃. The residence time is 2 to 5 minutes.

[0020] Step 4: Cool, granulate, and dry the extrudate to obtain the high-rigidity, low-permeability medical polyethylene material.

[0021] Preferably, in the first step, the drying temperature of the high-density polyethylene and maleic anhydride-grafted polyethylene is 80-100℃, and the drying time is 2-4 hours; the drying temperature of the ultra-high molecular weight polyethylene is 60-80℃, and the drying time is 4-6 hours.

[0022] Preferably, in the second step, the mixing speed of the high-speed mixer is 500-1500 r / min, and the mixing time is 5-15 min.

[0023] Preferably, in the fourth step, the cooling is performed using a water tank with a water temperature of 20–40°C; the drying temperature is 60–80°C, and the drying time is 4–8 hours.

[0024] This technical solution addresses the performance bottlenecks of medical-grade polyethylene materials in terms of rigidity, creep resistance, and barrier properties. It proposes a multi-layered synergistic modification strategy involving "molecular-level hybrid rigid network construction + covalent bridging interface reinforcement + long-chain entanglement anchoring." The mechanisms of action and innovative principles of each component are as follows: 1. In-situ rigidification and barrier mechanism of long alkyl chain Si-Al hybrid precursors: Unlike existing technologies that physically blend nano-SiO2 or Al2O3 particles, this method employs a sol-gel method to prepare long-alkyl-chain Si-Al hybrid precursor oligomers. The aluminum source is stabilized by chelation with ethyl acetoacetate, and its hydrolysis rate is controlled to match that of tetraethyl orthosilicate, achieving molecular-level co-condensation. The residual silanol and aluminum hydroxyl groups in this oligomer further condense during polyethylene melt processing, forming a uniformly distributed Si-O-Si and Si-O-Al inorganic network framework, directly providing rigid support. Simultaneously, the dense inorganic network increases the diffusion paths for small molecule gases or liquids, significantly reducing material permeability. The long alkyl side chains on the precursor are connected to the silicon atoms of the network framework via stable Si-C bonds, similar to the molecular chain structure of polyethylene. This allows for good interfacial affinity through intermolecular physical entanglement, effectively eliminating macroscopic phase separation between the inorganic and organic phases.

[0025] 2. Covalent bridging enhancement mechanism of TEMPO oxidized cellulose nanofibers: Traditional cellulose or microcrystalline cellulose readily aggregates in polyolefin matrices due to polarity differences, making it difficult to achieve theoretically high moduli. This solution introduces TEMPO-oxidized cellulose nanofibers, whose surfaces are rich in carboxyl groups (-COOH) due to the selective oxidation of TEMPO. Under the high-temperature shear conditions of a twin-screw extruder, the carboxyl groups on the surface of the TEMPO-oxidized cellulose nanofibers react with the anhydride groups of the compatibilizer PE-g-MAH to form covalent bonds; simultaneously, the polyethylene backbone of PE-g-MAH is connected to the long alkyl side chains of the precursor through intermolecular physical entanglement. Through the bridging effect of PE-g-MAH, the rigid whiskers of the TEMPO-oxidized cellulose nanofibers are indirectly anchored in the Si-Al inorganic network, forming an organic-inorganic interpenetrating network structure. Stress can be efficiently transferred from the polyethylene matrix to the TEMPO-oxidized cellulose nanofibers and the Si-Al network through the PE-g-MAH interface layer, avoiding the decrease in rigidity caused by interfacial debonding.

[0026] 3. Entanglement, anchoring, and creep resistance mechanisms of ultra-high molecular weight polyethylene (UHMWPE): The weight-average molecular weight is introduced to be 3.7 × 10⁻⁶. 6 ~4.0×10 6In this method, UHMWPE (g / mol) forms a high-density physically entangled network of ultra-long molecular chains within an HDPE matrix. In existing technologies, the blending of UHMWPE and HDPE relies solely on chain entanglement to improve toughness, but chain segments are prone to slippage under long-term stress. In this solution, an in-situ formed rigid network of Si-Al / TEMPO oxidized cellulose nanofibers is uniformly dispersed within the polyethylene matrix. This rigid network framework acts as a physical barrier, exerting a topological constraint effect on the ultra-long molecular chains of UHMWPE, limiting their macroscopic slippage under external forces. This interpenetrating structure of "organic flexible entangled chains - inorganic rigid anchor points" significantly improves the material's creep resistance and long-term rigidity retention while maintaining its toughness, overcoming the embrittlement problem caused by simply increasing filler content.

[0027] 4. Interfacial compatibility synergy of maleic anhydride-grafted polyethylene (PE-g-MAH): PE-g-MAH plays a dual role in the system. Its nonpolar HDPE backbone is completely compatible with the matrix; its grafted maleic anhydride groups undergo interfacial esterification with the carboxyl groups of TEMPO oxidized cellulose nanofibers, covalently linking the TEMPO oxidized cellulose nanofibers to the polyethylene molecular chain, further enhancing the bonding force at the organic-inorganic interface. Through the bridging of PE-g-MAH, a multi-level interfacial structure of "HDPE matrix - PE-g-MAH compatibility layer - covalent bond bridging - Si-Al / TEMPO oxidized cellulose nanofiber rigid network" is constructed.

