Antibacterial anti-aging white polyester film and preparation method thereof

Abstract

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

Description

Technical Field

[0001] The invention relates to the technical field of polyester films, in particular to an antibacterial and aging-resistant white polyester film and a preparation method thereof. Background Art

[0002] Polyester film (PET film) is a film with a wide range of properties. Compared to other thermoplastics, it boasts advantages such as high light transmittance, gloss, excellent mechanical properties, toughness, impact resistance, and dimensional stability. However, conventional polyester films suffer from mediocre mechanical properties and are susceptible to light aging. Therefore, the present invention provides a white polyester film with excellent mechanical properties, resistance to light aging, formaldehyde degradation, antibacterial properties, and aging resistance.

[0003] CN114316330A discloses an optical polyester film and its preparation method, comprising a base film and a primer coated on at least one side of the base film. The primer comprises the following substances in parts by weight: 53-91 parts polyurethane, 1-7 parts nanoparticles, and 8-40 parts crosslinking agent, wherein the polyurethane is a mixture of polycarbonate polyurethane and polyester polyurethane in a ratio of (1-5):1. The crosslinking agent is a mixture of crosslinker A, crosslinker B, and crosslinker C in any weight ratio. The crosslinking temperature of crosslinker A is TA < 80°C, the crosslinking temperature of crosslinker B is 80°C ≤ TB ≤ 120°C, and the crosslinking temperature of crosslinker C is TC > 120°C, thereby improving the adhesion of the polyester film. However, the polyester film of this invention may suffer from low mechanical properties.

[0004] CN111823680A discloses a light-blocking, low-density shrink film and its preparation method. Layer A is a black light-blocking layer comprising the following raw materials by weight: 0.1-30% black masking agent, 60-99.9% modified polyethylene terephthalate, and 0-30% pore-forming agent; and Layer B is a white masking layer comprising the following raw materials by weight: 5-40% white masking agent, 40-95% modified polyethylene terephthalate, and 0-30% pore-forming agent. The pore-forming agent content in layers A and B differs from being 0% simultaneously, thereby improving light-blocking performance. However, this invention may suffer from 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, resistance to ultraviolet aging, good antibacterial properties, etc.

[0006] To achieve the above-mentioned object, the present invention provides an antibacterial and aging-resistant white polyester film, which comprises the following raw material components in parts by mass: 100-140 parts of PETG polyester chips, 5-15 parts of PET polyester chips, 10-30 parts of white masterbatch, 20-40 parts of functional masterbatch, 1-5 parts of silica, 0.1-1 part of dispersant; The functional masterbatch is made by processing 50-70 parts by mass of modified titanium dioxide, 0.5-1.5 parts of PEG-20000 and 40-70 parts of PET polyester chips through a venting 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 composite modified by lignin and ionic liquid.

[0007] Preferably, the white masterbatch is made by processing 50-70 parts by mass of titanium dioxide, 0.5-1.5 parts by mass of PEG-20000, 5-15 parts by mass of foaming agent and 30-50 parts by mass of PET polyester chips through a venting 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 comprises the following steps, by mass: uniformly mixing 1-10 parts of tetrabutyl titanate and 10-20 parts of anhydrous ethanol to obtain an ethanol solution of tetrabutyl titanate; adding 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 ultrasonicating for 10-30 minutes to obtain an ionic liquid-nitric acid-ethanol mixed solution; adding the ionic liquid-nitric acid-ethanol mixed solution to the ethanol solution of tetrabutyl titanate under stirring to obtain a sol; adding 0.05-0.5 parts of sodium borohydride to the sol and stirring for 2-4 hours, then aging at room temperature for 20-28 hours, drying at 50-70°C for 1-3 hours, grinding the solid, and passing through a 50-80 mesh sieve to obtain a solid powder; heating the solid powder to 500°C at a heating rate of 5°C / min and calcining at 500°C for 2-4 hours to obtain ionic liquid modified titanium dioxide.

