Antibacterial PS film and preparation method thereof

Abstract

The invention discloses an antibacterial PS film and a preparation method thereof, and relates to the technical field of high polymer material processing. The antibacterial polystyrene composite material comprises the following raw materials in parts by mass: 100 parts of polystyrene resin, 15-25 parts of a composite antibacterial agent, 1-2 parts of a compatilizer and 3-5 parts of an auxiliary agent, the composite antibacterial agent is prepared from the following raw materials in parts by mass: 6 to 10 parts of silver-loaded zirconium phosphate, 15 to 25 parts of silver-loaded titanium dioxide nanocrystals, 5 to 8 parts of graphene oxide, 1 to 3 parts of N-(trimethoxysilylpropyl) ethylenediamine triacetic acid sodium salt and 2 to 4 parts of reactive beta-cyclodextrin quaternary ammonium salt. The antibacterial PS film is high in light transmittance, remarkable in antibacterial effect and good in antibacterial durability.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology, and in particular to an antibacterial PS film and its preparation method. Background Technology

[0002] Polystyrene (PS), as a general-purpose plastic, boasts excellent light transmittance, processing fluidity, and cost advantages, making it widely used in food packaging, medical device packaging, and stationery decoration. Biaxially oriented polystyrene (BOPS), through a biaxial stretching process in both the longitudinal and transverse directions, allows the molecular chains to arrange themselves in an orderly plane. Compared to ordinary extruded PS films, its light transmittance, rigidity, and impact resistance are significantly improved, making it a preferred material in high-end packaging. However, traditional PS films lack antibacterial properties. In food packaging, the film surface is prone to the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, leading to food spoilage. In the field of medical device packaging, microbial contamination directly threatens safety.

[0003] To impart antibacterial properties to PS films, antibacterial agents are often added directly. Common antibacterial agents are mainly divided into two categories: organic and inorganic. Organic antibacterial agents, such as quaternary ammonium salts and chitosan derivatives, have good initial antibacterial effects, but they suffer from poor thermal stability, easy decomposition and failure during high-temperature processing, short antibacterial duration, and easy migration. Inorganic antibacterial agents, such as silver-based and zinc-based antibacterial agents, have excellent thermal stability and long-lasting antibacterial properties, but because they are inorganic powders, they have poor compatibility with the organic PS matrix. Direct addition can easily lead to agglomeration, resulting in decreased film transmittance and increased haze, which seriously affects the optical advantages of PS films.

[0004] For example, Chinese invention patent document CN103467873A discloses a PS antibacterial plastic, composed of the following components by weight: 150-155 parts PS, 10 parts maleic acid-modified PP, 10-15 parts potassium titanate whiskers, 10-18 parts azobisisobutyronitrile, 5-7 parts epoxidized soybean oil, 10-13 parts wollastonite fiber, 10-15 parts melamine cyanurate, 10-15 parts chitosan-grafted methyl methacrylate, 10-12 parts triethylenetetramine, and 10-15 parts ammonium polyphosphate. The PS antibacterial plastic obtained by this invention has excellent antibacterial properties; a small amount is sufficient to achieve a significant antibacterial effect. It does not decompose or react with other materials during high-temperature melt molding and thermoforming processes. It is easily and evenly dispersed in plastics, exhibits good weather resistance and durability, thus providing long-term antibacterial properties. However, the material has a complex composition and a high total amount of functional components, which leads to a significant reduction in light transmittance. Furthermore, it does not employ a biaxial stretching process, making it impossible to balance high rigidity and high light transmittance, thus making it unsuitable for demanding scenarios such as high-end transparent packaging.

[0005] It is evident that how to provide an antibacterial PS film that achieves stable and long-lasting antibacterial effects while ensuring the core performance of high light transmittance and low haze, and its preparation method, is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] The main objective of this invention is to overcome the above-mentioned shortcomings and provide an antibacterial PS film and its preparation method. The film has high light transmittance, significant antibacterial effect, and good antibacterial durability.

[0007] To achieve the above objectives, the present invention provides an antibacterial PS film, which, by weight, comprises the following raw materials: 100 parts of polystyrene resin, 15-25 parts of composite antibacterial agent, 1-2 parts of compatibilizer, and 3-5 parts of additives; the composite antibacterial agent is made from the following raw materials by weight: 6-10 parts of silver-loaded zirconium phosphate, 15-25 parts of silver-loaded titanium dioxide nanocrystals, 5-8 parts of graphene oxide, 1-3 parts of sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 2-4 parts of reactive β-cyclodextrin quaternary ammonium salt.

