Antibacterial packaging film and preparation method thereof, and application of bifunctional quaternary ammonium salt in antibacterial agent

Abstract

The antibacterial packaging film comprises a first base layer and a second base layer which are sequentially arranged, the first base layer is selected from one or more of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene and high-density polyethylene, and the second base layer is selected from one or more of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene and high-density polyethylene. The second base layer is selected from one or more of polyethylene glycol terephthalate, polyamide, polypropylene or polyethylene, the first base layer comprises metal ions accounting for 4-6% of the total weight and a bifunctional quaternary ammonium salt compound accounting for 1-4% of the total weight, and the bifunctional quaternary ammonium salt compound comprises a main carbon chain with 10-22 carbon atoms and two ammonium groups; the invention further discloses a preparation method of the antibacterial packaging film, the quaternary ammonium salt compound has extremely high bactericidal activity, the long-chain quaternary ammonium salt compound is fixed in a polyethylene matrix through Van der Waals' force, the quaternary ammonium salt compound and a polyethylene chain are entangled, and the antibacterial packaging film is formed by compounding the quaternary ammonium salt compound, the long-chain quaternary ammonium salt compound and the polyethylene chain. Molecules can also be mechanically anchored in the matrix, thereby preventing them from leaching.

Description

[0001] This application is a divisional application of the invention patent application filed on October 20, 2023, entitled "An antibacterial packaging film and its preparation method" and with application number 2023113658013. Technical Field

[0002] This invention belongs to the field of flexible packaging technology, specifically relating to an antibacterial packaging film and its preparation method, as well as the application of bifunctional quaternary ammonium salts in antibacterial agents. Background Technology

[0003] Currently, products such as meat, bread, and cheese are typically packaged using ordinary thin film materials, resulting in a short shelf life. For example, fresh meat can be refrigerated for 3-4 days, and bread for 3-10 days. Prolonged storage allows for the growth of bacteria and other microorganisms, making it difficult to achieve efficient preservation and extended shelf life. Existing technologies have implemented several methods for efficient sterilization and extended shelf life. One method involves adding a bactericide to a slow-release substrate or coating, such as silver. Silver ions are released from the surface into the water where they develop their biocidal properties. However, such leaching coatings also have serious drawbacks. Their lifespan is limited because the bactericide will eventually be used up, and the water can be contaminated with potentially hazardous compounds.

[0004] Quaternary ammonium compounds possess biocidal properties, and numerous attempts have been made to immobilize them on surfaces. However, polyethylene is composed solely of carbon-carbon and carbon-hydrogen bonds, and due to its inertness and chemical inertness, most methods for attaching quaternary ammonium compounds to polyethylene surfaces are cumbersome. Furthermore, UV-induced free radical methods are unsuitable for large-scale production, and the hidden surfaces are difficult to expose to UV radiation. Therefore, a non-leaching, simple, durable, and inexpensive method is needed to immobilize quaternary ammonium compounds on polyethylene. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the prior art and provide a packaging structure that replaces traditional materials with an antibacterial composite film containing copper or silver ions. A small amount of bactericide polymer is melt-composite with polyethylene to produce a composite material with antibacterial properties on the surface.

[0006] Achieving sterilization properties in packaging can effectively eliminate bacteria or fungi that cause food spoilage, thereby extending the shelf life of food, improving food quality, and without requiring changes to the customer's product formula.

[0007] To achieve the above objectives, the technical solution of the present invention is to provide an antibacterial packaging film, comprising a first base layer and a second base layer arranged sequentially. The first base layer is selected from one or more of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene. The second base layer is selected from one or more of polyethylene terephthalate, polyamide, polypropylene, or polyethylene. The first base layer is characterized in that it contains 4-6% by weight of metal ions and 1-4% by weight of a bifunctional quaternary ammonium salt compound. The bifunctional quaternary ammonium salt compound comprises a main carbon chain having 10-22 carbon atoms and two ammonium groups, wherein the ammonium groups are attached to the carbon atoms located at the ends of the main carbon chain.

[0008] A further preferred technical solution is that the quaternary ammonium salt compound is selected from one or more of 1,12-bis(dimethyloctylammonium)dodecanedibromide and 1,20-bis(dimethylammonium)eicosenedibromide.

