High-fluidity medical polypropylene material and preparation method thereof

Abstract

The invention relates to the technical field of medical high polymer materials, and particularly discloses a high-fluidity medical polypropylene material and a preparation method thereof.The material is composed of polypropylene random copolymer, a structured compound stabilizer and a nucleating agent; the structured compound stabilizer is prepared by compounding phenolic group functional polyester and sulfo-modified polyester and adding surface modified silicon dioxide; the preparation method of the material comprises the following steps: pre-drying raw materials; premixing in a high-speed mixer; carrying out melt extrusion by adopting stepped temperature control twin-screw extrusion and vacuum exhaust; and finally, cooling, pelletizing and drying to obtain the product. Through the synergistic effect of the structured compound stabilizer and the nucleating agent, the heat stability and forming fluidity of polypropylene are improved, and the polypropylene material has the advantages of good processability and high stability.

Description

Technical Field

[0001] This invention relates to the field of medical polymer materials technology, and more specifically, to a high-flowability medical polypropylene material and its preparation method. Background Technology

[0002] Polypropylene (PP) is widely used in medical devices, pharmaceutical packaging, and disposable medical consumables due to its excellent chemical stability, non-toxicity, good processing performance, and low cost. With the increasing prevalence of precision medical devices, such as microcentrifuge tubes, pipette tips, reagent consumables, and transparent syringes, more stringent requirements are being placed on polypropylene materials, including high flowability, high transparency, low exudation, and resistance to radiation sterilization.

[0003] In the prior art, the main methods to improve the flowability of polypropylene include: (1) increasing the amount of degradation agent to improve the melt flow rate through chain scission; (2) adding external lubricants or plasticizers to reduce melt viscosity. However, these methods generally have the following shortcomings: (1) Peroxide degradation will destroy the polypropylene molecular chain, resulting in increased material brittleness, reduced mechanical properties, and easy severe yellowing after irradiation sterilization; (2) Traditional low molecular weight additives such as antioxidants and lubricants are easy to precipitate and migrate in medical devices, causing safety risks such as drug contamination and protein adsorption, which are difficult to meet increasingly stringent medical regulations; (3) Inorganic fillers have poor interfacial compatibility and are prone to increase haze, which is not conducive to the application of transparent medical products.

[0004] Furthermore, polypropylene in the medical industry often requires high-energy sterilization using gamma rays and electron beams. Homopolymer PP is prone to degradation under irradiation, while random copolymer PP, although possessing better radiation resistance, exhibits increased amorphous regions, making additives more susceptible to migration and placing higher demands on system stability. Therefore, a medical-grade polypropylene material is needed that combines high flowability, high transparency, low exudation, and radiation resistance, while maintaining stable mechanical properties and processing adaptability.

[0005] Based on the above statements, the present invention provides a high-flowability medical polypropylene material and its preparation method. Summary of the Invention

[0006] To address the shortcomings of existing medical polypropylene materials in terms of flowability, exudation characteristics, mechanical toughness, transparency, and resistance to yellowing, this invention provides a high-flowability medical polypropylene material and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions: A high-flowability medical polypropylene material comprises the following raw materials in parts by weight: 85-95 parts of random copolymer polypropylene, 10-15 parts of structured composite stabilizer, and 0.1-0.3 parts of nucleating agent; The preparation method of the structured composite stabilizer includes the following steps: A1. Preparation of phenolic functionalized polyester: 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid and 3,5-di-tert-butyl-4-hydroxybenzoic acid are mixed evenly, xylene is added, and then p-toluenesulfonic acid is added. The reaction is stirred under nitrogen protection. When the acid value of the reaction system drops to 5-10 mg KOH / g, vacuum devolatilization is performed, the material is discharged, and phenolic functionalized polyester is obtained after post-treatment. A2. Preparation of thiomodified polyester: Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid and sulfur-containing functional monomers are mixed evenly, p-toluenesulfonic acid is added, and the reaction is stirred under nitrogen protection. When the acid value of the reaction system drops to 15-20 mgKOH / g, vacuum devolatilization is performed, the material is discharged, and after post-treatment, thiomodified polyester is obtained. A3. Formulation of structured composite stabilizers: Phenolic functionalized polyester and thiomodified polyester are mixed evenly, surface-modified silica is added, the mixture is stirred and reacted, discharged, cooled to room temperature, and then pulverized to obtain structured composite stabilizers.

[0008] Preferably, in step A1, the mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene is 30-32:37-40:30-32:0.4-0.7:10-20.

[0009] Preferably, in step A1, the stirring temperature is 130-145℃, the stirring speed is 300-500 rpm, and the stirring time is 2-4 hours.

[0010] Preferably, in step A1, the vacuum devolatilization refers to controlling the vacuum level to -0.05 to -0.09 MPa and the devolatilization treatment for 0.5 to 1 hour.

[0011] Preferably, the post-processing in step A1 refers to: letting the system stand at 25-35℃ for 1-2 hours to transform it into a solid, then pulverizing the resulting solid and sieving it through a 50-80 mesh sieve.

[0012] Preferably, in step A2, the mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid and sulfur-containing functional monomer is 21-23:12-14:40-42:0.3-0.5:23-25.

[0013] Preferably, the preparation method of the sulfur-containing functional monomer in step A2 includes the following steps: 3,3'-Dithiodipropionic acid and ethylene glycol were added to a reaction flask equipped with a stirrer, reflux condenser and water separator, and mixed thoroughly. p-Toluenesulfonic acid was added, and the mixture was stirred for 2-3 hours under nitrogen protection, at a temperature of 100-110℃ and a rotation speed of 300-500 rpm. Water was collected through the water separator. The reaction was stopped when the cumulative amount of water reached 50-60% of the theoretical amount. The mixture was cooled to room temperature to obtain the sulfur-containing functional monomer.

