Pharmaceutical antibacterial polyethylene barrier film and its preparation method

Abstract

This invention belongs to the technical field of pharmaceutical packaging materials, specifically relating to a pharmaceutical antibacterial polyethylene barrier film and its preparation method. The pharmaceutical antibacterial polyethylene barrier film comprises polyethylene resin and modified attapulgite masterbatch; the polyethylene resin includes linear low-density polyethylene, metallocene low-density polyethylene, and high-density polyethylene; the modified attapulgite masterbatch comprises linear low-density polyethylene and modified attapulgite; the modified attapulgite is obtained by sequentially subjecting nano-attapulgite to acid activation, tea polyphenol adsorption, hydrophobic modification with a silane coupling agent and a cationic surfactant, and complexation with zinc chloride. The pharmaceutical antibacterial polyethylene barrier film prepared by this invention exhibits good barrier properties against water vapor and oxygen, good antibacterial properties, high mechanical properties, low production cost, and a simple and easy preparation method.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical packaging materials technology, specifically relating to pharmaceutical antibacterial polyethylene barrier film and its preparation method. Background Technology

[0002] Polyethylene film, as a traditional plastic material, is inexpensive and convenient, making it one of the most common and widely used packaging materials. However, its poor oxygen and water vapor barrier properties and limited antibacterial properties restrict its application in pharmaceutical packaging. Pharmaceutical packaging materials require both high barrier properties to prevent oxygen and water vapor from permeating the film and causing drug oxidation and deliquescence, and a certain level of antibacterial properties to prevent drug contamination. Therefore, improving the barrier and antibacterial properties of polyethylene film has become a key research focus in the industry. Currently, most industry practices involve adding antibacterial agents and barrier-forming fillers to the polyethylene system to enhance the antibacterial and barrier properties of PE films.

[0003] For example, patent CN108034113A discloses a PE film with excellent barrier properties and antibacterial properties. The raw materials include low-density polyethylene, metallocene linear low-density polyethylene, maleamide-grafted polyethylene, polyvinylpyrrolidone, glyceryl monostearate, polyglycerol fatty acid ester, antioxidant, bactericide, oleamide, calcium naphthenate, and modified diatomaceous earth. This invention improves the barrier and antibacterial properties of the PE film by adding modified diatomaceous earth and bactericide, and improves the compatibility of modified diatomaceous earth and bactericide in the raw material system by adding various lubricants. However, adding lubricants only improves the dispersibility of modified diatomaceous earth and bactericide in the raw material system during the preparation process; it does not improve the binding force between the functional additives and the polyethylene system. During the use of the PE film, the functional additives will gradually dissolve, causing contamination of the drug.

[0004] Patent CN118165331A discloses a method for preparing a high-antibacterial PE barrier film. This method involves introducing modified molecular sieves, modified nanocrystalline cellulose whiskers, 3-iodo-2-propynyl butylcarbamate, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] into a polyethylene system via blending modification technology, followed by blow molding to prepare the PE film. The modified molecular sieves and modified nanocrystalline cellulose whiskers enhance the barrier properties of the PE film, while 3-iodo-2-propynyl butylcarbamate improves its antibacterial properties. However, as a spherical filler, adding molecular sieves in excessive amounts can lead to a decrease in the mechanical properties of the PE film. Therefore, nanocrystalline cellulose whiskers are needed to further improve the mechanical properties of the PE film. Furthermore, the addition of multiple functional additives is detrimental to uniform dispersion and affects the performance stability of the PE film.

[0005] Patent CN118342874A describes the preparation of an ultra-high barrier film packaging material for traditional Chinese medicine. This film consists of a PET layer, a first modified PE layer, and a second modified PE layer, arranged sequentially from the outside in. Antibacterial properties are imparted to the film layers by adding silica-grafted quaternary ammonium salts. The barrier properties and mechanical properties of the film layers are improved by adding a PET layer and modified magnesium copper layered double hydroxides and hexagonal boron nitride. Furthermore, the grafting modification of these functional additives prevents their migration and dissolution within the polyethylene system. However, the preparation processes of magnesium copper layered double hydroxides and silica-grafted quaternary ammonium salts are quite complex, and hexagonal boron nitride is expensive, significantly increasing the production cost of the film. As a single-use product, the high price of this pharmaceutical packaging material hinders its market promotion. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a pharmaceutical antibacterial polyethylene barrier film that exhibits excellent barrier properties against water vapor and oxygen, strong antibacterial activity, high mechanical properties, and low production cost. This invention also provides a simple and easy-to-implement preparation method for it.

