A PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film and its preparation method and application

Abstract

The present invention discloses a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film and a preparation method and application thereof. The preparation method comprises the following steps: preparing biowax@SiO2 super-hydrophobic powder, dissolving PET in a solvent b to obtain a PET spinning solution, adding the biowax@SiO2 super-hydrophobic powder and an antibacterial agent to the PET spinning solution, sealing and stirring at room temperature to form a uniform, stable, transparent solution, and utilizing electrostatic spinning technology to obtain the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film. The prepared electrospun film has high hydrophobicity, can prevent bacterial adhesion and growth, has anti-adhesion function and high antibacterial property; and has a porous structure and adjustable pore size characteristics, can be suitable for packaging various active foods such as fruits and vegetables that require breathability, and provides a valuable method and idea for the fresh-keeping storage of active foods such as fruits and vegetables that continue to respire after harvest.

Description

Technical Field

[0001] The present invention belongs to the field of food packaging materials, and in particular relates to a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, a preparation method and an application thereof. Background Art

[0002] PET (polyethylene terephthalate) has excellent dimensional stability, is non-toxic, has good weather and chemical resistance, and has low water absorption. It is often used to make packaging materials such as bottles, films, sheets, and oven-resistant food containers. However, these forms of PET packaging materials are brittle, have poor toughness and impact resistance, and are poorly adaptable to antibacterial treatments. For example, PET plastic bottles cannot be cleaned in bottle washers and can only be rinsed with high-pressure sterile water, which cannot guarantee the sterility of the bottle. PET plastic bottles, which are not heat-resistant, cannot pass through pasteurization machines, which places high demands on the sterility of the packaging workshop. Furthermore, PET packaging materials are prone to static electricity, which can lead to food adhesion and bacterial growth. These problems still need to be addressed.

[0003] Biowax contains long-chain wax hydrocarbons in its molecular structure, exhibiting low surface energy and self-cleaning properties, laying the foundation for its application in antifouling, antibacterial, and self-cleaning fields. Nano-SiO2 is a multi-purpose inorganic material widely found in nature. Due to the dual effects of its microscopic to nanoscale structure and surface hydrophobicity, it has become an excellent choice for preparing super-hydrophobic surfaces. Its surface roughness reduces the actual contact area between the liquid and the surface, and its hydrophobic properties weaken the liquid's adhesion ability, allowing droplets to present a high contact angle on the surface, achieving a super-hydrophobic effect. The electrospinning method uses high voltage electricity to form a high-speed jet of charged polymers to prepare fibers ranging from 10nm to 10μm, which are then layered into membranes. The flexible membranes produced by this method have high porosity and adjustable pore size. They are easy to operate and have a wide range of applications, and have attracted much attention in the field of membrane preparation.

[0004] Although there have been reports on the direct preparation of micro-nanofiber membranes by electrospinning PET, there are relatively few studies on porous hydrophobic antibacterial membranes in the field of food packaging. Summary of the Invention

[0005] The purpose of the present invention is to provide a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film and a preparation method thereof.

[0006] The present invention also aims to provide the use of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film prepared by the above method in food preservation and storage packaging materials.

[0007] The first object of the present invention is achieved by the following technical solution: a method for preparing a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, comprising the following steps:

[0008] S1) biowax is dissolved in solvent a, heated and stirred to obtain a transparent wax mixture, and then hydrophobic nano-SiO2 is added thereto, and stirring is continued to fully dissolve it to obtain a uniformly dispersed suspension, and the suspension is subjected to rotary evaporation and drying to obtain biowax@SiO2 super-hydrophobic powder;

[0009] S2) dissolving PET in solvent b to obtain a PET spinning solution, adding the biowax@SiO2 superhydrophobic powder and antibacterial agent prepared in step S1) to the PET spinning solution, respectively, and stirring in a sealed manner at room temperature for 11 to 13 hours to form a uniform, stable, transparent solution;