[0028] In summary, the core innovation of this technical solution lies in the effective connection between TEMPO oxidized cellulose nanofibers with high aspect ratio and Si-Al hybrid networks through PE-g-MAH covalent bridging via chemical reaction design, thereby constraining UHMWPE long chains. This enhancement mechanism based on the synergistic effect of "covalent bridging" and "physical anchoring" breaks the constraint of increased rigidity and decreased compatibility / toughness in traditional filler modification, achieving a balance between high rigidity, low permeability, and medical safety.

[0029] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention employs a sol-gel method to synthesize long-alkyl-chain Si-Al hybrid precursor oligomers. During melt processing, these precursors further condense to form a uniformly distributed Si-O-Si and Si-O-Al inorganic network framework within the matrix, solving the problems of easy agglomeration and poor interfacial compatibility in traditional inorganic nanoparticle physical blending. This inorganic network framework directly provides rigid support, while its dense structure increases the diffusion paths of small molecule gases, reducing the material's oxygen and water vapor permeability.

[0030] 2. This invention introduces TEMPO oxidized cellulose nanofibers, which utilize the esterification reaction between the carboxyl groups on their surface and the anhydride groups of maleic anhydride-grafted polyethylene to form covalent bonds. Through the bridging effect of PE-g-MAH, the rigid whiskers of TEMPO oxidized cellulose nanofibers are anchored in the Si-Al inorganic network, solving the problems of difficult dispersion and weak interfacial bonding of nanocellulose in non-polar polyethylene matrix, and realizing the efficient transfer of stress from the matrix to the rigid network.

[0031] 3. This invention introduces ultra-high molecular weight polyethylene (UHMWPE), whose ultra-long molecular chains form a high-density physical entanglement network in the HDPE matrix. At the same time, the rigid Si-Al / TEMPO oxidized cellulose nanofiber network exerts a topological constraint effect on this entanglement network, restricting the macroscopic slippage of molecular chains under external force. This solves the problems of chain segment untangling and slippage and poor creep resistance in existing UHMWPE / HDPE blend systems under long-term stress. While maintaining the toughness of the material, it significantly improves the creep resistance and long-term dimensional stability.

[0032] 4. This invention uses pharmaceutical-grade glycerol to replace traditional toxic solvents, and combines vacuum distillation and twin-screw vacuum devouring to ensure that the residual low molecular weight alcohol is ≤500ppm. Furthermore, ICP-MS confirms that the Si-Al inorganic network is chemically stable and has extremely low soluble aluminum-silicon content, meeting the safety requirements for leachates in medical packaging materials. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0034] Example 1: A method for preparing a high-rigidity, low-permeability medical polyethylene material, comprising the following steps: (a) Raw material specifications and weight ratios: High-density polyethylene (HDPE, density 0.948 g / cm³) 3 (M4855, purchased from Shanghai Songhan Plastics Technology Co., Ltd.): 87.5 parts; Long alkyl chain Si-Al hybrid precursor oligomers: 5 parts; Ultra-high molecular weight polyethylene (UHMWPE, weight average molecular weight 3.7 × 10⁻⁶) 6 g / mol, model GUR5113, purchased from Dongguan Zhanyu Plastic Raw Materials Co., Ltd.): 3 parts; TEMPO oxidized cellulose nanofibers (5-10 nm in diameter, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.): 1 part; Maleic anhydride-grafted polyethylene (PE-g-MAH, HDPE substrate, grafting rate 0.8-1%, model PE-12H, purchased from Hangzhou Jinwei Nanomaterials Co., Ltd.): 2 parts; Hindered amine light stabilizer (light stabilizer 944): 0.2 parts; Compound antioxidant: 0.1 parts (composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1.0, i.e., antioxidant 1010 is 0.05 parts and antioxidant 168 is 0.05 parts). Calcium stearate: 0.1 parts.

[0035] (II) Preparation of long alkyl chain Si-Al hybrid precursor oligomers: S1: Under a nitrogen atmosphere, 61.2 g (0.3 mol) aluminum isopropoxide was dissolved in 200 mL of anhydrous isopropanol, followed by the addition of 39.0 g (0.3 mol) ethyl acetoacetate. The mixture was stirred at 40 °C for 30 min to form a coordination complex, thus obtaining an aluminum source solution.

[0036] S2: Under a nitrogen atmosphere, add 208.3 g (1 mol) tetraethyl orthosilicate and 18.4 g (0.2 mol) glycerol (pharmaceutical grade) and 553.0 g (2 mol) n-octyltriethoxysilane (i.e., the molar ratio of long alkyltriethoxysilane to tetraethyl orthosilicate is 1:0.5) to the reactor, stir at 30 °C for 10 min to make it completely mixed, and then slowly add the aluminum source solution from step S1 (i.e., the molar ratio of tetraethyl orthosilicate to aluminum source is 1:0.3), followed by adding 2 mL of glacial acetic acid as an acid catalyst to control the pH of the system at 3.