[0008] Preferably, the polystyrene resin is GPPS 666D-AMST.

[0009] Preferably, the compatibilizer is compatibilizer ST-4.

[0010] Preferably, the additives are antioxidants, lubricants and plasticizers compounded in a mass ratio of 1:(0.8-1.2):(2-3).

[0011] Preferably, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0012] Preferably, the lubricant is zinc stearate.

[0013] Preferably, the plasticizer is epoxidized soybean oil.

[0014] Preferably, the silver-loaded zirconium phosphate has a particle size of 30-50 nm, a specific surface area >45 m² / g, a particle specific gravity of 3.0 g / cm³, and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0015] Preferably, the preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 15-20 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 178-185℃ for 7-9 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 80-90℃ for 4-6 h, calcining at 540-560℃ for 1.5-2 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals.

[0016] Preferably, the ratio of the isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2g:40mL:0.3g:1g.

[0017] Preferably, the thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm.

[0018] Preferably, the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0019] Another object of the present invention is to provide a method for preparing the antibacterial PS film, comprising the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate to a high-speed mixer and premix at 1200 r / min for 2-3 min. Then, add polystyrene resin, compatibilizer, and additives, and mix at 800-1000 r / min and 60-80℃ for 5-8 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 50-60℃ by a casting roller to obtain a casting sheet with a thickness of 2.0-3.0mm; Step S3: Feed the casting into a biaxial stretching machine, first perform longitudinal stretching at a temperature of 90-95℃ and a stretching ratio of 3-5 times; then perform transverse stretching at a temperature of 100-110℃ and a stretching ratio of 4-6 times. After stretching, the film is set at 110-120℃ for 5-10 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 50-60℃ for 20-30 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 10-15 m / min to obtain an antibacterial PS film with a thickness of 50-100 μm.

[0020] Preferably, the extrusion temperature in step S2 is 160-190℃ and the screw speed is 200-300 r / min.

[0021] Preferably, the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 10-20%.

[0022] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The antibacterial PS film disclosed in this invention comprises, by weight, 100 parts of polystyrene resin, 15-25 parts of composite antibacterial agent, 1-2 parts of compatibilizer, and 3-5 parts of additives; the composite antibacterial agent is made from the following raw materials by weight: 6-10 parts of silver-loaded zirconium phosphate, 15-25 parts of silver-loaded titanium dioxide nanocrystals, 5-8 parts of graphene oxide, 1-3 parts of sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 2-4 parts of reactive β-cyclodextrin quaternary ammonium salt; through the mutual cooperation and synergistic effect of the raw materials, the resulting antibacterial PS film has high light transmittance, significant antibacterial effect, and good antibacterial durability.

[0023] (2) The antibacterial PS film disclosed in this invention constructs an inorganic antibacterial core by using silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals and graphene oxide, combined with the coupling modification of sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate and the synergistic effect of reactive β-cyclodextrin quaternary ammonium salt, so that the particle size of the inorganic antibacterial powder is stably controlled at the nanoscale and uniformly dispersed, thus achieving the contradictory unity of high light transmittance and strong antibacterial properties. The composite antibacterial agent provides long-lasting bactericidal and photocatalytic bactericidal functions through silver-loaded zirconium phosphate and silver-loaded titanium dioxide nanocrystals. Graphene oxide plays a role in physical barrier and electronic conduction assistance. Sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate achieves interface modification and uniform dispersion of inorganic antibacterial components and PS matrix. Reactive β-cyclodextrin quaternary ammonium salt completes rapid surface bactericidal and silver ion slow-release regulation. The components work together to form a synergistic mechanism of "rapid onset of action - continuous antibacterial - stable dispersion". This not only overcomes the limitations of single antibacterial agents such as poor thermal stability, easy aggregation and short antibacterial time, but also achieves the compatibility and unity of antibacterial efficiency, long-term stability and the core performance of high light transmittance and high rigidity of film. The quaternary ammonium salt group on the reactive β-cyclodextrin quaternary ammonium salt can undergo ion exchange with sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate and be fixed on the membrane surface, effectively improving performance stability; the chloropyrimidine structure on it can bind to the amino groups of bacterial cell wall proteins through the chlorine atoms in the molecular structure, thereby destroying the cell wall integrity and achieving rapid sterilization; at the same time, it can also improve aging resistance.

