Antibacterial and weatherable white polyester film and method of making the same

Abstract

The application discloses an antibacterial and aging-resistant white polyester film and a preparation method thereof. The antibacterial and aging-resistant white polyester film comprises the following raw material components: 100-140 parts of PETG polyester chips, 5-15 parts of PET polyester chips, 10-30 parts of white master batches, 20-40 parts of functional master batches, 1-5 parts of silicon dioxide and 0.1-1 part of a dispersing agent. The application also provides the preparation method. Compared with the prior art, the antibacterial and aging-resistant white polyester film prepared by the application has the advantages of high mechanical property, ultraviolet aging resistance, good antibacterial property and the like.

Description

Technical Field

[0001] This invention relates to the field of polyester film technology, and in particular to an antibacterial and aging-resistant white polyester film and its preparation method. Background Technology

[0002] Polyester film (PET film) is a film with comprehensive performance. Compared with other thermoplastics, it has advantages such as good light transmittance, gloss, excellent mechanical properties, toughness, and impact resistance, and it is also dimensionally stable. However, ordinary polyester film has general mechanical properties and is prone to photoaging. Therefore, this invention provides a white polyester film with good mechanical properties, resistance to photoaging, and formaldehyde degradation, which is antibacterial and aging-resistant.

[0003] CN114316330A discloses an optical polyester film and its preparation method, which involves a base film and a base coating applied to at least one side of the base film. The base coating comprises the following components in parts by weight: 53-91 parts polyurethane, 1-7 parts nanoparticles, and 8-40 parts crosslinking agent. The polyurethane is a mixture of polycarbonate-based polyurethane and polyester-based polyurethane in a ratio of (1-5):1. The crosslinking agent is a mixture of crosslinking agent A, crosslinking agent B, and crosslinking agent C in any weight ratio. The crosslinking temperature of crosslinking agent A is TA < 80℃, the crosslinking temperature of crosslinking agent B is 80℃ ≤ TB ≤ 120℃, and the crosslinking temperature of crosslinking agent C is TC > 120℃, which improves the adhesion of the polyester film. However, the polyester film of this invention may have relatively low mechanical properties.

[0004] CN111823680A discloses a light-blocking low-density shrink film and its preparation method. The method involves: Layer A being a black light-blocking layer comprising the following raw materials by weight percentage: 0.1-30% black opaque agent, 60-99.9% modified polyethylene terephthalate, and 0-30% pore-forming agent; Layer B being a white opaque layer comprising the following raw materials by weight percentage: 5-40% white opaque agent, 40-95% modified polyethylene terephthalate, and 0-30% pore-forming agent. The light-blocking performance is improved by not using 0% pore-forming agent in both Layer A and Layer B. However, this invention may have the problem of low UV aging resistance. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the antibacterial and aging-resistant white polyester film prepared by the present invention has the advantages of high mechanical properties, UV aging resistance, and good antibacterial properties.

[0006] To achieve the above objectives, the present invention provides an antibacterial and aging-resistant white polyester film, comprising the following raw material components by weight: 100-140 parts PETG polyester chips, 5-15 parts PET polyester chips, 10-30 parts white masterbatch, 20-40 parts functional masterbatch, 1-5 parts silica, 0.1-1 parts dispersant; The functional masterbatch, by weight, is made from 50-70 parts modified titanium dioxide, 0.5-1.5 parts PEG-20000 and 40-70 parts PET polyester chips processed by an exhaust-type twin-screw granulator. The modified titanium dioxide is selected from one of ionic liquid modified titanium dioxide and composite modified titanium dioxide; wherein the composite modified titanium dioxide is titanium dioxide modified by a combination of lignin and ionic liquid.

[0007] Preferably, the white masterbatch is made by processing 50-70 parts by weight of titanium dioxide, 0.5-1.5 parts by weight of PEG-20000, 5-15 parts by weight of foaming agent and 30-50 parts by weight of PET polyester chips using a vented twin-screw granulator.

[0008] Preferably, the foaming agent is selected from at least one of sodium bicarbonate and potassium bicarbonate.

