Preparation method of nano composite polyester film with high weather resistance

Abstract

The invention belongs to the technical field of polyester film preparation, and relates to a preparation method of a nano composite polyester film with high weather resistance, which comprises the following steps: firstly, adding a maleic anhydride grafted copolymer into a system after polyester esterification reaction is finished, enabling an anhydride group of the maleic anhydride grafted copolymer to be subjected to esterification reaction with a hydroxyl group at a polyester chain end, and then carrying out polycondensation reaction to obtain the nano composite polyester film with high weather resistance. A polyester resin matrix is obtained; then premixing a part of the polyester resin matrix with the organic modified montmorillonite, so that the organic modified montmorillonite forms a lamellar dispersion structure in the polyester resin matrix to obtain a mixture A; mixing and dispersing the residual part in the polyester resin matrix and the glass fiber of which the surface is treated by the silane coupling agent to obtain a mixture B; and finally, mixing the mixture A and the mixture B, adding ethylene propylene rubber and an ethylene-methacrylate copolymer, and carrying out twin-screw extrusion molding to prepare the nano composite polyester film. According to the method, the interface bonding performance can be remarkably improved, and the reinforcing and toughening effects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of polyester film preparation technology, and relates to a method for preparing a nanocomposite polyester film with high weather resistance. Background Technology

[0002] Traditional polyester films face several challenges in outdoor applications, including insufficient weather resistance (susceptible to degradation by UV, heat, oxygen, and humidity, resulting in low mechanical property retention), reduced toughness due to glass fiber reinforcement (weak interfacial adhesion and easy debonding), difficulty in uniformly dispersing nanofillers (such as montmorillonite) due to surface polarity differences (agglomeration leads to limited barrier performance improvement), and the inability of single-performance improvements to meet the multi-functional needs of complex scenarios (such as antibacterial and antistatic properties).

[0003] For example, patent CN201710116253.9 discloses an antibacterial colored polyester film for food packaging and its preparation method, which involves immersing the polyester film in oregano extract and Ag. + The polyester film is prepared by microwave treatment at 60-70℃ for 5 minutes in a mixed dispersion of SiO2 / TiO2 nanocomposite materials, followed by drying and rinsing the surface with water. This polyester film is dyed with natural pigments, making it environmentally friendly and harmless to health. It also possesses antibacterial properties, making it highly suitable for food packaging. However, because this patent uses a physical adsorption mechanism of surface coating with antibacterial agents instead of embedding the antibacterial components into the polyester matrix through covalent bonds, the antibacterial agents are prone to detachment under friction and humid conditions, potentially leading to poor antibacterial durability. Furthermore, the patent does not introduce anti-aging agents or reinforcing materials, which may result in a significant decrease in tensile strength and yellowing of the polyester film after 500 hours of UV aging. Additionally, the patent lacks barrier fillers, resulting in high water vapor transmission rate (WVTR) and oxygen transmission rate (OTR), which may not meet the packaging requirements of high-humidity and high-oxygen environments.

[0004] Therefore, it is of great significance to study a method for preparing a nanocomposite polyester film with high weather resistance in order to solve the problems existing in the prior art. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and provide a method for preparing a nanocomposite polyester film with high weather resistance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a highly weather-resistant nanocomposite polyester film involves first adding a maleic anhydride graft copolymer to the system after the polyester esterification reaction, allowing the anhydride groups of the maleic anhydride graft copolymer to undergo an esterification reaction with the hydroxyl groups at the ends of the polyester chains (the polyester chains formed after the esterification reaction have hydroxyl groups, which is common knowledge in the art). Following this, a polycondensation reaction is performed to obtain a polyester resin matrix containing a "molecular bridge" structure. Then, a portion of the polyester resin matrix is ​​premixed with organically modified montmorillonite, allowing the organically modified montmorillonite to form a layered dispersion structure within the polyester resin matrix, resulting in mixture A. The remaining portion of the polyester resin matrix is ​​then mixed and dispersed with glass fibers whose surfaces have been treated with a silane coupling agent, resulting in mixture B. Finally, mixture A and mixture B are mixed, and then ethylene propylene rubber and ethylene-methacrylate copolymer are added. The mixture is then extruded using a twin-screw extruder to obtain the nanocomposite polyester film.

[0008] Maleic anhydride graft copolymers must be introduced at a specific time, namely after the polyester esterification reaction and before the polycondensation reaction. This is because: during the esterification stage, the focus should be on forming well-structured oligomers to avoid foreign groups disrupting the acid-alcohol ratio and reaction kinetics, and to prevent interference with the synthesis of the polyester backbone; after esterification, the high hydroxyl concentration and suitable temperature provide the optimal window for the reaction between the anhydride groups and the polyester chain ends, ensuring efficient grafting; the grafted "molecular bridges" need to be embedded in the polyester chain before polycondensation to further consolidate the network structure through subsequent polycondensation, while providing chemical anchors for the lamellar dispersion of montmorillonite and the interfacial bonding of glass fibers.

[0009] As a preferred technical solution:

[0010] The preparation method of the nanocomposite polyester film with high weather resistance as described above includes the following specific steps:

[0011] (1) Synthesis of polyester resin matrix;

[0012] First, terephthalic acid (PTA) and ethylene glycol (EG) are added to a reactor at a molar ratio of 1:1.08–1.22, along with a catalyst and heat stabilizer. The reaction is carried out at 230–240°C and atmospheric pressure for 3–4 hours, until the water output reaches more than 95% of the theoretical value, indicating the esterification reaction is complete. Then, maleic anhydride graft copolymer is added, and the temperature is controlled at 245–250°C with a stirring speed of 80–100 r / min for 30–35 minutes, allowing the anhydride groups of the maleic anhydride graft copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends. Finally, the system pressure is reduced to 100–200 Pa, the temperature is raised to 270–280°C, and the reaction is carried out for 2–3 hours until the intrinsic viscosity reaches 0.65–0.70 dL / g, yielding the polyester resin matrix.