[0037] S3: Slowly heat the system obtained in step S2 to 60℃ and maintain it for 1 hour, then cool it down to 40℃ and remove the low molecular weight alcohol under reduced pressure at a vacuum of -0.08MPa. Control the total residual amount of low molecular weight alcohol (isopropanol, ethanol), acetic acid and free glycerol to ≤500ppm. Collect the product to obtain the long alkyl chain Si-Al hybrid precursor oligomer.

[0038] (III) Preparation of medical-grade polyethylene materials: Step 1: Dry high-density polyethylene and maleic anhydride-grafted polyethylene at 80℃ for 2 hours; dry ultra-high molecular weight polyethylene at 60℃ for 4 hours, controlling the moisture content to ≤0.05%; freeze-dry TEMPO oxidized cellulose nanofibers, controlling the moisture content to ≤0.5%.

[0039] Step 2: Weigh out each dried component by weight and put it into a high-speed mixer. Mix at 500 r / min for 5 minutes to obtain a premix.

[0040] Step 3: The premixed material is fed into a twin-screw extruder for melt blending and extrusion. The twin-screw extruder has a vacuum exhaust port in the middle section of the barrel, and the vacuum degree is controlled at -0.06MPa. The screw speed of the twin-screw extruder is 200r / min. The temperature from zone 1 to the die head is set as follows: zone 1 150℃, zone 2 180℃, zone 3 200℃, zone 4 200℃, zone 5 190℃, and die head 190℃. The residence time is 2min.

[0041] Step 4: After cooling the extrudate in a water bath at 20°C, granulate it and then dry it at 60°C for 4 hours to obtain a high-rigidity, low-permeability medical polyethylene material.

[0042] Example 2: A method for preparing a high-rigidity, low-permeability medical polyethylene material, comprising the following steps: (a) Raw material specifications and weight ratios: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (M3138, purchased from Shanghai Songhan Plastics Technology Co., Ltd.): 88 portions; Long alkyl chain Si-Al hybrid precursor oligomers: 7.5 parts; Ultra-high molecular weight polyethylene (UHMWPE, weight average molecular weight 4.0 × 10⁻⁶) 6 (g / mol, model GUR1050, purchased from Dongguan Zhanyu Plastic Raw Materials Co., Ltd.): 3.2 parts; TEMPO oxidized cellulose nanofibers (5-10 nm in diameter, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.): 1.5 parts; Maleic anhydride-grafted polyethylene (PE-g-MAH, HDPE substrate, grafting rate 0.8-1%, model PE-12H, purchased from Hangzhou Jinwei Nanomaterials Co., Ltd.): 2.5 parts; Hindered amine light stabilizer (light stabilizer 944): 0.25 parts; Compound antioxidant: 0.2 parts (composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1.5, i.e., antioxidant 1010 is 0.08 parts and antioxidant 168 is 0.12 parts). Calcium stearate: 0.15 parts.

[0043] (II) Preparation of long alkyl chain Si-Al hybrid precursor oligomers: S1: Under an argon atmosphere, 123.2 g (0.5 mol) of aluminum sec-butoxide was dissolved in 250 mL of anhydrous isopropanol, followed by the addition of 65.1 g (0.5 mol) of ethyl acetoacetate. The mixture was stirred at 50 °C for 45 min to form a coordination complex, thus obtaining an aluminum source solution.

[0044] S2: Under an argon atmosphere, add 208.3 g (1 mol) tetraethyl orthosilicate and 32.2 g (0.35 mol) glycerol (pharmaceutical grade) and 405.0 g (1.33 mol) n-decyltriethoxysilane (i.e., the molar ratio of long alkyltriethoxysilane to tetraethyl orthosilicate is 1:0.75) to the reactor, stir at 40 °C for 15 min to make it completely mixed, and then slowly add the aluminum source solution from step S1 (i.e., the molar ratio of tetraethyl orthosilicate to aluminum source is 1:0.5), followed by adding 3 mL of glacial acetic acid as an acid catalyst to control the pH of the system at 3.5.

[0045] S3: Slowly heat the system obtained in step S2 to 70℃ and maintain it for 1.5h, then cool it down to 50℃ and remove the low molecular weight alcohol under reduced pressure at a vacuum degree of -0.09MPa. Control the total residual amount of low molecular weight alcohol (isopropanol, ethanol), acetic acid and free glycerol to ≤500ppm. Collect the product to obtain the long alkyl chain Si-Al hybrid precursor oligomer.

[0046] (III) Preparation of medical-grade polyethylene materials: Step 1: Dry high-density polyethylene and maleic anhydride-grafted polyethylene at 90℃ for 3 hours; dry ultra-high molecular weight polyethylene at 70℃ for 5 hours, controlling the moisture content to ≤0.05%; spray dry TEMPO oxidized cellulose nanofibers, controlling the moisture content to ≤0.5%.

[0047] Step 2: Weigh out each dried component by weight and put it into a high-speed mixer. Mix at 1000 r / min for 10 min to obtain a premix.