[0007] One objective of this invention is to provide a pharmaceutical antibacterial polyethylene barrier film, comprising polyethylene resin and modified attapulgite masterbatch; wherein the polyethylene resin comprises linear low-density polyethylene, metallocene low-density polyethylene, and high-density polyethylene; and the modified attapulgite masterbatch comprises linear low-density polyethylene and modified attapulgite.

[0008] The method for preparing the modified attapulgite is as follows:

[0009] Nano-attapulgite was placed in hydrochloric acid solution for activation treatment, followed by centrifugation to obtain activated attapulgite. The activated attapulgite was dispersed in water, and tea polyphenols were added for adsorption. Then, silane coupling agent and cationic surfactant were added for hydrophobic modification. After centrifugation, the mixture was washed with water and anhydrous ethanol in sequence and dried to obtain hydrophobic attapulgite. The hydrophobic attapulgite was dispersed in anhydrous ethanol, and zinc chloride was added for complexation reaction. After centrifugation, the mixture was washed with anhydrous ethanol and dried to obtain modified attapulgite.

[0010] Preferably, the raw material composition of the polyethylene resin is: 52-58 wt.% linear low-density polyethylene, 12-25 wt.% metallocene low-density polyethylene, and 23-30 wt.% high-density polyethylene.

[0011] Preferably, the raw material composition of the modified attapulgite masterbatch is: 75-80 wt.% linear low-density polyethylene and 20-25 wt.% modified attapulgite.

[0012] Preferably, the modified attapulgite masterbatch accounts for 20-30% of the total mass of polyethylene resin.

[0013] In this invention, the linear low-density polyethylene has a melt index of 2 g / 10 min and a density of 0.918 g / cm³ under conditions of 190°C and 2.16 kg. 3 Preferably, it is 7042 produced by Yangzi Petrochemical Co., Ltd.; the metallocene low-density polyethylene has a melt index of 0.8 g / 10 min and a density of 0.916 g / cm³ at 190°C and 2.16 kg. 3 The preferred high-density polyethylene is Exceed XP8656ML manufactured by Mobil Exxon; the melt index of the high-density polyethylene at 190°C and 2.16 kg is 20 g / 10 min, and the density is 0.954 g / cm³. 3 The preferred choice is DMDA-8920 produced by Dushanzi Petrochemical Company.

[0014] This invention employs a blend of three polyethylene resins. Linear low-density polyethylene (LDPE) exhibits a linear chain structure, providing high flexibility and elongation. High-density polyethylene (HDPE) has high crystallinity and mechanical strength, enhancing the barrier properties of the polyethylene film against water vapor and gases. Metallocene LPE contains long branches in its molecular chain. When blended with linear LPE and HDPE containing short branches, the mixture undergoes high-temperature melting and cooling. The combination of long and short branches forms irregular grains and amorphous regions, further improving the barrier properties of the polyethylene film. Furthermore, the crystallinity and mechanical properties of metallocene LPE are significantly higher than those of traditional LPE, thus improving both the barrier properties and mechanical properties of the polyethylene film.

[0015] The condition parameters for each step in the preparation of modified attapulgite soil according to this invention are as follows:

[0016] During the activation treatment, the concentration of hydrochloric acid solution is 0.5-1.0 mol / L, the mass-to-volume ratio (solid-to-liquid ratio) of nano-attapulgite to hydrochloric acid solution is 1 g: (8-12) mL; the activation temperature is 30-50℃, and the activation time is 1-2 h.

[0017] The purpose of acid activation treatment of nano-attapulgite is to improve its adsorption performance, which is beneficial for the subsequent adsorption of adjuvants such as tea polyphenols. Since the tea polyphenols and cationic surfactants used in the subsequent adsorption modification treatment are more stable under acidic conditions, there is no need for water washing and drying after activation treatment. The centrifuged activated attapulgite can be directly subjected to adsorption and hydrophobic modification, which not only saves operation steps but also makes the aqueous solution acidic, which is beneficial to improving the stability of tea polyphenols and cationic surfactants.