[0011] As a further illustration of the present invention, an organic functional layer is formed on the surface of titanium dioxide by the surface coordination of 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 liquid are anchored on the titanium dioxide surface through electrostatic interaction or covalent bonds to form a stable coating structure. NaBH4, as a mild reducing agent, may partially reduce the TiO2.4 ⁺ is Ti 3 ⁺, introducing oxygen vacancies into the titanium dioxide lattice enhances photocatalytic activity and electron transport properties, promotes bonding, and improves mechanical properties. Titanium dioxide absorbs UV light, and ionic liquids may synergistically enhance UV absorption and improve UV resistance. Titanium dioxide can produce strong oxidative free radicals under ultraviolet light, which can have antibacterial effects. Ionic liquids can promote the destruction of microbial structures and enhance antibacterial effects.

[0012] Further preferably, the preparation method of the composite modified titanium dioxide comprises the following steps, calculated in parts by mass: Step 1, 20-30 parts of lignin and 70-80 parts of 1-5wt% sodium hydroxide aqueous solution are mixed evenly, stirred and heated to 80-90°C, 5-15 parts of 10-30wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution are added, the reaction is continued for 3-6 hours, concentrated to a solid, washed with water 3-5 times, filtered, and the solid is dried to obtain alkaline lignin; Step 2: Evenly mix 1-5 parts of alkaline lignin with 200-400 parts of water, adjust the pH to 1 with hydrochloric acid, then add 1-5 parts of tetrabutyl titanate under stirring, heat and react at 90-110°C for 5-7 hours, collect the precipitate, dry at 40-60°C for 3-5 hours, and then dry at 110-130°C for 10-14 hours to obtain alkaline lignin and titanium dioxide composite particles; Step 3: Evenly mix 1-5 parts of alkaline lignin and titanium dioxide composite particles with 40-60 parts of water, ultrasonicate for 20-40 minutes, add 0.1-1 parts of ionic liquid, stir for 1-3 hours, then heat to 50-70°C for reaction for 3-6 hours, centrifuge, collect the solid, wash with water 2-4 times, and dry at 50-70°C for 10-14 hours to obtain composite modified titanium dioxide.

[0013] As a further illustration 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 combine with the negatively charged sites on the surface of lignin-TiO2, such as deprotonated hydroxyl groups, to improve the mechanical effect. Titanium dioxide can produce strong oxidative free radicals under ultraviolet light to produce antibacterial effects. The ionic liquid can promote the destruction of microbial structure to enhance the antibacterial effect. Quaternized lignin introduces positively charged quaternary ammonium roots, which electrostatically adsorb to the negatively charged phospholipid layer on the surface of the bacterial cell membrane, destroying the integrity of the cell membrane, leading to leakage of intracellular substances, and ultimately killing the bacteria, further promoting the antibacterial effect.

[0014] Further 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 illustration of the present invention, the preparation method of tributylpropylphosphine tetrafluoroborate is as follows: 1-10 parts of bromopropyl n-propane and 10-30 parts of anhydrous toluene are uniformly mixed, then 10-20 parts of tributylphosphine are added, and the mixture is reacted at 70-90° C. for 20-28 hours under nitrogen protection. After the reaction, excess toluene and bromopropyl n-propane are removed, and the mixture is dried at 100-120° C. 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 uniformly mixed, stirred and reacted at room temperature for 20-28 hours, filtered, the filtrate is collected, the acetonitrile in the filtrate is removed, and dried to obtain tributylpropylphosphine tetrafluoroborate.