[0048] Step 3: The premixed material is fed into a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is equipped with a vacuum exhaust port in the middle section of the barrel, and the vacuum degree is controlled at -0.07MPa. The screw speed of the twin-screw extruder is 300r / min. The temperature from zone 1 to the die head is set as follows: zone 1 160℃, zone 2 190℃, zone 3 210℃, zone 4 210℃, zone 5 200℃, and die head 200℃. The residence time is 3.5min.

[0049] Step 4: After cooling the extrudate in a water bath at 30°C, granulate it and then dry it at 70°C for 6 hours to obtain a high-rigidity, low-permeability medical polyethylene material.

[0050] Example 3: A method for preparing a high-rigidity, low-permeability medical polyethylene material, comprising the following steps: (a) Raw material specifications and weight ratios: High-density polyethylene (HDPE, density 0.964 g / cm³) 3 (K606, purchased from Shanghai Songhan Plastics Technology Co., Ltd.): 91.5 parts; Long alkyl chain Si-Al hybrid precursor oligomers: 8 parts; Ultra-high molecular weight polyethylene (UHMWPE, weight average molecular weight 4.0 × 10⁻⁶) 6 g / mol, model GUR1050, purchased from Dongguan Zhanyu Plastic Raw Materials Co., Ltd.: 5 parts; TEMPO oxidized cellulose nanofibers (5-10 nm in diameter, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.): 2 parts; Maleic anhydride-grafted polyethylene (PE-g-MAH, HDPE substrate, grafting rate 0.8-1%, model PE-12H, purchased from Hangzhou Jinwei Nanomaterials Co., Ltd.): 3 parts; Hindered amine light stabilizer (light stabilizer 944): 0.5 parts; Compound antioxidant: 0.3 parts (composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:2.0, i.e., antioxidant 1010 is 0.1 parts and antioxidant 168 is 0.2 parts). Calcium stearate: 0.2 parts.

[0051] (II) Preparation of long alkyl chain Si-Al hybrid precursor oligomers: S1: Under a nitrogen atmosphere, 143.0 g (0.7 mol) aluminum isopropoxide was dissolved in 300 mL of anhydrous isopropanol, followed by the addition of 91.1 g (0.7 mol) ethyl acetoacetate. The mixture was stirred at 60 °C for 60 min to form a coordination complex, thus obtaining an aluminum source solution.

[0052] S2: Under a nitrogen atmosphere, add 208.3 g (1 mol) tetraethyl orthosilicate and 46.0 g (0.5 mol) glycerol (pharmaceutical grade) and 416.8 g (1 mol) octadecyltriethoxysilane (i.e., the molar ratio of long alkyltriethoxysilane to tetraethyl orthosilicate is 1:1.0) to the reactor, stir at 50 °C for 20 min to make it completely mixed, and then slowly add the aluminum source solution from step S1 (i.e., the molar ratio of tetraethyl orthosilicate to aluminum source is 1:0.7). Then add 5 mL of glacial acetic acid as an acid catalyst to control the pH of the system at 4.

[0053] S3: Slowly heat the system obtained in step S2 to 80℃ and maintain it for 2 hours, then cool it down to 60℃ and remove the low molecular weight alcohol under reduced pressure at a vacuum of -0.1MPa. Control the total residual amount of low molecular weight alcohol (isopropanol, ethanol), acetic acid and free glycerol to ≤500ppm. Collect the product to obtain the long alkyl chain Si-Al hybrid precursor oligomer.

[0054] (III) Preparation of medical-grade polyethylene materials: Step 1: Dry high-density polyethylene and maleic anhydride-grafted polyethylene at 100℃ for 4 hours; dry ultra-high molecular weight polyethylene at 80℃ for 6 hours, controlling the moisture content to ≤0.05%; freeze-dry TEMPO oxidized cellulose nanofibers, controlling the moisture content to ≤0.5%.

[0055] Step 2: Weigh out each dried component by weight and put it into a high-speed mixer. Mix at 1500 r / min for 15 min to obtain a premix.

[0056] Step 3: The premixed material is fed into a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is equipped with a vacuum exhaust port in the middle section of the barrel, and the vacuum degree is controlled at -0.08MPa. The screw speed of the twin-screw extruder is 400r / min. The temperature from zone 1 to the die head is set as follows: zone 1 170℃, zone 2 200℃, zone 3 220℃, zone 4 220℃, zone 5 210℃, and die head 210℃. The residence time is 5min.

[0057] Step 4: After cooling the extrudate in a water bath at 40°C, granulate it and then dry it at 80°C for 8 hours to obtain a high-rigidity, low-permeability medical polyethylene material.

[0058] Comparative Example 1 (pure HDPE): (a) Raw material weight ratio: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (Brand number M3138): 103.3 portions.