[0014] In the above reaction process, 3,3'-dithiodipropionic acid undergoes directional half-esterification with ethylene glycol through an acid-catalyzed carboxyl-hydroxy esterification reaction. Due to insufficient ethylene glycol and limited dehydration, the esterification reaction preferentially occurs on one side of the carboxyl group, generating a sulfur-containing functional monomer with a monoesterification structure. This monomer retains the disulfide bond structure and simultaneously possesses a free carboxyl group and an ester-terminal hydroxyl group. It can be embedded in the main chain as a reactive structural unit in the subsequent polyesterification reaction. Its disulfide bond can provide radiation resistance and free radical scavenging, thereby improving the stability of the final material.

[0015] Preferably, the mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol and p-toluenesulfonic acid is 100:26-28:0.3-0.5.

[0016] Preferably, in step A2, the stirring temperature is 120-135℃, the stirring speed is 400-600rpm, and the stirring time is 1.5-3h.

[0017] Preferably, in step A2, the vacuum devolatilization refers to controlling the vacuum level to -0.05 to -0.09 MPa and the devolatilization treatment for 0.5-1 h.

[0018] Preferably, the post-processing in step A2 refers to: letting the system stand at 25-35℃ for 1-2 hours to transform it into a solid, then pulverizing the resulting solid and sieving it through a 50-80 mesh sieve.

[0019] Preferably, in step A3, the mass ratio of phenolic functionalized polyester, thiolated modified polyester and surface-modified silica is 40-60:20-40:10-30.

[0020] Preferably, the method for preparing surface-modified silica in step A3 includes the following steps: Nano-silica was added to a mixed solvent and ultrasonically dispersed to form a dispersion. γ-glycidyl etheroxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.0-5.0 with glacial acetic acid. The mixture was stirred and reacted. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain surface-modified silica.

[0021] Preferably, the particle size of the nano-silica is 15-40 nm.

[0022] Preferably, the mass ratio of the nano-silica, γ-glycidyl etheroxypropyltrimethoxysilane and the mixed solvent is 10:0.5-0.8:80-120.

[0023] Preferably, the mixed solvent is anhydrous ethanol and deionized water in a volume ratio of 8.5-9.5:1.

[0024] Preferably, the ultrasonic dispersion refers to ultrasonic dispersion for 15-30 minutes under conditions of 20-40 kHz and 300-600 W.

[0025] Preferably, the stirring temperature is 60-80℃, the stirring speed is 300-500rpm, and the stirring time is 2-4h.

[0026] Preferably, the centrifugation refers to centrifugation at 7000-8000 rpm for 8-12 minutes.

[0027] Preferably, the washing refers to washing with anhydrous ethanol 2-3 times.

[0028] Preferably, the drying refers to drying in a vacuum drying oven at 90-100°C until constant weight.

[0029] Preferably, in step A3, the stirring temperature is 100-130℃, the stirring speed is 200-400rpm, and the stirring time is 1-2h.

[0030] Preferably, in step A3, pulverization refers to pulverizing the product and sieving it through a 50-80 mesh sieve.

[0031] Preferably, the nucleating agent is 1,3:2,4-di-p-methylbenzylsorbitol.

[0032] A method for preparing a high-flowability medical polypropylene material includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene is dried in a forced-air drying oven, and structured composite stabilizer and nucleating agent are dried in a vacuum oven. S2. Premixing: Random copolymer polypropylene is put into a high-speed mixer, nucleating agent and structured composite stabilizer are added in sequence, and the mixture is mixed evenly to obtain the material. S3, Melt Extrusion: The material from step S2 is added to a twin-screw extruder. The extruder uses a stepped temperature control and melt extrusion is carried out under vacuum exhaust. S4. Pelletizing and Drying: The extruded strips are cooled by a circulating water tank and dried by an air knife before being pelletized and dried to obtain high-flowability medical polypropylene material.

[0033] Preferably, in step S1, the temperature of the forced-air drying oven is 80-90℃ and the drying time is 2-4 hours, while the temperature of the vacuum drying oven is 60-80℃ and the drying time is 3-5 hours.

[0034] Preferably, the rotation speed at which the nucleating agent and the structured composite stabilizer are added in step S2 is 300-500 rpm.

[0035] Preferably, in step S2, mixing refers to mixing at 1000-1500 rpm for 3-5 minutes.

[0036] Preferably, the stepped temperature control in step S3 refers to the following temperature settings for each section of the twin-screw extruder: feeding section 170-180℃, melting section 190-210℃, homogenization section 210-220℃, and die section 200-210℃.

[0037] Preferably, in step S3, vacuum exhaust refers to a screw speed of 200-400 rpm and a vacuum degree of -0.07 to -0.09 MPa.

[0038] Preferably, the water temperature in the circulating water tank in step S4 is controlled at 30-40℃.

[0039] Preferably, the drying in step S4 refers to drying in a forced-air drying oven at 75-85℃ for 2-4 hours.

[0040] In summary, the present invention has the following beneficial effects: (1) This invention synthesizes phenolic functionalized polyesters and thiomodified polyesters with large molecular weights. During the preparation of the structured composite stabilizer, the terminal functional groups (such as carboxyl and hydroxyl groups) of the polyester react chemically with the active groups (such as epoxy groups) on the surface-modified silica to form a core-shell structure in which the stabilizer component is chemically bonded to the surface of inorganic particles. This structure combines the macromolecular characteristics of the polyester itself and effectively inhibits the migration of functional additives in the polypropylene matrix. Compared with the traditional technical solution of physical blending with small molecule additives, the polypropylene material prepared by this invention has a significantly reduced content of leaching substances in simulated solvents such as hexane and ethanol, thereby improving the biosafety of the material and making it suitable for medical applications where there are strict requirements for the control of leaching substances.