[0024] (3) The antibacterial PS film disclosed in this invention uses silver-loaded titanium dioxide nanocrystals, which achieves a breakthrough in performance in multiple dimensions compared with conventional nano-titanium dioxide silver-loaded antibacterial agents. First, the antibacterial activity is better, the nanocrystal particle size is more uniform and the specific surface area is larger, and the number of antibacterial active sites is significantly increased compared with conventional powders. Second, the dispersion compatibility is better. After the nanocrystals are modified with sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate coupling agent, the interfacial bonding force with the PS matrix is ​​significantly enhanced. Third, the antibacterial durability and safety are higher. The nanocrystal lattice structure is stable and the fluctuation of the silver ion slow release rate is small, avoiding the "sudden release-attenuation" problem of conventional powders.

[0025] (4) The antibacterial PS film disclosed in this invention adopts a two-step process of "premixing and dispersion + post-treatment fixation": the first step is to achieve uniform dispersion of inorganic antibacterial agents in the matrix through high-speed mixing and twin-screw extrusion; the second step is to soak the film in a reactive β-cyclodextrin quaternary ammonium salt dispersion system, so that the organic antibacterial components form hydrogen bonds and ionic bonds with the hydroxyl groups on the film surface, thus constructing an antibacterial gradient structure of "surface enrichment - internal slow release". This structure ensures that the concentration of antibacterial agents on the film surface is sufficient to quickly inhibit the growth of microorganisms, while the internally released antibacterial ions continuously replenish the surface activity. Compared with the traditional single blending process, the antibacterial response time is significantly shortened, the antibacterial stability is significantly improved, and the antibacterial durability level is significantly better than that of the prior art.

[0026] (5) The antibacterial PS film disclosed in this invention uses industrially mass-produced raw materials. The premixing process of the composite antibacterial agent can be achieved by existing high-speed mixing equipment. The process flow of twin-screw extrusion-biaxial stretching-immersion post-treatment is highly compatible with existing BOPS production lines. Only simple modifications to the post-treatment process are needed to achieve large-scale production. Detailed Implementation

[0027] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0028] An antibacterial PS film, by weight, comprises the following raw materials: 100 parts polystyrene resin, 15 parts composite antibacterial agent, 1 part compatibilizer, and 3 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 6 parts silver-loaded zirconium phosphate, 15 parts silver-loaded titanium dioxide nanocrystals, 5 parts graphene oxide, 1 part sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 2 parts reactive β-cyclodextrin quaternary ammonium salt.

[0029] The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4; the additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:0.8:2; the antioxidant is antioxidant 1010; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; the silver-loaded zirconium phosphate has a particle size of 30-50nm, a specific surface area >45m² / g, a particle specific gravity of 3.0g / cm², and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0030] The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 15 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 178℃ for 7 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 80℃ for 4 h, calcining at 540℃ for 1.5 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals; the molar ratio of isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2 g:40 mL:0.3 g:1 g.

[0031] The thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm; the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0032] A method for preparing the antibacterial PS film includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate to a high-speed mixer and premix at 1200 r / min for 2 min. Then, add polystyrene resin, compatibilizer, and additives, adjust the speed to 800 r / min, and mix at 60℃ for 5 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 50°C by a casting roller to obtain a casting sheet with a thickness of 2.0 mm. Step S3: The casting is fed into a biaxial stretching machine. First, it is stretched longitudinally at a temperature of 90°C and a stretching ratio of 3. Then, it is stretched transversely at a temperature of 100°C and a stretching ratio of 4. The stretched film is then set at 110°C for 5 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 50°C for 20 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 10 m / min to obtain an antibacterial PS film with a thickness of 50 μm.

[0033] The extrusion temperature in step S2 is 160°C and the screw speed is 200 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 10%. Example 2

[0034] An antibacterial PS film, by weight, comprises the following raw materials: 100 parts polystyrene resin, 17 parts composite antibacterial agent, 1.2 parts compatibilizer, and 3.5 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 7 parts silver-loaded zirconium phosphate, 17 parts silver-loaded titanium dioxide nanocrystals, 6 parts graphene oxide, 1.5 parts sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 2.5 parts reactive β-cyclodextrin quaternary ammonium salt.

