Antibacterial packaging film and method for preparing the same

Abstract

The application discloses an antibacterial packaging film, comprising a first base layer and a second base layer arranged in sequence, 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 and polyethylene, the first base layer contains 4-6% of metal ions and 1-4% of a bifunctional quaternary ammonium salt compound by total weight, the bifunctional quaternary ammonium salt compound comprises a main carbon chain with 10-22 carbon atoms and two ammonium groups, the ammonium groups are connected to carbon atoms at the ends of the main carbon chain, and the application further discloses a preparation method of the antibacterial packaging film; the quaternary ammonium salt compound has extremely strong 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 is entangled with a polyethylene chain, and can also mechanically anchor the molecule in a matrix, so that leaching of the quaternary ammonium salt compound is prevented.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of soft packaging, and particularly relates to an antibacterial packaging film and a preparation method thereof. BACKGROUND

[0002] The existing meat, bread, cheese and other products are usually packaged by using ordinary film materials, and have a short shelf life, such as 3-4 days for fresh meat in cold storage, 3-10 days for bread, etc. Long time will breed bacteria and other microorganisms, and it is difficult to achieve efficient preservation and long shelf life. The existing technology realizes several methods of efficient sterilization and prolonging shelf life. First, a bactericide is added to a slow-release substrate or coating, such as silver, and silver ions are released from the surface to water where they develop their biocidal properties. However, this leaching coating also has serious drawbacks. Their service life is limited because the bactericide will eventually be used up, and the water will be contaminated with potentially dangerous compounds.

[0003] Quaternary ammonium salt compounds have biocidal properties, and there have been many attempts to immobilize quaternary ammonium salt compounds on surfaces. However, polyethylene is composed only of carbon-carbon and carbon-hydrogen bonds, and due to its inertness and chemical unreactivity, methods for attaching quaternary ammonium salt compounds to the surface of polyethylene are mostly tedious. However, for large-scale production, methods using ultraviolet-induced free radicals are not suitable, and hidden surfaces are difficult to be irradiated by ultraviolet light. Therefore, a non-leaching, simple, durable and inexpensive method is needed to immobilize quaternary ammonium salt compounds on polyethylene. SUMMARY

[0004] The purpose of the present application is to overcome the defects in the prior art, and to provide an antibacterial composite film containing copper ions or silver ions to replace the traditional packaging structure of the material. A small amount of bactericide polymer is melt compounded with polyethylene to produce a composite material with antibacterial surface.

[0005] The packaging realizes the characteristics of sterilization, which can effectively eliminate bacteria or fungi that cause food deterioration, thereby prolonging the shelf life of food and improving the quality of food, and without changing the formula of the customer's product.

[0006] To achieve the above object, the technical scheme of the present application is to provide an antibacterial packaging film, comprising a first base layer and a second base layer arranged in sequence, the first base layer being selected from one or more of linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, and the second base layer being selected from one or more of polyethylene terephthalate, polyamide, polypropylene or polyethylene, characterized in that the first base layer contains 4-6% of metal ions and 1-4% of a bifunctional quaternary ammonium salt compound by total weight, the bifunctional quaternary ammonium salt compound comprising a main carbon chain with 10-22 carbon atoms and two ammonium groups, the ammonium groups being connected to carbon atoms at the ends of the main carbon chain.

[0007] Further preferred technical scheme is that the quaternary ammonium salt compound is selected from one or more of 1,12-bis(dimethyloctylammonium) dodecanedibromide and 1,20-bis(dimethylammonium) eicosanedibromide.

[0008] The present application also provides a method for preparing the antibacterial packaging film, characterized by comprising the following steps:

[0009] S1, preparing a bifunctional quaternary ammonium salt compound comprising a main carbon chain with 10-22 carbon atoms and two ammonium groups connected to carbon atoms at the ends of the main carbon chain;

[0010] S2, mixing the bifunctional quaternary ammonium salt compound and the metal ions with polyethylene particles respectively, regranulating, then mixing the bifunctional quaternary ammonium salt compound master batch, the metal ion master batch and the polyethylene resin for 1-2 hours, and preparing the first base layer by film blowing;

[0011] S3, placing the second base layer on the first unwinding frame to expand, applying solvent-based adhesive on the second base layer through the gluing unit, placing the first base layer on the second unwinding frame to expand, setting one unwinding tension, two unwinding tensions and a winding tension suitable for the materials, and using guide rollers to send the first base material and the second base material coated with solvent-free glue to the compounding device for compounding to obtain a composite film;

[0012] S4, placing the composite film obtained in step S3 into a curing chamber for curing, the curing temperature being 30-40℃ and the curing time being 36-48H.