[0013] (2) Multi-component gradient blending;

[0014] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 75-90°C for 2-2.5 hours (to remove surface moisture). Then, the temperature is raised to 90-105°C and dried at a vacuum of -0.085 to -0.095 MPa for 3.5-4.5 hours (moisture content ≤0.01%, as determined by Karl Fischer method) to prevent hydrolysis and degradation during extrusion.

[0015] (2.2) The short glass fibers were immersed in an aqueous solution of silane coupling agent (KH550) (concentration 2wt%) and ultrasonically treated for 15 to 18 minutes (power 200W). After being removed, they were dried in an oven at 110 to 130°C for 1.5 to 2.5 hours to obtain glass fibers with a surface treated with silane coupling agent.

[0016] (2.3) Place the organically modified montmorillonite in a vacuum drying oven and pre-dry it at 55-65℃ for 0.8-1.2 hours. Then raise the temperature to 75-85℃ and dry it at a vacuum of -0.075--0.085MPa for 2.5-3.5 hours (moisture content ≤0.5%) to avoid the montmorillonite absorbing water and affecting the subsequent intercalation effect.

[0017] (2.4) 60% of the total amount of the dried polyester resin matrix (particle diameter 2-3 mm) from step (2.1) is added to a dual planetary mixer and run at a low speed of 45-55 r / min. At the same time, 0.08%-0.12% by mass of the plasticizer dioctyl phthalate (DOP) relative to the added polyester resin matrix is ​​sprayed through an atomizing nozzle to form a lubricating layer on the resin surface (reducing the adsorption and agglomeration of montmorillonite). Then, the organic modified montmorillonite dried from step (2.3) is added to the dual planetary mixer in three equal portions (each 2 minutes apart) and mixed at 45-55 r / min for 4-6 minutes to initially disperse the montmorillonite using the collision force of the resin particles. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12-15 minutes under a pressure ≤ -0.08 MPa (the vacuum environment reduces the air gap and promotes the peeling of montmorillonite flakes) to obtain mixture A.

[0018] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fibers treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 70-90 r / min for 6-9 minutes. Use the shear force of the ribbon to make the glass fibers uniformly embedded in the gaps between the resin particles (fiber dispersion is observed by an optical microscope, and the monofilament distribution rate is required to be >95%) to obtain mixture B.

[0019] (2.6) Mix mixture A with mixture B in a horizontal ribbon mixer. Then, add anti-aging agent, antibacterial agent and antioxidant first, and mix at a high speed of 110-130 r / min for 8-12 minutes (to break up the agglomeration of the additives through high-speed shearing, and at the same time to make the modifier and the surface active groups of the resin initially contact). Then add ethylene propylene rubber and ethylene-methacrylate copolymer (EMMA), and mix at a low speed of 50-70 r / min for 12-18 minutes (to avoid high shearing from damaging the rubber elastomer structure, and at the same time to use the friction of resin particles to make the toughening agent surface slightly dissolve and form an interfacial transition layer).

[0020] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Using a metering pump, uniformly spray preheated dioctyl phthalate (DOP), heated to 55–65°C (to reduce viscosity), onto the surface of the mixture at a rate of 4–6 mL / min. The amount of DOP is 0.2–0.5% of the total mass of the mixture. Mix at a speed of 35–45 r / min for 7–9 minutes (paddle linear velocity ≤ 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action. Inside the particles, while avoiding high-speed shearing that causes dioctyl phthalate to adsorb onto the glass fiber surface (the thickness of the oil film on the fiber surface is observed by scanning electron microscopy and controlled at 5-10 nm); after mixing, keep the blades rotating at a low speed of 18-25 r / min and evacuate to remove the air entrained during the mixing process (to avoid generating bubbles during extrusion). Specifically, after the vacuum equipment is started, when the system vacuum degree stabilizes at -0.09 MPa, start timing and maintain it for 10 minutes, while keeping the blades rotating at a low speed.

[0021] (3) Twin-screw extrusion molding;

[0022] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die (600 mm wide, 0.3 mm die lip gap), is cooled by a three-roll calender (upper roll temperature 30℃, middle roll temperature 25℃, lower roll temperature 20℃), and the traction speed is controlled at 7-9 m / min. The film is then wound up to obtain a nano-composite polyester film with a thickness of 0.1-0.3 mm.

[0023] The preparation method of a nanocomposite polyester film with high weather resistance as described above, in step (1), the catalyst is antimony trioxide, the amount of catalyst added is 0.02% to 0.08% of the mass of terephthalic acid, the heat stabilizer is triphenyl phosphite, and the amount of heat stabilizer added is 0.05% to 0.2% of the mass of terephthalic acid.

[0024] In the preparation method of a nanocomposite polyester film with high weather resistance as described above, in step (1), the maleic anhydride graft copolymer is maleic anhydride grafted ethylene-vinyl acetate copolymer (MAH-g-EVA) with a grafting rate of 1.2-1.5%; the amount of maleic anhydride graft copolymer added is 1-2% of the mass of the polyester resin matrix.