[0010] S3) using the transparent solution in step S2) to perform electrospinning. After the electrospinning is completed, the electrospun membrane is peeled off and vacuum dried to evaporate the residual solvent in the electrospun membrane, thereby obtaining a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0011] To prevent food from sticking and bacterial growth, the present invention uses PET as a raw material to prepare a spinning solution, combines biowax and nano-SiO2, prepares a super-hydrophobic powder, and uses electrospinning technology to combine the PET spinning solution, biowax@SiO2 super-hydrophobic powder, and an antibacterial agent to prepare a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film. This electrospun film has high hydrophobicity, can prevent bacterial adhesion and growth, and has anti-adhesion function and high antibacterial properties. The PET composite film has a porous structure and adjustable pore size characteristics, and is suitable for packaging active foods that require ventilation, such as various fruits and vegetables.

[0012] In the preparation method of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film:

[0013] Preferably, the biowax in step S1) is any one of beeswax, paraffin, rice bran wax, palm wax and candelilla wax.

[0014] Preferably, the solvent a in step S1) is any one of ethanol, acetone, ethyl acetate, 1,4-dioxane, dimethyl carbonate, isoamyl acetate and dimethyl sulfoxide.

[0015] Preferably, the amount of the bio-wax and solvent a in step S1) is 4-6 g:100 mL; the temperature during heating and stirring is 65-75° C., and the mass ratio of the hydrophobic nano-SiO 2 to the bio-wax is 1-3:4-6.

[0016] Preferably, the solvent b in step S2) is one or a mixed solvent of any proportion of acetone, tetrahydrofuran, N,N-dimethylformamide, hexafluoroisopropanol, dichloromethane and trifluoroacetic acid.

[0017] Preferably, the concentration of the PET spinning solution in step S2) is 10-20 wt%.

[0018] Preferably, the antibacterial agent in step S2) is any one of nanosilver, ZnO, calcium propionate, cinnamaldehyde and polyhexamethyleneguanidine hydrochloride (PHGH).

[0019] Preferably, the biowax@SiO2 super-hydrophobic powder in step S2) accounts for 1% to 10% of the total mass of the PET.

[0020] Preferably, the antibacterial agent in step S2) accounts for 0.5% to 1.5% of the total mass of the PET.

[0021] Preferably, the electrospinning conditions in step S3) are as follows: controlling the liquid feeding speed to 10-20 μL / min, the spray distance to 15-20 cm, the spinning voltage to 16-20 kV, and the spinning process temperature to 30°C.

[0022] The PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film in the present invention is prepared by using PET as raw material to prepare a spinning solution, combining biowax and nano-SiO2 to prepare a super-hydrophobic powder. By electrospinning technology, PET spinning solution, biowax@SiO2 super-hydrophobic powder and an antibacterial agent are combined to prepare a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film. While preventing food from adhering to and bacterial adhesion and breeding, the electrospun film has high hydrophobicity, high antibacterial property, porous structure and adjustable pore size characteristics, extending the shelf life of food, while protecting food from external extrusion, impact and pollution, and also having good antibacterial properties to avoid bacterial adhesion and breeding.

[0023] The present invention also provides a PET-biowax-SiO2 hydrophobic and antibacterial electrospun food packaging film prepared by the above method.

[0024] The above-mentioned second object of the present invention can be achieved through the following technical solution: application of the above-mentioned PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film in food preservation and storage packaging materials.