[0041] (2) By introducing a structured composite stabilizer with core-shell structure characteristics, the flexible segments of the polyester shell can effectively reduce melt viscosity and significantly improve melt flow rate during high-temperature processing of polypropylene; at the same time, inorganic silica provides rigid support for the system. Compared with the traditional technical solution that relies on peroxide degradation to improve fluidity, the present invention achieves high melt fluidity without destroying the main chain structure of polypropylene, and takes into account the balance between the rigidity and toughness of the material.

[0042] (3) This invention constructs a system composed of hindered phenolic groups, thioether groups, and inorganic silica in synergy. The hindered phenolic group acts as the main antioxidant to capture oxidative free radicals, the thioether structure acts as an auxiliary antioxidant to decompose hydrogen peroxide, and the inorganic silica inhibits the chain segment cleavage caused by thermo-oxidation through interfacial stabilization. During the sterilization process by gamma rays or electron beam irradiation, this system can effectively inhibit the free radical degradation reaction induced by irradiation, avoid yellowing of the material, and ensure that the prepared material maintains a low yellowing index and high transparency after sterilization, meeting the strict requirements of medical materials for irradiation adaptability.

[0043] (4) This invention uses random copolymer polypropylene as the matrix and adds sorbitol-based nucleating agents. Through a high-temperature melt extrusion process, the sorbitol-based nucleating agents are dispersed at the molecular level to form a uniform microcrystalline structure, thereby improving light transmittance. Simultaneously, surface-modified nano-silica is introduced as nucleation sites to further promote spherulite refinement. This invention effectively overcomes the defect of decreased transparency caused by traditional inorganic fillers, enabling the material to maintain excellent optical transparency while achieving high rigidity and high processing stability through inorganic modification. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments.

[0045] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0046] The key raw materials used in this invention are sourced from the following sources: Random copolymer polypropylene: part number Adflex Q300F, supplied by LyondellBasell Polyolefins (Shanghai) Co., Ltd.; 2,2-Bis(hydroxymethyl)1,3-propanediol: CAS: 115-77-5, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.; isophthalic acid: CAS: 121-91-5, provided by Nantong Runfeng Petrochemical Co., Ltd.; 3,5-Di-tert-butyl-4-hydroxybenzoic acid: CAS: 1421-49-4, provided by Sigma-Aldrich (Shanghai) Trading Co., Ltd.; p-Toluenesulfonic acid: CAS: 104-15-4, provided by Shanghai Jizhi Biochemical Technology Co., Ltd.; 3,3'-Dithiodipropionic acid: CAS: 1119-62-6, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.; Nano silica: Model: N20, CAS: 112945-52-5, provided by Shanghai Yunhe Materials Technology Co., Ltd. γ-glycidoxypropyltrimethoxysilane: CAS: 2530-83-8, provided by Wuhan Jixin Yibang Biotechnology Co., Ltd.; 1,3:2,4-Di-p-methylbenzyl sorbitol: CAS: 54686-97-4, provided by Shanghai Hanhong Technology Co., Ltd.; Tris(2,4-di-tert-butylphenyl) phosphite: CAS: 31570-04-4, provided by Nanjing Milan Chemical Co., Ltd.

[0047] Examples 1-3 provide a high-flowability medical polypropylene material and its preparation method.

[0048] Example 1 The preparation method of the structured composite stabilizer includes the following steps: A1. The mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene was controlled at 30:37:30:0.4:10. The 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, and 3,5-di-tert-butyl-4-hydroxybenzoic acid were mixed evenly, and xylene and p-toluenesulfonic acid were added. The reaction was carried out under nitrogen protection, at a temperature of 130℃ and a rotation speed of 300 rpm for 4 hours. When the acid value of the reaction system dropped to 6 mg KOH / g, the vacuum degree was controlled at -0.05 MPa, and the devolatilization treatment was carried out for 0.5 hours. The vacuum was released, the material was discharged, and the system was allowed to stand at 25℃ for 1 hour to transform into a solid. The obtained solid was pulverized and sieved through a 50-mesh sieve to obtain phenolic functionalized polyester. A2. The mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and sulfur-containing functional monomers was controlled at 21:12:40:0.3:23. Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, and sulfur-containing functional monomers were added to a reaction vessel and mixed evenly. P-toluenesulfonic acid was added, and the reaction was carried out at 120℃ and 400rpm for 3 hours. When the acid value of the reaction system dropped to 15mgKOH / g, the vacuum degree was controlled at -0.05MPa, and the devolatilization treatment was carried out for 0.5 hours. The vacuum was released, the material was discharged, and the system was allowed to stand at 25℃ for 1 hour to transform into a solid. The obtained solid was pulverized and sieved through a 50-mesh sieve to obtain the thiolated modified polyester. The preparation method of the sulfur-containing functional monomer in step A2 includes the following steps: The mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol, and p-toluenesulfonic acid was controlled at 100:26:0.3. 3,3'-dithiodipropionic acid and ethylene glycol were added to a reaction flask equipped with a stirrer, reflux condenser, and water separator. After mixing evenly, p-toluenesulfonic acid was added. The reaction was stirred for 3 hours under nitrogen protection, at a temperature of 100℃ and a rotation speed of 300 rpm. Water was collected through the water separator. When the cumulative amount of water reached 50% of the theoretical amount, the reaction was stopped and cooled to room temperature to obtain the sulfur-containing functional monomer. A3. Control the mass ratio of phenolic functionalized polyester, thiomodified polyester and surface-modified silica to 40:20:10. Mix the phenolic functionalized polyester and thiomodified polyester evenly, add the surface-modified silica, stir for 2 hours at 100℃ and 200rpm, discharge the material, cool to room temperature, pulverize the product and sieve it through a 50-mesh sieve to obtain the structured composite stabilizer. The preparation method of surface-modified silica in step A3 includes the following steps: The mass ratio of nano-silica, γ-glycidoxypropyltrimethoxysilane, and mixed solvent was controlled at 10:0.5:80. Nano-silica was added to the mixed solvent (volume ratio of anhydrous ethanol and deionized water was 8.5:1) and ultrasonically dispersed for 30 min at 20 kHz and 300 W to form a dispersion. γ-glycidoxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.0 with glacial acetic acid. The mixture was stirred for 4 h at 300 rpm and 60 °C. After the reaction was completed, the solid was separated by centrifugation at 7000 rpm for 12 min. The solid was washed three times with anhydrous ethanol and then dried in a vacuum drying oven at 90 °C until constant weight to obtain surface-modified silica. A high-flowability medical polypropylene material comprises the following raw materials in parts by weight: 85 parts of random copolymer polypropylene, 10 parts of structured composite stabilizer, and 0.1 parts of 1,3:2,4-di-p-methylbenzyl sorbitol; The preparation method includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene is dried in an 80°C forced-air drying oven for 4 hours, and the structured composite stabilizer and 1,3:2,4-di-p-methylbenzyl sorbitol are dried in a 60°C vacuum oven for 5 hours. S2. Premixing: Random copolymer polypropylene is put into a high-speed mixer. 1,3:2,4-di-p-methylbenzyl sorbitol and a structured composite stabilizer are added sequentially at a speed of 300 rpm. The speed of the high-speed mixer is increased to 1000 rpm and mixed for 5 minutes to obtain the material. S3. Melt extrusion: The material from step S2 is added to a twin-screw extruder. The temperature of each section of the twin-screw extruder is set as follows: feeding section 170℃, melting section 190℃, homogenization section 210℃, and die section 200℃. Extrusion is carried out under the conditions of screw speed of 200 rpm and vacuum degree of -0.07 MPa. S4. Pelletizing and Drying: The extruded strips are cooled in a circulating water tank at 30°C and dried by an air knife before being pelletized. The resulting pellets are then placed in a 75°C forced-air drying oven for 4 hours to obtain high-flowability medical polypropylene material.