[0016] As a further illustration of the present invention, the preparation method of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate is as follows: by weight, 1-3 parts of 1,4-dimethylpiperazine, 3-5 parts of 1,3-propane sultone and 10-15 parts of ethyl acetate are mixed, reacted at 60-80°C for 10-16 hours, cooled to room temperature, filtered, and the filter cake is dried at 50-70°C for 5-8 hours 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°C for 40-70 minutes until it becomes a viscous liquid, thereby obtaining 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

[0017] The present invention also provides a method for preparing an antibacterial and aging-resistant white polyester film, comprising the following steps: Step 1: Mix PETG polyester chips, PET polyester chips, white masterbatch, functional masterbatch, silica, and dispersant, melt them at 240-300°C, and 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 18-40°C; Step 3: preheat the cooled polyester film sheet at 80-100°C, and then stretch it by 2.0-4.4 times in the longitudinal direction and 2.5-4.5 times in the transverse direction; Step 4: heat-set the stretched film at 170-200° C., and roll it up after cooling to obtain an antibacterial and aging-resistant white polyester film.

[0018] Beneficial effects of the present invention: 1. The present invention utilizes the interaction between various substances in a reasonable proportion 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 the present invention has the advantages of high mechanical properties, UV resistance, and good antibacterial properties.

[0019] 2. Compared with the existing technology, 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 produce strong oxidative free radicals under ultraviolet light to produce antibacterial effects, and ionic liquids can promote the destruction of microbial structure to improve the antibacterial effect. Quaternized lignin introduces positively charged quaternary ammonium roots, which electrostatically adsorb with the negatively charged phospholipid layer on the surface of the bacterial cell membrane, destroying the integrity of the cell membrane, causing leakage of intracellular substances, and ultimately killing the bacteria, further promoting the antibacterial effect. DETAILED DESCRIPTION

[0020] The sources and parameters of some chemical substances in the examples are as follows: PETG polyester chips, brand: YH101, manufacturer: Henan Yuanhong; PET polyester chips, brand: BG80, manufacturer: Yizheng Chemical Fiber; Silicon dioxide, average particle size: 20 nm, color: white; Titanium dioxide, average particle size: 20nm, color: white; Polyethylene wax, serial number / product number: DN-108, viscosity: 30cps±10, color: white, from Shanghai Dana Chemical Products Co., Ltd. Lignin was obtained from Wuhan Jixinyibang Biotechnology Co., Ltd. 1-Butyl-3-methylimidazolium hexafluorophosphate, CAS number: 174501-64-5.

[0021] Example 1 A method for preparing an antibacterial and aging-resistant white polyester film, comprising the following steps: Step 1: 120 parts by mass of PETG polyester chips, 10 parts by mass of PET polyester chips, 20 parts by mass of white masterbatch, 30 parts by mass of functional masterbatch, 3 parts by mass of silica, and 0.5 parts by mass of polyethylene wax are mixed, melted at 280° C., and then extruded 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: preheat the cooled polyester film sheet at 80°C, and then stretch it 2.8 times in the longitudinal direction and 3 times in the transverse direction; Step 4: heat-set the stretched film at 185° C., and roll it up after cooling to obtain an antibacterial and aging-resistant white polyester film.

[0022] The white masterbatch is prepared by processing 60 parts by mass of titanium dioxide, 1.0 part by mass of PEG-20000, 10 parts by mass of sodium bicarbonate and 40 parts by mass of PET polyester chips through a venting twin-screw granulator.

[0023] The functional masterbatch is prepared by processing 60 parts by mass of ionic liquid modified titanium dioxide, 1.0 part by mass of PEG-20000 and 60 parts by mass of PET polyester chips through a venting twin-screw pelletizer.

[0024] The preparation method of the ionic liquid modified titanium dioxide comprises the following steps: 5 parts by mass of tetrabutyl titanate and 15 parts by mass of anhydrous ethanol are uniformly mixed to obtain an ethanol solution of tetrabutyl titanate; 1.0 parts by mass of tributylpropylphosphine tetrafluoroborate and 2 parts by mass of 0.6 mol / L nitric acid are added to 15 parts by mass of anhydrous ethanol, and ultrasonicated at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz for 20 minutes to obtain an ionic liquid-nitric acid-ethanol mixed solution; the ionic liquid-nitric acid-ethanol mixed solution is added to the ethanol solution of tetrabutyl titanate under stirring to obtain a sol; 0.2 parts by mass of sodium borohydride is added to the sol and stirred for 3 hours, then aged at room temperature for 24 hours, dried at 60°C for 2 hours, and the solid is ground and passed through a 60-mesh sieve to obtain a solid powder; the solid powder is heated to 500°C at a heating rate of 5°C / min and calcined at 500°C for 3 hours to obtain ionic liquid-modified titanium dioxide.