[0009] Preferably, the dispersant is selected from at least one of Honeywell AC-6A and polyethylene wax.

[0010] Preferably, the preparation method of the ionic liquid modified titanium dioxide includes the following steps, by mass: 1-10 parts of tetrabutyl titanate and 10-20 parts of anhydrous ethanol are mixed evenly to obtain an ethanol solution of tetrabutyl titanate; 0.5-1.5 parts of ionic liquid and 1-3 parts of 0.6 mol / L nitric acid are added to 10-20 parts of anhydrous ethanol, and the mixture is sonicated for 10-30 min to obtain an ionic liquid-nitric acid-ethanol mixed solution; under stirring conditions, the ionic liquid-nitric acid-ethanol mixed solution is added to the ethanol solution of tetrabutyl titanate to obtain a sol; 0.05-0.5 parts of sodium borohydride are added to the sol and stirred for 2-4 h, then aged at room temperature for 20-28 h, dried at 50-70℃ for 1-3 h, the solid is ground and passed through a 50-80 mesh sieve to obtain a solid powder; the solid powder is heated to 500℃ at a heating rate of 5℃ / min and calcined at 500℃ for 2-4 h to obtain ionic liquid modified titanium dioxide.

[0011] As a further explanation of the present invention, an organic functional layer is formed on the surface of titanium dioxide through the surface coordination of the ionic liquids tributylpropylphosphine tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, and the hydrolysis product of tetrabutyl titanate. The cationic groups of the ionic liquids are anchored to the titanium dioxide surface through electrostatic interactions or covalent bonds, forming a stable coating structure. NaBH4, as a mild reducing agent, may partially reduce Ti.4 ⁺ for Ti 3 Introducing oxygen vacancies into the titanium dioxide lattice enhances photocatalytic activity and electron transport performance, and also promotes bonding, thereby improving mechanical properties. Titanium dioxide absorbs UV radiation, and ionic liquids may synergistically enhance UV absorption, improving its UV protection. Titanium dioxide generates strong oxidizing free radicals under UV light, which can produce antibacterial effects; ionic liquids can further enhance the antibacterial effect by promoting the disruption of microbial structures.

[0012] More preferably, the preparation method of the composite modified titanium dioxide includes the following steps, in parts by mass: Step 1: Mix 20-30 parts of lignin with 70-80 parts of 1-5 wt% sodium hydroxide aqueous solution, stir and heat to 80-90℃, add 5-15 parts of 10-30 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, continue to react for 3-6 hours, concentrate into a solid, wash with water 3-5 times, filter, and dry the solid to obtain alkaline lignin; Step 2: Mix 1-5 parts of alkaline lignin with 200-400 parts of water evenly, adjust the pH to 1 with hydrochloric acid, then add 1-5 parts of tetrabutyl titanate while stirring, heat to 90-110℃ and react for 5-7 hours, collect the precipitate, dry at 40-60℃ for 3-5 hours, and then dry at 110-130℃ for 10-14 hours to obtain alkaline lignin and titanium dioxide composite particles. Step 3: Mix 1-5 parts of alkaline lignin and titanium dioxide composite particles with 40-60 parts of water until homogeneous, sonicate for 20-40 minutes, add 0.1-1 parts of ionic liquid, stir for 1-3 hours, then heat to 50-70℃ and react for 3-6 hours. Centrifuge, collect the solid, wash with water 2-4 times, and dry at 50-70℃ for 10-14 hours to obtain composite modified titanium dioxide.

[0013] As a further explanation of the present invention, the phenolic hydroxyl and carboxyl groups of lignin form hydrogen bonds or Ti-OC bonds with the hydroxyl groups (-OH) on the surface of titanium dioxide to achieve chemical bonding. The cations of the ionic liquid bind to the negatively charged sites on the surface of lignin-TiO2, such as deprotonated hydroxyl groups, which can improve the mechanical effect. Titanium dioxide can generate strong oxidizing free radicals under ultraviolet light to produce antibacterial effects. The ionic liquid can promote the destruction of microbial structure and improve the antibacterial effect. Quaternized lignin introduces positively charged quaternary ammonium groups, which electrostatically adsorb onto the negatively charged phospholipid layer on the surface of bacterial cell membranes, destroying the integrity of the cell membrane, causing leakage of intracellular substances, and ultimately causing bacterial death, further promoting the antibacterial effect.