[0049] Example 2 The preparation method of the structured composite stabilizer includes the following steps: A1. The mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene was controlled at 31:38.5:31:0.5:15. The 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, and 3,5-di-tert-butyl-4-hydroxybenzoic acid were mixed evenly, and xylene and p-toluenesulfonic acid were added. The reaction was carried out under nitrogen protection, at a speed of 400 rpm and a temperature of 135℃ for 3 hours. When the acid value of the reaction system dropped to 8 mg KOH / g, the vacuum degree was controlled at -0.07 MPa, and the devolatilization treatment was carried out for 0.75 hours. The vacuum was released, the material was discharged, and the system was allowed to stand at 30℃ for 1.5 hours to allow the system to transform into a solid. The obtained solid was pulverized and sieved through a 65-mesh sieve to obtain phenolic functionalized polyester. A2. The mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and sulfur-containing functional monomers was controlled at 22:13:41:0.4:24. Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, and sulfur-containing functional monomers were added to a reaction vessel and mixed evenly. The mixture was heated to 100°C until completely melted. Then, p-toluenesulfonic acid was added, and the reaction was carried out at 130°C and 500 rpm for 2.5 hours. When the acid value of the reaction system dropped to 17 mg KOH / g, the vacuum degree was controlled at -0.07 MPa, and the devolatilization treatment was carried out for 0.75 hours. The vacuum was then released, the material was discharged, and the mixture was allowed to stand at 30°C for 1.5 hours to allow the system to transform into a solid. The resulting solid was then pulverized and sieved through a 65-mesh sieve to obtain the thiolated modified polyester. The preparation method of the sulfur-containing functional monomer in step A2 includes the following steps: The mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol, and p-toluenesulfonic acid was controlled at 100:27:0.4. 3,3'-dithiodipropionic acid and ethylene glycol were added to a reaction flask equipped with a stirrer, reflux condenser, and water separator, and mixed evenly. p-Toluenesulfonic acid was then added, and the reaction was stirred for 2.5 h under nitrogen protection, at a temperature of 105 °C and a rotation speed of 400 rpm. Water was collected through the water separator. When the cumulative amount of water reached 55% of the theoretical amount, the reaction was stopped and cooled to room temperature to obtain the sulfur-containing functional monomer. A3. Control the mass ratio of phenolic functionalized polyester, thiomodified polyester and surface-modified silica to 50:30:20. Mix the phenolic functionalized polyester and thiomodified polyester evenly, add the surface-modified silica, stir for 1.5 hours at 115℃ and 300rpm, discharge the material, cool to room temperature, pulverize the product and sieve it through a 65-mesh sieve to obtain the structured composite stabilizer. The preparation method of surface-modified silica in step A3 includes the following steps: The mass ratio of nano-silica, γ-glycidoxypropyltrimethoxysilane, and mixed solvent was controlled at 10:0.65:100. Nano-silica was added to the mixed solvent (volume ratio of anhydrous ethanol and deionized water was 9:1) and ultrasonically dispersed for 23 min at 30 kHz and 450 W to form a dispersion. γ-glycidoxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.5 with glacial acetic acid. The reaction was stirred at 400 rpm and 70 °C for 3 h. After the reaction was completed, the solid was separated by centrifugation at 7500 rpm for 10 min. The solid was washed three times with anhydrous ethanol and then dried in a vacuum drying oven at 95 °C to constant weight to obtain surface-modified silica. A high-flowability medical polypropylene material comprises the following raw materials in parts by weight: 90 parts of random copolymer polypropylene, 12 parts of structured composite stabilizer, and 0.2 parts of 1,3:2,4-di-p-methylbenzyl sorbitol; The preparation method includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene is dried in an 85°C forced-air drying oven for 3 hours, and the structured composite stabilizer and 1,3:2,4-di-p-methylbenzyl sorbitol are dried in a 70°C vacuum oven for 4 hours. S2, Premixing: Random copolymer polypropylene is put into a high-speed mixer, and 1,3:2,4-di-p-methylbenzyl sorbitol and structured composite stabilizer are added sequentially at a speed of 400 rpm. The speed of the high-speed mixer is increased to 1250 rpm and mixed for 4 minutes to obtain the material. S3. Melt extrusion: The material from step S2 is added to a twin-screw extruder. The temperature of each section of the twin-screw extruder is set as follows: feeding section 175℃, melting section 200℃, homogenization section 215℃, and die section 205℃. Extrusion is carried out under the conditions of screw speed 300rpm and vacuum degree -0.08MPa. S4. Pelletizing and Drying: The extruded strips are cooled in a circulating water tank at 35°C and dried by an air knife before being pelletized. The resulting pellets are then placed in an 80°C forced-air drying oven for 3 hours to obtain high-flowability medical polypropylene material.