[0025] The preparation method of the tributylpropylphosphine tetrafluoroborate is as follows: Mix 5 parts by mass of n-propane bromide and 20 parts by mass of anhydrous toluene, then add 15 parts by mass of tributylphosphine, and react at 80°C for 24 hours under nitrogen protection. After the reaction, remove excess toluene and n-propane bromide, and dry at 110°C for 5 hours to obtain tributylpropylphosphine bromide. Mix 3 parts by mass of tetrafluoroboric acid, 5 parts by mass of tributylpropylphosphine bromide, and 110 parts by mass of acetonitrile, stir and react at room temperature for 24 hours, filter, collect the filtrate, remove the acetonitrile in the filtrate, and dry at 80°C for 6 hours to obtain tributylpropylphosphine tetrafluoroborate. Example 2 A method for preparing an antibacterial and aging-resistant white polyester film, which differs from Example 1 only in that the method for preparing ionic liquid-modified titanium dioxide comprises the following steps: 5 parts by mass of tetrabutyl titanate and 15 parts by mass of anhydrous ethanol are uniformly mixed to obtain an ethanol solution of tetrabutyl titanate; 1.0 parts by mass of 1-butyl-3-methylimidazolium hexafluorophosphate and 2 parts by mass of 0.6 mol / L nitric acid are added to 15 parts by mass of anhydrous ethanol, and ultrasonicated at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz for 20 minutes to obtain an ionic liquid-nitric acid-ethanol mixed solution; the ionic liquid-nitric acid-ethanol mixed solution is added to the ethanol solution of tetrabutyl titanate under stirring to obtain a sol; 0.2 parts by mass of sodium borohydride is added to the sol and stirred for 3 hours, then aged at room temperature for 24 hours, dried at 60°C for 2 hours, and the solid is ground and passed through a 60-mesh sieve to obtain a solid powder; the solid powder is heated to 500°C at a heating rate of 5°C / min and calcined at 500°C for 3 hours to obtain ionic liquid-modified titanium dioxide.

[0026] Example 3 A method for preparing an antibacterial and aging-resistant white polyester film, which differs from Example 1 only in that the method for preparing ionic liquid-modified titanium dioxide comprises the following steps, calculated by weight: 5 parts by weight of tetrabutyl titanate and 15 parts by weight of anhydrous ethanol are mixed uniformly to obtain an ethanol solution of tetrabutyl titanate; 1.0 parts by weight of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, 2 parts by weight of 0.6 1 mol / L nitric acid is added to 15 parts by mass of anhydrous ethanol, and ultrasonicated at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz for 20 minutes to obtain an ionic liquid-nitric acid-ethanol mixed solution; the ionic liquid-nitric acid-ethanol mixed solution is added to an ethanol solution of tetrabutyl titanate under stirring to obtain a sol; 0.2 parts by mass of sodium borohydride is added to the sol and stirred for 3 hours, then aged at room temperature for 24 hours, dried at 60°C for 2 hours, and the solid is ground and passed through a 60-mesh sieve to obtain a solid powder; the solid powder is heated to 500°C at a heating rate of 5°C / min and calcined at 500°C for 3 hours 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: Mix 2 parts by mass of 1,4-dimethylpiperazine, 4 parts by mass of 1,3-propane sultone and 12 parts by mass of ethyl acetate, react at 70°C for 14 hours, cool to room temperature, filter, and dry the filter cake at 60°C for 6 hours to obtain the intermediate; mix 3 parts by mass of p-toluenesulfonic acid, 2 parts by mass of the intermediate and 0.2 parts by mass of water, stir at 100°C for 50 minutes until it becomes a viscous liquid, and obtain 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, which differs from Example 1 only in that different functional masterbatch is used.

