High-barrier polypropylene medical material and preparation method thereof

Abstract

The application relates to a high-barrier polypropylene medical material and a preparation method thereof, and belongs to the technical field of high polymer materials. The components of the medical material are as follows: modified graphene 2.2-3.5 wt%, antioxidant 0.35-0.4 wt%, lubricant 0.6-0.8 wt%, and the balance is polypropylene resin; the modified graphene induces the polypropylene to generate a beta crystal extension zone along the sheet layer edge of the graphene, forms an inorganic-organic barrier surface, increases the shielding barrier effect, increases the tortuosity of the permeation path, solves the core technical problems that large sheet layer graphene is difficult to disperse and small sheet diameter graphene is difficult to form a large shielding barrier layer, meanwhile, the beta phase polypropylene formed at the edge of the graphene has excellent toughness, weakens the toughness gradient of the graphene and the polypropylene matrix, reduces the defects between the interfaces, and improves the stability of the barrier property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a high-barrier polypropylene medical material and a preparation method thereof. BACKGROUND

[0002] Polypropylene has become the first choice of material for medical products such as medical device packaging, infusion containers, surgical instrument trays, etc. due to its excellent chemical stability, biocompatibility, easy processability and cost-effectiveness. Its lightweight property can reduce transportation energy consumption, and its good environmental tolerance meets the medical disinfection requirements such as ethylene oxide sterilization and gamma ray sterilization. However, the inherent barrier defects of polypropylene limit its application in high-end medical fields: the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) are high, and this insufficient barrier can lead to risks such as drug oxidation failure and instrument aseptic barrier failure, especially in long-term storage or sensitive biological agent packaging.

[0003] To improve the barrier performance, the traditional strategy increases the tortuosity of the gas molecule penetration path by adding sheet-like fillers, and its core mechanism follows the "tortuous path model", which shows that the higher the aspect ratio of the filler, the more significant the barrier improvement under the same addition amount. According to the current research, graphene has an ultra-high aspect ratio (usually >1000), which becomes an ideal high-efficiency barrier filler.

[0004] However, the practical application of graphene faces the following technical bottlenecks: there is strong van der Waals force between the graphene sheets, and the dispersibility in the polypropylene matrix is not good, especially for large-diameter graphene with high aspect ratio. In addition, there is a three-order difference between the Young's modulus of graphene and polypropylene, which leads to the formation of a toughness gradient at the interface between the two, and when the material is bent or impacted, micron-sized holes are easily generated at the interface. These defects become "high-speed channels" for gas penetration, and thus, the penetration channels formed by these interface defects offset the advantages brought by graphene, becoming a bottleneck for the development of high-barrier polypropylene materials. SUMMARY

[0005] In order to solve the technical problems mentioned in the background art, the purpose of the present application is to provide a high-barrier polypropylene medical material and a preparation method thereof.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A high-barrier polypropylene medical material, which comprises the following components: modified graphene 2.2-3.5 wt%, antioxidant 0.35-0.4 wt%, and lubricant 0.6-0.8 wt%, and the balance is polypropylene resin.

[0008] The modified graphene is prepared by the following method:

[0009] Step A1: Mix p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine and tetrahydrofuran, protect with nitrogen, control the temperature at 30-40°C with water bath, stir for 5-7h, then add dicyclohexyl carbodiimide and heat to reflux for 1.5-2.2h, after the reaction kettle cools to room temperature, add saturated sodium bicarbonate solution, separate the water phase, then remove residual tetrahydrofuran by rotary evaporation to obtain the modifier;

[0010] In the above step A1 reaction, the amount ratio of p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine, dicyclohexyl carbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.35-0.4g:0.8-1g:150-200mL, the amidation reaction of p-tert-butyl benzoic acid and diethylene triamine is as follows:

[0011]

[0012] Step A2: Mix ethanol, p-toluenesulfonic acid and toluene, add graphene oxide and stir to disperse, then pressurize to 6-8bar, heat to 110-120°C and reflux for 3-4.5h, after the reaction ends, centrifuge to take the bottom precipitate, wash with water and dry to obtain activated graphene;

[0013] In the above step A2 reaction, the amount ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g:80-100mL:0.15-0.2g:120-160mL, the edge of the graphene oxide sheet is rich in carboxyl groups, and ethanol esterifies with the edge carboxyl groups to introduce active ethyl ester structures to the edge of the graphene sheet.