[0050] Example 3 The preparation method of the structured composite stabilizer includes the following steps: A1. The mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene was controlled at 32:40:32:0.7:20. The 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, and 3,5-di-tert-butyl-4-hydroxybenzoic acid were mixed evenly, and xylene and p-toluenesulfonic acid were added. The reaction was carried out under nitrogen protection, at a temperature of 145℃ and a rotation speed of 500 rpm for 2 hours. When the acid value of the reaction system dropped to 9 mg KOH / g, the vacuum degree was controlled at -0.09 MPa, and the system was subjected to devolatilization treatment for 1 hour. The vacuum was then released, the material was discharged, and the system was allowed to stand at 35℃ for 2 hours to allow it to transform into a solid. The resulting solid was then pulverized and sieved through an 80-mesh sieve to obtain phenolic functionalized polyester. A2. The mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and sulfur-containing functional monomers was controlled at 23:14:42:0.5:25. Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, and sulfur-containing functional monomers were added to a reaction vessel and mixed evenly. P-toluenesulfonic acid was added, and the reaction was carried out at 135℃ and 600 rpm for 1.5 h. When the acid value of the reaction system dropped to 20 mg KOH / g, the vacuum degree was controlled at -0.09 MPa, and the devolatilization treatment was carried out for 1 h. The vacuum was released, the material was discharged, and the system was allowed to stand at 35℃ for 2 h to transform into a solid. The obtained solid was pulverized and sieved through an 80-mesh sieve to obtain the thiolated modified polyester. The preparation method of the sulfur-containing functional monomer in step A2 includes the following steps: The mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol, and p-toluenesulfonic acid was controlled at 100:28:0.5. 3,3'-dithiodipropionic acid and ethylene glycol were added to a reaction flask equipped with a stirrer, reflux condenser, and water separator, and mixed evenly. p-Toluenesulfonic acid was then added, and the reaction was stirred for 2 hours under nitrogen protection, at a temperature of 110℃ and 500rpm. Water was collected through the water separator. When the cumulative amount of water reached 60% of the theoretical amount, the reaction was stopped and cooled to room temperature to obtain the sulfur-containing functional monomer. A3. Control the mass ratio of phenolic functionalized polyester, thiomodified polyester and surface-modified silica to 60:40:30. Mix the phenolic functionalized polyester and thiomodified polyester evenly, add the surface-modified silica, and stir and react for 1 hour at 130℃ and 400rpm. Discharge the material, cool it to room temperature, crush the product and sieve it through an 80-mesh sieve to obtain the structured composite stabilizer. The preparation method of surface-modified silica in step A3 includes the following steps: The mass ratio of nano-silica, γ-glycidoxypropyltrimethoxysilane, and mixed solvent was controlled at 10:0.8:120. Nano-silica was added to the mixed solvent (volume ratio of anhydrous ethanol and deionized water was 9.5:1) and ultrasonically dispersed for 15 min at 40 kHz and 600 W to form a dispersion. γ-glycidoxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 5 with glacial acetic acid. The reaction was stirred at 500 rpm and 80 °C for 2 h. After the reaction was completed, the solid was separated by centrifugation at 8000 rpm for 8 min. The solid was washed twice with anhydrous ethanol and then dried in a vacuum drying oven at 100 °C to constant weight to obtain surface-modified silica. A high-flowability medical polypropylene material comprises the following raw materials in parts by weight: 95 parts of random copolymer polypropylene, 15 parts of structured composite stabilizer, and 0.3 parts of 1,3:2,4-di-p-methylbenzyl sorbitol; The preparation method includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene is dried in a 90℃ forced-air drying oven for 2 hours, and the structured composite stabilizer and 1,3:2,4-di-p-methylbenzyl sorbitol are dried in a vacuum oven at 80℃ for 3 hours. S2, Premixing: Random copolymer polypropylene is put into a high-speed mixer. 1,3:2,4-di-p-methylbenzyl sorbitol and a structured composite stabilizer are added sequentially at a speed of 500 rpm. The speed of the high-speed mixer is increased to 1500 rpm and mixed for 3 minutes to obtain the material. S3, Melt Extrusion: The material from step S2 is added to a twin-screw extruder. The temperature of each section of the twin-screw extruder is set as follows: feeding section 180℃, melting section 210℃, homogenization section 220℃, and die section 210℃. Extrusion is carried out under the conditions of screw speed 400rpm and vacuum degree -0.09MPa. S4. Pelletizing and Drying: The extruded strips are cooled in a circulating water tank at 40°C and dried by an air knife before being pelletized. The resulting pellets are then placed in an 85°C forced-air drying oven for 2 hours to obtain high-flowability medical polypropylene material.