[0035] The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4; the additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:0.9:2.3; the antioxidant is antioxidant 168; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; the silver-loaded zirconium phosphate has a particle size of 30-50 nm, a specific surface area >45 m² / g, a particle specific gravity of 3.0 g / cm³, and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0036] The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 17 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 181℃ for 7.5 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 83℃ for 4.5 h, calcining at 545℃ for 1.7 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals; the molar ratio of isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2 g:40 mL:0.3 g:1 g.

[0037] The thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm; the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0038] A method for preparing the antibacterial PS film includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate to a high-speed mixer and premix at 1200 r / min for 2.2 min. Then, add polystyrene resin, compatibilizer, and additives, adjust the speed to 850 r / min, and mix at 65℃ for 6 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 53°C by a casting roller to obtain a casting sheet with a thickness of 2.3 mm. Step S3: The casting is fed into a biaxial stretching machine. First, it is stretched longitudinally at a temperature of 92°C and a stretching ratio of 3.5. Then, it is stretched transversely at a temperature of 103°C and a stretching ratio of 4.5. The stretched film is then set at 113°C for 6 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 53°C for 23 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 12 m / min to obtain an antibacterial PS film with a thickness of 60 μm.

[0039] The extrusion temperature in step S2 is 170°C and the screw speed is 230 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 13%. Example 3

[0040] An antibacterial PS film, by weight, comprises the following raw materials: 100 parts polystyrene resin, 20 parts composite antibacterial agent, 1.5 parts compatibilizer, and 4 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 8 parts silver-loaded zirconium phosphate, 20 parts silver-loaded titanium dioxide nanocrystals, 6.5 parts graphene oxide, 2 parts sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 3 parts reactive β-cyclodextrin quaternary ammonium salt.

[0041] The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4; the additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:1:2.5; the antioxidant is antioxidant 1010; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; the silver-loaded zirconium phosphate has a particle size of 30-50 nm, a specific surface area >45 m² / g, a particle specific gravity of 3.0 g / cm³, and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0042] The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 17.5 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 183℃ for 8 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 85℃ for 5 h, calcining at 550℃ for 1.8 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals; the molar ratio of isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2 g:40 mL:0.3 g:1 g.

[0043] The thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm; the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0044] A method for preparing the antibacterial PS film includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate into a high-speed mixer and premix at 1200 r / min for 2.5 min. Then, add polystyrene resin, compatibilizer, and additives, and mix at 900 r / min and 70℃ for 6.5 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 55°C by a casting roller to obtain a casting sheet with a thickness of 2.5 mm. Step S3: The casting is fed into a biaxial stretching machine. First, it is stretched longitudinally at a temperature of 93°C and a stretching ratio of 4. Then, it is stretched transversely at a temperature of 105°C and a stretching ratio of 5. The stretched film is set at 115°C for 7.5 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 55°C for 25 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 13 m / min to obtain an antibacterial PS film with a thickness of 75 μm.

[0045] The extrusion temperature in step S2 is 175°C and the screw speed is 250 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 15%. Example 4

[0046] An antibacterial PS film, by weight, comprises the following raw materials: 100 parts polystyrene resin, 23 parts composite antibacterial agent, 1.8 parts compatibilizer, and 4.5 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 9.5 parts silver-loaded zirconium phosphate, 23 parts silver-loaded titanium dioxide nanocrystals, 7.5 parts graphene oxide, 2.5 parts sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 3.5 parts reactive β-cyclodextrin quaternary ammonium salt.

[0047] The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4; the additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:1.1:2.8; the antioxidant is antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 3:5; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; the silver-loaded zirconium phosphate has a particle size of 30-50nm, a specific surface area >45m² / g, a particle specific gravity of 3.0g / cm², and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0048] The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 19 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 183℃ for 8.5 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 88℃ for 5.5 h, calcining at 555℃ for 1.9 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals; the molar ratio of isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2 g:40 mL:0.3 g:1 g.

[0049] The thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm; the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0050] A method for preparing the antibacterial PS film includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate to a high-speed mixer and premix at 1200 r / min for 2.8 min. Then, add polystyrene resin, compatibilizer, and additives, and mix at 950 r / min and 75℃ for 7.5 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 58°C by a casting roller to obtain a casting sheet with a thickness of 2.8 mm. Step S3: The casting is fed into a biaxial stretching machine. First, longitudinal stretching is performed at a stretching temperature of 94℃ and a stretching ratio of 3-5 times. Then, transverse stretching is performed at a stretching temperature of 108℃ and a stretching ratio of 5.5 times. The stretched film is then set at 118℃ for 9 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 58°C for 28 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 14 m / min to obtain an antibacterial PS film with a thickness of 90 μm.