[0009] The present invention also provides a method for preparing an antibacterial packaging film, characterized by comprising the following steps: S1. Prepare a bifunctional quaternary ammonium salt compound having a main carbon chain comprising 10 to 22 carbon atoms and two ammonium groups attached to the carbon atoms at the ends of the main carbon chain. S2, bifunctional quaternary ammonium salt compound, and metal ions are mixed with polyethylene particles, re-granulated, and then the bifunctional quaternary ammonium salt compound masterbatch, metal ion masterbatch and polyethylene resin are mixed for 1-2 hours and blown into film to obtain the first base layer. S3. The second base layer is placed on the first unwinding frame and unwound. Solvent-based adhesive is applied to the second base layer through the gluing unit. At the same time, the first base layer is placed on the second unwinding frame and unwound. The first unwinding tension, the second unwinding tension, and the winding tension are set according to the material. The first substrate and the second substrate coated with solvent-free adhesive are sent to the laminating device for lamination to obtain a composite film. S4. Place the composite membrane obtained in step S3 into a curing chamber for curing at a temperature of 30-40℃ for 36-48 hours.

[0010] A further preferred technical solution is that the second base layer in step S3 is specifically prepared through the following steps: polyethylene terephthalate film is placed on the first unwinding frame of the unwinding unit of a dry laminating machine and unwound; a solvent-based adhesive is applied; simultaneously, nylon film is placed on the second unwinding frame and unwound; the film is then sent to the laminating device for lamination. The first unwinding tension is 2~12 kgf, the second unwinding tension is 2~15 kgf, the winding tension is 12~30 kgf, the winding taper is 60~85%, the oven tension is 2~16 kgf, the lamination temperature is 55~80℃, the oven temperature is 65~90℃, the adhesive application rate is 2.8~3.5 g / m², the pressure of the laminating roller is 2.5~5 bar, the adhesive application pressure is 2~4 bar, and the lamination speed is 90~200 m / min.

[0011] A further preferred technical solution is to set the first unwinding tension to 4~16 kgf, the second unwinding tension to 2~10%, the winding tension to 8~20 kgf, the winding taper to 60~85%, the oven tension to 10~18 kgf, the laminating temperature to 35~48℃, the oven temperature to 55~95℃, the adhesive application rate to 2.8~3.4 g / m2, the pressure of the laminating roller to 2~5 bar, the adhesive application pressure to 2~4 bar, and the laminating speed to 90~180 m / min.

[0012] A further preferred technical solution is that the preparation of the bifunctional quaternary ammonium salt compound in step S1 is specifically as follows: dimethyl octylamine is added to 1,12-dibromododecane, dissolved in methanol, the mixture is refluxed for 20 hours, washed with ethyl acetate solution, water is distilled off, the residue is dissolved in dichloromethane, dried with anhydrous sodium sulfate, filtered, and distilled to remove dichloromethane, to obtain 1,12-bis(dimethyloctylammonium)dodecane dibromide.

[0013] A further preferred technical solution is that the preparation of the bifunctional quaternary ammonium salt compound in step S1 is specifically as follows: 1,20-dibromoeicosane is dissolved in tetrahydrofuran, dimethyl octylamine is added, the solution is refluxed for 20 hours, and tetrahydrofuran is removed by distillation using a rotary evaporator to obtain 1,20-di(dimethylammonium)eicosane dibromide.

[0014] The beneficial effects of this invention are as follows: Quaternary ammonium compounds are immobilized in the polyethylene matrix by van der Waals forces. Although the van der Waals forces are relatively weak, they are proportional to the length of the hydrocarbon chain of the quaternary ammonium compound. Furthermore, the quaternary ammonium compound is immiscible with polyethylene. During the separation of the ammonium groups to the polyethylene surface, the long chains of the quaternary ammonium compound may become entangled with the polyethylene chains. In addition to the anchoring effect of van der Waals forces, this also mechanically anchors the molecules in the matrix. The sufficiently long hydrocarbon chains can prevent their leaching.