[0051] To verify the antioxidant properties of the high-flowability medical polypropylene materials prepared in Examples 1-3 of this invention, the inventors set up Comparative Examples 1-5, as follows: Comparative Example 1 The difference between this comparative example and Example 1 is that, in preparing the high-flowability medical polypropylene material, the structured composite stabilizer is replaced with 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis(hydroxymethyl)1,3-propanediol ester and tris(2,4-di-tert-butylphenyl)phosphite, while the remaining steps and raw materials are the same as in Example 1; A medical polypropylene material comprises the following raw materials in parts by weight: 85 parts of random copolymer polypropylene, 0.06 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 0.1 parts of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis(hydroxymethyl)1,3-propanediol ester, 0.2 parts of tris(2,4-di-tert-butylphenyl) phosphite, and 0.1 parts of 1,3:2,4-di-p-methylbenzylsorbitol; The preparation method includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene was dried in an 80°C forced-air drying oven for 4 hours. 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis(hydroxymethyl)1,3-propanediol ester, tris(2,4-di-tert-butylphenyl)phosphite and 1,3:2,4-di-p-methylbenzylsorbitol were dried in a 60°C vacuum oven for 5 hours. S2. Premixing: Random copolymer polypropylene is fed into a high-speed mixer. 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]2,2-bis(hydroxymethyl)1,3-propanediol ester, tris(2,4-di-tert-butylphenyl)phosphite and 1,3:2,4-di-p-methylbenzylsorbitol are added sequentially at a speed of 300 rpm. The speed of the high-speed mixer is increased to 1000 rpm and mixed for 5 min to obtain the material. S3. Melt extrusion: The material from step S2 is added to a twin-screw extruder. The temperature of each section of the twin-screw extruder is set as follows: feeding section 170℃, melting section 190℃, homogenization section 210℃, and die section 200℃. Extrusion is carried out under the conditions of screw speed of 200 rpm and vacuum degree of -0.07 MPa. S4. Pelletizing and Drying: The extruded strips are cooled in a circulating water tank at 30°C and dried by an air knife before being pelletized. The resulting pellets are then placed in a 75°C forced-air drying oven for 4 hours to obtain medical-grade polypropylene material.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that in step A1, 2,2-bis(hydroxymethyl)1,3-propanediol is replaced with ethylene glycol by mass, while the remaining steps and raw materials are the same as in Example 1. A1. The mass ratio of ethylene glycol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene was controlled at 30:37:30:0.4:10. Ethylene glycol, isophthalic acid, and 3,5-di-tert-butyl-4-hydroxybenzoic acid were mixed evenly, and xylene and p-toluenesulfonic acid were added. The mixture was reacted for 4 hours under nitrogen protection, at 130℃ and 300 rpm. When the acid value of the reaction system dropped to 8 mg KOH / g, the vacuum was controlled at -0.05 MPa, and the mixture was subjected to devolatilization for 0.5 hours. The vacuum was then released, the mixture was discharged, and allowed to stand at 25℃ for 1 hour to allow the system to solidify. The resulting solid was then pulverized and sieved through a 50-mesh sieve to obtain phenolic functionalized polyester.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that in step A2, the sulfur-containing functional monomer is replaced by 3,3'-dithiodipropionic acid by the same mass, while the remaining steps and raw materials are the same as in Example 1. The mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and 3,3'-dithiodipropionic acid was controlled at 21:12:40:0.3:23. Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, and 3,3'-dithiodipropionic acid were added to a reaction vessel and mixed evenly. P-toluenesulfonic acid was added, and the reaction was carried out at 120℃ and 400 rpm for 3 hours. When the acid value of the reaction system dropped to 15 mg KOH / g, the vacuum degree was controlled at -0.05 MPa, and the system was subjected to devolatilization for 0.5 hours. The vacuum was then released, the material was discharged, and the system was allowed to stand at 25℃ for 1 hour to allow it to solidify. The resulting solid was then pulverized and sieved through a 50-mesh sieve to obtain the thiomodified polyester.

[0054] Comparative Example 4 The difference between this comparative example and Example 1 is that, in the preparation of the structured composite stabilizer, only thiomodified polyester and surface-modified silica are used to react, and the original step A1 is deleted. The remaining steps and raw materials are the same as in Example 1. A1. The mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and sulfur-containing functional monomers was controlled at 21:12:40:0.3:23. Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, and sulfur-containing functional monomers were added to a reaction vessel and mixed evenly. P-toluenesulfonic acid was added, and the reaction was carried out at 120℃ and 400rpm for 3 hours. When the acid value of the reaction system dropped to 15mgKOH / g, the vacuum degree was controlled at -0.05MPa, and the devolatilization treatment was carried out for 0.5 hours. The vacuum was released, the material was discharged, and the system was allowed to stand at 25℃ for 1 hour to allow the system to transform into a solid. The obtained solid was pulverized and sieved through a 50-mesh sieve to obtain thiolated modified polyester. The preparation method of the sulfur-containing functional monomer in step A1 includes the following steps: The mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol, and p-toluenesulfonic acid was controlled at 100:26:0.3. 3,3'-dithiodipropionic acid and ethylene glycol were added to a reaction flask equipped with a stirrer, reflux condenser, and water separator. After mixing evenly, p-toluenesulfonic acid was added. The reaction was stirred for 3 hours under nitrogen protection, at a temperature of 100℃ and a rotation speed of 300 rpm. Water was collected through the water separator. When the cumulative amount of water reached 50% of the theoretical amount, the reaction was stopped and cooled to room temperature to obtain the sulfur-containing functional monomer. A2. Control the mass ratio of thiomodified polyester to surface-modified silica to be 60:10. Mix the thiomodified polyester and surface-modified silica evenly, stir for 2 hours at 100℃ and 200rpm, discharge the material, cool to room temperature, crush the product, and sieve it through a 50-mesh sieve to obtain the structured composite stabilizer. The preparation method of surface-modified silica in step A2 includes the following steps: The mass ratio of nano-silica, γ-glycidoxypropyltrimethoxysilane, and mixed solvent was controlled at 10:0.5:80. Nano-silica was added to the mixed solvent (volume ratio of anhydrous ethanol and deionized water was 8.5:1) and ultrasonically dispersed for 30 min at 20 kHz and 300 W to form a dispersion. γ-glycidoxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.0 with glacial acetic acid. The mixture was stirred for 4 h at 300 rpm and 60 °C. After the reaction was completed, the solid was separated by centrifugation at 7000 rpm for 12 min. The solid was washed three times with anhydrous ethanol and then dried in a vacuum drying oven at 90 °C until constant weight to obtain surface-modified silica.