[0014] More preferably, the ionic liquid is selected from at least one of tributylpropylphosphine tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

[0015] As a further explanation of the present invention, the preparation method of the tributylpropylphosphine tetrafluoroborate is as follows: 1-10 parts by mass of bromopropane and 10-30 parts by mass of anhydrous toluene are mixed evenly, and then 10-20 parts by mass of tributylphosphine are added. Under nitrogen protection, the mixture is reacted at 70-90°C for 20-28 hours. After the reaction, excess toluene and bromopropane are removed, and the mixture is dried at 100-120°C for 4-6 hours to obtain tributylpropylphosphine bromide. 1-5 parts by mass of tetrafluoroboric acid, 1-10 parts by mass of tributylpropylphosphine bromide, and 80-140 parts by mass of acetonitrile are mixed evenly and stirred at room temperature for 20-28 hours. The mixture is filtered, the filtrate is collected, the acetonitrile in the filtrate is removed, and the mixture is dried to obtain tributylpropylphosphine tetrafluoroborate.

[0016] As a further explanation of the present invention, the preparation method of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate is as follows: 1-3 parts by mass of 1,4-dimethylpiperazine, 3-5 parts by mass of 1,3-propanesulfonic acid lactone, and 10-15 parts by mass of ethyl acetate are mixed and reacted at 60-80°C for 10-16 h. The mixture is then cooled to room temperature, filtered, and the filter cake is dried at 50-70°C for 5-8 h to obtain the intermediate. 2-4 parts by mass of p-toluenesulfonic acid, 1-3 parts by mass of the intermediate, and 0.1-0.3 parts by mass of water are mixed and stirred at 80-120°C for 40-70 min until it becomes a viscous liquid, thus obtaining 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

[0017] This invention also provides a method for preparing an antibacterial and aging-resistant white polyester film, comprising the following preparation steps: Step 1: Mix PETG polyester chips, PET polyester chips, white masterbatch, functional masterbatch, silica, and dispersant, melt them at 240-300℃, and then extrude the melt through a co-extrusion die. Step 2: The melt forms an amorphous polyester film sheet on a rotating cooling roller, with a cooling temperature of 18-40℃; Step 3: After preheating the cooled polyester film sheet at 80-100℃, stretch it longitudinally by 2.0-4.4 times and transversely by 2.5-4.5 times. Step 4: Heat set the stretched film at 170-200℃, cool it, and then roll it up to obtain an antibacterial and aging-resistant white polyester film.

[0018] The beneficial effects of this invention are: 1. This invention utilizes the interaction between various substances through reasonable proportioning and optimizes the preparation process to obtain an antibacterial and aging-resistant white polyester film. The antibacterial and aging-resistant white polyester film obtained by this invention has advantages such as high mechanical properties, UV resistance, and good antibacterial properties.

[0019] 2. Compared with the prior art, the present invention adds titanium dioxide selected from ionic liquid modified titanium dioxide or lignin and ionic liquid composite modified titanium dioxide, which can improve the mechanical effect; titanium dioxide can generate strong oxidizing free radicals under ultraviolet light to produce antibacterial effect, and ionic liquid can promote the destruction of microbial structure and improve antibacterial effect. Quaternized lignin introduces positively charged quaternary ammonium ions, which electrostatically adsorb with the negatively charged phospholipid layer on the surface of bacterial cell membrane, destroying the integrity of cell membrane, causing leakage of intracellular substances, and ultimately causing bacterial death, further promoting the antibacterial effect. Detailed Implementation

[0020] The sources and parameters of some chemical substances in the examples are as follows: PETG polyester chips, grade: YH101, manufacturer: Henan Yuanhong; PET polyester chips, grade: BG80, manufacturer: Yizheng Chemical Fiber; Silica, average particle size: 20nm, color: white; Titanium dioxide, average particle size: 20nm, color: white; Polyethylene wax, item number: DN-108, viscosity: 30cps±10, color: white, sourced from Shanghai Dynaudio Chemical Products Co., Ltd. Lignin, derived from Wuhan Jixin Yibang Biotechnology Co., Ltd.; 1-Butyl-3-methylimidazolium hexafluorophosphate, CAS No.: 174501-64-5.