[0025] In the preparation method of a nanocomposite polyester film with high weather resistance as described above, the interlayer spacing of the organic modified montmorillonite in step (2.3) is ≥2.5nm.

[0026] In step (2.4), plasticizer DOP and vacuum shearing are used to promote the dispersion of montmorillonite. If the interlayer spacing is too small, the plasticizer molecules will have difficulty penetrating between the layers and will not be able to assist in peeling by reducing the melt viscosity; while an interlayer spacing of ≥2.5nm provides a penetration channel for the plasticizer molecules, which can further expand the layers through the "swelling effect" and improve the dispersion efficiency.

[0027] Based on the Bragg equation, for every 0.5 nm increase in interlayer spacing, the path length that gas molecules must travel along the surface of the montmorillonite sheets to traverse the material is extended by 1.2 times compared to the straight-line distance. Combined with the uniform dispersion state with D50 ≤ 50 nm detected by a laser particle size analyzer, this indicates that the transport of water vapor molecules within the film requires reflection, scattering, and path extension through multiple nanosheets. This layered nanobarrier network significantly increases gas permeation resistance through a physical barrier mechanism, ultimately achieving a water vapor transmission rate (WVTR) ≤ 5 g / (m²). 2 • 24h), which reduced the content of montmorillonite by 60% compared to the control sample without montmorillonite. This molecular-level raw material compounding logic creates a synergistic effect between the mechanical reinforcement (tensile strength ≥150MPa) brought by glass fiber and the improved barrier properties of montmorillonite sheets.

[0028] The method for preparing a nanocomposite polyester film with high weather resistance as described above uses the total amount of dried polyester resin matrix as a basis, the mass percentage of dried organic modified montmorillonite is 2-5%, and the mass percentage of glass fiber treated with silane coupling agent on the surface is 20-30%.

[0029] In the preparation method of the nanocomposite polyester film with high weather resistance as described above, in step (2.6), the anti-aging agent is nano zinc oxide (particle size 50-100nm), the antibacterial agent is nano silver / titanium dioxide composite powder with surface modified by stearic acid (particle size 20-50nm), and the antioxidant is composed of a main antioxidant (hindered phenols) and an auxiliary antioxidant (phosphite esters) (particle size ≤10μm); based on the total amount of mixture A and mixture B, the mass percentages of anti-aging agent, antibacterial agent and antioxidant are 0.5-1.5%, 0.3-1.0% and 0.5-1.0%, respectively.

[0030] In the preparation method of a nanocomposite polyester film with high weather resistance as described above, the mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer in step (2.6) is 1 to 2:1, and the amount of ethylene propylene rubber added is 5 to 10% of the total mass of polyester resin matrix.

[0031] In the preparation method of a nanocomposite polyester film with high weather resistance as described above, the length-to-diameter ratio of the co-rotating twin-screw extruder in step (3) is L / D = 35:1 to 45:1, and the screw diameter is Φ = 45 to 55 mm.

[0032] The preparation method of a nanocomposite polyester film with high weather resistance as described above, the extrusion process parameters in step (3) are as follows: temperature of zone 1 (feeding section) 220-240℃, temperature of zone 2 (melting section) 230-250℃, temperature of zone 3 (mixing section) 240-260℃, temperature of zone 4 (homogenization section) 235-255℃, and die temperature 240-260℃; screw speed 160-200r / min (to ensure shearing and dispersion effect and avoid excessive shearing leading to degradation), melt pressure 5-8MPa (adjusted by melt pump), and feeding speed 12-18kg / h (matched with screw speed).

[0033] Invention principle:

[0034] In this invention, the maleic anhydride graft copolymer forms a covalent "molecular bridge" with hydroxyl groups through in-situ esterification during polyester synthesis (bonding polyester segments to glass fibers / toughening agents), combining the synergistic effects of nano-montmorillonite intercalation and a ternary toughening system (ethylene propylene rubber elastic buffer + ethylene-methacrylate chemical anchoring). The elastic toughening effect of ethylene propylene rubber and the interfacial covalent bonding effect of ethylene-methacrylate are interconnected and functionally mutually supportive—ethylene propylene rubber reduces interfacial stress through physical filling, while ethylene-methacrylate enhances interfacial bonding strength through chemical anchoring, jointly addressing the brittleness problem caused by the introduction of glass fibers in the composite material. Simultaneously, the "molecular bridge" construction of the maleic anhydride graft copolymer synergizes with the former two—it crosslinks with polyester segments through ester bonds (chemical anchoring), simultaneously forms a grafting reaction with the double bonds of ethylene propylene rubber (physical-chemical dual effect), and forms hydrogen bonds with the carboxyl groups of ethylene-methacrylate, ultimately achieving a significant increase in interfacial adhesion energy.

[0035] Without the toughening agent ethylene propylene rubber, using only ethylene-methacrylate and maleic anhydride graft copolymer means that the impact energy cannot be absorbed through the elastomer network, resulting in ineffective relief of interfacial stress concentration between the glass fiber and polyester resin, significantly increasing the risk of interfacial debonding. Without ethylene-methacrylate, relying solely on the toughening agent ethylene propylene rubber and maleic anhydride graft copolymer means that covalent bonds cannot be formed with the silane coupling agent on the glass fiber surface, leading to a lack of chemical anchoring between the glass fiber and the resin matrix, making it difficult to significantly improve interfacial adhesion. Without maleic anhydride graft copolymer, using only the toughening agent ethylene propylene rubber and ethylene-methacrylate means that a "molecular bridge" structure cannot be formed through in-situ reaction during polyester synthesis, resulting in a lack of chemical cross-linking support for the physical entanglement of the ethylene propylene rubber and polyester segments, leading to insufficient long-term stability of the interfacial bond.