[0055] Comparative Example 5 The difference between this comparative example and Example 1 is that, in the preparation of the structured composite stabilizer, only phenolic functionalized polyester and surface-modified silica are used to react, and the original step A2 is deleted. The remaining steps and raw materials are the same as in Example 1. A1. The mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene was controlled at 30:37:30:0.4:10. The 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, and 3,5-di-tert-butyl-4-hydroxybenzoic acid were mixed evenly, and xylene and p-toluenesulfonic acid were added. The reaction was carried out under nitrogen protection, at a temperature of 130℃ and a rotation speed of 300 rpm for 4 hours. When the acid value of the reaction system dropped to 8 mg KOH / g, the vacuum degree was controlled at -0.05 MPa, and the devolatilization treatment was carried out for 0.5 hours. The vacuum was released, the material was discharged, and the system was allowed to stand at 25℃ for 1 hour to allow the system to transform into a solid. The obtained solid was pulverized and sieved through a 50-mesh sieve to obtain phenolic functionalized polyester. A2. Control the mass ratio of phenolic functionalized polyester to surface-modified silica to be 60:10. Mix the phenolic functionalized polyester and surface-modified silica evenly, stir for 2 hours at 100℃ and 200rpm, discharge the material, cool to room temperature, crush the product, and sieve it through a 50-mesh sieve to obtain the structured composite stabilizer. The preparation method of surface-modified silica in step A2 includes the following steps: The mass ratio of nano-silica, γ-glycidoxypropyltrimethoxysilane, and mixed solvent was controlled at 10:0.5:80. Nano-silica was added to the mixed solvent (volume ratio of anhydrous ethanol and deionized water was 8.5:1) and ultrasonically dispersed for 30 min at 20 kHz and 300 W to form a dispersion. γ-glycidoxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.0 with glacial acetic acid. The mixture was stirred for 4 h at 300 rpm and 60 °C. After the reaction was completed, the solid was separated by centrifugation at 7000 rpm for 12 min. The solid was washed three times with anhydrous ethanol and then dried in a vacuum drying oven at 90 °C until constant weight to obtain surface-modified silica.

[0056] Performance testing The high-flowability medical polypropylene materials prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests, and the specific test standards are as follows: Melt flow rate: The test was conducted in accordance with the national standard GB / T3682.1-2018 "Determination of melt mass flow rate (MFR) and melt volumetric flow rate (MVR) of thermoplastic plastics". The test conditions were: temperature 230℃, load 2.16kg, barrel inner diameter 9.55mm, and die size 2.095mm in diameter and 8.0mm in length. The sample was preheated at the test temperature for 6min before the measurement began. Melt segments were cut and weighed at 40s intervals, and the melt mass flow rate value was finally calculated.

[0057] Evaporation residue: The test was conducted in accordance with the national standard GB / T14233.1-2008 "Test Methods for Medical Infusion, Transfusion and Injection Equipment". The sample was refluxed in n-hexane medium for extraction, and the total amount of dissolved substances was determined.

[0058] Notched impact strength of cantilever beam: Tested in accordance with the national standard GB / T1843-2008 "Determination of impact strength of plastic cantilever beam".

[0059] Yellowing index: The yellowing index of the particles was determined using a colorimeter in accordance with the national standard ASTM E313-20, "Standard Practice for Calculating Yellowness and Whiteness Indices from Instrument-Measured Color Coordinates".

[0060] Haze: Tested in accordance with the national standard ASTM D1003, "Standard Test Method for Haze and Transmittance of Transparent Plastics".

[0061] The test results are shown in Table 1: Table 1: Comparison of overall performance data between the examples and comparative examples As shown in Table 1 above, the high-flowability medical polypropylene materials prepared in Examples 1-3 of this invention all exhibit excellent comprehensive performance. While achieving high flowability, they still maintain excellent mechanical toughness and optical transparency, and effectively reduce the content of chemical leachates, thereby giving the obtained materials excellent medical safety and processing stability. Their comprehensive performance is significantly better than that of Comparative Examples 1-5.

[0062] As can be seen from Example 1 and Comparative Example 1, Comparative Example 1 obtains higher fluidity by using molecular chain degradation, but its cantilever beam notched impact strength is significantly reduced. At the same time, due to the generation of small molecule degradation byproducts, the content of solvent precipitates increases significantly. In addition, because the low molecular weight chain segments formed during the peroxide degradation process interfere with the crystal morphology of polypropylene, the size of the spherulites increases, which in turn leads to enhanced light scattering. Therefore, the haze is significantly higher than that of Example 1, and the transparency decreases.