[0025] The present invention successfully prepared a micro-nano hydrophobic antibacterial electrospun membrane with a porous structure. This innovation will provide valuable methods and ideas for the preservation and storage of active foods such as fruits and vegetables that continue to respire after harvest.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The biowax in the present invention is derived from nature, can be recycled and reused, and conforms to the principle of sustainable development. The molecular structure of biowax contains long-chain wax hydrocarbons with low surface energy, which can reduce the adhesion of pollutants, inhibit food oxidation and corruption, and extend the shelf life. Nano-SiO2 is a safe and non-toxic inorganic material with unique porous adsorption properties. It can absorb moisture and oxygen in food packaging and extend the shelf life of food. The hydrophobic PET electrospinning additive made by combining biowax and SiO2 can reduce the electrostatic force between the packaging and the contents, prevent food adhesion, effectively prevent bacterial adhesion, avoid packaging contamination, and is safe and reliable in food contact applications. In addition, the present invention also introduces food-contactable antibacterial agents such as nanosilver, ZnO, calcium propionate, cinnamaldehyde and polyhexamethyleneguanidine hydrochloride (PHGH), which enhance the antibacterial function of the packaging material, prevent bacterial adhesion and growth, and extend the shelf life of food. This comprehensive solution integrates freshness preservation, food safety, cleanliness and environmental protection, and provides valuable ideas for the field of food packaging;

[0028] (2) The present invention combines PET spinning solution, biowax@SiO2 superhydrophobic powder and antibacterial agent through electrospinning technology to prepare PET-biowax-SiO2 hydrophobic and antibacterial electrospun food packaging film. The packaging film has a micro-convex and concave structure at the micro to nano level, which promotes the rolling of droplets contacting the packaging film and achieves self-cleaning. The electrospun film has a porous structure and adjustable pore size characteristics, which is suitable for the packaging of various active foods with respiratory function such as fruits and vegetables. The pore size can be adjusted according to the respiratory intensity requirements of the active food contents, avoiding anaerobic respiration of the food contents caused by closed packaging, extending the shelf life of the food, and providing a multifunctional solution for the field of food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of static contact angles of different electrospun membranes of the present invention;

[0030] Figure 2 5000x SEM schematic diagram of the electrospun membrane prepared in Example 4;

[0031] Figure 3 This is a SEM schematic diagram of the concave-convex structure of the electrospun membrane prepared in Example 4;

[0032] Figure 4 This is a SEM diagram of different pore sizes at different positions of the electrospun membrane prepared in Example 4 at the same magnification;

[0033] Figure 5 Schematic diagram of the inhibition zones of different bacteria on the electrospun membranes prepared in Comparative Example 4 and Example 4. DETAILED DESCRIPTION

[0034] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0035] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0036] The present invention tests the mechanical properties and wetting properties of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, and the method is as follows:

[0037] (1) Mechanical properties

[0038] According to GB / T1040.1-2018, the electrospun membrane was first cut into 50 mm × 20 mm rectangular strips, and then its thickness was measured using a thickness gauge. The mechanical properties of the electrospun membrane were then tested using an electronic tensile testing machine (GBH-1500N).

[0039] (2) Hydrophobicity

[0040] The present invention uses a JC2000C1 contact angle meter to measure hydrophobicity: 2 μL of ultrapure water is dropped onto the surface of the spinning membrane for measurement. Five different locations are tested in parallel, and the results are averaged.

[0041] Example 1

[0042] S1): 5 g of beeswax was dissolved in 100 mL of ethanol, and the mixture was heated and stirred at 70° C. to obtain a transparent wax mixture; 1 g of hydrophobic nano-SiO2 was then added thereto, and stirring was continued to fully dissolve the mixture to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain a beeswax@SiO2 super-hydrophobic powder;

[0043] S2): 1.90 g of PET was dissolved in a mixed solvent of acetone and N,N-dimethylformamide in a volume ratio of 1:2 to prepare a 15 wt% PET spinning solution; 0.019 g of beeswax@SiO2 superhydrophobic powder and 0.01 g of nanosilver were added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0044] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning process temperature controlled at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-beeswax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0045] Example 2

[0046] S1): 5 g of paraffin wax was dissolved in 100 mL of dimethyl sulfoxide, and heated and stirred at 70° C. to obtain a transparent wax mixture; 1.5 g of hydrophobic nano-SiO2 was then added to the mixture, and stirring was continued to fully dissolve it to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain paraffin wax@SiO2 super hydrophobic powder;

