Polyvinyl alcohol / lignosulfonate reduction-stabilized silver nanoparticle composite membrane as well as preparation method and application thereof

Abstract

The invention discloses a polyvinyl alcohol / lignosulfonate reduction-stabilized silver nanoparticle composite membrane as well as a preparation method and application thereof. The preparation method of the composite membrane comprises the following steps: dissolving silver nitrate in deionized water to form a silver nitrate solution, adding ammonia water into the silver nitrate solution, and uniformly stirring to form a silver ammonia solution; dropwise adding the lignosulfonate solution into the silver-ammonia solution for reaction to obtain a lignosulfonate reduced and stabilized silver nanoparticle suspension; uniformly mixing and stirring a polyvinyl alcohol solution and the lignosulfonate reduced and stabilized silver nanoparticle suspension to obtain an electrostatic spinning solution; and performing electrostatic spinning on the electrostatic spinning solution to obtain the polyvinyl alcohol / lignosulfonate reduced and stabilized silver nanoparticle composite membrane. The silver nanoparticles endow the composite film with excellent antibacterial performance; the film material prepared through electrostatic spinning has a rich pore structure, and provides conditions for gas permeation, so that the composite film has relatively excellent mechanical strength and fruit fresh-keeping capability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film, its preparation method, and its application. Background Technology

[0002] Fruit waste is a major global problem, with approximately one-third (over 120 million tons) of fruit spoiling during transportation each year, seriously affecting fruit safety. Fruit packaging plays a crucial role in ensuring fruit safety and extending the shelf life of perishable fruits. Traditional petroleum-based fruit packaging (polyethylene, polypropylene, and polycarbonate), while having a long service life, suffers from drawbacks such as lack of antibacterial properties and poor air permeability. The lack of antibacterial properties leads to microbial contamination, accelerating fruit spoilage; poor air permeability hinders the timely release of ethylene and carbon dioxide, resulting in increased anaerobic respiration and metabolic putrefaction. Therefore, developing fruit packaging that is both breathable and antibacterial is of great significance for fruit preservation.

[0003] Silver nanoparticles, as a broad-spectrum and highly effective antibacterial agent, can disrupt the integrity of bacterial cell membranes and are widely used in antibacterial packaging. However, the high surface energy and small size effect of silver nanoparticles make them prone to aggregation, thereby reducing the antibacterial and mechanical properties of composite packaging materials. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film, its preparation method, and its application.

[0006] In a first aspect, the present invention provides a method for preparing a polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film, comprising the following steps: (1) Dissolve silver nitrate in deionized water to form a silver nitrate solution, and add ammonia water to the silver nitrate solution and stir until uniform to form a silver ammonia solution; (2) The lignin sulfonate solution was added dropwise to the silver ammonia solution to react and obtain a lignin sulfonate reduced and stabilized silver nanoparticle suspension; (3) Mix the polyvinyl alcohol solution with the lignin sulfonate reduced and stabilized silver nanoparticle suspension and stir evenly to obtain an electrospinning solution; (4) Electrospinning the electrospinning solution yields a polyvinyl alcohol / lignin sulfonate reduced stable silver nanoparticle composite film.

[0007] Furthermore, based on the silver nitrate content, the silver nitrate concentration in the lignin sulfonate reduced stable silver nanoparticle suspension is 9~11 mg / ml.

[0008] Furthermore, the lignin sulfonate solution is obtained by adding lignin sulfonate to deionized water and sonicating.

[0009] Furthermore, the concentration of the lignin sulfonate solution is 19~21 mg / ml.

[0010] Furthermore, the lignin sulfonate includes one or more of sodium lignin sulfonate, calcium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and ammonium lignin sulfonate.

[0011] Furthermore, the polyvinyl alcohol solution is obtained by adding polyvinyl alcohol to deionized water and heating and stirring at 80-90°C for 2-3 hours.

[0012] Furthermore, the concentration of the polyvinyl alcohol solution is 9% to 11%.

[0013] Furthermore, based on the mass content of silver nitrate, the mass percentage of silver nitrate in the electrospinning solution is 1.0% to 5.0%.

[0014] Secondly, the present invention provides a polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film prepared by the method proposed in the first aspect above.