[0021] Example 1 A method for preparing an antibacterial and aging-resistant white polyester film includes the following preparation steps: Step 1: Mix 120 parts by weight of PETG polyester chips, 10 parts by weight of PET polyester chips, 20 parts by weight of white masterbatch, 30 parts by weight of functional masterbatch, 3 parts by weight of silica, and 0.5 parts by weight of polyethylene wax. After melting at 280°C, extrude the melt through a co-extrusion die. Step 2: The melt forms an amorphous polyester film sheet on a rotating cooling roller at a cooling temperature of 25°C. Step 3: After preheating the cooled polyester film sheet to 80°C, stretch it longitudinally by 2.8 times and transversely by 3 times. Step 4: Heat set the stretched film at 185℃, cool it, and then roll it up to obtain an antibacterial and aging-resistant white polyester film.

[0022] The white masterbatch is made from 60 parts by weight of titanium dioxide, 1.0 part by weight of PEG-20000, 10 parts by weight of sodium bicarbonate and 40 parts by weight of PET polyester chips by a vented twin-screw granulator.

[0023] The functional masterbatch is made by processing 60 parts by weight of ionic liquid modified titanium dioxide, 1.0 parts by weight of PEG-20000 and 60 parts by weight of PET polyester chips through a vented twin-screw granulator.

[0024] The preparation method of the ionic liquid modified titanium dioxide includes the following steps: Five parts by mass of tetrabutyl titanate and 15 parts by mass of anhydrous ethanol were mixed evenly to obtain an ethanol solution of tetrabutyl titanate. One part by mass of tributylpropylphosphine tetrafluoroborate and two parts by mass of 0.6 mol / L nitric acid were added to 15 parts by mass of anhydrous ethanol, and the mixture was ultrasonicated at 100 W and 40 kHz for 20 min to obtain an ionic liquid-nitric acid-ethanol mixed solution. Under stirring, the ionic liquid-nitric acid-ethanol mixed solution was added to the ethanol solution of tetrabutyl titanate to obtain a sol. 0.2 parts by mass of sodium borohydride were added to the sol and stirred for 3 h, then aged at room temperature for 24 h, dried at 60 °C for 2 h, and the solid was ground and passed through a 60-mesh sieve to obtain a solid powder. The solid powder was heated to 500 °C at a heating rate of 5 °C / min and calcined at 500 °C for 3 h to obtain ionic liquid modified titanium dioxide.

[0025] The preparation method of the tributylpropylphosphine tetrafluoroborate is as follows: Five parts by mass of bromopropane and 20 parts by mass of anhydrous toluene were mixed evenly, and then 15 parts by mass of tributylphosphine were added. The mixture was reacted at 80°C for 24 hours under nitrogen protection. After the reaction, excess toluene and bromopropane were removed, and the mixture was dried at 110°C for 5 hours to obtain tributylpropylphosphine bromide. Three parts by mass of tetrafluoroboric acid, five parts by mass of tributylpropylphosphine bromide, and 110 parts by mass of acetonitrile were mixed evenly and stirred at room temperature for 24 hours. The mixture was filtered, the filtrate was collected, and the acetonitrile in the filtrate was removed. The filtrate was dried at 80°C for 6 hours to obtain tributylpropylphosphine tetrafluoroborate. Example 2 A method for preparing an antibacterial and aging-resistant white polyester film differs from Example 1 only in that the method for preparing ionic liquid-modified titanium dioxide includes the following steps: Five parts by mass of tetrabutyl titanate and 15 parts by mass of anhydrous ethanol were mixed evenly to obtain an ethanol solution of tetrabutyl titanate. One part by mass of 1-butyl-3-methylimidazolium hexafluorophosphate and two parts by mass of 0.6 mol / L nitric acid were added to 15 parts by mass of anhydrous ethanol, and the mixture was ultrasonicated at 100 W and 40 kHz for 20 min to obtain an ionic liquid-nitric acid-ethanol mixed solution. Under stirring, the ionic liquid-nitric acid-ethanol mixed solution was added to the ethanol solution of tetrabutyl titanate to obtain a sol. 0.2 parts by mass of sodium borohydride were added to the sol and stirred for 3 h, then aged at room temperature for 24 h, dried at 60 °C for 2 h, and the solid was ground and passed through a 60-mesh sieve to obtain a solid powder. The solid powder was heated to 500 °C at a heating rate of 5 °C / min and calcined at 500 °C for 3 h to obtain ionic liquid modified titanium dioxide.