[0015] Bifunctional quaternary ammonium salts are characterized by two cationic heads and two long-chain hydrophobic tails. As antibacterial additives, bifunctional quaternary ammonium salt bactericides exhibit extremely strong bactericidal activity. This is due to two factors: firstly, the presence of two long-chain hydrophobic groups in the molecule; and secondly, the presence of two positively charged ammonium groups. Through induction, the positive charge density on the quaternary nitrogen increases, facilitating the adsorption of the bactericide molecule onto the surface of bacterial and algal cells. This alters the cell wall permeability, causing cell rupture. Furthermore, after adsorption onto the cell surface, the hydrophobic and hydrophilic groups penetrate deeply into the lipid and protein layers of the bacterial cell, respectively, leading to enzyme inactivation and protein denaturation. The combined effect of these two mechanisms results in a strong bactericidal capability.

[0016] After the packaging film is made into packaging bags and filled with contents, when bacteria, fungi and other microorganisms are formed inside the packaging, the metal ions in the packaging film and the bifunctional quaternary ammonium salt work together to enter the microbial cells, causing them to rupture or damage the bacterial cell membranes. At the same time, it can promote the formation of reactive oxygen species and cause catalytic reactions, ultimately killing the bacteria, fungi and other microorganisms that have multiplied, thus extending the shelf life of the contents. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0018] In the following examples, the preparation steps of 1,12-bis(dimethyloctylammonium)dodecanedibromide are as follows: 17.3 g (110 mmol) of dimethyloctylamine was added to a solution of 16.4 g (50 mmol) of 1,12-dibromododecane in 100 mL of methanol, and the mixture was refluxed for 20 hours. The mixture was washed with 100 mL of ethyl acetate solution, and water was distilled off. The residue was dissolved in 100 mL of dichloromethane, dried over anhydrous sodium sulfate, filtered, and the dichloromethane was distilled off to give 29.27 g (91%) of a pale yellow oil.

[0019] The preparation steps of 1,20-bis(dimethylammonium)eicosene dibromide are as follows: 3.0 g (6.81 mmol) of 1,20-dibromoeicosane was dissolved in 20 mL of tetrahydrofuran (THF), and 2.14 g (13.6 mmol) of dimethyloctylamine was added. The solution was refluxed for 20 hours, and then THF was distilled off using a rotary evaporator to obtain 1,20-di(dimethylammonium)eicosane dibromide.

[0020] Taking PET14 / NY15 / PE50 as an example, the numerical value represents the film thickness in μm. PE50 indicates a polyethylene (PE) layer with a thickness of 50 μm.

[0021] Example 1 This embodiment uses a polyethylene film containing nano-sized silver ions and 1,12-bis(dimethyloctylammonium)dodecane dibromide. The 1,12-bis(dimethyloctylammonium)dodecane dibromide accounts for 3% of the total weight of the first layer, and the nano-sized silver ions account for 5% of the total weight. It can be applied to cooked food products. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,12-bis(dimethyloctylammonium)dodecane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch. The 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0022] The PE film obtained by this method has better uniformity, and the 1,12-bis(dimethyloctylammonium)dodecanedibromide masterbatch and silver ions are better dispersed in the PE film.

[0023] Step 2, Preparation of the second layer: A 14μm thick polyethylene terephthalate (PET14) film is unwound on the first unwinding frame of the dry laminating machine. Solvent-based adhesive is then applied to the PET14 semi-finished product via the coating unit. Simultaneously, a 15μm thick nylon (NY15) film is unwound on the second unwinding frame. Guide rollers feed the first and second substrates, coated with solvent-free adhesive, to the laminating device for lamination, resulting in a PET14 / NY15 composite semi-finished product. The material width is 400mm-1000mm. The unwinding tension is set to 2-12kgf, the second unwinding tension to 2-15kgf, the winding tension to 12-30kgf, the winding taper to 60-85%, the oven tension to 2-16kgf, the laminating temperature to 55-80℃, the oven temperature to 65-90℃, and the adhesive application rate to 2.8-3.5g / m². 2 The pressure of the laminating roller is 2.5~5 bar, the gluing pressure is 2~4 bar, and the laminating speed is 90~200 m / min; Step 3: Dry bonding of the first and second base layers: The PET14 / NY15 composite semi-finished product prepared in step 2 is placed on the first unwinding frame of the unwinding unit of the dry laminating machine and unwound. Solvent-based adhesive is then applied to the PET14 / NY15 composite semi-finished product through the gluing unit. At the same time, the PE50 film (containing silver ions) is placed on the second unwinding frame and unwound. The first and second substrates coated with solvent-free adhesive are fed to the laminating device for lamination using guide rollers. The first unwinding tension is 4~16 kgf, the second unwinding tension is 2~10%, the winding tension is 8~20 kgf, the winding taper is 60~85%, the oven tension is 10~18 kgf, the laminating temperature is 35~48℃, the oven temperature is 55~95℃, the adhesive application amount is 2.8~3.4 g / m2, the pressure of the laminating roller is 2~5 bar, the adhesive application pressure is 2~4 bar, and the laminating speed is 90~180 m / min. Step 4, Curing: Place the PET14 / NY15 / PE50 (containing silver ions) composite film into the curing chamber for curing. The curing temperature is controlled at 30-40℃ and the curing time is controlled at 36-48H to obtain the PET14 / NY15 / PE50 composite film.