[0014] Preferably, the sheet diameter of graphene oxide is 3-15μm, which is good for dispersion in the polypropylene matrix and is conducive to forming more barrier units, increasing the penetration path and ensuring good barrier properties.

[0015] Step A3: Mix the modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide, protect with dry nitrogen, add activated graphene and stir to disperse, then heat to 60-80°C and stir for 10-14h, after the reaction ends, centrifuge to take the bottom precipitate, wash with cyclohexane and water in sequence, and dry to obtain modified graphene;

[0016] In the above step A3 reaction, the amount ratio of activated graphene, modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide is 10g:1.3-1.7g:0.4-0.5mL:60-80mL, the modifier and the active ethyl ester introduced to the edge of the activated graphene sheet undergo amine-ester exchange reaction to graft aromatic amide modification to the edge of the graphene sheet.

[0017] Preferably, the antioxidant is composed of antioxidant 1010 and antioxidant DLTP, which has stable anti-migration and thermal stability, and meets the medical safety requirements.

[0018] Preferably, the lubricant is calcium stearate, which has stable lubricating effect and high biological safety, and meets the medical safety requirements.

[0019] A preparation method of high-barrier polypropylene medical material, specifically comprising: uniformly mixing raw materials, and adopting a double-screw extruder to melt mix, extrude and pelletize, so as to obtain the high-barrier polypropylene medical material.

[0020] The beneficial effects of the present application are as follows:

[0021] The present application utilizes the characteristic that the edges of graphene oxide sheets are rich in carboxyl groups, and esterifies ethanol with graphene oxide to prepare activated graphene, which has a higher activity and a characteristic reaction of ethyl ester formed on the edges. A modifier is prepared by amidation reaction of p-tert-butyl benzoic acid and diethylenetriamine. Finally, an amine-ester exchange reaction is carried out between the modifier and the ethyl ester structure on the edges of the activated graphene sheets to prepare modified graphene. Compared with the prior art, the modified graphene has a tertiary butyl-containing aromatic amide chemical structure grafted on the edges, and the terminal tertiary butyl group and the methyl side chain on the polypropylene main chain are both saturated alkyl structures with similar polarity, which reduces the interface energy difference between the graphene sheets and the polypropylene matrix, increases the compatibility and dispersibility, and the steric hindrance effect of the tertiary butyl group interferes with the regular arrangement of the polypropylene molecular chain, which, together with the aromatic amide structure, induces the formation of beta phase crystallization of polypropylene along the edges of the graphene sheets. On the one hand, an inorganic-organic barrier surface of "graphene-beta crystal extension area" is formed in the polypropylene matrix, which increases the shielding and barrier effect and the tortuosity of the penetration path, solving the core technical problems of large-scale graphene dispersion and small-scale graphene forming a large shielding barrier layer. On the other hand, the beta phase polypropylene formed on the edges of graphene has excellent toughness, which weakens the toughness gradient between graphene and the polypropylene matrix, reduces the defects between the interfaces, and improves the stability of the barrier performance. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0023] Embodiment 1: A high-barrier polypropylene medical material is prepared, and the specific implementation process is as follows:

[0024] (1) Preparation of modified graphene

[0025] Step A1: Take p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine and tetrahydrofuran, mix, protect with nitrogen, control temperature with water bath at 30℃, stir for 7h, then add dicyclohexyl carbodiimide and heat to reflux for 2.2h, wherein the ratio of p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine, dicyclohexyl carbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.35g:0.8g:150mL, after the reaction kettle cools to room temperature, add saturated sodium bicarbonate solution, separate the aqueous phase, then rotary evaporate to remove residual tetrahydrofuran, to obtain a modifier.