[0018] During hydrophobic modification, the mass-to-volume ratio (solid-liquid ratio) of activated attapulgite to water was 1 g:(15-20) mL; the amount of tea polyphenols added accounted for 0.5-1% of the mass of activated attapulgite; the amount of silane coupling agent added accounted for 10-15% of the mass of activated attapulgite; and the amount of cationic surfactant added accounted for 1-2% of the mass of activated attapulgite. The adsorption temperature was 60-80℃, and the time was 0.5-1.5 h; the hydrophobic modification temperature was 60-80℃, and the time was 2-3 h.

[0019] Among them, silane coupling agents can be KH550, KH560, KH570, etc.; cationic surfactants can be hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, etc.

[0020] Tea polyphenols can be adsorbed onto the surface of attapulgite through van der Waals forces and hydrogen bonds, thus endowing attapulgite with certain antibacterial and antioxidant properties. Cationic surfactants and silane coupling agents can respectively bind to the attapulgite surface, which carries a small amount of negative charge and a large number of hydroxyl groups, changing the surface from hydrophilic to lipophilic. The combined effect of these two agents can significantly improve the hydrophobicity of attapulgite, greatly enhancing its dispersibility and compatibility in polyethylene resin. Since the presence of water affects the dispersibility of the hydrophobically modified attapulgite, it is necessary to dry the attapulgite before the complexation reaction in the ethanol solution.

[0021] During the complexation reaction, the mass-to-volume ratio (solid-to-liquid ratio) of hydrophobic attapulgite to anhydrous ethanol is 1 g: (15-20) mL; the amount of zinc chloride added accounts for 5-10% of the mass of hydrophobic attapulgite; the complexation reaction temperature is 40-70℃, and the time is 0.5-2 h.

[0022] Attapulgite has a good adsorption effect on zinc ions. On the one hand, zinc ions can be adsorbed on attapulgite, giving it antibacterial properties. On the other hand, they can undergo a complexation reaction with tea polyphenols adsorbed on attapulgite to form tea polyphenol-zinc complexes, which improve the adsorption stability of tea polyphenols. Since tea polyphenols and zinc ions have different antibacterial mechanisms, their synergistic effect can significantly improve the antibacterial properties of attapulgite and make up for the shortcomings of single antibacterial agents.

[0023] This invention selects nano-attapulgite as a functional filler for two main reasons. First, attapulgite possesses abundant pores, making it difficult for non-polar molecules such as oxygen to enter its internal channels, thus significantly improving the oxygen barrier properties of polyethylene films. Second, the layered chain-like crystal structure of attapulgite, primarily exhibiting high aspect ratio fibrous or narrow band-like forms, allows it to be well embedded in polyethylene materials, increasing the cross-linking degree of polyethylene molecular chains and thereby improving its mechanical properties. However, attapulgite has excellent hydrophilicity, resulting in low water vapor barrier properties, and its compatibility with polyethylene systems is poor, necessitating modification treatment.

[0024] In this invention, when modifying nano-attapulgite, the surface of attapulgite carries a small amount of negative charge and a large number of hydroxyl groups. Its high hydrophilicity and the charge repulsion effect between its layers make it easier to disperse evenly in aqueous solution. Therefore, activated attapulgite is first dispersed in water for adsorption and hydrophobic modification. On the one hand, the adsorption properties of attapulgite itself allow tea polyphenols to be adsorbed onto its surface, endowing it with antibacterial and antioxidant properties. On the other hand, cationic surfactants and silane coupling agents can respectively bind to the small amount of negative charge and the large number of hydroxyl groups on the surface of attapulgite, working together to greatly improve the hydrophobicity of attapulgite and its compatibility in polyethylene systems. Furthermore, the cationic surfactants also possess certain antibacterial properties, providing antibacterial effects to the attapulgite. Attapulgite modified with cationic surfactants exhibits enhanced hydrophobicity and better dispersibility in oily solvents. Therefore, using anhydrous ethanol as a solvent during the complexation reaction is more conducive to the uniform dispersion of attapulgite. Zinc ions can be adsorbed on the surface of attapulgite and undergo complexation reactions with tea polyphenols, increasing the stability of tea polyphenols. Furthermore, the addition of zinc ions can further enhance antibacterial properties.