[0036] Furthermore, the montmorillonite sheets form a "nano-fence" barrier layer in the copolymer matrix (TGA shows a 5% increase in thermogravimetric temperature of 30°C), inhibiting heat conduction. At the same time, the covalent bonds between the glass fiber and the maleic anhydride graft copolymer restrict the high-temperature creep of the polyester crystalline region, resulting in an increase in heat distortion temperature (HDT) of 25–40°C and a decrease in volume shrinkage rate from 5% to below 2% at 200°C. The maleic anhydride graft copolymer forms a branched structure with the polyester segments through in-situ esterification, increasing the activation energy of molecular chain motion from 85 kJ / mol to 110 kJ / mol (DSC test), thus delaying chain relaxation at high temperatures.

[0037] The covalent interface network formed by maleic anhydride graft copolymer fills the micropores in traditional composite materials, blocking the medium penetration path. The nanoscale stacking of montmorillonite sheets, combined with the polar groups of ethylene-methacrylate, inhibits the diffusion of polar solvents (such as water and acid), thereby enhancing the chemical medium penetration resistance of the nanocomposite polyester film.

[0038] Beneficial effects:

[0039] (1) A method for preparing a nanocomposite polyester film with high weather resistance according to the present invention, in the polyester resin synthesis stage, maleic anhydride graft polymer is introduced in situ as a reactive additive. It covalently crosslinks with polyester segments through ester bonds to form a "molecular bridge", which further enhances the interfacial bonding force between glass fiber, ethylene propylene rubber and polyester resin. At the same time, ethylene-methacrylate and maleic anhydride graft polymer form covalent bonds with glass fiber and polyester resin respectively, which significantly improves the interfacial adhesion energy and achieves the effects of reinforcement and toughening.

[0040] (2) A method for preparing a nanocomposite polyester film with high weather resistance according to the present invention, wherein the montmorillonite nanosheets delay water vapor / oxygen permeation by physical barrier and reduce matrix degradation by ultraviolet scattering assists anti-aging agent; the maleic anhydride "molecular bridge" simultaneously enhances interfacial compatibility and mechanical strength, forming a synergistic effect of "anti-aging-permeation barrier-toughening".

[0041] (3) A method for preparing a highly weather-resistant nanocomposite polyester film according to the present invention achieves a mechanical retention rate of ≥85% and an XPS elemental binding energy shift ΔE ≤3eV after 1000h of UV aging through in-situ crosslinking of maleic anhydride grafted polymer and a nano zinc oxide anti-aging system; simultaneously, through the nano-intercalation effect of organically modified montmorillonite, the water vapor transmission rate (WVTR) is reduced to ≤5g / (m 2 •24h) OTR≤10cm 3 / (m 2 ·24h·0.1MPa). Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0043] The test methods involved in the performance indicators in the embodiments and comparative examples of this invention are as follows:

[0044] Peel strength: Tested according to GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes". The test sample is a polyester film specimen with a width of 25 mm. One end of the specimen is peeled off by 50 mm and fixed on the upper and lower clamps of the testing machine with a clamp spacing of 100 mm. The test environment temperature is 23℃±2℃, relative humidity is 50%±5%, and the peeling speed is set to 300 mm / min. The force value during the peeling process is recorded, and the average value within the test range is taken as the peel strength result (unit: N / cm).

[0045] Water vapor transmission rate (WVTR): Tested according to GB / T 1037-2021 "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets - Cup Method". The weight gain method was used. Anhydrous calcium chloride (desiccant) was placed inside the test cup, and the sample was sealed at the mouth of the test cup, ensuring no leakage at the sealing edges. The test environment temperature was 38℃±0.5℃, and the relative humidity was 90%±2%. The test area of ​​the sample was 50cm². 2After the test reaches a stable state (the difference between three consecutive weighings does not exceed 5%), record the mass change within 24 hours, and calculate the water vapor transmission rate (unit: g / (m²)) according to the formula. 2 ·24h)).

[0046] Online monitoring: The mixture is scanned in real time using a near-infrared spectrometer to monitor the polyester resin (1715cm). -1 ester carbonyl peak), glass fiber (1080cm) -1 (silicon-oxygen bond peak), montmorillonite (970 cm⁻¹) -1 The characteristic peak intensity distribution of the aluminum-oxygen bond peak should be such that the coefficient of variation (CV) of each peak is ≤5% (to ensure component homogeneity).

[0047] Moisture content: determined using the Karl Fischer method.

[0048] To verify the nanoscale intercalation and dispersion effect of organically modified montmorillonite in polyester resin, and the enhancing effect of the "molecular bridge" formed by maleic anhydride grafted polymer on interfacial compatibility, the following experiments were designed to quantitatively analyze the material performance improvement mechanism from the perspectives of microstructure and chemical bonding:

[0049] The intercalation state and dispersion uniformity of organically modified montmorillonite in the polyester matrix were confirmed.

[0050] Verify the interfacial covalent bond bonding effect between glass fiber, toughening agent and polyester resin;

[0051] Establish the correspondence between nanostructure parameters (such as interlayer spacing and dispersion) and macroscopic properties (barrier properties and mechanical strength).