[0047] S2): 1.92 g of PET was dissolved in a mixed solvent of acetone and N,N-dimethylformamide in a volume ratio of 1:3 to prepare a 15 wt% PET spinning solution; 0.048 g of paraffin wax@SiO2 superhydrophobic powder and 0.014 g of ZnO were added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0048] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning process temperature controlled at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-paraffin-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0049] Example 3

[0050] S1): 5 g of rice bran wax was dissolved in 100 mL of 1,4-dioxane, and heated and stirred at 70° C. to obtain a transparent wax mixture; 2 g of hydrophobic nano-SiO2 was then added to the mixture, and stirring was continued to fully dissolve it to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain rice bran wax@SiO2 super-hydrophobic powder;

[0051] S2): 3.38 g of PET was dissolved in hexafluoroisopropanol to prepare a 15 wt% PET spinning solution; 0.169 g of rice bran wax @ SiO2 superhydrophobic powder and 0.034 g of calcium propionate were added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0052] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning process temperature controlled at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-rice bran wax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0053] Example 4

[0054] S1): 5 g of palm wax was dissolved in 100 mL of ethyl acetate, heated and stirred at 70° C. to obtain a transparent wax mixture; 2.5 g of hydrophobic nano-SiO2 was then added to the mixture, and stirring was continued to fully dissolve it to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain palm wax@SiO2 super-hydrophobic powder;

[0055] S2): 3.95 g of PET was dissolved in a mixed solvent of dichloromethane and trifluoroacetic acid in a volume ratio of 1:4 to prepare a 15 wt% PET spinning solution; 0.296 g of palm wax@SiO2 superhydrophobic powder and 0.049 g of cinnamaldehyde were added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0056] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning process temperature controlled at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-palm wax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0057] Example 5

[0058] S1): 5 g of candelilla wax was dissolved in 100 mL of dimethyl carbonate, and the mixture was heated and stirred at 70° C. to obtain a transparent wax mixture; 3 g of hydrophobic nano-SiO2 was then added to the mixture, and stirring was continued to fully dissolve the mixture to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain candelilla wax@SiO2 super-hydrophobic powder;

[0059] S2): 1.632 g of PET was dissolved in a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 3:2 to prepare a 15 wt% PET spinning solution; 0.163 g of candelilla wax@SiO2 superhydrophobic powder and 0.025 g of polyhexamethyleneguanidine hydrochloride (PHGH) were added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0060] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning temperature at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-candelilla wax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0061] Comparative Example 1

[0062] The difference from Example 4 is that step S1) is not provided, that is, no biowax@SiO2 superhydrophobic powder is added, and no antibacterial agent is added in step S2).

[0063] S1): 3.95 g of PET was dissolved in a mixed solvent of dichloromethane and trifluoroacetic acid in a volume ratio of 1:4 to prepare a PET spinning solution with a mass fraction of 15 wt%;

[0064] S2): The PET spinning solution was electrospun at a liquid feed rate of 15 μL / min, a spray distance of 18 cm, a spinning voltage of 18 kV, and a spinning temperature of 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum dried at 60°C to obtain the PET electrospun membrane.

[0065] Comparative Example 2

[0066] The difference from Example 4 is that only palm wax is added in step S1) without adding hydrophobic nano-SiO2, and no antibacterial agent is added in step S2).

[0067] S1): 3.95 g of PET was dissolved in a mixed solvent of dichloromethane and trifluoroacetic acid in a volume ratio of 1:4 to prepare a 15 wt% PET spinning solution; 5 g of palm wax was added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0068] S2): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning temperature at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain the PET-palm wax electrospun membrane.

[0069] Comparative Example 3

[0070] The difference from Example 4 is that only hydrophobic nano-SiO2 powder is added in step S1) without palm wax, and no antibacterial agent is added in step S2).

[0071] S1): 3.95 g of PET was dissolved in a mixed solvent of dichloromethane and trifluoroacetic acid in a volume ratio of 1:4 to prepare a 15 wt% PET spinning solution; 2.5 g of hydrophobic nano-SiO2 powder was added to the PET spinning solution, and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0072] S2): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning temperature at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum dried at 60°C to obtain a PET-SiO2 electrospun membrane.