[0024] Example 2 In this embodiment, 1,20-bis(dimethylammonium)eicosene dibromide accounts for 3% of the total weight of the first base layer, and nano-sized silver ions account for 5% of the total weight. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,20-Di(dimethylammonium)eicosane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch. The 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0025] The PE film obtained by this method has better uniformity, and the 1,20-bis(dimethylammonium)eicosane dibromide masterbatch and silver ions are better dispersed in the PE film.

[0026] Steps 2-4 are the same as in Example 1.

[0027] Example 3 This embodiment uses a polyethylene film containing silver ions and 1,12-bis(dimethyloctylammonium)dodecane dibromide. The 1,12-bis(dimethyloctylammonium)dodecane dibromide accounts for 4% of the total weight of the first layer, and the silver ions account for 5% of the total weight. It can be applied to cooked food products. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,12-bis(dimethyloctylammonium)dodecane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch. The 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0028] The PE film obtained by this method has better uniformity, and the 1,12-bis(dimethyloctylammonium)dodecanedibromide masterbatch and silver ions are better dispersed in the PE film.

[0029] Steps 2-4 are the same as in Example 1.

[0030] Example 4 In this embodiment, 1,20-bis(dimethylammonium)eicosene dibromide accounts for 4% of the total weight of the first base layer, and nano-sized silver ions account for 5% of the total weight. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,20-Di(dimethylammonium)eicosane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch. The 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0031] The PE film obtained by this method has better uniformity, and the 1,20-bis(dimethylammonium)eicosane dibromide masterbatch and silver ions are better dispersed in the PE film.

[0032] Steps 2-4 are the same as in Example 1.

[0033] Example 5 This embodiment uses a polyethylene film containing nano-sized silver ions and 1,12-bis(dimethyloctylammonium)dodecane dibromide. The 1,12-bis(dimethyloctylammonium)dodecane dibromide accounts for 5% of the total weight of the first layer, and the nano-sized silver ions account for 5% of the total weight. It can be applied to cooked food products. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,12-bis(dimethyloctylammonium)dodecane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch. The 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0034] The PE film obtained by this method has better uniformity, and the 1,12-bis(dimethyloctylammonium)dodecanedibromide masterbatch and silver ions are better dispersed in the PE film.

[0035] Steps 2-4 are the same as in Example 1.

[0036] Example 6 In this embodiment, 1,20-bis(dimethylammonium)eicosene dibromide accounts for 5% of the total weight of the first base layer, and nano-sized silver ions account for 5% of the total weight. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,20-Di(dimethylammonium)eicosane dibromide and nano-sized silver ions were mixed with polyethylene particles and regranulated to obtain 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch. The 1,20-di(dimethylammonium)eicosane dibromide masterbatch and silver ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0037] The PE film obtained by this method has better uniformity, and the 1,20-bis(dimethylammonium)eicosane dibromide masterbatch and silver ions are better dispersed in the PE film.

[0038] Steps 2-4 are the same as in Example 1.

[0039] Example 7 This embodiment uses a polyethylene film containing nano-sized copper ions and 1,12-bis(dimethyloctylammonium)dodecane dibromide. The 1,12-bis(dimethyloctylammonium)dodecane dibromide accounts for 3% of the total weight of the first layer, and the nano-sized copper ions account for 5% of the total weight. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,12-bis(dimethyloctylammonium)dodecane dibromide and nano-sized copper ions were mixed with polyethylene particles and regranulated to obtain 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch and copper ion masterbatch. The 1,12-bis(dimethyloctylammonium)dodecane dibromide masterbatch, copper ion masterbatch, and polyethylene resin were extruded in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared using a screw extrusion-blown film process.