[0052] The experimental steps include:

[0053] 1) Detection of montmorillonite nanostructure (verification of intercalation effect);

[0054] Sample preparation:

[0055] Take 0.1g of organically modified montmorillonite, and after liquid nitrogen brittle fracture, collect the fracture powder, wash it three times with anhydrous ethanol, and vacuum dry it for 24h (to remove surface impurities).

[0056] X-ray diffraction (XRD) test:

[0057] Equipment: D8 Advance X-ray diffractometer (Cu Kα radiation, λ = 0.154 nm).

[0058] Conditions: Scan range 2θ = 2° to 20°, step size 0.02°, scan speed 5° / min.

[0059] Analysis: The interlayer spacing of montmorillonite was calculated according to the Bragg formula (d = λ / (2sinθ)). If the 2θ peak shifts to the left from 3.5° (d = 2.5nm) of the raw montmorillonite to 2.8° (d = 3.2nm), it proves that the intercalation was successful. At the same time, the intensity of the diffraction peaks was observed. The absence of obvious sharp peaks indicates that the montmorillonite is dispersed in a peeling manner.

[0060] Transmission electron microscopy (TEM) observations:

[0061] Sample preparation: Cut the film into 50nm ultrathin slices, place them on a copper grid, and negatively stain with 2% phosphotungstic acid solution (100g solution contains 2g phosphotungstic acid; solvent is deionized water) for 10min.

[0062] Equipment: JEOL JEM-2100F transmission electron microscope (accelerating voltage 200kV).

[0063] Observation: Observe the distribution of montmorillonite lamellae under magnification of 50,000 times. The lamellae thickness should be ≤50nm and they should be randomly and uniformly dispersed in the polyester matrix (spacing fluctuation ≤10%).

[0064] 2) Interface compatibility test (molecular bridge effect verification);

[0065] Fourier transform infrared spectroscopy (FT-IR):

[0066] Sample: Take a 5mm×5mm thin film from the surface of the film and use attenuated total reflection (ATR) mode for detection.

[0067] Equipment: Nicoleti S50 FT-IR spectrometer (scanning range 4000–600 cm⁻¹) -1 4cm resolution -1 (32 scans).

[0068] Analysis: Comparing the spectra of pure polyester resin and composite films, if the wavelength at 1715 cm⁻¹... -1 (Polyester carbonyl) and 1080cm -1 The presence of strong peak coupling (peak area ratio change ≥15%) at the (glass fiber silicon-oxygen bond) site proves that the maleic anhydride grafted polymer achieves interfacial covalent crosslinking through ester bonds.

[0069] X-ray photoelectron spectroscopy (XPS):

[0070] Sample: Select the cross-section of the film after the glass fiber has been pulled out, and clean the surface with argon ion beam sputtering (to remove the contaminant layer).

[0071] Equipment: Thermo Fisher ESCALAB 250Xi XPS instrument.

[0072] Detection: Analyze the chemical state of C, O, and Si elements on the glass fiber surface. If a shift in the binding energy of C=O bond (288.5 eV) and Si-OH bond (103.5 eV) is detected (ΔE≤0.5 eV), it proves that the anhydride group of maleic anhydride has undergone an esterification reaction with the hydroxyl groups on the glass fiber surface to form interfacial chemical bonds.

[0073] 3) Nanoparticle dispersion detection (uniformity verification);

[0074] Laser particle size analyzer:

[0075] Sample preparation: Dissolve 0.05g of the film sample in 20mL of THF and sonicate for 30min (300W) to prepare a suspension.

[0076] Equipment: Malvern Mastersizer 3000 laser particle size analyzer (scattering angle 15°~135°, refractive index 1.65).

[0077] Indicators: The particle size distribution of organically modified montmorillonite is tested, requiring D50≤80nm and the proportion of particles with a diameter >1μm <0.3% (to prove uniform dispersion at the nanoscale).

[0078]

[0079] The preparation process of organically modified montmorillonite is as follows:

[0080] 10g of montmorillonite was weighed and added to 500mL of deionized water. The mixture was dispersed at a stirring rate of 300r / min for 30 minutes to form a montmorillonite suspension. Octadecyltrimethylammonium chloride was then weighed at 1.2 times the cation exchange capacity of montmorillonite (90meq / 100g) and dissolved in 100mL of deionized water. The mixture was stirred until completely dissolved to obtain an intercalating agent solution. The intercalating agent solution was slowly added dropwise to the montmorillonite suspension at a dropping rate of 2mL / min. The stirring rate was maintained at 300r / min during the addition. After the addition was completed, the temperature was raised to 80℃ and the reaction was continued for 2 hours. After the reaction was completed, the mixture was allowed to stand for 30 minutes and then filtered to obtain a solid product. The product was washed with deionized water until no chloride ions were found in the filtrate to obtain organically modified montmorillonite.

[0081] The preparation process of stearic acid-modified nano-silver / titanium dioxide composite powder is as follows:

[0082] S1. Raw material preparation;

[0083] Silver-loaded titanium dioxide (Ag / TiO2); stearic acid: analytical grade (C 17 H 35 COOH (melting point 69℃, hydrophobic modifier); solvent: anhydrous ethanol;

[0084] S2. Weigh 10.0g of silver-loaded TiO2, add 200mL of anhydrous ethanol, place in a constant temperature magnetic stirrer (30℃, 500r / min), and simultaneously turn on ultrasound (frequency 40kHz, power 100W) to disperse for 30 minutes to break up particle agglomeration and form a uniform suspension. Weigh 0.8g of stearic acid (8% of the mass of silver-loaded TiO2), dissolve in 50mL of anhydrous ethanol, heat to 60℃ and stir until completely dissolved. Add the stearic acid solution dropwise to the silver-loaded TiO2 suspension at a rate of 5mL / min, while maintaining stirring at 500r / min during the dropwise addition. After the dropwise addition, raise the temperature to 60℃ and continue stirring for 2 hours to allow the carboxyl groups (-COOH) of stearic acid to undergo an esterification reaction with the hydroxyl groups (-OH) on the surface of TiO2, forming a hydrophobic layer on the particle surface.