[0026] Step A2: Take ethanol, p-toluenesulfonic acid and toluene, mix, add graphene oxide, stir and disperse, then pressurize to 6bar with nitrogen, heat to 110℃ and reflux for 4.5h, wherein the average diameter of graphene oxide is 10μm, the diameter distribution is 3-12μm, the ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g:80mL:0.15g:120mL, after the reaction ends, centrifuge to take the bottom layer of the precipitate, wash with water and dry, to obtain activated graphene.

[0027] Step A3: Take the modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide, mix, protect with dry nitrogen, add activated graphene, stir and disperse, then heat to 60℃ and stir for 14h, wherein the ratio of activated graphene, modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide is 10g:1.3g:0.4mL:60mL, after the reaction ends, centrifuge to take the bottom layer of the precipitate, wash with cyclohexane and water in turn, and dry, to obtain modified graphene.

[0028] (2) Mixing and granulation

[0029] Take the raw materials according to the weight percentage, 2.2wt% of modified graphene, made by the present embodiment; 0.4wt% of antioxidant, made by compounding antioxidant 1010 and antioxidant DLTP according to the weight ratio of 2:1; 0.6wt% of lubricant, selected from medical grade calcium stearate; and the rest is polypropylene resin, selected from M800E type resin raw material.

[0030] Put each component raw material into a high mixer to mix at 600rpm for 10min, then send the mixture into a double screw extruder, melt mix at 200℃, then extrude and granulate, to obtain high barrier polypropylene medical material.

[0031] Example 2, preparation of high barrier polypropylene medical material, the specific implementation process is as follows:

[0032] (1) Preparation of modified graphene

[0033] Step A1: Take p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine and tetrahydrofuran, mix, protect with nitrogen, control temperature with water bath at 40℃, stir for 5h, then add dicyclohexyl carbodiimide and heat to reflux for 1.5h, wherein the ratio of p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine, dicyclohexyl carbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.4g:1g:200mL, after the reaction kettle is cooled to room temperature, add saturated sodium bicarbonate solution, separate the aqueous phase, then rotary evaporate to remove residual tetrahydrofuran, to obtain a modifier.

[0034] Step A2: Take ethanol, p-toluenesulfonic acid and toluene, mix, add graphene oxide, stir and disperse, then pressurize to 8bar with nitrogen, heat to 1120℃ and reflux for 3h, wherein the commercially available material is selected for graphene oxide, the average flake diameter is 10μm, the flake diameter distribution is 3-12μm, the ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g:100mL:0.2g:160mL, after the reaction is completed, centrifuge to take the bottom layer precipitate, wash with water and dry, to obtain activated graphene.

[0035] Step A3: Take the modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide, mix, protect with dry nitrogen, add activated graphene, stir and disperse, then heat to 80℃ and stir for 10h, wherein the ratio of activated graphene, modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide is 10g:1.7g:0.5mL:80mL, after the reaction is completed, centrifuge to take the bottom layer precipitate, sequentially wash with cyclohexane and water, dry, to obtain modified graphene.

[0036] (2) Mixing and granulation

[0037] Take the raw materials according to the weight percentage, 3.5wt% of modified graphene, made by the present example; 0.35wt% of antioxidant, compounded by using antioxidant 1010 and antioxidant DLTP according to the weight ratio of 2:1; 0.8wt% of lubricant, selected as medical grade calcium stearate; the rest is polypropylene resin, selected as M800E type resin raw material.

[0038] Put each component raw material into a high mixer to mix for 10min at 600rpm, then send the mixed material into a double screw extruder, melt mix at 200℃, then extrude and granulate, to obtain high barrier polypropylene medical material.

[0039] Example 3, preparation of high barrier polypropylene medical material, the specific implementation process is as follows:

[0040] (1) Preparation of modified graphene

[0041] Step A1: Take p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine and tetrahydrofuran, mix them, protect them with nitrogen, control the temperature with water bath at 35℃, stir for 6h, then add dicyclohexyl carbodiimide and heat to reflux for 2h, wherein the ratio of p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine, dicyclohexyl carbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.35g:0.9g:170mL, after the reaction kettle cools to room temperature, add saturated sodium bicarbonate solution, separate the aqueous phase, then remove the residual tetrahydrofuran by rotary evaporation to obtain the modifier.