[0063] As can be seen from Example 1 and Comparative Example 2, the melt flow rate of Comparative Example 2 was significantly reduced, which verifies that the hyperbranched structure of the structured composite stabilizer can effectively reduce molecular chain entanglement compared with the linear structure, thereby significantly improving fluidity without destroying the main chain structure. At the same time, since the linear polyester segments are difficult to form effective steric stabilization protection for nano-silica, its dispersibility in polypropylene melt is reduced, resulting in local agglomeration and insufficient spherulite refinement ability, making the haze higher than that of Example 1.

[0064] As can be seen from Example 1 and Comparative Example 3, the content of solvent precipitates in Comparative Example 3 is significantly increased, indicating that omitting the prepolymerization reaction step reduces the dispersibility and stability of functional components in the polypropylene matrix, making them prone to migration and precipitation.

[0065] As can be seen from Example 1 and Comparative Examples 4 and 5, the samples in Comparative Examples 4 and 5 showed obvious yellowing, proving that the synergistic antioxidant mechanism of hindered phenolic groups and thioether groups in the structured composite stabilizer molecule of the present invention is the key factor to ensure that the material maintains color stability and antioxidant aging resistance during high-temperature processing.

[0066] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A high-flowability medical polypropylene material, characterized in that, The raw materials include the following parts by weight: 85-95 parts of random copolymer polypropylene, 10-15 parts of structured composite stabilizer, and 0.1-0.3 parts of nucleating agent; The preparation method of the structured composite stabilizer includes the following steps: A1. Preparation of phenolic functionalized polyester: 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid and 3,5-di-tert-butyl-4-hydroxybenzoic acid are mixed evenly, xylene is added, and then p-toluenesulfonic acid is added. The reaction is stirred under nitrogen protection. When the acid value of the reaction system drops to 5-10 mg KOH / g, vacuum devolatilization is performed, the material is discharged, and phenolic functionalized polyester is obtained after post-treatment. A2. Preparation of thiomodified polyester: Glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid and sulfur-containing functional monomers are mixed evenly, p-toluenesulfonic acid is added, and the reaction is stirred under nitrogen protection. When the acid value of the reaction system drops to 15-20 mgKOH / g, vacuum devolatilization is performed, the material is discharged, and after post-treatment, thiomodified polyester is obtained. A3. Formulation of structured composite stabilizers: Phenolic functionalized polyester and thiomodified polyester are mixed evenly, surface-modified silica is added, the mixture is stirred and reacted, discharged, cooled to room temperature, and then pulverized to obtain structured composite stabilizers.

2. The high-flowability medical polypropylene material according to claim 1, characterized in that, In step A1, the mass ratio of 2,2-bis(hydroxymethyl)1,3-propanediol, isophthalic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, p-toluenesulfonic acid, and xylene is 30-32:37-40:30-32:0.4-0.7:10-20.

3. The high-flowability medical polypropylene material according to claim 1, characterized in that, In step A2, the mass ratio of glycerol, 2,2-bis(hydroxymethyl)1,3-propanediol, adipic acid, p-toluenesulfonic acid, and sulfur-containing functional monomers is 21-23:12-14:40-42:0.3-0.5:23-25.

4. The high-flowability medical polypropylene material according to claim 3, characterized in that, The preparation method of the sulfur-containing functional monomer in step A2 includes the following steps: 3,3'-dithiodipropionic acid and ethylene glycol were added to a reaction flask and mixed thoroughly. Then, p-toluenesulfonic acid was added and the mixture was stirred. Water was collected using a water separator. The reaction was stopped when the cumulative amount of water reached 50-60% of the theoretical amount. The mixture was then cooled to room temperature to obtain the sulfur-containing functional monomer.

5. The high-flowability medical polypropylene material according to claim 4, characterized in that, The mass ratio of 3,3'-dithiodipropionic acid, ethylene glycol, and p-toluenesulfonic acid is 100:26-28:0.3-0.

5.

6. The high-flowability medical polypropylene material according to claim 1, characterized in that, In step A3, the mass ratio of phenolic functionalized polyester, thiolated modified polyester, and surface-modified silica is 40-60:20-40:10-30.

7. The high-flowability medical polypropylene material according to claim 1, characterized in that, The preparation method of surface-modified silica in step A3 includes the following steps: Nano-silica was added to a mixed solvent and ultrasonically dispersed to form a dispersion. γ-glycidyl etheroxypropyltrimethoxysilane was added to the dispersion, and the pH of the system was adjusted to 4.0-5.0 with glacial acetic acid. The mixture was stirred and reacted. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain surface-modified silica.

8. The high-flowability medical polypropylene material according to claim 1, characterized in that, The nucleating agent is 1,3:2,4-di-p-methylbenzylsorbitol.

9. A method for preparing a high-flowability medical polypropylene material as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Raw material pretreatment: Random copolymer polypropylene is dried in a forced-air drying oven, and structured composite stabilizer and nucleating agent are dried in a vacuum oven. S2. Premixing: Random copolymer polypropylene is put into a high-speed mixer, nucleating agent and structured composite stabilizer are added in sequence, and the mixture is mixed evenly to obtain the material. S3, Melt Extrusion: The material from step S2 is added to a twin-screw extruder. The extruder uses a stepped temperature control and melt extrusion is carried out under vacuum exhaust. S4. Pelletizing and Drying: The extruded strips are cooled by a circulating water tank and dried by an air knife before being pelletized and dried to obtain high-flowability medical polypropylene material.

10. The method for preparing the high-flowability medical polypropylene material according to claim 9, characterized in that, In step S3, the stepped temperature control refers to the following temperature settings for each section of the twin-screw extruder: feeding section 170-180℃, melting section 190-210℃, homogenization section 210-220℃, and die section 200-210℃.

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