[0026] Example 3 A method for preparing an antibacterial and aging-resistant white polyester film differs from Example 1 only in that the method for preparing the ionic liquid-modified titanium dioxide includes the following steps, by mass parts: 5 parts by mass of tetrabutyl titanate and 15 parts by mass of anhydrous ethanol are mixed evenly to obtain an ethanol solution of tetrabutyl titanate; 1.0 parts by mass of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, 2 parts by mass of 0.6 15 parts by mass of anhydrous ethanol were added to 1 mol / L nitric acid and sonicated for 20 min at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz to obtain an ionic liquid-nitric acid-ethanol mixed solution. Under stirring, the ionic liquid-nitric acid-ethanol mixed solution was added to an ethanol solution of tetrabutyl titanate to obtain a sol. 0.2 parts by mass of sodium borohydride were added to the sol and stirred for 3 h. The mixture was then aged at room temperature for 24 h and dried at 60 °C for 2 h. The solid was ground and passed through a 60-mesh sieve to obtain a solid powder. The solid powder was heated to 500 °C at a heating rate of 5 °C / min and calcined at 500 °C for 3 h to obtain ionic liquid modified titanium dioxide.

[0027] The preparation method of the 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate is as follows: Two parts by mass of 1,4-dimethylpiperazine, four parts by mass of 1,3-propanesulfonic acid lactone, and 12 parts by mass of ethyl acetate were mixed and reacted at 70°C for 14 h. The mixture was then cooled to room temperature, filtered, and the filter cake was dried at 60°C for 6 h to obtain the intermediate. Three parts by mass of p-toluenesulfonic acid, two parts by mass of the intermediate, and 0.2 parts by mass of water were mixed and stirred at 100°C for 50 min until it became a viscous liquid, thus obtaining 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

[0028] Example 4 A method for preparing an antibacterial and aging-resistant white polyester film differs from Example 1 only in the use of a different functional masterbatch.

[0029] The functional masterbatch described in this embodiment is made by processing 60 parts by weight of composite modified titanium dioxide, 1.0 parts by weight of PEG-20000 and 60 parts by weight of PET polyester chips through a vented twin-screw granulator.

[0030] The preparation method of the composite modified titanium dioxide includes the following steps: Step 1: Mix 25 parts by weight of lignin with 75 parts by weight of 4wt% sodium hydroxide aqueous solution, stir and heat to 85°C, add 10 parts by weight of 20wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, continue to react for 5 hours, concentrate into a solid, wash with water 4 times, filter, and dry the solid to obtain alkaline lignin. Step 2: Mix 3 parts by weight of alkaline lignin with 300 parts by weight of water evenly, adjust the pH to 1 with hydrochloric acid, then add 3 parts by weight of tetrabutyl titanate while stirring, heat to 100℃ and react for 6 hours, collect the precipitate, dry at 50℃ for 4 hours, and then dry at 120℃ for 12 hours to obtain alkaline lignin-titanium dioxide composite particles. Step 3: Mix 3 parts by weight of alkaline lignin-titanium dioxide composite particles with 50 parts by weight of water until homogeneous. Sonicate the mixture for 30 min at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz. Add 0.5 parts by weight of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, stir for 2 h, then heat to 60 °C and react for 4 h. Centrifuge, collect the solid, wash it 3 times with water, and dry it at 60 °C for 12 h to obtain the composite modified titanium dioxide.