[0040] The PE film obtained by this method has better uniformity, and the 1,12-bis(dimethyloctylammonium)dodecanedibromide masterbatch and copper ions are better dispersed in the PE film.

[0041] Step 2, Solvent-free lamination: A 19-micron thick polypropylene film (TOPP19) is placed on the first unwinding frame of the unwinding unit of the solvent-free laminator and unwound. Solvent-free adhesive is applied to the TOPP19 film via the gluing unit. Simultaneously, the first substrate, PE30 (containing nano-sized copper ions), is placed on the second unwinding frame and unwound. Guide rollers are used to feed the first and second substrates coated with solvent-free adhesive to the lamination device for lamination, resulting in a TOPP19 / PE30 (containing nano-sized copper ions) composite film. The material width is 400mm-1000mm. The first unwinding tension is set to 16-28 kgf, the second unwinding tension to 2-8%, the winding tension to 18-28 kgf, the winding taper to 30-50%, the lamination temperature to 35℃-48℃, and the adhesive application rate to 1.5-2.0 g / m². The pressure of the lamination roller is 2-4 bar, and the adhesive application pressure is 2-4 bar. Step 3, Curing: Place the TOPP19 / PE30 (containing nano-sized copper ions) composite film into the curing chamber for curing. The curing temperature is controlled at 30-40℃ and the curing time is controlled at 36-48 hours. Example 8 This embodiment uses a polyethylene film containing nano-sized copper ions and 1,20-di(dimethylammonium)eicosane dibromide. The 1,20-di(dimethylammonium)eicosane dibromide accounts for 3% of the total weight of the first base layer, and the nano-sized copper ions account for 5% of the total weight. The specific preparation process is as follows: Step 1: Preparation of the first base layer PE50 film 1,20-Di(dimethylammonium)eicosane dibromide and nano-sized copper ions were mixed with polyethylene particles and regranulated to obtain 1,20-di(dimethylammonium)eicosane dibromide masterbatch and copper ion masterbatch. The 1,20-di(dimethylammonium)eicosane dibromide masterbatch and copper ion masterbatch were extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1×20 mm). The extruder temperatures were 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw speed was 125 r / min. A polyethylene film with a thickness of 50 micrometers was prepared by screw extrusion-blown film process.

[0042] The PE film obtained by this method has better uniformity, and the 1,20-bis(dimethylammonium)eicosane dibromide masterbatch and copper ions are better dispersed in the PE film.

[0043] Steps 2 and 3 are the same as in Example 7.

[0044] Performance testing: The test subjects were modified polyethylene samples containing bifunctional quaternary ammonium salt polymers, which exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Bacterial survival rates in tap water varied; therefore, this table only considers experiments where at least 50% of the bacteria survived in pure PE suspension. ++: Most bacteria died; +: The proportion of dead bacteria increased significantly compared to the PE reference; + / -: Results varied among different samples; -: The proportion of dead bacteria did not increase compared to the PE reference. sample Staphylococcus aureus E. coli Pseudomonas aeruginosa Example 1 ++ ++ - Example 2 + + - Example 3 ++ ++ - Example 4 + + ++ Example 5 + + ++ Example 6 ++ + ++ Example 7 + + ++ Example 8 ++ + ++ Mechanical testing: The effect of quaternary ammonium salt compounds on the mechanical properties of PE matrix was studied by tensile testing of modified PE film samples. Tensile strength and elongation at break were determined using tensile tests. The mechanical properties of films containing 5% by weight of bifunctional quaternary ammonium salt compounds changed significantly, with a greatly reduced elongation at break. The modified PE samples became noticeably more brittle. Therefore, the optimal proportion of bifunctional quaternary ammonium salt compounds in the total weight of the first base layer is 1–4%. sample Tensile strength (MPa) Elongation at break (%) Example 1 1.03 840.5 Example 2 0.96 920.4 Example 3 0.82 935.2 Example 4 0.98 955.7 Example 5 0.61 373.3 Example 6 0.69 388.1 Example 7 0.81 815.3 Example 8 0.88 778.4 The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An antibacterial packaging film, comprising a first base layer and a second base layer disposed sequentially, wherein the first base layer is selected from one or more of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene, and the second base layer is selected from one or more of polyethylene terephthalate, polyamide, polypropylene, or polyethylene, characterized in that, The first base layer contains 4-6% by weight of metal ions and 1-4% by weight of a bifunctional quaternary ammonium salt compound. The bifunctional quaternary ammonium salt compound includes a main carbon chain with 10-22 carbon atoms and two ammonium groups, wherein the ammonium groups are attached to the carbon atoms at the end of the main carbon chain.