[0025] The second objective of this invention is to provide a method for preparing a pharmaceutical antibacterial polyethylene barrier film, comprising the following steps:

[0026] Linear low-density polyethylene and modified attapulgite are fused at high temperature and granulated to obtain modified attapulgite masterbatch; linear low-density polyethylene, metallocene low-density polyethylene, high-density polyethylene and modified attapulgite masterbatch are mixed evenly, and then plasticized at high temperature and blow-molded to obtain a pharmaceutical antibacterial polyethylene barrier film.

[0027] This invention first prepares modified attapulgite masterbatch by mixing modified attapulgite with linear low-density polyethylene, and then mixes it with polyethylene resin to form a blown film. On the one hand, this can improve the dispersion uniformity of the modified attapulgite, and on the other hand, it can shorten the mixing and blown film forming time, thereby improving production efficiency.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] (1) This invention uses nano-attapulgite as a filler, which utilizes its excellent gas barrier properties and layered crystal structure to improve the gas barrier properties and mechanical properties of polyethylene film; at the same time, cationic surfactants, silane coupling agents, tea polyphenols and zinc chloride are used to perform hydrophobic modification and functional modification on attapulgite, which not only improves the compatibility and dispersion uniformity of attapulgite in polyethylene resin, but also endows attapulgite with excellent hydrophobicity, antibacterial and antioxidant properties, so that it has the multifunctionality of water vapor barrier, oxygen barrier, antibacterial and antioxidant properties at the same time, which can reduce the types of functional additives added, thereby avoiding the problems of additive migration, dissolution, uneven dispersion and poor compatibility caused by adding multiple additives;

[0030] (2) In the modification of nano-attapulgite, the present invention first adsorbs and hydrophobically modifies the acid-activated attapulgite in an aqueous solution based on the characteristics of the negative charge and good hydrophilicity of the attapulgite surface, so that the surface changes from hydrophilic to lipophilic. Then, the complexation reaction of zinc chloride is carried out in an ethanol solution. The change of solvent is conducive to the uniform dispersion of attapulgite and the modification effect is better. In addition, tea polyphenols, zinc ions and cationic surfactants all have antibacterial properties. The simultaneous use can significantly improve the antibacterial effect. Moreover, the complexation between tea polyphenols and zinc ions can also improve the adsorption stability of both.

[0031] (3) The present invention uses three types of polyethylene resins to blend together. The high flexibility of linear low-density polyethylene and the high mechanical strength of high-density polyethylene are used to balance the mechanical properties of polyethylene film. At the same time, metallocene low-density polyethylene is introduced. When it is melt-blended at high temperature, the long branches in its molecular chain combine with the short branches in the molecular chains of linear low-density polyethylene and high-density polyethylene to form irregular grains and amorphous regions, which can further improve the barrier properties of polyethylene film. Moreover, the crystallinity and mechanical properties of metallocene low-density polyethylene are better than those of traditional low-density polyethylene, which can improve the mechanical properties of polyethylene film.

[0032] (4) In this invention, tea polyphenols with antibacterial and antioxidant properties and zinc ions with antibacterial properties are combined with attapulgite clay through adsorption and complexation. The attapulgite clay can be stably embedded in polyethylene material, avoiding the migration and dissolution of functional additives, improving the functional stability of polyethylene film, and reducing the need for surface modification of different additives when using multiple additives, thus improving production efficiency. At the same time, the raw materials used are low in cost and widely available, reducing product cost. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the embodiments. Unless otherwise specified, all raw materials used in the embodiments are commercially available.

[0034] The raw materials used in the examples are described below:

[0035] Linear low-density polyethylene, 7042 produced by Yangzi Petrochemical Co., Ltd.

[0036] Metallocene low-density polyethylene, ExceedXP8656ML manufactured by Mobil Exxon;

[0037] High-density polyethylene, DMDA-8920 produced by Dushanzi Petrochemical Company.

[0038] The polyethylene film performance testing method used in the examples is as follows:

[0039] The oxygen permeability was tested in accordance with the standard GB / T1038-2000;

[0040] Water vapor transmission rate was tested in accordance with standard GB / T1037-1988;

[0041] The antibacterial rate was tested according to standard GB / T31402-2015;

[0042] Tensile strength was tested in accordance with standard GB / T1040.3-2006.