[0031] The preparation method of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate is the same as that in Example 3.

[0032] Comparative Example 1 A method for preparing an antibacterial and aging-resistant white polyester film differs from Example 1 only in that the functional masterbatch is made by processing 60 parts by weight of titanium dioxide, 1.0 parts by weight of PEG-20000 and 60 parts by weight of PET polyester chips through a vented twin-screw granulator.

[0033] Comparative Example 2 A method for preparing an antibacterial and aging-resistant white polyester film differs from Example 1 only in that the functional masterbatch is made by processing 60 parts by weight of lignin-modified titanium dioxide, 1.0 parts by weight of PEG-20000 and 60 parts by weight of PET polyester chips through a vented twin-screw granulator.

[0034] The preparation method of the lignin-modified titanium dioxide includes the following steps: Step 1: Mix 25 parts by weight of lignin with 25 parts by weight of 4 wt% sodium hydroxide aqueous solution, stir and heat to 85°C, add 10 parts by weight of 20 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, continue to react for 5 hours, concentrate into a solid, wash with water 4 times, filter, and dry the solid to obtain alkaline lignin. Step 2: Mix 3 parts by weight of alkaline lignin with 300 parts by weight of water until homogeneous, adjust the pH to 1 with hydrochloric acid, then add 3 parts by weight of tetrabutyl titanate while stirring, heat to 100℃ and react for 6 hours, collect the precipitate, dry at 50℃ for 4 hours, and then dry at 120℃ for 12 hours to obtain lignin-modified titanium dioxide.

[0035] Test Example 1 Performance testing The antibacterial and aging-resistant polyester films prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to the following performance tests, and the results are shown in Table 1: The tensile strength was tested according to GB / T 25255-2010 Determination of Tensile Properties of Optical Functional Film Polyethylene Terephthalate (PET) Film. Then, the tensile strength retention rate was tested according to GB / T 14522-2008 Artificial Climate Aging Test Method for Plastics, Coatings and Rubber Materials for Mechanical Industry Products Using Fluorescent Ultraviolet Lamp with UVA-340 fluorescent ultraviolet lamp for 500 hours.

[0036] Table 1 Performance Tests Example 1 216 204 94.4 Example 2 232 224 96.6 Example 3 228 215 94.3 Example 4 271 268 98.9 Comparative Example 1 196 175 89.3 Comparative Example 2 239 218 91.2 A comparison of Examples 1-3 reveals that Example 2 exhibits the highest tensile strength and tensile strength retention rate. This may be because the functional particles in Example 2 are modified titanium dioxide with 1-butyl-3-methylimidazolium hexafluorophosphate. The imidazole ring in 1-butyl-3-methylimidazolium hexafluorophosphate can enhance ultraviolet absorption, resulting in superior UV resistance compared to Examples 1 and 3.

[0037] A comparison of Examples 1-4 and Comparative Examples 1-2 reveals that Example 4 exhibits the highest tensile strength and tensile strength retention. This may be because the functional particles in Example 4 are modified titanium dioxide with a composite of lignin and ionic liquid. Quaternized lignin binds to titanium dioxide via chemical bonds (Ti-OC), forming a rigid-flexible composite structure that enhances the mechanical strength of the film. Its hydrophobic framework and hydrophilic quaternary ammonium groups improve the dispersion of TiO2 in the polyester matrix, reducing stress concentration points. The sulfonic acid groups of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate form hydrogen bonds with polyester segments, strengthening the filler-matrix interface bonding. This process can absorb ultraviolet light and inhibit free radical chain reactions, significantly reducing molecular chain breakage caused by damp heat aging. The addition of lignin and ionic liquid composite modification provides synergistic benefits.