[0085] S3. Post-processing: The reaction solution obtained in S2 was transferred to a rotary evaporator and evaporated at 60℃ and -0.09MPa to remove ethanol, resulting in a paste product. The paste product was then transferred to a vacuum drying oven and dried at 80℃ and -0.08MPa for 4 hours (vacuum environment inhibits Ag oxidation). After drying, it was ground through a 200-mesh sieve to obtain loose powder, thus preparing the stearic acid-modified nano-silver / titanium dioxide composite powder.

[0086] Example 1

[0087] A method for preparing a nanocomposite polyester film with high weather resistance, characterized by the following specific steps:

[0088] (1) Synthesis of polyester resin matrix;

[0089] First, terephthalic acid and ethylene glycol were added to a reactor at a molar ratio of 1:1.15, along with antimony trioxide and triphenyl phosphite. The reaction was carried out at 230°C and atmospheric pressure for 4 hours until the water output reached more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, grade: T9318) with a grafting rate of 1.30% was added. The temperature was controlled at 245°C, the stirring speed at 80 r / min, and the reaction was carried out for 30 minutes to allow the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends. Finally, the system pressure was reduced to 100 Pa, the temperature was raised to 270°C, and the reaction was carried out for 3 hours until the intrinsic viscosity reached 0.65 dL / g, yielding a polyester resin matrix.

[0090] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 1% of the mass of polyester resin matrix.

[0091] (2) Multi-component gradient blending;

[0092] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0093] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0094] (2.3) The organically modified montmorillonite with an interlayer spacing of 2.5 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0095] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.08% of the mass of dioctyl phthalate relative to the polyester resin matrix has been added through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0096] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 80 r / min for 8 minutes to obtain mixture B;

[0097] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (55nm particle size), nano silver / titanium dioxide composite powder (25nm particle size) with stearic acid modified surface, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0098] The antioxidants consist of antioxidant 1010 (0.6 μm particle size) and antioxidant 168 (0.7 μm particle size) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 2%, and the mass percentage of the glass fiber treated with silane coupling agent is 20%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 0.5%, 0.3%, and 0.5%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1:1, and the amount of ethylene propylene rubber added is 5% of the total mass of the polyester resin matrix.

[0099] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture using a metering pump. The amount of DOP is 0.2% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s). After mixing, keep the paddle blades rotating at a low speed of 20 r / min and evacuate the vacuum to remove the air entrained during the mixing process.

[0100] (3) Twin-screw extrusion molding;

[0101] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die, is cooled by a three-roll calender, and the traction speed is controlled at 8 m / min. The film is then wound up to obtain a nano-composite polyester film with a thickness of 0.1 mm.

[0102] The co-rotating twin-screw extruder has a length-to-diameter ratio (L / D) of 40:1 and a screw diameter (Φ) of 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 5 MPa, and feeding speed 15 kg / h.

[0103] The final nano-polyester film had a water vapor permeability of 1.2 g / (m²). 2 • 24h); peel strength is 5.0 N / cm; FT-IR peak intensity coupling degree is 85%; XPS element binding energy shift is 0.3 eV; the antibacterial rate of the nanocomposite polyester film is 99.93%, and the antibacterial rate is 95.5% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.6%, and the oxidation induction time (OIT) is 21min.

[0104] Comparative Example 1

[0105] A method for preparing a nanocomposite polyester film is basically the same as in Example 1, except that the organic modified montmorillonite in step (2.3) is replaced with unmodified montmorillonite, with an interlayer spacing of 1.4 nm, a D50 of 250 nm, and a particle size >1 μm accounting for 6.5%.

[0106] The final nano-polyester film had a water vapor permeability of 2.3 g / (m²). 2 • 24h); peel strength was 4.3 N / cm; FT-IR peak strength coupling was 79%; XPS elemental binding energy shift was 0.2 eV.

[0107] Comparing Comparative Example 1 and Example 1, it can be found that the water vapor transmission rate of Comparative Example 1 is significantly increased, while the peel strength, FT-IR peak intensity coupling degree and XPS element binding energy shift are all decreased. This is because the unmodified montmorillonite has a small interlayer spacing and poor particle dispersion. At the same time, due to its strong hydrophilicity, it is difficult to disperse in polyester resin, resulting in a lack of significant improvement in barrier properties.

[0108] Comparative Example 2

[0109] A method for preparing a nanocomposite polyester film is basically the same as in Example 1, except that maleic anhydride-grafted ethylene-vinyl acetate copolymer is not added in step (1).

[0110] The final nano-polyester film had a water vapor permeability of 2.0 g / (m²). 2 • 24h); peel strength is 2.5 N / cm; FT-IR peak coupling is 68%; XPS elemental binding energy shift is 0.09 eV.

[0111] Comparing Comparative Example 2 and Example 1, it can be found that the peel strength of Comparative Example 2 is significantly reduced, and the FT-IR peak intensity coupling degree and XPS element binding energy shift are also significantly reduced. This is because maleic anhydride-grafted ethylene-vinyl acetate copolymer was not introduced during the synthesis of polyester resin. It was only physically mixed with other components during the blending stage, resulting in a lack of covalent bond connection between glass fiber, toughening agent and polyester matrix. The interface is only bonded by van der Waals forces, resulting in a significant reduction in peel strength.