[0015] Thirdly, the present invention proposes the application of the polyvinyl alcohol / lignin sulfonate reduced stabilized silver nanoparticle composite film prepared by the method proposed in the first aspect above, or the polyvinyl alcohol / lignin sulfonate reduced stabilized silver nanoparticle composite film proposed in the second aspect above, in fruit preservation packaging.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, lignin sulfonate prevents the aggregation of silver nanoparticles through electrostatic repulsion and steric hindrance, ensuring uniform dispersion of the composite membrane and improving its mechanical properties. The silver nanoparticles endow the composite membrane with excellent antibacterial properties, while the phenolic hydroxyl groups in lignin sulfonate also have a certain antibacterial effect. The membrane material prepared by electrospinning has a rich pore structure, providing conditions for gas permeation, thus giving the composite membrane of this invention relatively excellent mechanical strength and fruit preservation ability. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1This is a flowchart illustrating the preparation method of the polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film of the present invention. Figure 2 This is a schematic diagram of the composite membrane prepared in Example 5 of the present invention; Figure 3 The diagram shows the storage conditions of strawberries packaged using the composite film of Example 5, the film of Comparative Example 1, the PE film, and the blank control group, respectively. Figure 4 This is a schematic diagram showing the tensile strength of the composite films in Examples 1-5; Figure 5 These are schematic diagrams illustrating the antibacterial tests of the composite membranes in Examples 1-5; Figure 6 This is a schematic diagram of the antibacterial test of the composite membranes in Comparative Examples 4-8; Figure 7 This is a schematic diagram of the antibacterial test of the composite membranes in Comparative Examples 9-13. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The following description, in conjunction with the accompanying drawings, illustrates the polyvinyl alcohol / lignin sulfonate reduced stabilized silver nanoparticle composite film proposed in this invention, its preparation method, and its applications.

[0020] like Figure 1 As shown, the preparation method of the polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film of the present invention includes the following steps: (1) Dissolve silver nitrate in deionized water to form silver nitrate solution, and add ammonia water to silver nitrate solution and stir evenly to form silver ammonia solution; (2) The lignin sulfonate solution was added dropwise to the silver ammonia solution to react and obtain a lignin sulfonate reduced and stabilized silver nanoparticle suspension; (3) Mix the polyvinyl alcohol solution with the lignin sulfonate reduced and stabilized silver nanoparticle suspension and stir evenly to obtain the electrospinning solution; (4) Electrospinning was performed on the electrospinning solution to obtain a polyvinyl alcohol / lignin sulfonate reduced stable silver nanoparticle composite film.

[0021] Step (1) is the preparation process of silver ammonia solution. First, silver nitrate is dissolved in deionized water, and then ammonia water is added to obtain silver ammonia solution.

[0022] In some embodiments, a certain amount of silver nitrate is weighed, added to deionized water, and stirred at room temperature for 1-2 hours to obtain a silver nitrate solution.

[0023] In some embodiments, when ammonia is added to silver nitrate solution and stirred until a silver ammonia solution is formed, the ammonia is dilute ammonia with a molar concentration of 3-5M, and the excess ammonia completely dissolves the silver ions.

[0024] Step (2) is the preparation process of lignin sulfonate reduced stable silver nanoparticle suspension. The lignin sulfonate solution is added dropwise to the silver ammonia solution prepared in step (1), and the mixture is stirred at room temperature for 1-2 hours.

[0025] In this process, lignin sulfonate acts as a reducing agent to reduce silver ions into silver nanoparticles. To ensure complete reduction, an excessive amount of lignin sulfonate is added. During the reduction process, the phenolic hydroxyl groups of lignin sulfonate are oxidized to quinone structures, simultaneously transferring electrons to the silver ions, thus reducing them into silver nanoparticles. The redox process of lignin sulfonate is milder than that of chemical reducing agents, allowing for the slow and uniform formation of small-sized silver nanoparticles, resulting in better antibacterial properties and improved mechanical properties. Furthermore, the electrostatic repulsion and steric hindrance of the hydrophilic groups in lignin sulfonate prevent silver nanoparticles from approaching each other; the phenolic hydroxyl groups can also form coordination bonds with the silver surface, resulting in "lignin sulfonate-coated" silver nanoparticles, which prevents aggregation and improves the stability of the silver nanoparticles.

[0026] In this application, the lignin sulfonate solution is added dropwise to the silver ammonia solution instead of directly to the silver nitrate solution, which shortens the reaction time.

[0027] In some embodiments, the silver nitrate concentration in the lignin sulfonate-reduced stable silver nanoparticle suspension is 9-11 mg / ml, calculated by the mass content of silver nitrate. In this suspension, silver ions are reduced to silver particles. Since the mass of silver nitrate is weighed, for ease of calculation of the silver particle content, the mass of silver nitrate added earlier is used directly, i.e., the silver nitrate content represents the silver content. A suitable concentration of silver nitrate solution ensures the antibacterial properties of the composite membrane without affecting the electrospinning process. When the concentration of silver nitrate solution is too low, the antibacterial performance of the prepared composite membrane is low; when the concentration of silver nitrate solution is too high, it adversely affects the electrospinning process.