[0013] Further preferably, the second base layer in step S3 is prepared by the following steps: the polyethylene terephthalate film is unwound on the first unwinding frame of the unwinding unit of the dry compound machine, the solvent adhesive is coated, the nylon film is unwound on the second unwinding frame, and is sent to the compound device for compounding, 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 compounding temperature is 55-80℃, the oven temperature is 65-90℃, the adhesive amount is 2.8-3.5 g / m2, the compounding roller pressure is 2.5-5 bar, the adhesive pressure is 2-4 bar, and the compounding speed is 90-200 m / min.

[0014] Further preferably, 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 compounding temperature is 35-48℃, the oven temperature is 55-95℃, the adhesive amount is 2.8-3.4 g / m2, the compounding roller pressure is 2-5 bar, the adhesive pressure is 2-4 bar, and the compounding speed is 90-180 m / min.

[0015] Further preferably, the preparation of the bifunctional quaternary ammonium salt compound in step S1 is specifically as follows: dimethyloctylamine is added to 1,12-dibromododecane, and the mixture is dissolved in methanol, the mixture is refluxed for 20 hours, washed with ethyl acetate solution, distilled water, the residue is dissolved in dichloromethane, dried with anhydrous sodium sulfate, filtered, and the dichloromethane is distilled off to obtain 1,12-bis(dimethyloctylammonium) dodecane dibromide.

[0016] Further preferably, the preparation of the bifunctional quaternary ammonium salt compound in step S1 is specifically as follows: 1,20-dibromoeicosane is dissolved in tetrahydrofuran, dimethyloctylamine is added, the solution is refluxed for 20 hours, and the tetrahydrofuran is distilled off with a rotary evaporator to obtain 1,20-bis(dimethylammonium) eicosane dibromide.

[0017] The beneficial effects of the present application are as follows:

[0018] 1. The quaternary ammonium salt compound is fixed in the polyethylene matrix by van der Waals force, although the van der Waals force is relatively weak, but it is proportional to the length of the hydrocarbon chain of the quaternary ammonium salt compound, and the quaternary ammonium salt compound is immiscible with polyethylene, in the process of separating the ammonium group to the surface of polyethylene, the long chain of the quaternary ammonium salt compound can be entangled with the polyethylene chain, in addition to the anchoring effect of van der Waals force, it can also mechanically anchor the molecule in the matrix, and the long enough hydrocarbon chain can prevent leaching.

[0019] 2. The bifunctional quaternary ammonium salt structure is characterized by two cationic heads and two long-chain hydrophobic tails. As an antibacterial additive, bifunctional quaternary ammonium salt bactericides exhibit extremely strong bactericidal activity. This is due to two long-chain hydrophobic groups in the molecule, and also to the two positively charged ammonium groups. Through induction, the positive charge density on the quaternary nitrogen increases, which is more conducive to the adsorption of bactericide molecules on the surface of bacterial and algal cells, thereby altering the permeability of the cell wall and causing cell rupture. Furthermore, after the bactericide is adsorbed onto the bacterial surface, the hydrophobic and hydrophilic groups penetrate deep 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 gives the bactericide its strong bactericidal ability.

[0020] 3. 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

[0021] 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.

[0022] In the following examples, the preparation steps of 1,12-bis(dimethyloctylammonium)dodecanedibromide are as follows:

[0023] 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.

[0024] The preparation steps of 1,20-bis(dimethylammonium)eicosene dibromide are as follows:

[0025] 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.

[0026] PET14 / NY15 / PE50, the numerical value represents the thickness of the film layer, unit: μm, PE50 represents a polyethylene (PE) layer with a thickness of 50 μm.

[0027] Example One

[0028] In this embodiment, a polyethylene film containing nanoscale silver ions and 1,12-bis(dimethyloctylammonium) dodecanedibromide is used, 1,12-bis(dimethyloctylammonium) dodecanedibromide accounts for 3% of the total weight of the first base layer, and the weight of nanoscale silver ions accounts for 5% of the total weight. It can be applied to cooked food products. The specific preparation process is as follows:

[0029] Step 1, preparation of the first base layer PE50 film

[0030] 1,12-bis(dimethyloctylammonium) dodecanedibromide and nanoscale silver ions are mixed with polyethylene particles respectively, and then granulated to obtain 1,12-bis(dimethyloctylammonium) dodecanedibromide masterbatch and silver ion masterbatch. 1,12-bis(dimethyloctylammonium) dodecanedibromide masterbatch, silver ion masterbatch and polyethylene resin are extruded in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm). The temperature of each section of the extruder is 180℃, 195℃, 200℃, 230℃, 230℃, 210℃, and the screw rotation speed is 125 r / min. The thickness of the polyethylene film prepared by the screw extrusion-blow film process is 50 microns.