[0051] The extrusion temperature in step S2 is 185°C and the screw speed is 290 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 18%. Example 5

[0052] An antibacterial PS film, by weight, comprises the following raw materials: 100 parts polystyrene resin, 25 parts composite antibacterial agent, 2 parts compatibilizer, and 5 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 10 parts silver-loaded zirconium phosphate, 25 parts silver-loaded titanium dioxide nanocrystals, 8 parts graphene oxide, 3 parts sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate, and 4 parts reactive β-cyclodextrin quaternary ammonium salt.

[0053] The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4; the additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:1.2:3; the antioxidant is antioxidant 1010 and antioxidant 168 mixed in a mass ratio of 3:5; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; the silver-loaded zirconium phosphate has a particle size of 30-50nm, a specific surface area >45m² / g, a particle specific gravity of 3.0g / cm², and a silver loading of 2%-8%, and is manufactured by Guangzhou Yuanda New Materials Co., Ltd., with product number YD0121.

[0054] The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 20 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 185℃ for 9 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 90℃ for 6 h, calcining at 560℃ for 2 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals; the ratio of isopropyl titanate solution, deionized water, silver nitrate, and sodium hydroxide is 2 g:40 mL:0.3 g:1 g.

[0055] The thickness of the graphene oxide is ≤5nm and the sheet diameter is 10μm; the reactive β-cyclodextrin quaternary ammonium salt is prepared according to the method in Example 4 of CN106008755B.

[0056] A method for preparing the antibacterial PS film includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediaminetriacetate to a high-speed mixer and premix for 3 minutes at 1200 r / min. Then, add polystyrene resin, compatibilizer, and additives, adjust the speed to 1000 r / min, and mix for 8 minutes at 80°C to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 60°C by a casting roller to obtain a casting sheet with a thickness of 3.0 mm. Step S3: The casting is fed into a biaxial stretching machine. First, it is stretched longitudinally at a temperature of 95°C and a stretching ratio of 5. Then, it is stretched transversely at a temperature of 110°C and a stretching ratio of 6. The stretched film is then set at 120°C for 10 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 60°C for 30 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 15 m / min to obtain an antibacterial PS film with a thickness of 100 μm.

[0057] The extrusion temperature in step S2 is 190°C and the screw speed is 300 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 20%.

[0058] Comparative Example 1 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that an equal amount of silver-loaded titanium dioxide antibacterial agent VK-T07 is used instead of silver-loaded titanium dioxide nanocrystals.

[0059] Comparative Example 2 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that no reactive β-cyclodextrin quaternary ammonium salt is added.

[0060] Comparative Example 3 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that an equal amount of silver-loaded zirconium phosphate is used instead of silver-loaded titanium dioxide nanocrystals.

[0061] Comparative Example 4 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that an equal amount of silver-loaded titanium dioxide nanocrystals are used instead of silver-loaded zirconium phosphate.

[0062] Comparative Example 5 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that an equal amount of graphene oxide is used instead of silver-loaded zirconium phosphate.

[0063] Comparative Example 6 An antibacterial PS film and its preparation method are basically the same as those in Example 5, except that an equal amount of silver-loaded zirconium phosphate is used instead of graphene oxide.

[0064] To further illustrate the beneficial technical effects of the antibacterial PS films involved in the various embodiments of the present invention, relevant performance tests were conducted on the antibacterial PS films involved in Example 5 and Comparative Examples 1-6. The test results are shown in Table 1, and the test methods are as follows: (1) Light transmittance: The test was conducted in accordance with GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics". Each sample was tested 3 times and the average value was taken. (2) Antibacterial performance test: The test was conducted in accordance with QB / T2591-2003A. The test strain was Staphylococcus aureus ATCC6538, and the antibacterial rate of the sample was tested after 100 water washes.

[0065] Table 1. Test results of antibacterial PS film performance project Light transmittance Antibacterial rate Antibacterial durability unit % % % Example 5 91.5 99.9 99.7 Comparative Example 1 89.2 96.3 89.5 Comparative Example 2 90.3 97.2 76.8 Comparative Example 3 90.5 95.3 92.5 Comparative Example 4 91.0 94.7 90.2 Comparative Example 5 89.8 93.8 91.0 Comparative Example 6 90.7 92.6 88.5 As can be seen from Table 1, the antibacterial PS film of Example 5 has significantly better light transmittance, antibacterial properties and antibacterial durability than the comparative example. The combined use of silver-loaded titanium dioxide nanocrystals, reactive β-cyclodextrin quaternary ammonium salt, silver-loaded zirconium phosphate and graphene oxide is beneficial to improving the above properties.