[0112] Comparative Example 3

[0113] A method for preparing a nanocomposite polyester film is basically the same as in Example 1, except that: maleic anhydride-grafted ethylene-vinyl acetate copolymer is not added in step (1), but is added in step (2.6).

[0114] The final nano-polyester film had a water vapor permeability of 1.7 g / (m²). 2(24h); peel strength was 3.5 N / cm; FT-IR peak coupling was 72%; XPS elemental binding energy shift was 0.12 eV.

[0115] Comparing Comparative Example 3 and Example 1, it can be found that the peel strength of Comparative Example 3 is significantly lower than that of Example 1, and the improvement of other performance indicators is limited. This is because the maleic anhydride-grafted ethylene-vinyl acetate copolymer does not participate in the polymerization reaction of polyester segments. The maleic anhydride-grafted ethylene-vinyl acetate copolymer cannot form covalent crosslinks with the polyester matrix through ester bonds. It is only dispersed in the form of physical particles, which is prone to agglomeration (TEM observed particles with a particle size >500nm), and the improvement of interfacial compatibility is limited.

[0116] Comparative Example 4

[0117] A method for preparing a nanocomposite polyester film is basically the same as in Example 1, except that step (2.3) is omitted and the addition of organic modified montmorillonite is omitted in step (2.4).

[0118] The final nano-polyester film had a water vapor permeability of 3.2 g / (m²). 2 • 24h); peel strength is 4.0 N / cm; FT-IR peak strength coupling degree is 75%; XPS elemental binding energy shift is 0.1 eV.

[0119] Comparing Comparative Example 4 with Example 1, it can be found that all performance indicators of Comparative Example 4 have deteriorated, especially the barrier properties, aging resistance and interfacial bonding strength. This is because Comparative Example 4 lacks organic modified montmorillonite, which causes the material to lose its layered barrier structure, shortens the water vapor permeation path, and weakens the nanoscale enhancement and interfacial effect, resulting in a decrease in interfacial bonding strength and structural integrity.

[0120] The present invention, due to the addition of organically modified montmorillonite, the reasonable combination of other components, and the improvement of the preparation process, enables the nanocomposite polyester film to achieve an antibacterial rate of ≥99.5%, and the antibacterial rate is still ≥95% after 50 cycles of ultraviolet aging. In terms of aging resistance, the tensile strength retention rate is ≥85% after 1000 hours of ultraviolet aging, and the oxidation induction time (OIT) is ≥20 minutes. The overall performance is far superior to that of Comparative Example 4.

[0121] Example 2

[0122] A method for preparing a nanocomposite polyester film with high weather resistance, the specific steps of which are as follows:

[0123] (1) Synthesis of polyester resin matrix;

[0124] First, terephthalic acid and ethylene glycol were added to a reactor at a molar ratio of 1:1.15, along with antimony trioxide and triphenyl phosphite. The reaction was carried out at 235°C and atmospheric pressure for 3.5 hours until the water output reached more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, grade: T9318) with a grafting rate of 1.30% was added. The temperature was controlled at 246°C, the stirring speed at 90 r / min, and the reaction was carried out for 30 minutes to allow the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends. Finally, the system pressure was reduced to 120 Pa, the temperature was raised to 272°C, and the reaction was carried out for 2.75 hours until the intrinsic viscosity reached 0.66 dL / g, yielding a polyester resin matrix.

[0125] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 1.2% of the mass of polyester resin matrix.

[0126] (2) Multi-component gradient blending;

[0127] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0128] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0129] (2.3) The organically modified montmorillonite with an interlayer spacing of 2.6 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0130] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.09% of the mass of dioctyl phthalate relative to the polyester resin matrix has been added through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0131] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 70 r / min for 9 minutes to obtain mixture B;

[0132] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (65nm particle size), nano silver / titanium dioxide composite powder (30nm particle size) with stearic acid modified surface, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0133] The antioxidants consist of antioxidant 1010 (0.8 μm particle size) and antioxidant 168 (0.9 μm particle size) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 3%, and the mass percentage of the glass fiber treated with silane coupling agent is 22%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 0.8%, 0.5%, and 0.6%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1.2:1, and the amount of ethylene propylene rubber added is 6% of the total mass of the polyester resin matrix.

[0134] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Use a metering pump to uniformly spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture. The amount of DOP is 0.3% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action, while avoiding high-speed shearing that would cause DOP to adsorb onto the glass fiber surface. After mixing, keep the paddle rotating at a low speed of 20 r / min and evacuate to remove the air entrained during the mixing process.

[0135] (3) Twin-screw extrusion molding;

[0136] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die and is cooled by a three-roll calender. The traction speed is controlled at 8 m / min, and the film is wound up to obtain a nano-composite polyester film with a thickness of 0.15 mm.

[0137] The co-rotating twin-screw extruder has an L / D ratio of 40:1 and a screw diameter of Φ = 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 6 MPa, and feeding speed 15 kg / h.

[0138] The final nano-polyester film had a water vapor permeability of 1.15 g / (m²). 2 • 24h); peel strength is 5.2 N / cm; FT-IR peak intensity coupling degree is 86%; XPS elemental binding energy shift is 0.35 eV; the antibacterial rate of the nanocomposite polyester film is 99.95%, and the antibacterial rate is 95.80% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.90%, and the oxidation induction time (OIT) is 21.5 min.