[0031] The PE film obtained by this method has better uniformity, and 1,12-bis(dimethyloctylammonium) dodecanedibromide masterbatch and silver ion have better dispersibility in the PE film.

[0032] Step 2, preparation of the second base layer:

[0033] A polyethylene terephthalate (PET14) film with a thickness of 14 μm is unwound on the first unwinding frame of the unwinding unit of the dry compound machine, and a solvent-based adhesive is applied to the PET14 semi-finished product through the gluing unit. At the same time, a nylon (NY15) film with a thickness of 15 μm is unwound on the second unwinding frame, and the first and second substrates coated with solvent-free glue are sent to the compounding device for compounding by using the guide roller. The PET14 / NY15 compound semi-finished product is obtained. The material width is 400mm-1000mm, the first unwinding tension is set to 2-12kgf, the second unwinding tension is set to 2-15kgf, the winding tension is set to 12-30kgf, the winding taper is set to 60-85%, the oven tension is set to 2-16kgf, the compounding temperature is set to 55-80℃, the oven temperature is set to 65-90℃, the gluing amount is set to 2.8-3.5g / m2, the compounding roller pressure is set to 2.5-5bar, the gluing pressure is set to 2-4bar, and the compounding speed is set to 90-200m / min.

[0034] Step 3, dry compounding of the first base layer and the second base layer:

[0035] The PET14 / NY15 composite semi-finished product prepared in step 2 is unwound on the first unwinding frame of the unwinding unit of the dry compounding machine, and a solvent-based adhesive is applied to the PET14 / NY15 composite semi-finished product through the gluing unit, while the PE50 film (containing silver ions) is unwound on the second unwinding frame. The first substrate coated with solvent-free glue and the second substrate are sent to the compounding device for compounding by using guide rollers, with a first unwinding tension of 4-16 kgf, a second unwinding tension of 2-10%, a winding tension of 8-20 kgf, a winding taper of 60-85%, an oven tension of 10-18 kgf, a compounding temperature of 35-48℃, an oven temperature of 55-95℃, a gluing amount of 2.8-3.4 g / m2, a compounding roller pressure of 2-5 bar, a gluing pressure of 2-4 bar, and a compounding speed of 90-180 m / min.

[0036] Step 4, curing: the PET14 / NY15 / PE50 (containing silver ions) composite film is placed in a curing chamber for curing, with a curing temperature controlled at 30-40℃ and a curing time controlled at 36-48H, to obtain a PET14 / NY15 / PE50 composite film.

[0037] Example 2

[0038] In this example, 20-di(dimethylammonium) eicosane 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:

[0039] Step 1, preparation of the first base layer PE50 film

[0040] 1,20-di(dimethylammonium) eicosane dibromide and nano-sized silver ions are mixed with polyethylene particles respectively, and then granulated to obtain 1,20-di(dimethylammonium) eicosane dibromide masterbatch and silver ion masterbatch. The 1,20-di(dimethylammonium) eicosane dibromide masterbatch and the silver ion masterbatch are extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm), with the temperature of each section of the extruder being 180℃, 195℃, 200℃, 230℃, 230℃, and 210℃, and the screw rotation speed being 125 r / min. The polyethylene film with a thickness of 50 microns is prepared by screw extrusion-blow film process.

[0041] The PE film obtained by this method has better uniformity, and the 1,20-di(dimethylammonium) eicosane dibromide masterbatch and the silver ion masterbatch have better dispersibility in the PE film.

[0042] Steps 2-4 are the same as in Example 1.