[0043] Example 1

[0044] A pharmaceutical-grade antibacterial polyethylene barrier film, prepared by the following method:

[0045] (1) Preparation of modified attapulgite soil:

[0046] Nano-attapulgite was placed in a 1.0 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 10 mL, stirred at 40 °C for 2 h, and then centrifuged to obtain activated attapulgite.

[0047] Activated attapulgite was dispersed in water at a solid-liquid ratio of 1g:18mL. First, 0.8% of tea polyphenols by weight of the activated attapulgite were added, and the mixture was stirred at 70℃ for 1h. Then, 12% of KH550 and 1.5% of hexadecyltrimethylammonium bromide by weight of the activated attapulgite were added, and the mixture was stirred at 70℃ for 3h. After centrifugation, the mixture was washed with water and anhydrous ethanol in sequence, and then dried to obtain hydrophobic attapulgite.

[0048] Hydrophobic attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 1 g: 18 mL. Zinc chloride, accounting for 8% of the mass of activated attapulgite, was added. The mixture was stirred at 60 °C for 1 h, then centrifuged, washed with anhydrous ethanol, and dried to obtain modified attapulgite.

[0049] (2) Preparation of modified attapulgite masterbatch:

[0050] 80 wt.% of linear low-density polyethylene and 20 wt.% of modified attapulgite were fused at high temperature and granulated to obtain modified attapulgite masterbatch.

[0051] (3) Preparation of pharmaceutical antibacterial polyethylene barrier film:

[0052] Weigh out 55 wt.% of linear low-density polyethylene, 20 wt.% of metallocene low-density polyethylene, and 25 wt.% of high-density polyethylene to make polyethylene resin. Add 25% of modified attapulgite masterbatch, which accounts for 25% of the total mass of polyethylene resin, mix evenly, and then plasticize at high temperature and blow mold to obtain a pharmaceutical antibacterial polyethylene barrier film.

[0053] The pharmaceutical antibacterial polyethylene barrier membrane prepared in this embodiment was subjected to performance testing, and its water vapor permeability was 0.6 g / m³. 2 • 24h, oxygen permeability 1.4cm 3 / m 2 ·24h·0.1MPa, Escherichia coli inhibition rate 99.7%, Staphylococcus aureus inhibition rate 99.6%, longitudinal tensile strength 50.4MPa, transverse tensile strength 42.0MPa.

[0054] Example 2

[0055] A pharmaceutical-grade antibacterial polyethylene barrier film, prepared by the following method:

[0056] (1) Preparation of modified attapulgite soil:

[0057] Nano-attapulgite was placed in a 0.5 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 8 mL, stirred at 50 °C for 1 h, and then centrifuged to obtain activated attapulgite.

[0058] Activated attapulgite was dispersed in water at a solid-liquid ratio of 1g:15mL. First, 0.5% of tea polyphenols by mass of activated attapulgite were added, and the mixture was stirred at 60℃ for 1.5h. Then, 10% of KH570 and 2% of hexadecyltrimethylammonium chloride by mass of activated attapulgite were added, and the mixture was stirred at 60℃ for 3h. After centrifugation, the mixture was washed with water and anhydrous ethanol in sequence, and then dried to obtain hydrophobic attapulgite.

[0059] Hydrophobic attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 1 g: 15 mL. Zinc chloride, accounting for 5% of the mass of activated attapulgite, was added. The mixture was stirred at 70 °C for 0.5 h, then centrifuged, washed with anhydrous ethanol, and dried to obtain modified attapulgite.

[0060] (2) Preparation of modified attapulgite masterbatch:

[0061] 75 wt.% of linear low-density polyethylene and 25 wt.% of modified attapulgite were fused at high temperature and granulated to obtain modified attapulgite masterbatch.

[0062] (3) Preparation of pharmaceutical antibacterial polyethylene barrier film:

[0063] Weigh out 58 wt.% of linear low-density polyethylene, 12 wt.% of metallocene low-density polyethylene, and 30 wt.% of high-density polyethylene to make polyethylene resin. Add 20% of modified attapulgite masterbatch, which accounts for 20% of the total mass of polyethylene resin, mix evenly, and then plasticize at high temperature and blow mold to obtain a pharmaceutical antibacterial polyethylene barrier film.