[0028] In some embodiments, the lignin sulfonate solution is obtained by adding lignin sulfonate to deionized water and sonicating it for 20-30 minutes at a temperature of 20-30 minutes.

[0029] In some embodiments, the concentration of the lignin sulfonate solution is 19-21 mg / ml. The concentration of the lignin sulfonate solution is within a suitable range so that the silver ions are completely reduced. If the concentration of the lignin sulfonate solution is too low, the silver nanoparticles will not react completely. If the concentration of the lignin sulfonate solution is too high, it will affect the mechanical properties of the membrane.

[0030] In some embodiments, lignin sulfonate includes one or more of sodium lignin sulfonate, calcium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and ammonium lignin sulfonate.

[0031] Step (3) is the preparation process of the electrospinning solution, which is obtained by mixing and stirring a polyvinyl alcohol solution with a lignin sulfonate-reduced and stabilized silver nanoparticle suspension. Stirring ensures that the polyvinyl alcohol and silver nanoparticles are evenly dispersed. Polyvinyl alcohol is used as the carrier of the electrospinning solution.

[0032] In some embodiments, when preparing a polyvinyl alcohol solution, polyvinyl alcohol powder is first dispersed in deionized water, and then heated and stirred in a water bath at 80-90°C for 2-3 hours to completely dissolve the polyvinyl alcohol.

[0033] In some embodiments, the concentration (mass fraction) of the polyvinyl alcohol solution is 9% to 11%. When the concentration of the polyvinyl alcohol solution is within a suitable range, electrospinning can proceed smoothly. If the concentration of the polyvinyl alcohol solution is too low, electrospinning cannot be performed. If the concentration of the polyvinyl alcohol solution is too high, the fibers produced by electrospinning will become thicker, making spinning difficult.

[0034] In some embodiments, the mass percentage of silver nitrate in the electrospinning solution is 1.0% to 5.0%, calculated based on the mass content of silver nitrate. Silver in the electrospinning solution exists in the form of silver particles. Since the mass of silver nitrate is measured, for ease of calculation, the mass of previously added silver nitrate is used directly for calculation; that is, the content of silver nitrate represents the content of silver. When the mass percentage of silver nanoparticles is too low, the antibacterial properties are poor; when the mass percentage of silver nanoparticles is too high, electrospinning is difficult due to their excellent electrical conductivity.

[0035] Step (4) is the electrospinning process, in which the electrospinning solution prepared in step (3) is electrospinned to obtain a composite membrane.

[0036] In some embodiments, the electrospinning process parameters are: voltage 24 kV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h.

[0037] This invention utilizes sodium lignosulfonate as a reducing agent for silver ions, which can slowly and uniformly form small-sized silver nanoparticles with good antibacterial properties. The hydrophilic groups of lignosulfonate prevent the silver nanoparticles from approaching through electrostatic repulsion and steric hindrance. The phenolic hydroxyl groups can also form coordination bonds with the silver surface, thereby forming lignosulfonate-coated silver nanoparticles, achieving high-strength composite membrane preparation and improving its mechanical properties. Electrospinning technology provides a large number of pore structures for the composite membrane, improving its air permeability.

[0038] The polyvinyl alcohol / lignin sulfonate reduced and stabilized silver nanoparticle composite film of the present invention has good bactericidal properties as well as good air permeability and mechanical properties. Its application in fruit preservation packaging extends the shelf life of fruit and reduces losses.

[0039] The present invention will now be described in detail with reference to specific embodiments.

[0040] Sodium lignosulfonate: Purchased from Yuan Ye, S30635-100g, CAS#8061-51-6, BR, 96%.

[0041] Polyvinyl alcohol: purchased from Aladdin, degree of alcoholysis: 97.5-99.0 mol%, viscosity: 25.0-30.0 mPa.s, CAS: 9002-89-5.

[0042] Example 1 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution; mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 10:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 KV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h. The resulting composite membrane is denoted as AL. 10 P 10 .

[0043] Example 2 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 8:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 KV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h. The resulting composite membrane is denoted as AL. 10 P8.

[0044] Example 3 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 6:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 KV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h. The resulting composite membrane is denoted as AL. 10 P6.

[0045] Example 4 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 4:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 KV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h. The resulting composite membrane is denoted as AL. 10 P4.

[0046] Example 5 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 KV, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h. The resulting composite membrane is denoted as AL. 10 P2, such as Figure 2 As shown.