[0043] Example 3

[0044] The polyethylene film of this embodiment contains silver ions and 1,12-bis(dimethyloctylammonium) dodecane dibromide, which accounts for 4% of the total weight of the first base layer, and the weight of the silver ions accounts for 5% of the total weight. It can be applied to cooked food products. The specific preparation process is as follows:

[0045] Step 1, Preparation of the first base layer PE50 film

[0046] 1,12-bis(dimethyloctylammonium) dodecane dibromide and nanoscale silver ions are mixed with polyethylene particles respectively, and then granulated to obtain 1,12-bis(dimethyloctylammonium) dodecane dibromide masterbatch and silver ion masterbatch. The 1,12-bis(dimethyloctylammonium) dodecane dibromide masterbatch and the silver ion masterbatch are extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm), with the temperature of each section of the extruder being 180°C, 195°C, 200°C, 230°C, 230°C, and 210°C, and the screw rotation speed being 125 r / min. The thickness of the polyethylene film prepared by the screw extrusion-blowing film process is 50 microns.

[0047] The PE film obtained by this method has better uniformity, and the 1,12-bis(dimethyloctylammonium) dodecane dibromide masterbatch and the silver ions have better dispersibility in the PE film.

[0048] Steps 2-4 are the same as in Example 1.

[0049] Example 4

[0050] In this embodiment, 1,20-bis(dimethylammonium) eicosane dibromide accounts for 4% of the total weight of the first base layer, and the weight of the nanoscale silver ions accounts for 5% of the total weight. The specific preparation process is as follows:

[0051] Step 1, Preparation of the first base layer PE50 film

[0052] 1,20-bis(dimethylammonium) eicosane dibromide and nanoscale silver ions are mixed with polyethylene particles respectively, and then granulated to obtain 1,20-bis(dimethylammonium) eicosane dibromide masterbatch and silver ion masterbatch. The 1,20-bis(dimethylammonium) eicosane dibromide masterbatch and the silver ion masterbatch are extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm), with the temperature of each section of the extruder being 180°C, 195°C, 200°C, 230°C, 230°C, and 210°C, and the screw rotation speed being 125 r / min. The thickness of the polyethylene film prepared by the screw extrusion-blowing film process is 50 microns.

[0053] The PE film obtained by this method has better uniformity, and the 1, 20-bis (dimethylammonium) eicosane dibromide master batch and silver ions have better dispersibility in the PE film.

[0054] Steps 2-4 are the same as in Example 1.

[0055] Example 5

[0056] In this example, the polyethylene film contains nanoscale silver ions and 1, 12-bis (dimethyloctylammonium) dodecane dibromide, the content of 1, 12-bis (dimethyloctylammonium) dodecane dibromide is 5% of the total weight of the first base layer, and the content of nanoscale silver ions is 5% of the total weight. It can be applied to cooked food products, and the specific preparation process is as follows:

[0057] Step 1, preparation of the first base layer PE50 film

[0058] 1, 12-bis (dimethyloctylammonium) dodecane dibromide and nanoscale silver ions are mixed with polyethylene particles respectively, and then granulated to obtain 1, 12-bis (dimethyloctylammonium) dodecane dibromide master batch and silver ion master batch. The 1, 12-bis (dimethyloctylammonium) dodecane dibromide master batch and the silver ion master batch are extruded with polyethylene resin in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm). The temperature of each section of the extruder is 180℃, 195℃, 200℃, 230℃, 230℃, 210℃, and the screw rotation speed is 125r / min. The thickness of the polyethylene film prepared by the screw extrusion-blowing film process is 50 microns.

[0059] The PE film obtained by this method has better uniformity, and the 1, 12-bis (dimethyloctylammonium) dodecane dibromide master batch and silver ions have better dispersibility in the PE film.

[0060] Steps 2-4 are the same as in Example 1.

[0061] Example 6

[0062] In this example, the content of 1, 20-bis (dimethylammonium) eicosane dibromide is 5% of the total weight of the first base layer, and the content of nanoscale silver ions is 5% of the total weight. The specific preparation process is as follows:

[0063] Step 1, preparation of the first base layer PE50 film

[0064] 1,20-bis(dimethylammonium)icosanedibromide, nano silver ions were mixed with polyethylene particles respectively, and regranulated to obtain 1,20-bis(dimethylammonium)icosanedibromide master batch and silver ion master batch. 1,20-bis(dimethylammonium)icosanedibromide master batch, silver ion master batch and polyethylene resin were extruded in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm), and the temperature of each section of the extruder was 180°C, 195°C, 200°C, 230°C, 230°C, and 210°C, and the screw rotation speed was 125 r / min. The thickness of the polyethylene film prepared by the screw extrusion-blow film process was 50 microns.

[0065] The PE film obtained by this method has better uniformity, and 1,20-bis(dimethylammonium)icosanedibromide master batch and silver ion have better dispersibility in the PE film.