2. The antibacterial packaging film according to claim 1, characterized in that, The quaternary ammonium salt compound is selected from one or more of 1,12-bis(dimethyloctylammonium)dodecanedibromide and 1,20-bis(dimethylammonium)eicosenedibromide.

3. A method for preparing an antibacterial packaging film as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Prepare a bifunctional quaternary ammonium salt compound having a main carbon chain comprising 10 to 22 carbon atoms and two ammonium groups attached to the carbon atoms at the ends of the main carbon chain. S2, bifunctional quaternary ammonium salt compound, and metal ions are mixed with polyethylene particles, re-granulated, and then the bifunctional quaternary ammonium salt compound masterbatch, metal ion masterbatch and polyethylene resin are mixed for 1-2 hours and blown into film to obtain the first base layer. S3. The second base layer is placed on the first unwinding frame and unwound. Solvent-based adhesive is applied to the second base layer through the gluing unit. At the same time, the first base layer is placed on the second unwinding frame and unwound. The first unwinding tension, the second unwinding tension, and the winding tension are set according to the material. The first substrate and the second substrate coated with solvent-free adhesive are sent to the laminating device for lamination to obtain a composite film. S4. Place the composite membrane obtained in step S3 into a curing chamber for curing at a temperature of 30-40℃ for 36-48 hours.

4. The manufacturing method according to claim 3, characterized in that, The second base layer in step S3 is specifically prepared through the following steps: A polyethylene terephthalate film is unwound onto the first unwinding frame of the unwinding unit of a dry laminating machine, coated with a solvent-based adhesive, while a nylon film is unwound onto the second unwinding frame. The film is then fed to the laminating device for lamination. The first unwinding tension is 2~12 kgf, the second unwinding tension is 2~15 kgf, the winding tension is 12~30 kgf, the winding taper is 60~85%, the oven tension is 2~16 kgf, the lamination temperature is 55~80℃, the oven temperature is 65~90℃, and the adhesive application rate is 2.8~3.5 g / m². 2 The pressure of the composite roller is 2.5~5 bar, the gluing pressure is 2~4 bar, and the composite speed is 90~200 m / min.

5. The manufacturing method according to claim 3, characterized in that, Set the first unwinding tension to 4~16 kgf, the second unwinding tension to 2~10%, the winding tension to 8~20 kgf, the winding taper to 60~85%, the oven tension to 10~18 kgf, the laminating temperature to 35~48℃, the oven temperature to 55~95℃, and the adhesive application rate to 2.8~3.4 g / m. 2 The pressure of the composite roller is 2~5 bar, the gluing pressure is 2~4 bar, and the composite speed is 90~180 m / min.

6. The manufacturing method according to claim 3, characterized in that, Dimethyl octylamine was added to 1,12-dibromododecane and dissolved in methanol. The mixture was refluxed for 20 hours, washed with ethyl acetate solution, and water was distilled off. The residue was dissolved in dichloromethane, dried with anhydrous sodium sulfate, filtered, and distilled to remove dichloromethane, yielding 1,12-bis(dimethyloctylammonium)dodecane dibromide.

7. The manufacturing method according to any one of claims 3-6, characterized in that, The preparation of the bifunctional quaternary ammonium salt compound in step S1 is specifically as follows: 1,20-dibromoeicosane is dissolved in tetrahydrofuran, dimethyl octylamine is added, the solution is refluxed for 20 hours, and tetrahydrofuran is removed by distillation using a rotary evaporator to obtain 1,20-di(dimethylammonium)eicosane dibromide.

8. Application of a bifunctional quaternary ammonium salt in antibacterial agents.