[0059] (II) Preparation method: High-density polyethylene (HDPE) was dried at 90℃ for 3 hours, with a moisture content controlled to ≤0.05%. The dried HDPE was then directly fed into a twin-screw extruder for melt extrusion. The screw speed of the twin-screw extruder was 300 r / min, and the temperatures from zone 1 to the die head were set as follows: zone 1 160℃, zone 2 190℃, zone 3 210℃, zone 4 210℃, zone 5 200℃, and die head 200℃, with a residence time of 3.5 min. The extrudate was cooled in a water bath at 30℃ and then granulated. Finally, it was dried at 70℃ for 6 hours to obtain pure HDPE material.

[0060] Comparative Example 2 (using nano-SiO2 instead of Si-Al hybrid precursor): (a) Raw material weight ratio: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (Brand number M3138): 88 portions; Nano-silica (nano-SiO2, average particle size 20nm, surface hydrophobic modification treatment with octyltrimethoxysilane): 7.5 parts; The types and weights of the remaining components (ultra-high molecular weight polyethylene, TEMPO oxidized cellulose nanofibers, maleic anhydride grafted polyethylene, light stabilizer, composite antioxidant, calcium stearate) are the same as in Example 2.

[0061] (II) Preparation method: The drying process for the first step, including high-density polyethylene, maleic anhydride-grafted polyethylene, ultra-high molecular weight polyethylene, and TEMPO oxidized cellulose nanofibers, is the same as in Example 2.

[0062] Step 2: Weigh out the dried high-density polyethylene, ultra-high molecular weight polyethylene, maleic anhydride-grafted polyethylene, nano silica, dried TEMPO oxidized cellulose nanofibers, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, put them into a high-speed mixer, and mix them at a speed of 1000 r / min for 10 min to obtain the premix.

[0063] Steps three and four are the same as in Example 2.

[0064] The difference from Example 2 is that the long alkyl chain Si-Al hybrid precursor oligomer is replaced with an equal part by weight of nano-silica; the preparation step of the long alkyl chain Si-Al hybrid precursor oligomer is omitted.

[0065] Comparative Example 3 (using unmodified microcrystalline cellulose instead of TEMPO oxidized cellulose nanofibers): (a) Raw material weight ratio: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (Brand number M3138): 88 portions; Unmodified microcrystalline cellulose (MCC, average particle size 20 μm): 1.5 parts; The types and weights of the remaining components (long alkyl chain Si-Al hybrid precursor oligomer, ultra-high molecular weight polyethylene, maleic anhydride grafted polyethylene, light stabilizer, composite antioxidant, calcium stearate) are the same as in Example 2.

[0066] (II) Preparation method: The preparation of long alkyl chain Si-Al hybrid precursor oligomers is the same as in Example 2.

[0067] Step 1: Dry high-density polyethylene and maleic anhydride-grafted polyethylene at 90℃ for 3 hours; dry ultra-high molecular weight polyethylene at 70℃ for 5 hours, controlling the moisture content to ≤0.05% in both cases; dry unmodified microcrystalline cellulose at 80℃ for 4 hours.

[0068] Step 2: Weigh out the dried high-density polyethylene, ultra-high molecular weight polyethylene, maleic anhydride grafted polyethylene, long alkyl chain Si-Al hybrid precursor oligomer, dried microcrystalline cellulose, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, put them into a high-speed mixer, mix at 1000 r / min for 10 min to obtain the premix.

[0069] Steps three and four are the same as in Example 2.

[0070] Comparative Example 4 (lacking ultra-high molecular weight polyethylene): (a) Raw material weight ratio: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (M3138): 91.2 portions; The types and weights of the remaining components (long alkyl chain Si-Al hybrid precursor oligomer, TEMPO oxidized cellulose nanofiber, maleic anhydride grafted polyethylene, light stabilizer, composite antioxidant, calcium stearate) are the same as in Example 2.

[0071] (II) Preparation method: The preparation of long alkyl chain Si-Al hybrid precursor oligomers is the same as in Example 2.

[0072] Step 1: Dry high-density polyethylene and maleic anhydride-grafted polyethylene at 90℃ for 3 hours; spray dry TEMPO oxidized cellulose nanofibers to control the moisture content ≤0.5%.

[0073] Step 2: Weigh out the dried high-density polyethylene, maleic anhydride grafted polyethylene, long alkyl chain Si-Al hybrid precursor oligomer, dried TEMPO oxidized cellulose nanofiber, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, put them into a high-speed mixer, and mix them at a speed of 1000 r / min for 10 min to obtain the premix.

[0074] Steps three and four are the same as in Example 2.

[0075] Comparative Example 5 (Si-Al precursor-deficient and TEMPO oxidized cellulose nanofibers): (a) Raw material weight ratio: High-density polyethylene (HDPE, density 0.961 g / cm³) 3 (Brand number M3138): 95 portions; Ultra-high molecular weight polyethylene (UHMWPE, weight average molecular weight 4.0 × 10⁻⁶) 6 g / mol (model GUR1050): 5 portions; The weight proportions of light stabilizer, compound antioxidant, and calcium stearate are the same as in Example 2.

[0076] (II) Preparation method: Step 1: Dry high-density polyethylene at 90℃ for 3 hours; dry ultra-high molecular weight polyethylene at 70℃ for 5 hours, controlling the moisture content to ≤0.05% in both cases.