[0064] The pharmaceutical antibacterial polyethylene barrier membrane prepared in this embodiment was subjected to performance testing, and its water vapor permeability was 0.7 g / m³. 2 • 24h, oxygen permeability 1.5cm 3 / m 2 ·24h·0.1MPa, Escherichia coli inhibition rate 99.7%, Staphylococcus aureus inhibition rate 99.5%, longitudinal tensile strength 48.5MPa, transverse tensile strength 40.7MPa.

[0065] Example 3

[0066] A pharmaceutical-grade antibacterial polyethylene barrier film, prepared by the following method:

[0067] (1) Preparation of modified attapulgite soil:

[0068] Nano-attapulgite was placed in a 0.8 mol / L hydrochloric acid solution at a solid-liquid ratio of 1 g: 12 mL, stirred at 30 °C for 2 h, and then centrifuged to obtain activated attapulgite.

[0069] Activated attapulgite was dispersed in water at a solid-liquid ratio of 1g:20mL. First, 1% of tea polyphenols by mass of activated attapulgite were added and stirred at 80℃ for 0.5h. Then, 15% of KH560 and 1% of hexadecyltrimethylammonium chloride by mass of activated attapulgite were added and stirred at 80℃ for 2h. After centrifugation, the mixture was washed with water and anhydrous ethanol in sequence and dried to obtain hydrophobic attapulgite.

[0070] Hydrophobic attapulgite was dispersed in anhydrous ethanol at a solid-liquid ratio of 1g:20mL. Zinc chloride, accounting for 10% of the mass of activated attapulgite, was added. The mixture was stirred at 40℃ for 2 hours, then centrifuged, washed with anhydrous ethanol, and dried to obtain modified attapulgite.

[0071] (2) Preparation of modified attapulgite masterbatch:

[0072] 77 wt.% of linear low-density polyethylene and 23 wt.% of modified attapulgite were fused at high temperature and granulated to obtain modified attapulgite masterbatch.

[0073] (3) Preparation of pharmaceutical antibacterial polyethylene barrier film:

[0074] Weigh out 52 wt.% of linear low-density polyethylene, 25 wt.% of metallocene low-density polyethylene, and 23 wt.% of high-density polyethylene to make polyethylene resin. Add 30% of modified attapulgite masterbatch, which accounts for 30% of the total mass of polyethylene resin, mix evenly, and then plasticize at high temperature and blow mold to obtain a pharmaceutical antibacterial polyethylene barrier film.

[0075] The pharmaceutical antibacterial polyethylene barrier membrane prepared in this embodiment was subjected to performance testing, and its water vapor permeability was 0.4 g / m³. 2 • 24h, oxygen permeability 1.3cm 3 / m 2 ·24h·0.1MPa, Escherichia coli inhibition rate 99.9%, Staphylococcus aureus inhibition rate 99.7%, longitudinal tensile strength 52.8MPa, transverse tensile strength 44.5MPa.

[0076] Comparative Example 1

[0077] The only difference between this comparative example and Example 1 is that the nano-attapulgite clay is replaced with an equal mass of nano-molecular sieve.

[0078] The performance of the pharmaceutical antibacterial polyethylene barrier membrane prepared in this comparative example was tested, and its water vapor permeability was 1.4 g / m³. 2 • 24h, oxygen permeability 2.5cm 3 / m 2 At 0.1 MPa for 24 hours, the inhibition rate of *E. coli* was 99.5%, the inhibition rate of *Staphylococcus aureus* was 99.5%, the longitudinal tensile strength was 43.4 MPa, and the transverse tensile strength was 38.8 MPa. The barrier properties and tensile strength of the polyethylene film decreased compared to Example 1. This is because the crystal structure of nano-molecular sieves differs from that of nano-attapulgite. Nano-attapulgite has abundant pores and exhibits a high aspect ratio, appearing as fibrous or narrow bands. This crystal structure can be well embedded in polyethylene materials, increasing the cross-linking degree of polyethylene molecular chains, thereby improving its mechanical properties. Furthermore, the barrier barrier formed is more complex, which is beneficial for improving barrier properties. In contrast, nano-molecular sieves are mainly spherical, with limited effect on increasing the cross-linking degree of polyethylene molecular chains, and their barrier barrier is relatively simple. Therefore, their improvement in the barrier properties and tensile strength of the polyethylene film is lower than that of nano-attapulgite.