[0066] Steps 2-4 are the same as in Example 1.

[0067] Example 7

[0068] In this example, polyethylene film containing nano copper ions and 1,12-bis(dimethyloctylammonium)dodecanedibromide was used, and the content of 1,12-bis(dimethyloctylammonium)dodecanedibromide was 3% of the total weight of the first base layer, and the weight of nano copper ions was 5% of the total weight. The specific preparation process is as follows:

[0069] Step 1, preparation of PE50 film of the first base layer

[0070] 1,12-bis(dimethyloctylammonium)dodecanedibromide, nano copper ions were mixed with polyethylene particles respectively, and regranulated to obtain 1,12-bis(dimethyloctylammonium)dodecanedibromide master batch and copper ion master batch. 1,12-bis(dimethyloctylammonium)dodecanedibromide master batch, copper ion master batch and polyethylene resin were extruded in a parallel twin-screw extruder equipped with a slit die (slit: 1 x 20 mm), and the temperature of each section of the extruder was 180°C, 195°C, 200°C, 230°C, 230°C, and 210°C, and the screw rotation speed was 125 r / min. The thickness of the polyethylene film prepared by the screw extrusion-blow film process was 50 microns.

[0071] The PE film obtained by this method has better uniformity, and 1,12-bis(dimethyloctylammonium)dodecanedibromide master batch and copper ion have better dispersibility in the PE film.

[0072] Step 2, solvent-free compounding: the second substrate of polypropylene film (TOPP19) with a thickness of 19 microns is placed on the first unwinding frame of the unwinding unit of the solvent-free compounding machine and unwound, the solvent-free adhesive is coated on the TOPP19 film through the gluing unit, at the same time, the first substrate PE30 (containing nano-sized copper ions) film is placed on the second unwinding frame and unwound, the first substrate coated with solvent-free glue and the second substrate are sent to the compounding device for compounding by using the guide roller to obtain the compounded film of TOPP19 / PE30 (containing nano-sized copper ions); the material width is 400mm-1000mm, the first unwinding tension is set to 16-28kgf, the second unwinding tension is set to 2-8%, the winding tension is set to 18-28kgf, the winding taper is set to 30-50%, the compounding temperature is set to 35-48℃, the gluing amount is set to 1.5-2.0g / m2; the compounding roller pressure is set to 2-4bar, and the gluing pressure is set to 2-4bar;

[0073] Step 3, curing: the TOPP19 / PE30 (containing nano-sized copper ions) compounded film is placed in the curing room for curing, the curing temperature is controlled at 30-40℃, and the curing time is controlled at 36-48H;

[0074] Example 8

[0075] In this embodiment, the polyethylene film containing nano-sized copper ions and 1,20-bis(dimethylammonium) eicosane dibromide accounts for 3% of the total weight of the first substrate, and the weight of nano-sized copper ions accounts for 5% of the total weight. The specific preparation process is as follows:

[0076] Step 1, preparation of the first substrate PE50 film

[0077] 1,20-bis(dimethylammonium) eicosane dibromide and nano-sized copper ions are mixed with polyethylene particles respectively, and then granulated to obtain 1,20-bis(dimethylammonium) eicosane dibromide master batch and copper ion master batch. 1,20-bis(dimethylammonium) eicosane dibromide master batch, copper ion master batch and polyethylene resin are extruded in a parallel twin-screw extruder equipped with a slit die (slit: 1x20mm), the temperature of each section of the extruder is 180℃, 195℃, 200℃, 230℃, 230℃, 210℃, and the screw rotation speed is 125r / min. The polyethylene film with a thickness of 50 microns is prepared by screw extrusion-blow film process.

[0078] The PE film obtained by this method has better uniformity, and the 1,20-bis(dimethylammonium) eicosane dibromide master batch and the copper ion have better dispersibility in the PE film.

[0079] Steps 2-3 are the same as example 7.

[0080] Performance test:

[0081] The test subjects were modified polyethylene samples of the bifunctional quaternary ammonium salt polymer for antibacterial activity against S. aureus, E. coli and P. aeruginosa. The survival rates of the bacteria in tap water were different; therefore, this table only considers experiments in which at least 50% of the bacteria survived in the pure PE suspension. ++: most of the bacteria died; +: the proportion of dead bacteria increased significantly compared with the PE reference; + / -: the results varied between different samples; -: the proportion of dead bacteria did not increase compared with the PE reference.