[0047] Example 6 (1) Add 110 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0048] Example 7 (1) Add 90 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0049] Example 8 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a polyvinyl alcohol solution with a concentration of 11%. Mix the polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0050] Example 9 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 9% polyvinyl alcohol solution. Mix the 9% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0051] Example 10 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 0.95g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0052] Example 11 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1.05 g of sodium lignosulfonate in 50 mL of deionized water and sonicate at 25 °C for 30 min to obtain sodium lignosulfonate solution; add 5 mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1 h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) Disperse a certain amount of polyvinyl alcohol powder into deionized water and stir for 2 hours under 80°C water bath conditions to obtain a 10% polyvinyl alcohol solution. Mix the 10% polyvinyl alcohol solution with the suspension obtained in step (3) at a volume ratio of 2:1 and stir for 1 hour to obtain an electrospinning solution. (4) Add the electrospinning solution to a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 24 Kv, spinning distance 12 cm, feed speed 0.8 mL / min, and spinning time 4 h to obtain a composite membrane.

[0053] Comparative Example 1 (1) Weigh 10g of polyvinyl alcohol into 100mL of deionized water and heat and stir at 80℃ for 3h; (2) Add the solution from step (1) into a 10 mL syringe for electrospinning. The electrospinning process parameters are: voltage 18 Kv, spinning distance 12 cm, feed speed 1 mL / min, and spinning time 4 h. Finally, a pure polyvinyl alcohol film is obtained.

[0054] Comparative Example 2 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) A certain amount of polyvinyl alcohol powder is dispersed in deionized water and stirred for 2 hours in an 80°C water bath to obtain a 15% polyvinyl alcohol solution. The 15% polyvinyl alcohol solution is mixed with the suspension obtained in step (3) at a volume ratio of 2:1 and stirred for 1 hour to obtain an electrospinning solution. Due to the high concentration of polyvinyl alcohol, a composite membrane cannot be obtained by electrospinning.

[0055] Comparative Example 3 (1) Add 100 mg of silver nitrate to 4 mL of deionized water and stir at room temperature for 1 h to form a silver nitrate solution. Add 1 mL of 5 M ammonia solution to the silver nitrate solution and stir until uniform to form a silver ammonia solution. (2) Dissolve 1g of sodium lignosulfonate in 50mL of deionized water and sonicate at 25℃ for 30min to obtain sodium lignosulfonate solution; add 5mL of sodium lignosulfonate solution dropwise to silver ammonia solution and stir at room temperature for 1h to obtain sodium lignosulfonate reduced and stabilized silver nanoparticle suspension. (3) A certain amount of polyvinyl alcohol powder was dispersed in deionized water and stirred for 2 hours in an 80°C water bath to obtain a 5% polyvinyl alcohol solution. The 5% polyvinyl alcohol solution was mixed with the suspension obtained in step (3) at a volume ratio of 2:1 and stirred for 1 hour to obtain an electrospinning solution. Due to the low concentration of polyvinyl alcohol, a composite membrane could not be obtained by electrospinning.

[0056] Comparative Example 4 The difference from Example 1 is that 50 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 1. The resulting composite membrane was designated AL5P. 10 .

[0057] Comparative Example 5 The difference from Example 2 is that 50 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 h to form a silver nitrate solution. Then, 1 mL of a 5 M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 2, and the resulting composite membrane was designated AL5P8.

[0058] Comparative Example 6 The difference from Example 3 is that 50 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 h to form a silver nitrate solution. Then, 1 mL of a 5 M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 3, and the resulting composite membrane was designated AL5P6.

[0059] Comparative Example 7 The difference from Example 4 is that 50 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 h to form a silver nitrate solution. Then, 1 mL of a 5 M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 4, and the resulting composite membrane was designated AL5P4.

[0060] Comparative Example 8 The difference from Example 5 is that 50 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 h to form a silver nitrate solution. Then, 1 mL of a 5 M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 5, and the resulting composite membrane was designated AL5P2.

[0061] Comparative Example 9 The difference from Example 1 is that 25 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 1. The resulting composite membrane is denoted as AL. 2.5 P 10 .

[0062] Comparative Example 10 The difference from Example 2 is that 25 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 2. The resulting composite membrane was denoted as AL. 2.5 P8.

[0063] Comparative Example 11 The difference from Example 3 is that 25 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 3. The resulting composite membrane is denoted as AL. 2.5 P6.

[0064] Comparative Example 12 The difference from Example 4 is that 25 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 4. The resulting composite membrane is denoted as AL. 2.5 P4.