[0042] Step A2: Take ethanol, p-toluenesulfonic acid and toluene, mix them, add graphene oxide, stir and disperse, then pressurize to 7bar with nitrogen, heat to 115℃ and reflux for 4h, wherein the commercially available graphene oxide is used, the average flake diameter is 10μm, the flake diameter distribution is 3-12μm, the ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g:90mL:0.18g:140mL, after the reaction is completed, centrifuge to take the bottom layer precipitate, wash and dry with water to obtain activated graphene.

[0043] Step A3: Take the modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide, mix them, protect them with dry nitrogen, add activated graphene, stir and disperse, then heat to 70℃ and stir for 12h, wherein the ratio of activated graphene, modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide is 10g:1.5g:0.5mL:70mL, after the reaction is completed, centrifuge to take the bottom layer precipitate, wash with cyclohexane and water in turn, and dry to obtain modified graphene.

[0044] (2) Mixing and granulation

[0045] Take the raw materials according to the weight percentage, 3wt% of modified graphene, which is self-made in this example; 0.4wt% of antioxidant, which is a composite of antioxidant 1010 and antioxidant DLTP with a weight ratio of 2:1; 0.7wt% of lubricant, which is medical grade calcium stearate; and the rest is polypropylene resin, which is M800E type resin raw material.

[0046] Add each component raw material to the high mixer to mix at 600rpm for 10min, then send the mixture to the twin-screw extruder, melt mix at 200℃, then extrude and granulate to obtain high-barrier polypropylene medical material.

[0047] Example 4, preparation of high-barrier polypropylene medical material, the specific implementation process is as follows:

[0048] (1) Preparation of modified graphene

[0049] Step A1: Take p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine and tetrahydrofuran, mix them, protect them with nitrogen, control the temperature at 40℃ with water bath, stir for 5.5h, then add dicyclohexyl carbodiimide and heat to reflux for 1.8h, wherein the ratio of p-tert-butyl benzoic acid, diethylene triamine, 4-dimethyl amino pyridine, dicyclohexyl carbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.35g:0.9g:180mL, after the reactor cools to room temperature, add saturated sodium bicarbonate solution, separate the aqueous phase, then remove the residual tetrahydrofuran by rotary evaporation to obtain the modifier.

[0050] Step A2: Take ethanol, p-toluenesulfonic acid and toluene, mix them, add graphene oxide, stir and disperse, then pressurize to 8bar with nitrogen, heat to 120℃ and reflux for 3.5h, wherein the average diameter of graphene oxide is 10μm, the diameter distribution is 3-12μm, the ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g:100mL:0.17g:150mL, after the reaction is completed, centrifuge to obtain the bottom layer precipitate, wash and dry it to obtain activated graphene.

[0051] Step A3: Take the modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide, mix them, protect them with dry nitrogen, add activated graphene, stir and disperse, then heat to 75℃ and stir for 11h, wherein the ratio of activated graphene, modifier, trimethyl aluminum and anhydrous dimethyl sulfoxide is 10g:1.6g:0.5mL:80mL, after the reaction is completed, centrifuge to obtain the bottom layer precipitate, wash it with cyclohexane and water in sequence, and dry it to obtain modified graphene.

[0052] (2) Mixing and granulation

[0053] Take the raw materials according to the weight percentage, 2.8wt% of modified graphene, which is self-made in this example; 0.4wt% of antioxidant, which is a composite of antioxidant 1010 and antioxidant DLTP with a weight ratio of 2:1; 0.7wt% of lubricant, which is medical grade calcium stearate; and the rest is polypropylene resin, which is M800E type resin raw material.

[0054] Add each component raw material to the high mixer to mix for 10min at 600rpm, then send the mixture to the twin-screw extruder, melt and mix at 200℃, then extrude and granulate to obtain high-barrier polypropylene medical material.

[0055] Comparative Example 1, this comparative example is a blank control, refer to Example 4, without adding modified graphene, and the rest of the implementation process is exactly the same.