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

[0030] The preparation method of the composite modified titanium dioxide comprises the following steps: Step 1, 25 parts by mass of lignin and 75 parts by mass of 4 wt% sodium hydroxide aqueous solution were uniformly mixed, stirred and heated to 85°C, 10 parts by mass of 20 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution were added, and the reaction was continued for 5 hours, concentrated to a solid, washed with water 4 times, filtered, and the solid was dried to obtain alkaline lignin; Step 2: 3 parts by mass of alkaline lignin and 300 parts by mass of water were mixed uniformly, the pH was adjusted to 1 with hydrochloric acid, and then 3 parts by mass of tetrabutyl titanate were added under stirring. The temperature was raised to 100°C for reaction for 6 hours, and the precipitate was collected and dried at 50°C for 4 hours and then at 120°C for 12 hours to obtain alkaline lignin-titanium dioxide composite particles; Step 3: Evenly mix 3 parts by mass of alkaline lignin-titanium dioxide composite particles with 50 parts by mass of water, ultrasonicate for 30 minutes at an ultrasonic power of 100 W and an ultrasonic frequency of 40 kHz, add 0.5 parts by mass of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate, stir for 2 hours, then heat to 60°C and react for 4 hours, centrifuge, collect the solid, wash with water three times, and dry at 60°C for 12 hours to obtain a composite modified titanium dioxide.

[0031] The preparation method of the 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, which differs from Example 1 only in that the functional masterbatch is made by processing 60 parts by mass of titanium dioxide, 1.0 part by mass of PEG-20000 and 60 parts by mass of PET polyester chips through a venting twin-screw granulator.

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

[0034] The preparation method of the lignin-modified titanium dioxide comprises the following steps: Step 1, 25 parts by mass of lignin and 25 parts by mass of 4 wt% sodium hydroxide aqueous solution were mixed uniformly, stirred and heated to 85°C, 10 parts by mass of 20 wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution were added, and the reaction was continued for 5 hours, concentrated to a solid, washed with water 4 times, filtered, and the solid was dried to obtain alkaline lignin; Step 2: Evenly mix 3 parts by mass of alkaline lignin with 300 parts by mass of water, adjust the pH to 1 with hydrochloric acid, then add 3 parts by mass of tetrabutyl titanate under stirring, heat and react at 100°C for 6 hours, collect the precipitate, dry at 50°C for 4 hours, and then dry at 120°C 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. The results are shown in Table 1: The tensile strength was tested according to GB / T 25255-2010 Determination of tensile properties of polyethylene terephthalate (PET) films for optical functional films. The samples were then artificially aged for 500 hours using a UVA-340 fluorescent UV lamp in accordance with GB / T 14522-2008 Test method for artificial weathering of plastics, coatings, and rubber materials for use in mechanical industrial products - Fluorescent UV lamps. The tensile strength retention was then tested.

[0036] Table 1 Performance test serial number Tensile strength (MPa) - before aging Tensile strength (MPa) - after aging Tensile strength retention rate (%) 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 By comparing Examples 1-3, it can be found that Example 2 has the highest tensile strength and tensile strength retention rate. The reason may be that the functional particles of Example 2 are added with titanium dioxide modified with 1-butyl-3-methylimidazolium hexafluorophosphate. The imidazole ring in 1-butyl-3-methylimidazolium hexafluorophosphate can enhance ultraviolet absorption, and the anti-ultraviolet ability is better than that of Examples 1 and 3.