[0065] Comparative Example 13 The difference from Example 5 is that 25 mg of silver nitrate was added to 4 mL of deionized water and stirred at room temperature for 1 hour to form a silver nitrate solution. Then, 1 mL of a 5M ammonia solution was added to the silver nitrate solution and stirred until homogeneous to form a silver ammonia solution. Other steps were the same as in Example 5. The resulting composite membrane is denoted as AL. 2.5 P2.

[0066] Experimental Example 1 Using strawberries as the experimental subject, strawberries were packaged using the composite film prepared in Example 5, the pure polyvinyl alcohol film prepared in Comparative Example 1, and commercially available PE preservation film. The state of the strawberries was observed and recorded, and the fruit preservation performance of the films was tested. The test results are as follows: Figure 3 As shown.

[0067] from Figure 3 It can be seen that the composite film of Example 5 can preserve strawberries for up to 7 days, and has good preservation performance.

[0068] Experimental Example 2 The mechanical properties of the composite films prepared in Examples 1-5 were tested, and the test results are as follows: Figure 4 As shown.

[0069] from Figure 4 It can be seen that with the increase of silver nanoparticles, the composite film of Example 5 exhibits better mechanical properties, with a tensile strength as high as 11.8 MPa.

[0070] Experimental Example 3 The antibacterial properties of the composite films in Examples 1-5 were analyzed using the inhibition zone method, and the test results are as follows: Figure 5 As shown.

[0071] from Figure 5 It can be seen that the composite membranes of Examples 1 to 5 all have different degrees of antibacterial properties. The composite membrane of Example 5 has the largest antibacterial ring area, with a diameter of 10.4 mm.

[0072] Test Example 4 The antibacterial properties of the composite films in comparative examples 4-8 were analyzed using the inhibition zone method. The test results are as follows: Figure 6 As shown.

[0073] from Figure 6 It can be seen that the composite films in comparative proportions 4 to 8 did not form obvious antibacterial rings and had poor antibacterial properties.

[0074] Experimental Example 5 The antibacterial properties of the composite films in comparative examples 9-13 were analyzed using the inhibition zone method. The test results are as follows: Figure 7 As shown.

[0075] from Figure 7It can be seen that the composite films in comparative proportions 9 to 13 did not form obvious antibacterial rings and had poor antibacterial properties.

[0076] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film, characterized in that, Includes the following steps: (1) Dissolve silver nitrate in deionized water to form a silver nitrate solution, and add ammonia water to the silver nitrate solution and stir until uniform to form a silver ammonia solution; (2) The lignin sulfonate solution was added dropwise to the silver ammonia solution to react and obtain a lignin sulfonate reduced and stabilized silver nanoparticle suspension; (3) Mix the polyvinyl alcohol solution with the lignin sulfonate reduced and stabilized silver nanoparticle suspension and stir evenly to obtain an electrospinning solution; (4) Electrospinning the electrospinning solution yields a polyvinyl alcohol / lignin sulfonate reduced stable silver nanoparticle composite film.

2. The method as described in claim 1, characterized in that, Based on the silver nitrate content, the silver nitrate concentration in the lignin sulfonate reduced stable silver nanoparticle suspension is 9~11 mg / ml.

3. The method as described in claim 1, characterized in that, The lignin sulfonate solution is obtained by adding lignin sulfonate to deionized water and sonicating.

4. The method as described in claim 3, characterized in that, The concentration of the lignin sulfonate solution is 19~21 mg / ml.

5. The method as described in claim 3, characterized in that, The lignin sulfonate includes one or more of sodium lignin sulfonate, calcium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate, and ammonium lignin sulfonate.

6. The method as described in claim 1, characterized in that, The polyvinyl alcohol solution is obtained by adding polyvinyl alcohol to deionized water and heating and stirring at 80-90°C for 2-3 hours.

7. The method as described in claim 6, characterized in that, The concentration of the polyvinyl alcohol solution is 9% to 11%.

8. The method as described in claim 1, characterized in that, Based on the mass content of silver nitrate, the mass percentage of silver nitrate in the electrospinning solution is 1.0% to 5.0%.

9. A polyvinyl alcohol / lignin sulfonate reduction-stabilized silver nanoparticle composite film, characterized in that, Prepared by the method described in any one of claims 1 to 8.

10. The application of the polyvinyl alcohol / lignin sulfonate reduced stabilized silver nanoparticle composite film prepared by the method according to any one of claims 1 to 8 or the polyvinyl alcohol / lignin sulfonate reduced stabilized silver nanoparticle composite film according to claim 9 in fruit preservation packaging.

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