[0038] Test Example 2 Antibacterial rate test The antibacterial and aging-resistant polyester films prepared in Examples 1-4 and Comparative Examples 1-2 were used as the experimental group, and the polyester films of the same specifications prepared from pure PETG polyester chips were used as the blank group, with 5 samples in each group. The antibacterial rate was tested under no light according to GB / T31402-2023 "Determination of antibacterial activity of plastics and other non-porous materials". Another group was tested under sunlight using the same method, for a duration of 8 hours. The calculation formula is as follows: Antibacterial rate = (number of colonies in the blank group - number of colonies in the experimental group) / number of colonies in the blank group × 100%. The test results are shown in Table 2.

[0039] Table 2 Antibacterial Rate Example 1 80.2 86.9 Example 2 85.4 88.6 Example 3 89.6 92.8 Example 4 94.3 99.9 Comparative Example 1 31.9 35.3 Comparative Example 2 42.3 48.7 A comparison of Examples 1-4 and Comparative Examples 1-2 reveals that Example 4 exhibits an antibacterial rate of 94.3% under light-free conditions and 99.9% under sunlight. This may be because the functional particles in Example 4 are modified titanium dioxide with a composite of lignin and ionic liquid. Titanium dioxide generates strong oxidizing free radicals under ultraviolet light, degrading formaldehyde molecules. 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, with its sulfonic acid groups, depolarizes the cell membrane. Simultaneously, the sulfonic acid groups regulate the band structure of TiO2, enhancing visible light response and promoting the generation of strong oxidizing free radicals, synergistically enhancing the antibacterial effect. Quaternized lignin introduces positively charged quaternary ammonium groups, which electrostatically adsorb onto the negatively charged phospholipid layer on the bacterial cell membrane surface, disrupting cell membrane integrity, leading to intracellular leakage, and ultimately bacterial death, further promoting the antibacterial effect.

Claims

1. A white polyester film with antibacterial and aging-resistant properties, characterized in that, By weight, it includes the following raw material components: 100-140 parts PETG polyester chips, 5-15 parts PET polyester chips, 10-30 parts white masterbatch, 20-40 parts functional masterbatch, 1-5 parts silica, 0.1-1 parts dispersant; The functional masterbatch, by weight, is made from 50-70 parts modified titanium dioxide, 0.5-1.5 parts PEG-20000 and 40-70 parts PET polyester chips processed by an exhaust-type twin-screw granulator. The modified titanium dioxide is selected from one of ionic liquid modified titanium dioxide and composite modified titanium dioxide; the composite modified titanium dioxide is titanium dioxide modified by a combination of lignin and ionic liquid. The preparation method of the ionic liquid modified titanium dioxide includes the following steps, in parts by mass: Mix 1-10 parts of tetrabutyl titanate and 10-20 parts of anhydrous ethanol evenly to obtain an ethanol solution of tetrabutyl titanate; add 0.5-1.5 parts of ionic liquid and 1-3 parts of 0.6 mol / L nitric acid to 10-20 parts of anhydrous ethanol, and sonicate for 10-30 min to obtain solution B; under stirring conditions, add solution B to the ethanol solution of tetrabutyl titanate to obtain a sol; add 0.05-0.5 parts of sodium borohydride to the sol and stir for 2-4 h, then age at room temperature for 20-28 h, dry at 50-70℃ for 1-3 h, grind the solid, and pass it through a 50-80 mesh sieve to obtain a solid powder; heat the solid powder to 500℃ at a heating rate of 5℃ / min and calcine at 500℃ for 2-4 h to obtain ionic liquid modified titanium dioxide; The preparation method of the composite modified titanium dioxide includes the following steps, in parts by mass: Step 1: Mix 20-30 parts of lignin with 70-80 parts of 1-5 wt% sodium hydroxide aqueous solution, stir and heat to 80-90℃, add 5-15 parts of 10-30 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution, continue to react for 3-6 hours, concentrate into a solid, wash with water 3-5 times, filter, and dry the solid to obtain alkaline lignin; Step 2: Mix 1-5 parts of alkaline lignin with 200-400 parts of water evenly, adjust the pH to 1 with hydrochloric acid, then add 1-5 parts of tetrabutyl titanate while stirring, heat to 90-110℃ and react for 5-7 hours, collect the precipitate, dry at 40-60℃ for 3-5 hours, and then dry at 110-130℃ for 10-14 hours to obtain alkaline lignin and titanium dioxide composite particles. Step 3: Mix 1-5 parts of alkaline lignin and titanium dioxide composite particles with 40-60 parts of water until homogeneous, sonicate for 20-40 minutes, add 0.1-1 parts of ionic liquid, stir for 1-3 hours, then heat to 50-70℃ and react for 3-6 hours. Centrifuge, collect the solid, wash with water 2-4 times, and dry at 50-70℃ for 10-14 hours to obtain composite modified titanium dioxide.