[0037] By comparing Examples 1-4 and Comparative Examples 1-2, it can be found that Example 4 has the highest tensile strength and tensile strength retention rate. The reason may be that the functional particles of Example 4 are added with lignin and ionic liquid composite modified titanium dioxide. The quaternized lignin is combined with titanium dioxide through chemical bonds (Ti-OC) to form a rigid-flexible composite structure, which improves the mechanical strength of the film. Its hydrophobic skeleton and hydrophilic quaternary ammonium groups improve the dispersibility of TiO2 in the polyester matrix and reduce stress concentration points; the sulfonic acid group of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate forms hydrogen bonds with the polyester chain segments, enhancing the filler-matrix interface bonding force, absorbing ultraviolet rays and inhibiting free radical chain reactions, significantly reducing molecular chain breakage caused by wet-heat aging, and the addition of lignin and ionic liquid composite modification can synergistically enhance the effect.

[0038] Test Example 2 Antibacterial rate test The antibacterial and aging-resistant polyester films prepared in Examples 1-4 and Comparative Examples 1-2 served as the experimental group, and a polyester film of the same specification prepared from pure PETG polyester chips served as the blank group, with five samples in each group. Antibacterial rates were tested in the dark according to "GB / T31402-2023 Determination of Surface Antimicrobial Activity of Plastics and Other Non-porous Materials." Another group was tested in sunlight according to the above method for 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 serial number Antibacterial rate without light (%) Sunlight 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 Comparison of Examples 1-4 and Comparative Examples 1-2 reveals that Example 4 exhibits an antibacterial rate of 94.3% under dark conditions and 99.9% under sunlight. This may be because the functional particles in Example 4 incorporate lignin and ionic liquid-modified titanium dioxide. Titanium dioxide generates strong oxidative free radicals under ultraviolet light, degrading formaldehyde molecules. The sulfonic acid groups of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine-p-toluenesulfonate depolarize the cell membrane. Furthermore, the sulfonic acid groups modulate the TiO2 band structure, enhancing visible light response and promoting the generation of strong oxidative free radicals, synergistically boosting the antibacterial effect. The quaternized lignin, through the introduction of positively charged quaternary ammonium groups, electrostatically adsorbs to the negatively charged phospholipid layer on the bacterial cell membrane surface, disrupting cell membrane integrity and leading to leakage of intracellular substances, ultimately killing the bacteria and further enhancing the antibacterial effect.

Claims

1. The antibacterial and aging-resistant white polyester film according to claim 1, characterized in that: Calculated by mass, it includes the following raw material components: 100-140 parts of PETG polyester chips, 5-15 parts of PET polyester chips, 10-30 parts of white masterbatch, 20-40 parts of functional masterbatch, 1-5 parts of silica, 0.1-1 part of dispersant; The functional masterbatch is made by processing 50-70 parts by mass of modified titanium dioxide, 0.5-1.5 parts of PEG-20000 and 40-70 parts of PET polyester chips through a venting 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 composite modified by lignin and ionic liquid.

2. The antibacterial and aging-resistant white polyester film according to claim 1, characterized in that: The white masterbatch is made by processing 50-70 parts by mass of titanium dioxide, 0.5-1.5 parts by mass of PEG-20000, 5-15 parts by mass of a foaming agent and 30-50 parts by mass of a venting twin-screw pelletizer.

3. The antibacterial and aging-resistant white polyester film according to 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 according to 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 according to claim 1, characterized in that: The preparation method of the ionic liquid modified titanium dioxide comprises the following steps, calculated by mass: 1-10 parts of tetrabutyl titanate and 10-20 parts of anhydrous ethanol are uniformly mixed 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 ultrasonicated for 10-30 minutes to obtain a solution B; the solution B is added to the ethanol solution of tetrabutyl titanate under stirring to obtain a sol; 0.05-0.5 parts of sodium borohydride are added to the sol and stirred for 2-4 hours, then aged at room temperature for 20-28 hours, dried at 50-70°C for 1-3 hours, and the solid is ground and passed through a 50-80 mesh sieve to obtain a solid powder; the solid powder is heated to 500°C at a heating rate of 5°C / min and calcined at 500°C for 2-4 hours to obtain ionic liquid-modified titanium dioxide.