[0079] Comparative Example 2

[0080] The only difference between this comparative example and Example 1 is that the metallocene low-density polyethylene in step (3) is replaced with an equal mass of linear low-density polyethylene.

[0081] The performance of the pharmaceutical antibacterial polyethylene barrier membrane prepared in this comparative example was tested, and its water vapor permeability was 0.9 g / m³. 2 • 24h, oxygen permeability 2.0 cm 3 / m 2 At 0.1 MPa for 24 hours, the inhibition rate of Escherichia coli was 99.7%, and the inhibition rate of Staphylococcus aureus was 99.6%. The longitudinal tensile strength was 40.8 MPa, and the transverse tensile strength was 37.4 MPa. It can be seen that without the addition of metallocene polyethylene, which has excellent mechanical properties, the tensile strength of the polyethylene film is significantly reduced. Furthermore, the lack of irregular grains formed between the long branches of metallocene low-density polyethylene and the short branches of linear low-density polyethylene and high-density polyethylene also slightly reduces the barrier properties of the polyethylene film.

[0082] Comparative Example 3

[0083] The only difference between this comparative example and Example 1 is that, in the preparation of the modified attapulgite, the adsorption and complexation of tea polyphenols and zinc ions are not performed. That is, the activated attapulgite is dispersed in water at a solid-liquid ratio of 1g:18mL, and 12% KH550 and 1.5% hexadecyltrimethylammonium bromide by mass of the activated attapulgite are added. The mixture is stirred at 70°C for 3 hours, then centrifuged, washed successively with water and anhydrous ethanol, and dried to obtain the modified attapulgite.

[0084] The performance of the pharmaceutical antibacterial polyethylene barrier membrane prepared in this comparative example was tested, and its water vapor permeability was 0.6 g / m³. 2 • 24h, oxygen permeability 1.6cm 3 / m 2 At 0.1 MPa for 24 hours, the inhibition rates of Escherichia coli and Staphylococcus aureus were both less than 50%, with a longitudinal tensile strength of 50.6 MPa and a transverse tensile strength of 41.9 MPa. It can be seen that, without the addition of additional antibacterial agents, the resulting polyethylene film essentially lacks antibacterial properties.

[0085] Comparative Example 4

[0086] The only difference between this comparative example and Example 1 is that, in the preparation of the modified attapulgite, the adsorption of tea polyphenols is not performed. Specifically, activated attapulgite is dispersed in water at a solid-liquid ratio of 1g:18mL, and 12% KH550 and 1.5% hexadecyltrimethylammonium bromide (by mass of activated attapulgite) are added. The mixture is stirred at 70°C for 3 hours, then centrifuged, washed successively with water and anhydrous ethanol, and dried to obtain hydrophobic attapulgite. The hydrophobic attapulgite is then dispersed in anhydrous ethanol at a solid-liquid ratio of 1g:18mL, and 8% zinc chloride (by mass of activated attapulgite) is added. The mixture is stirred at 60°C for 1 hour, then centrifuged, washed with anhydrous ethanol, and dried to obtain modified attapulgite.

[0087] The performance of the pharmaceutical antibacterial polyethylene barrier membrane prepared in this comparative example was tested, and its water vapor permeability was 0.6 g / m³. 2 • 24h, oxygen permeability 1.5cm 3 / m 2 At 0.1 MPa for 24 hours, the inhibition rate of *E. coli* was 90.5%, and the inhibition rate of *Staphylococcus aureus* was 86.9%. The longitudinal tensile strength was 50.3 MPa, and the transverse tensile strength was 42.1 MPa. However, the antibacterial properties of the polyethylene film were significantly lower than in Example 1. This invention introduces zinc ions into attapulgite clay through adsorption before adding it to the polyethylene resin. However, the adsorption capacity of zinc ions is limited, resulting in a relatively low antibacterial property of the obtained polyethylene film.

[0088] Comparative Example 5

[0089] The only difference between this comparative example and Example 1 is that the hydrophobic modification with a cationic surfactant is not performed. That is, when preparing modified attapulgite, the cationic surfactant hexadecyltrimethylammonium bromide is replaced with an equal mass of silane coupling agent KH550.