[0077] Step 2: Weigh out the dried high-density polyethylene, ultra-high molecular weight polyethylene, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, put them into a high-speed mixer, mix at 1000 r / min for 10 min to obtain the premix.

[0078] Steps three and four are the same as in Example 2.

[0079] Performance testing: Samples were prepared from the materials obtained in Examples 1-3 and Comparative Examples 1-5 according to the corresponding testing standards, and the following performance tests were performed respectively: (1) Bending performance: The bending strength and bending modulus of the material were determined in accordance with GB / T9341-2008 "Determination of bending performance of plastics".

[0080] (2) Tensile properties: The tensile strength and elongation at break of the material were determined in accordance with GB / T1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics".

[0081] (3) Impact strength: The notched impact strength of the cantilever beam of the material was determined in accordance with GB / T1843-2008 "Determination of impact strength of plastic cantilever beam".

[0082] (4) Heat distortion temperature: The heat distortion temperature of the material shall be determined in accordance with GB / T1634.1-2025 "Determination of load distortion temperature of plastics - Part 1: General test method" and GB / T1634.2 "Determination of load distortion temperature of plastics - Part 2: Plastics and hard rubber" (Method A, bending stress 1.80 MPa).

[0083] (5) Tensile creep properties: The test was conducted in accordance with GB / T11546.1-2008 "Determination of creep properties of plastics - Part 1: Tensile creep". A constant tensile stress of 10 MPa was applied to the specimen at 23 °C, and the creep strain rate after 1 h of loading was recorded to characterize the creep resistance of the material.

[0084] (6) Gas permeability: The oxygen permeability of the material was determined in accordance with GB / T1038.1-2022 "Test method for gas permeability of plastic films and sheets - Part 1: Differential pressure method" with a test sample thickness of 0.1 mm.

[0085] (7) Water vapor transmission rate: The water vapor transmission rate of the material was determined according to GB / T1037-2021 "Determination of water vapor transmission performance of plastic films and sheets by cup weight gain and weight loss method". The thickness of the test sample was 0.1 mm.

[0086] (8) Biocompatibility: The in vitro cytotoxicity of the material was determined according to GB / T 16886.5-2017 "Biological Evaluation of Medical Devices Part 5: In Vitro Cytotoxicity Tests" (using L929 mouse fibroblasts, extract method, MTT colorimetric method, cell relative proliferation rate RPR ≥ 70% was considered as non-cytotoxic); the skin sensitization of the material was determined according to GB / T 16886.10-2024 "Biological Evaluation of Medical Devices Part 10: Skin Sensitization Tests"; the skin irritation performance of the material was determined according to GB / T 16886.23-2023 "Biological Evaluation of Medical Devices Part 23: Irritation Tests".

[0087] (9) Dissolution test: Referring to the dissolution test method in YBB00122002-2015 "High-density polyethylene bottles for oral solid medicines", water, 65% ethanol, and n-hexane were used as extraction media to determine the content of easily oxidized substances, non-volatile substances, and heavy metals (calculated as lead) in the extract. The soluble aluminum and silicon contents were determined by inductively coupled plasma mass spectrometry (ICP-MS) in GB / T 14233.1-2022 "Test methods for medical infusion, transfusion and injection equipment - Part 1: Chemical analysis methods" to verify the chemical stability of the inorganic hybrid network and the absence of harmful substance migration. The test results are as follows: Table 1. Performance test results of the examples and comparative examples

[0088] Table 2. Biocompatibility and leachate test results of the examples

[0089] Data Analysis: Analysis of Table 1 shows that the medical polyethylene materials prepared in Examples 1-3 all exhibit excellent rigidity, heat resistance, creep resistance, and gas barrier properties. This indicates that the present invention, through the synergistic effect of the rigid inorganic network formed by the Si-Al hybrid precursor, the covalent bonding reinforcement of TEMPO oxidized cellulose nanofibers, and the long-chain entanglement anchoring of ultra-high molecular weight polyethylene, constructs a complete stress transfer and molecular chain motion constraint mechanism in the HDPE matrix. Simultaneously, a dense physical barrier is formed to effectively hinder the diffusion of small molecule gases, thereby achieving significant improvements in rigidity, heat resistance, creep resistance, and gas barrier properties.

[0090] Comparative Example 1 is pure HDPE with a flexural modulus of 1100 MPa, a heat distortion temperature of 52.0℃, a creep strain rate of 1.85%, and an oxygen permeability of 270 cm³. 3 / (m 2 (24h·0.1MPa), all properties were the lowest among all samples. This comparative example shows that pure HDPE has significant deficiencies in rigidity, heat resistance, and barrier properties.