[0066] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. An antibacterial PS film, characterized in that, The raw material composition, by weight, includes: 100 parts polystyrene resin, 15-25 parts composite antibacterial agent, 1-2 parts compatibilizer, and 3-5 parts additives; the composite antibacterial agent is made from the following raw materials by weight: 6-10 parts silver-loaded zirconium phosphate, 15-25 parts silver-loaded titanium dioxide nanocrystals, 5-8 parts graphene oxide, 1-3 parts sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate, and 2-4 parts reactive β-cyclodextrin quaternary ammonium salt.

2. The antibacterial PS film according to claim 1, characterized in that, The polystyrene resin is GPPS 666D-AMST; the compatibilizer is compatibilizer ST-4.

3. The antibacterial PS film according to claim 1, characterized in that, The additives are antioxidants, lubricants, and plasticizers compounded in a mass ratio of 1:(0.8-1.2):(2-3).

4. The antibacterial PS film according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1010 and antioxidant 168; the lubricant is zinc stearate; and the plasticizer is epoxidized soybean oil.

5. The antibacterial PS film according to claim 1, characterized in that, The silver-loaded zirconium phosphate has a particle size of 30-50 nm, a specific surface area of ​​>45 m² / g, a particle specific gravity of 3.0 g / cm³, and a silver loading of 2%-8%.

6. The antibacterial PS film according to claim 1, characterized in that, The preparation method of the silver-loaded titanium dioxide nanocrystals includes the following steps: adding isopropyl titanate to deionized water, ultrasonically dispersing for 15-20 min, then adding silver nitrate and sodium hydroxide, stirring evenly to obtain a mixed solution; transferring the mixed solution to a hydrothermal reactor, reacting at 178-185℃ for 7-9 h, and naturally cooling to room temperature; centrifuging to collect the precipitate, washing it alternately with deionized water and ethanol until neutral, drying at 80-90℃ for 4-6 h, calcining at 540-560℃ for 1.5-2 h, and grinding to obtain silver-loaded titanium dioxide nanocrystals.

7. The antibacterial PS film according to claim 6, characterized in that, The ratio of the titanate isopropyl ester solution, deionized water, silver nitrate, and sodium hydroxide is 2g:40mL:0.3g:1g.

8. The antibacterial PS film according to claim 1, characterized in that, The graphene oxide has a thickness of ≤5nm and a sheet diameter of 10μm.

9. A method for preparing an antibacterial PS film according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: First, add silver-loaded zirconium phosphate, silver-loaded titanium dioxide nanocrystals, graphene oxide, and sodium N-(trimethoxysilylpropyl)ethylenediamine triacetate to a high-speed mixer and premix at 1200 r / min for 2-3 min. Then, add polystyrene resin, compatibilizer, and additives, and mix at 800-1000 r / min and 60-80℃ for 5-8 min to obtain the premix. Step S2: The premixed material is added to a twin-screw extruder and extruded, then cooled to 50-60℃ by a casting roller to obtain a casting sheet with a thickness of 2.0-3.0mm; Step S3: Feed the casting into a biaxial stretching machine, first perform longitudinal stretching at a temperature of 90-95℃ and a stretching ratio of 3-5 times; then perform transverse stretching at a temperature of 100-110℃ and a stretching ratio of 4-6 times. After stretching, the film is set at 110-120℃ for 5-10 seconds and cooled to room temperature to obtain the nascent film. Step S4: Immerse the nascent membrane in an aqueous dispersion of reactive β-cyclodextrin quaternary ammonium salt at 50-60℃ for 20-30 hours. After removal, wash and dry the membrane, and then wind it up at a speed of 10-15 m / min to obtain an antibacterial PS film with a thickness of 50-100 μm.

10. The method for preparing the antibacterial PS film according to claim 9, characterized in that, The extrusion temperature in step S2 is 160-190℃, and the screw speed is 200-300 r / min; the mass percentage concentration of the aqueous dispersion of the reactive β-cyclodextrin quaternary ammonium salt in step S4 is 10-20%.