2. The antibacterial and aging-resistant white polyester film as described in claim 1, characterized in that: The white masterbatch, by weight, is made from 50-70 parts titanium dioxide, 0.5-1.5 parts PEG-20000, 5-15 parts foaming agent, and 30-50 parts PET polyester chips processed by a vented twin-screw granulator.

3. The antibacterial and aging-resistant white polyester film as described in claim 2, characterized in that: The foaming agent is selected from at least one of sodium bicarbonate and potassium bicarbonate.

4. The antibacterial and aging-resistant white polyester film as described in claim 1, characterized in that: The dispersant is selected from at least one of Honeywell AC-6A and polyethylene wax.

5. The antibacterial and aging-resistant white polyester film as described in claim 1, characterized in that: The ionic liquid is selected from at least one of tributylpropylphosphine tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

6. The antibacterial and aging-resistant white polyester film as described in claim 5, characterized in that: The preparation method of the tributylpropylphosphine tetrafluoroborate is as follows: by mass, 1-10 parts of bromopropane and 10-30 parts of anhydrous toluene are mixed evenly, and then 10-20 parts of tributylphosphine are added. Under nitrogen protection, the mixture is reacted at 70-90℃ for 20-28 hours. After the reaction, excess toluene and bromopropane are removed, and the mixture is dried at 100-120℃ for 4-6 hours to obtain tributylpropylphosphine bromide. 1-5 parts of tetrafluoroboric acid, 1-10 parts of tributylpropylphosphine bromide, and 80-140 parts of acetonitrile are mixed evenly and stirred at room temperature for 20-28 hours. The mixture is filtered, the filtrate is collected, the acetonitrile in the filtrate is removed, and the mixture is dried to obtain tributylpropylphosphine tetrafluoroborate.

7. The antibacterial and aging-resistant white polyester film as described in claim 5, characterized in that: The method for preparing 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate is as follows: by mass, 1-3 parts of 1,4-dimethylpiperazine, 3-5 parts of 1,3-propanesulfonic acid lactone and 10-15 parts of ethyl acetate are mixed and reacted at 60-80℃ for 10-16 h. After cooling to room temperature, the mixture is filtered, and the filter cake is dried at 50-70℃ for 5-8 h to obtain an intermediate. 2-4 parts of p-toluenesulfonic acid, 1-3 parts of the intermediate and 0.1-0.3 parts of water are mixed and stirred at 80-120℃ for 40-70 min until it becomes a viscous liquid, thus obtaining 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

8. The method for preparing the antibacterial and aging-resistant white polyester film according to any one of claims 1-7, characterized in that, The preparation steps include the following: Step 1: Mix PETG polyester chips, PET polyester chips, white masterbatch, functional masterbatch, silica, and dispersant, melt them at 240-300℃, and then extrude the melt through a co-extrusion die. Step 2: The melt forms an amorphous polyester film sheet on a rotating cooling roller, with a cooling temperature of 18-40℃; Step 3: After preheating the cooled polyester film sheet at 80-100℃, stretch it longitudinally by 2.0-4.4 times and transversely by 2.5-4.5 times. Step 4: Heat set the stretched film at 170-200℃, cool it, and then roll it up to obtain an antibacterial and aging-resistant white polyester film.