[0091] Comparative Example 2 used nano-SiO2 to replace the long-chain Si-Al hybrid precursor. Its flexural modulus was 1150 MPa, its heat distortion temperature was 61.5 °C, and its oxygen permeability was 225 cm⁻¹. 3 / (m 2 The stress intensity (24h·0.1MPa) was improved compared to pure HDPE, but still far lower than in Example 2. Nano-SiO2 is physically dispersed in the matrix as discrete particles, lacking a continuous network structure connected by chemical bonds, resulting in low stress transfer efficiency. In contrast, the Si-Al hybrid precursor, through co-condensation, forms a continuous inorganic network with Si-O-Si and Si-O-Al bonds as its framework, exhibiting a significantly higher reinforcement efficiency than physically blended nanoparticles.

[0092] Comparative Example 3 used unmodified microcrystalline cellulose to replace TEMPO oxidized cellulose nanofibers. Its flexural modulus was 1050 MPa, and its impact strength was only 9.8 kJ / m. 2 The elongation at break was only 210%, the lowest among all comparative studies. Microcrystalline cellulose, containing only hydroxyl groups on its surface, exhibited a significant polarity difference from HDPE, leading to agglomeration in the matrix and the formation of micron-scale stress concentration points, inducing brittle fracture. In contrast, TEMPO-oxidized cellulose nanofibers, due to the introduction of numerous carboxyl groups on their surface through TEMPO oxidation, underwent esterification with the anhydride groups of PE-g-MAH, anchoring themselves covalently to the polyethylene molecular chains, achieving uniform dispersion at the nanoscale and efficient stress transfer.

[0093] Comparative Example 4 omitted ultra-high molecular weight polyethylene. Its flexural modulus was 1320 MPa, its heat distortion temperature was 67.5℃, and its barrier properties were also at a mid-to-high level among the comparative examples, but its impact strength was only 4.8 kJ / m². 2 The elongation at break was only 120%, while the creep strain rate was as high as 1.62%. This indicates that although the rigid framework of Si-Al / TEMPO oxidized cellulose nanofibers can independently provide rigidity and barrier properties, it lacks the connection and buffering of the UHMWPE physical entanglement network. Cracks propagate rapidly along the interface between the rigid network and the matrix, and the material exhibits brittle fracture. The ultralong molecular chains of UHMWPE form an interpenetrating structure of "flexible entangled chains" and "rigid anchor points" through the topological constraint effect between them and the rigid network. This structure provides the material with toughness reserves and inhibits long-term slippage of molecular chains under external forces.

[0094] Comparative Example 5 retained only the blend of UHMWPE and HDPE, omitting the Si-Al precursor, TEMPO oxidized cellulose nanofibers, and PE-g-MAH. Its impact strength was 14.5 kJ / m². 2 It has an elongation at break of 520% ​​and good toughness, but its flexural modulus is only 1080 MPa, its heat distortion temperature is only 55.0℃, and its oxygen permeability is as high as 240 cm³. 3 / (m 2 With a tensile strength of 0.1 MPa (24h), UHMWPE exhibits rigidity and barrier properties approaching those of pure HDPE. However, the physical entanglement in UHMWPE involves non-covalent interactions, resulting in a modulus and thermal stability far lower than that of a covalent backbone. This prevents the formation of a sufficiently rigid three-dimensional network to resist bending deformation and thermal softening, and also hinders the construction of a dense physical barrier to impede gas diffusion. The primary contribution of UHMWPE lies in its toughening and creep resistance; a synergistic enhancement of rigidity and toughness can only be achieved when both the Si-Al inorganic network and the TEMPO oxidized cellulose nanofiber covalently bonded network are present.

[0095] Analysis of the data in Table 2 shows that the relative cell proliferation rates of Examples 1-3 were 92.6%, 94.1% and 93.5%, respectively, and the cytotoxicity rating was Grade 1, which meets the requirement of RPR≥70% for no cytotoxicity. The results of skin sensitization and skin irritation tests were negative, and the PII was 0, indicating that the material is non-cytotoxic, non-sensitizing and non-irritating.

[0096] In terms of solubility tests, the easily oxidized substances in each example were 0.46–0.52 mL, the non-volatile substances were 2.4–2.8 mg / 50 mL, and the heavy metal content was below 0.1 μg / mL. All indicators were far below the limits of the YBB00122002-2015 standard. ICP-MS results showed that the soluble aluminum content in the extract was 0.8–1.2 μg / L, and the soluble silicon content was 1.8–2.5 μg / L, which were at extremely low levels, proving that the Si-Al inorganic network did not undergo significant hydrolysis or dissolution under the extraction conditions, and had good chemical stability. Among them, the solubility indicators of Example 2 were the lowest in all three groups, indicating that the ratio of precursor / TEMPO oxidized cellulose nanofiber / UHMWPE in its formulation achieved the best synergy, the tightest interfacial binding, and the least amount of leachable matter. The results show that the material of the present invention meets the safety requirements for medical packaging materials in terms of cytotoxicity, sensitization, irritation, and solubility indicators.