[0056] Comparative Example 2, use 2.5wt% of coupled graphene and 0.3wt% of WBG-Ⅱ type β nucleating agent to replace modified graphene, and the rest of the implementation process is exactly the same

[0057] The material prepared as above was injection molded into a sheet sample with a thickness of 1 mm, and the tensile property test was performed according to the ASTM D638-2022 standard, the impact property test was performed according to the ASTM D256-2024 standard, the oxygen transmission rate test was performed according to the ASTM D3985-2024 standard, the oxygen transmission rate reduction rate (OTR reduction rate) was calculated with reference to Comparative Example 1, the water vapor transmission rate was performed according to the ASTM F1249-2020 standard, the water vapor transmission rate reduction rate (WVTR) was calculated with reference to Comparative Example 1, and the sample was subjected to 90° bending 20 times according to the ASTM D2176-2016 standard, and the oxygen transmission rate was detected again and the oxygen transmission rate change rate (OTR change rate) was calculated, and the specific test results are shown in Table 1:

[0058] Table 1

[0059]

[0060] From the test results in Table 1, it can be seen that the tensile strength and impact strength of the polypropylene medical material of the examples are higher than those of the comparative examples, indicating that the introduction of modified graphene has a lower effect on the mechanical properties of the matrix. In the barrier test, the transmission rate reduction rate of the examples is higher than that of the comparative examples, especially the oxygen transmission rate reduction rate is significantly increased, showing excellent barrier performance, and the stability of the examples is extremely high under the action of external force deformation.

[0061] In the description of the specification, the description of the reference terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0062] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A high-barrier polypropylene medical material, characterized in that, The specific components are: 2.2-3.5 wt% modified graphene, 0.35-0.4 wt% antioxidant, and 0.6-0.8 wt% lubricant, with the balance being polypropylene resin; The modified graphene is prepared by the following method: Step A1: Mix p-tert-butylbenzoic acid, diethylenetriamine, 4-dimethylaminopyridine and tetrahydrofuran, purge with nitrogen for protection, stir and react in a water bath at 30-40℃ for 5-7 hours, then add dicyclohexylcarbodiimide and reflux for 1.5-2.2 hours to prepare the modifier. Step A2: Mix ethanol, p-toluenesulfonic acid and toluene, add graphene oxide and stir to disperse, then pressurize to 6-8 bar, heat to 110-120℃ and reflux for 3-4.5 h to prepare activated graphene; Step A3: Mix the modifier, trimethylaluminum and anhydrous dimethyl sulfoxide, purge with dry nitrogen gas for protection, add activated graphene and stir to disperse, then heat to 60-80℃ and stir to react for 10-14 hours to prepare modified graphene.

2. The high-barrier polypropylene medical material according to claim 1, characterized in that, The ratio of p-tert-butylbenzoic acid, diethylenetriamine, 4-dimethylaminopyridine, dicyclohexylcarbodiimide and tetrahydrofuran is 0.2mol:0.1mol:0.35-0.4g:0.8-1g:150-200mL.

3. The high-barrier polypropylene medical material according to claim 2, characterized in that, The ratio of graphene oxide, ethanol, p-toluenesulfonic acid and toluene is 10g: 80-100mL: 0.15-0.2g: 120-160mL.

4. The high-barrier polypropylene medical material according to claim 3, characterized in that, The sheet diameter of graphene oxide is 3-15 μm.

5. A high-barrier polypropylene medical material according to claim 4, characterized in that, The ratio of activated graphene, modifier, trimethylaluminum and anhydrous dimethyl sulfoxide is 10g: 1.3-1.7g: 0.4-0.5mL: 60-80mL.

6. The high-barrier polypropylene medical material according to claim 1, characterized in that, The antioxidant is a combination of antioxidant 1010 and antioxidant DLTP.

7. The high-barrier polypropylene medical material according to claim 1, characterized in that, The lubricant is calcium stearate.

8. A method for preparing a high-barrier polypropylene medical material according to any one of claims 1-7, characterized in that, Specifically, the raw materials are mixed evenly, and then melt-extruded and granulated using a twin-screw extruder to obtain high-barrier polypropylene medical materials.

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