[0073] Example 4

[0074] Different from Example 4, the antibacterial agent cinnamaldehyde is not added in step S2).

[0075] S1): 5 g of palm wax was dissolved in 100 mL of ethyl acetate, heated and stirred at 70° C. to obtain a transparent wax mixture; 2.5 g of hydrophobic nano-SiO2 was then added to the mixture, and stirring was continued to fully dissolve it to obtain a uniformly dispersed suspension; the suspension was subjected to rotary evaporation and drying to obtain palm wax@SiO2 super-hydrophobic powder;

[0076] S2): 3.95 g of PET was dissolved in a mixed solvent of dichloromethane and trifluoroacetic acid in a volume ratio of 1:4 to prepare a 15 wt% PET spinning solution; 0.296 g of palm wax@SiO2 superhydrophobic powder was added to the PET spinning solution and the mixture was sealed and stirred at room temperature for 12 h to form a uniform, stable, transparent solution;

[0077] S3): Electrospinning was performed using the transparent solution, with the liquid feed rate controlled at 15 μL / min, the spray distance at 18 cm, the spinning voltage at 18 kV, and the spinning process temperature controlled at 30°C. After the electrospinning was completed, the electrospun membrane was gently peeled off from the release paper with tweezers and vacuum-dried at 60°C to obtain a PET-palm wax-SiO2 hydrophobic antibacterial electrospun food packaging film.

[0078] The PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging films prepared in Examples 1-5 and Comparative Examples 1-4 were tested for mechanical properties and hydrophobic properties according to the corresponding test methods. The test results are shown in Table 1.

[0079] Table 1: Test results of PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film

[0080]

[0081] The tensile strength and elongation at break reflect the mechanical properties of the electrospun membrane, and the water contact angle reflects the hydrophobicity of the electrospun membrane.

[0082] Table 1 shows that the addition of biowax@SiO2 hydrophobic powder improves the mechanical and hydrophobic properties of the electrospun membrane. With increasing addition levels, the tensile strength and elongation at break of the electrospun membrane increase. Compared to Comparative Example 1 (pure PET electrospun membrane), the tensile strength of Example 4 (i.e., 7.5% addition) increased by 9.68 MPa, and the elongation at break increased by 2.37 times.

[0083] The hydrophobic performance test shows that ( Figure 1 It can also be seen that the water contact angle of the antibacterial PET-biowax@SiO2 hydrophobic electrospun membrane is greater than 115°, reaching a hydrophobic state. In Example 4, the water contact angle reaches 159.02°, achieving super hydrophobic performance. Compared with Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, Example 4 has excellent hydrophobic performance, can achieve self-cleaning and anti-fouling, and bacteria do not adhere.

[0084] The 5000x SEM results of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film prepared in Example 4 are shown in FIG. Figure 2 .

[0085] from Figure 2 Scanning images show that the composite fibers are approximately 10μm in diameter. The hydrophobic layer tightly wraps around the fibers, making their surface rougher and accumulating with hydrophobic particles, forming a large protective layer. At 5000x magnification, the fibers become coarser, making them more likely to adhere to each other.

[0086] The SEM diagram of the concave-convex structure of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film prepared in Example 4 is shown in Figure 3 .

[0087] Depend on Figure 3 It can be seen that the electrospun membrane exhibits a tiny concave-convex structure. This is because bio-wax is added to the electrospun membrane. The long carbon chain structure of the bio-wax reduces the free energy of the PET substrate surface and forms a concave-convex rough structure.

[0088] The SEM results of different pores of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film prepared in Example 4 are shown in Figure 4 .

[0089] Figure 4 The thickness of the silk and the pore size of the silk at different positions of the electrospun membrane are different at the same magnification.