[0090] The performance of the pharmaceutical antibacterial polyethylene barrier membrane prepared in this comparative example was tested, and its water vapor permeability was 1.2 g / m³. 2 • 24h, oxygen permeability 1.7cm 3 / m 2 At 0.1 MPa for 24 hours, the inhibition rate of *Escherichia coli* was 98.6%, the inhibition rate of *Staphylococcus aureus* was 97.2%, the longitudinal tensile strength was 50.2 MPa, and the transverse tensile strength was 42.5 MPa. The water vapor permeability was significantly increased compared to Example 1. This is because the hydrophobic modifier alone has a limited effect on the hydrophobic modification of attapulgite, leading to a decrease in its water vapor barrier properties. Simultaneously, the antibacterial properties also decreased slightly, possibly due to the lack of antibacterial activity from the cationic surfactant.

Claims

1. A pharmaceutical-grade antibacterial polyethylene barrier film, characterized in that: It includes polyethylene resin and modified attapulgite masterbatch; the polyethylene resin includes linear low-density polyethylene, metallocene low-density polyethylene and high-density polyethylene; the modified attapulgite masterbatch includes linear low-density polyethylene and modified attapulgite. The method for preparing the modified attapulgite is as follows: Attapulgite was activated by placing it in hydrochloric acid solution and then centrifuged to obtain activated attapulgite. The activated attapulgite was dispersed in water, and tea polyphenols were added for adsorption. Then, silane coupling agent and cationic surfactant were added for hydrophobic modification. The mixture was then centrifuged, washed with water and anhydrous ethanol in sequence, and dried to obtain hydrophobic attapulgite. The hydrophobic attapulgite was dispersed in anhydrous ethanol, and zinc chloride was added for complexation reaction. The mixture was then centrifuged, washed with anhydrous ethanol, and dried to obtain modified attapulgite.

2. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: The raw material composition of polyethylene resin is: 52-58 wt.% linear low-density polyethylene, 12-25 wt.% metallocene low-density polyethylene, and 23-30 wt.% high-density polyethylene.

3. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: The raw material composition of the modified attapulgite masterbatch is: 75-80 wt.% linear low-density polyethylene and 20-25 wt.% modified attapulgite.

4. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: Modified attapulgite masterbatch accounts for 20-30% of the total mass of polyethylene resin.

5. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: The linear low-density polyethylene has a melt index of 2 g / 10 min and a density of 0.918 g / cm³ at 190°C and 2.16 kg. 3 The metallocene low-density polyethylene described above has a melt index of 0.8 g / 10 min and a density of 0.916 g / cm³ at 190°C and 2.16 kg. 3 The high-density polyethylene described above has a melt flow index of 20 g / 10 min and a density of 0.954 g / cm³ at 190°C and 2.16 kg. 3 .

6. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: During the activation treatment, the concentration of hydrochloric acid solution is 0.5-1.0 mol / L, and the mass-to-volume ratio of attapulgite to hydrochloric acid solution is 1 g: (8-12) mL; the activation temperature is 30-50℃, and the activation time is 1-2 h.

7. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: During hydrophobic modification, the mass-to-volume ratio of activated attapulgite to water is 1g:(15-20)mL; the amount of tea polyphenols added accounts for 0.5-1% of the mass of activated attapulgite; the amount of silane coupling agent added accounts for 10-15% of the mass of activated attapulgite; and the amount of cationic surfactant added accounts for 1-2% of the mass of activated attapulgite.

8. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: The adsorption temperature is 60-80℃ and the time is 0.5-1.5h; the hydrophobic modification temperature is 60-80℃ and the time is 2-3h.

9. The pharmaceutical antibacterial polyethylene barrier film according to claim 1, characterized in that: During the complexation reaction, the mass-to-volume ratio of hydrophobic attapulgite to anhydrous ethanol is 1 g: (15-20) mL; the amount of zinc chloride added accounts for 5-10% of the mass of hydrophobic attapulgite; the complexation reaction temperature is 40-70℃, and the time is 0.5-2 h.

10. A method for preparing a pharmaceutical antibacterial polyethylene barrier film according to any one of claims 1-9, characterized in that: Includes the following steps: Linear low-density polyethylene and modified attapulgite are fused at high temperature and granulated to obtain modified attapulgite masterbatch; linear low-density polyethylene, metallocene low-density polyethylene, high-density polyethylene and modified attapulgite masterbatch are mixed evenly, and then plasticized at high temperature and blow-molded to obtain a pharmaceutical antibacterial polyethylene barrier film.