[0082] Sample Staphylococcus aureus Escherichia coli Pseudomonas aeruginosa Example 1 ++ ++ - Example 2 + + - Example 3 ++ ++ - Example 4 + + ++ Example 5 + + ++ Example 6 ++ + ++ Example 7 + + ++ Example 8 ++ + ++

[0083] Mechanical test:

[0084] The effect of the quaternary ammonium salt compound on the mechanical properties of the PE matrix was studied by performing tensile tests on the modified PE film samples. The tensile strength and elongation at break were determined according to the tensile test. The mechanical properties of the film containing 5% by weight of the bifunctional quaternary ammonium salt compound changed significantly, with a large decrease in the elongation at break. The modified PE sample became significantly brittle, so the bifunctional quaternary ammonium salt compound should preferably account for 1-4% of the total weight of the first base layer.

[0085] 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

[0086] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the technical principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. An antibacterial packaging film comprising a first base layer and a second base layer disposed in sequence, the first base layer being selected from one or more of linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, the second base layer being selected from one or more of polyethylene terephthalate, polyamide, polypropylene or polyethylene, characterized in that, The first base layer contains 4-6% of metal ions and 1-4% of bifunctional quaternary ammonium salt compound by total weight, the bifunctional quaternary ammonium salt compound is selected from 1,12-bis(dimethyloctylammonium) dodecanedibromide or 1,20-bis(dimethylammonium) eicosanedibromide.

2. A method for preparing the antibacterial packaging film according to claim 1, characterized by, The method comprises the following steps: S1, preparing a bifunctional quaternary ammonium salt compound having a main carbon chain comprising 10-22 carbon atoms and two ammonium groups connected to carbon atoms at the ends of the main carbon chain; S2, mixing the bifunctional quaternary ammonium salt compound and the metal ions with polyethylene particles respectively, regranulating, mixing the bifunctional quaternary ammonium salt compound master batch, the metal ion master batch and the polyethylene resin for 1-2 hours, and preparing the first base layer by film blowing; S3, placing the second base layer on the first unwinding frame to expand, applying the solvent type adhesive on the second base layer through the gluing unit, placing the first base layer on the second unwinding frame to expand, setting the first unwinding tension, the second unwinding tension and the winding tension suitable for the materials, and sending the first base material and the second base material coated with the solvent-free glue to the compounding device for compounding to obtain a composite film; S4, placing the composite film obtained in step S3 into a curing chamber for curing, the curing temperature is 30-40℃, and the curing time is 36-48H.

3. The preparation method according to claim 2, characterized in that, The second base layer in step S3 is prepared by the following steps: placing a polyethylene terephthalate film on the first unwinding frame of the unwinding unit of the dry compounding machine to expand, applying the solvent type adhesive, placing the nylon film on the second unwinding frame to expand, and sending to the compounding device for compounding, the first unwinding tension is 2-12kgf, the second unwinding tension is 2-15kgf, the winding tension is 12-30kgf, the winding taper is 60-85%, the oven tension is 2-16kgf, the compounding temperature is 55-80℃, the oven temperature is 65-90℃, the gluing amount is 2.8-3.5g / m2, the compounding roller pressure is 2.5-5bar, the gluing pressure is 2-4bar, and the compounding speed is 90-200m / min.

4. The preparation method according to claim 2, characterized in that, Set a tension of 4~16kgf, two tension of 2~10%, winding tension of 8~20kgf, winding taper of 60~85%, oven tension of 10~18kgf, composite temperature of 35~48℃, oven temperature of 55~95℃, glue amount of 2.8~3.4g / m 2 , the pressure of the composite roller is 2~5bar, the pressure of the glue is 2~4bar, and the composite speed is 90~180m / min.

5. The preparation method according to claim 2, characterized in that, Dimethyloctylamine is added to 1,12-dibromododecane, dissolved in methanol, the mixture is refluxed for 20 hours, washed with ethyl acetate solution, distilled water is distilled off, the remaining substance is dissolved in dichloromethane, dried with anhydrous sodium sulfate, filtered, and dichloromethane is distilled off to obtain 1,12-bis(dimethyloctylammonium) dodecanedibromide.

6. The preparation method according to claim 2, characterized in that, The preparation of the bifunctional quaternary ammonium salt compound in step S1 is as follows: 1,20-dibromoeicosane is dissolved in tetrahydrofuran, dimethyloctylamine is added, the solution is refluxed for 20 hours, and tetrahydrofuran is distilled off by a rotary evaporator to obtain 1,20-bis(dimethylammonium) eicosanedibromide.