[0090] Depend on Figure 4As can be seen from the SEM image, the thickness of the silk and the pore size of the silk are different at different positions of the electrospun membrane at the same magnification. This is because porous nano-SiO2 is added to the electrospun membrane. The combination of SiO2 and the micron-scale structure of the wax increases the surface roughness and also forms structures with different pore sizes on the electrospun membrane.

[0091] Example 4 Antibacterial properties of PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film Figure 5 .

[0092] from Figure 5 It can be seen that compared with Comparative Example 4, the electrospun membrane prepared in Example 4 added cinnamaldehyde as an antibacterial agent, and the antibacterial PET-palm wax@SiO2 hydrophobic electrospun membrane had a certain antibacterial effect on the inhibition rate of Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Bacillus subtilis, among which the inhibition zones of Staphylococcus aureus, Aspergillus niger, and Bacillus subtilis were more obvious, and the overall antibacterial effect was excellent.

[0093] As can be seen, the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, especially the PET-palm wax-SiO2 hydrophobic antibacterial electrospun food packaging film, has excellent mechanical properties, high hydrophobicity, and good antibacterial properties. It prevents food from adhering to food and the growth of bacteria, extending the shelf life of food while protecting food from external extrusion, impact, and contamination. It also has good antibacterial properties, preventing bacterial adhesion and growth. Its porous structure and adjustable pore size make it suitable for packaging various active foods such as fruits and vegetables that require breathability, providing valuable methods and ideas for the preservation and storage of active foods such as fruits and vegetables that continue to respire after harvest.

[0094] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A method for preparing a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, characterized in that The following steps are involved: S1) dissolving the biowax in solvent a, heating and stirring to obtain a transparent wax mixture, then adding hydrophobic nano-SiO2 to the mixture, continuing to stir to fully dissolve it to obtain a uniformly dispersed suspension, and rotary evaporating and drying the suspension to obtain the biowax@SiO2 super-hydrophobic powder; S2) dissolving PET in solvent b to obtain a PET spinning solution, adding the biowax@SiO2 superhydrophobic powder and the antibacterial agent prepared in step S1) to the PET spinning solution, respectively, and stirring the mixture in a sealed state at room temperature for 11-13 hours to form a uniform, stable, transparent solution; S3) performing electrospinning using the transparent solution in step S2), peeling off the electrospun membrane after the electrospinning is completed, and vacuum drying to evaporate the residual solvent in the electrospun membrane, thereby obtaining a PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film; The antibacterial agent in step S2) is any one of nanosilver, ZnO, calcium propionate, cinnamaldehyde and polyhexamethyleneguanidine hydrochloride.

2. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: The biowax in step S1) is any one of beeswax, paraffin wax, rice bran wax, palm wax and candelilla wax.

3. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: The solvent a in step S1) is any one of ethanol, acetone, ethyl acetate, 1,4-dioxane, dimethyl carbonate, isoamyl acetate and dimethyl sulfoxide.

4. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: In step S1), the amount of the bio-wax and solvent a is 4-6 g:100 mL; the temperature during heating and stirring is 65-75° C., and the mass ratio of the hydrophobic nano-SiO 2 to the bio-wax is 1-3:4-6.

5. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: In step S2), the solvent b is one or a mixed solvent of any proportion of acetone, tetrahydrofuran, N,N-dimethylformamide, hexafluoroisopropanol, dichloromethane and trifluoroacetic acid; the concentration of the PET spinning solution is 10-20 wt%.

6. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: The biowax@SiO2 super-hydrophobic powder in step S2) accounts for 1% to 10% of the total mass of the PET; the antibacterial agent in step S2) accounts for 0.5% to 1.5% of the total mass of the PET.

7. The method for preparing the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 1, characterized in that: The electrospinning conditions in step S3) are as follows: the liquid feeding speed is controlled at 10-20 μL / min, the spray distance is 15-20 cm, the spinning voltage is 16-20 kV, and the spinning process temperature is controlled at 30°C.

8. A PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film, characterized by: The PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film is prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the PET-biowax-SiO2 hydrophobic antibacterial electrospun food packaging film according to claim 8 in food preservation and storage packaging materials.

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