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-rigidity, low-permeability medical polyethylene material, characterized in that, It is made from the following components in parts by weight: High-density polyethylene: 87.5–91.5 parts; Long alkyl chain Si-Al hybrid precursor oligomers: 5-8 parts; Ultra-high molecular weight polyethylene: 3-5 parts; TEMPO oxidized cellulose nanofibers: 1-2 parts; Compatibilizer: 2-3 parts; Light stabilizer: 0.2–0.5 parts; Compound antioxidant: 0.1–0.3 parts; Calcium stearate: 0.1–0.2 parts; The density of the high-density polyethylene is 0.948–0.964 g / cm³. 3 The weight-average molecular weight of the ultra-high molecular weight polyethylene is 3.7 × 10⁻⁶. 6 ~4.0×10 6 g / mol; the diameter of the TEMPO oxidized cellulose nanofibers is 5-10 nm; the compatibilizer is maleic anhydride-grafted polyethylene, the base material of the maleic anhydride-grafted polyethylene is high-density polyethylene, and the grafting rate is 0.8-1.0%; the light stabilizer is a hindered amine light stabilizer; the composite antioxidant is composed of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:(1.0-2.0).

2. The high-rigidity, low-permeability medical polyethylene material according to claim 1, characterized in that, The method for preparing the long alkyl chain Si-Al hybrid precursor oligomer includes the following steps: S1: Under an inert atmosphere, aluminum source is dissolved in anhydrous isopropanol, followed by the addition of ethyl acetoacetate. The mixture is stirred at 40–60 °C for 30–60 min to form a coordination complex, thus obtaining an aluminum source solution. S2: Under an inert atmosphere, tetraethyl orthosilicate, glycerol, and long alkyltriethoxysilane are added to the reactor and stirred at 30-50°C for 10-20 minutes to ensure complete mixing. Then, the aluminum source solution from step S1 is slowly added dropwise, followed by the addition of acetic acid as an acid catalyst to control the pH of the system at 3-4. S3: Slowly heat the system obtained in step S2 to 60-80℃ and maintain it for 1-2 hours, then cool it down to 40-60℃ and remove the low molecular weight alcohol under reduced pressure at a vacuum of -0.08 to -0.1 MPa. Collect the product to obtain the long alkyl chain Si-Al hybrid precursor oligomer.

3. The high-rigidity, low-permeability medical polyethylene material according to claim 2, characterized in that, In step S1, the aluminum source is aluminum isopropoxide or aluminum sec-butoxide.

4. The high-rigidity, low-permeability medical polyethylene material according to claim 2, characterized in that, In step S2, the long alkyltriethoxysilane is selected from one of n-octyltriethoxysilane, n-decyltriethoxysilane, and octadecyltriethoxysilane.

5. The high-rigidity, low-permeability medical polyethylene material according to claim 2, characterized in that, In step S2, the molar ratio of tetraethyl orthosilicate to glycerol is 1:(0.2-0.5); the molar ratio of tetraethyl orthosilicate to aluminum source is 1:(0.3-0.7); and the molar ratio of long alkyltriethoxysilane to tetraethyl orthosilicate is 1:(0.5-1.0).

6. A method for preparing a high-rigidity, low-permeability medical polyethylene material as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: High-density polyethylene, ultra-high molecular weight polyethylene, and maleic anhydride-grafted polyethylene are dried separately to control the moisture content ≤0.05%; TEMPO oxidized cellulose nanofibers are freeze-dried or spray-dried to control the moisture content ≤0.5%. Step 2: Weigh out the dried high-density polyethylene, ultra-high molecular weight polyethylene, maleic anhydride grafted polyethylene, long alkyl chain Si-Al hybrid precursor oligomer, TEMPO oxidized cellulose nanofiber, light stabilizer, composite antioxidant and calcium stearate according to the weight parts, and put them into a high-speed mixer to mix and obtain a premix. Step 3: The premixed material is fed into a twin-screw extruder for melt blending and extrusion. The twin-screw extruder is equipped with a vacuum exhaust port in the middle section of the barrel, and the vacuum degree is controlled at -0.06 to -0.08 MPa. The screw speed of the twin-screw extruder is 200 to 400 r / min. The temperature from zone 1 to the die head is set as follows: zone 1 150 to 170℃, zone 2 180 to 200℃, zone 3 200 to 220℃, zone 4 200 to 220℃, zone 5 190 to 210℃, and die head 190 to 210℃. The residence time is 2 to 5 minutes. Step 4: Cool, granulate, and dry the extrudate to obtain the high-rigidity, low-permeability medical polyethylene material.

7. The method for preparing the high-rigidity, low-permeability medical polyethylene material according to claim 6, characterized in that, In the first step, the drying temperature of the high-density polyethylene and maleic anhydride-grafted polyethylene is 80-100℃, and the drying time is 2-4 hours; the drying temperature of the ultra-high molecular weight polyethylene is 60-80℃, and the drying time is 4-6 hours.

8. The method for preparing the high-rigidity, low-permeability medical polyethylene material according to claim 6, characterized in that, In the second step, the mixing speed of the high-speed mixer is 500-1500 r / min, and the mixing time is 5-15 min.

9. The method for preparing the high-rigidity, low-permeability medical polyethylene material according to claim 6, characterized in that, In the fourth step, the cooling is carried out using a water tank with a water temperature of 20-40℃; the drying temperature is 60-80℃ and the drying time is 4-8 hours.

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