6. The antibacterial and aging-resistant white polyester film according to claim 1, characterized in that: The preparation method of the composite modified titanium dioxide comprises the following steps, calculated by mass: Step 1, 20-30 parts of lignin and 70-80 parts of 1-5wt% sodium hydroxide aqueous solution are mixed evenly, stirred and heated to 80-90°C, 5-15 parts of 10-30wt% 3-chloro-2-hydroxypropyltrimethylammonium chloride aqueous solution are added, the reaction is continued for 3-6 hours, concentrated to a solid, washed with water 3-5 times, filtered, and the solid is dried to obtain alkaline lignin; Step 2: Evenly mix 1-5 parts of alkaline lignin with 200-400 parts of water, adjust the pH to 1 with hydrochloric acid, then add 1-5 parts of tetrabutyl titanate under stirring, heat and react at 90-110°C for 5-7 hours, collect the precipitate, dry at 40-60°C for 3-5 hours, and then dry at 110-130°C for 10-14 hours to obtain alkaline lignin and titanium dioxide composite particles; Step 3: Evenly mix 1-5 parts of alkaline lignin and titanium dioxide composite particles with 40-60 parts of water, ultrasonicate for 20-40 minutes, add 0.1-1 parts of ionic liquid, stir for 1-3 hours, then heat to 50-70°C for reaction for 3-6 hours, centrifuge, collect the solid, wash with water 2-4 times, and dry at 50-70°C for 10-14 hours to obtain composite modified titanium dioxide.

7. The antibacterial and aging-resistant white polyester film according to claim 5 or 6, 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.

8. The antibacterial and aging-resistant white polyester film according to claim 7, characterized in that: The preparation method of tributylpropylphosphine tetrafluoroborate comprises the following steps: uniformly mixing 1-10 parts of n-propane bromide and 10-30 parts of anhydrous toluene, then adding 10-20 parts of tributylphosphine, reacting at 70-90° C. for 20-28 hours under nitrogen protection, removing excess toluene and n-propane bromide after the reaction, and drying at 100-120° C. for 4-6 hours to obtain tributylpropylphosphine bromide; uniformly mixing 1-5 parts of tetrafluoroboric acid, 1-10 parts of tributylpropylphosphine bromide and 80-140 parts of acetonitrile, stirring and reacting at room temperature for 20-28 hours, filtering, collecting the filtrate, removing the acetonitrile in the filtrate, and drying to obtain tributylpropylphosphine tetrafluoroborate.

9. The antibacterial and aging-resistant white polyester film according to claim 7, characterized in that: The preparation method of 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate comprises the following steps: mixing 1-3 parts of 1,4-dimethylpiperazine, 3-5 parts of 1,3-propane sultone and 10-15 parts of ethyl acetate, reacting at 60-80°C for 10-16 hours, cooling to room temperature, filtering, and drying the filter cake at 50-70°C for 5-8 hours to obtain an intermediate; and mixing 2-4 parts of p-toluenesulfonic acid, 1-3 parts of the intermediate and 0.1-0.3 parts of water, stirring at 80-120°C for 40-70 minutes until the mixture becomes a viscous liquid, thereby obtaining 1,4-bis[N-methyl-N-(3-sulfopropyl)]piperazine p-toluenesulfonate.

10. The method for preparing the antibacterial and aging-resistant white polyester film according to any one of claims 1 to 9, characterized in that: The method comprises 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°C, and 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 18-40°C; Step 3: preheat the cooled polyester film sheet at 80-100°C, and then stretch it by 2.0-4.4 times in the longitudinal direction and 2.5-4.5 times in the transverse direction; Step 4: heat-set the stretched film at 170-200° C., and roll it up after cooling to obtain an antibacterial and aging-resistant white polyester film.