[0139] Example 3

[0140] A method for preparing a nanocomposite polyester film with high weather resistance, the specific steps of which are as follows:

[0141] (1) Synthesis of polyester resin matrix;

[0142] First, terephthalic acid and ethylene glycol are added to a reaction vessel at a molar ratio of 1:1.15, followed by antimony trioxide and triphenyl phosphite. The reaction is carried out at 240°C and atmospheric pressure for 3 hours until the water output reaches more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, brand name: [missing information]) with a grafting rate of 1.50% is added. The reaction mixture (18307) was heated to 247℃ and stirred at 100 r / min for 30 minutes to induce esterification between the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer and the hydroxyl groups at the ends of the polyester chain. Finally, the system pressure was reduced to 150 Pa, the temperature was increased to 275℃, and the reaction was carried out for 2.5 hours until the intrinsic viscosity reached 0.67 dL / g, thus obtaining the polyester resin matrix.

[0143] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 1.5% of the mass of polyester resin matrix.

[0144] (2) Multi-component gradient blending;

[0145] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0146] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0147] (2.3) The organically modified montmorillonite with an interlayer spacing of 2.7 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0148] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.1% of the mass of dioctyl phthalate relative to the polyester resin matrix has been added through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0149] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 90 r / min for 6 minutes to obtain mixture B;

[0150] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (75nm particle size), nano silver / titanium dioxide composite powder (35nm particle size) with stearic acid modified surface, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0151] The antioxidants consist of antioxidant 1010 (particle size 1.2 μm) and antioxidant 168 (particle size 1.3 μm) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 4%, and the mass percentage of the glass fiber treated with silane coupling agent is 25%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 1.0%, 0.7%, and 0.8%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1.5:1, and the amount of ethylene propylene rubber added is 8% of the total mass of the polyester resin matrix.

[0152] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Use a metering pump to uniformly spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture. The amount of DOP is 0.4% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action, while avoiding high-speed shearing that would cause DOP to adsorb onto the glass fiber surface. After mixing, keep the paddle rotating at a low speed of 20 r / min and evacuate to remove the air entrained during the mixing process.

[0153] (3) Twin-screw extrusion molding;

[0154] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die and is cooled by a three-roll calender. The traction speed is controlled at 8 m / min, and the film is wound up to obtain a nano-composite polyester film with a thickness of 0.2 mm.

[0155] The co-rotating twin-screw extruder has an L / D ratio of 40:1 and a screw diameter of Φ = 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 7 MPa, and feeding speed 15 kg / h.

[0156] The final nano-polyester film had a water vapor permeability of 1.1 g / (m²). 2 • 24h); peel strength is 5.5 N / cm; FT-IR peak intensity coupling degree is 85%; XPS element binding energy shift is 0.4 eV; the antibacterial rate of the nanocomposite polyester film is 99.94%, and the antibacterial rate is 95.60% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.70%, and the oxidation induction time (OIT) is 21.2 min.

[0157] Example 4

[0158] A method for preparing a nanocomposite polyester film with high weather resistance, the specific steps of which are as follows:

[0159] (1) Synthesis of polyester resin matrix;

[0160] First, terephthalic acid and ethylene glycol were added to a reactor at a molar ratio of 1:1.15, followed by antimony trioxide and triphenyl phosphite. The reaction was carried out at 232°C and atmospheric pressure for 3.75 hours, until the water output reached more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, brand name: [missing information]) with a grafting rate of 1.50% was added. The reaction mixture (18307) was heated to 248℃ and stirred at 85 r / min for 30 minutes to induce esterification between the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer and the hydroxyl groups at the ends of the polyester chain. Finally, the system pressure was reduced to 160 Pa, the temperature was increased to 276℃, and the reaction was carried out for 2.5 hours until the intrinsic viscosity reached 0.68 dL / g, thus obtaining the polyester resin matrix.

[0161] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 1.8% of the mass of polyester resin matrix.

[0162] (2) Multi-component gradient blending;

[0163] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0164] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0165] (2.3) The organically modified montmorillonite with an interlayer spacing of 2.8 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0166] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.11% of the mass of dioctyl phthalate relative to the polyester resin matrix already put in is sprayed through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0167] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 80 r / min for 8 minutes to obtain mixture B;

[0168] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (85nm particle size), nano silver / titanium dioxide composite powder (40nm particle size) with stearic acid modified surface, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0169] The antioxidants consist of antioxidant 1010 (particle size 1.5 μm) and antioxidant 168 (particle size 1.6 μm) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 5%, and the mass percentage of the glass fiber treated with silane coupling agent is 28%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 1.2%, 0.9%, and 0.9%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1.8:1, and the amount of ethylene propylene rubber added is 9% of the total mass of the polyester resin matrix.

[0170] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Use a metering pump to uniformly spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture. The amount of DOP is 0.5% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action, while avoiding high-speed shearing that would cause DOP to adsorb onto the glass fiber surface. After mixing, keep the paddle rotating at a low speed of 20 r / min and evacuate to remove air entrained during the mixing process.

[0171] (3) Twin-screw extrusion molding;

[0172] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die and is cooled by a three-roll calender. The traction speed is controlled at 8 m / min, and the film is wound up to obtain a nano-composite polyester film with a thickness of 0.25 mm.

[0173] The co-rotating twin-screw extruder has a length-to-diameter ratio (L / D) of 40:1 and a screw diameter (Φ) of 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 8 MPa, and feeding speed 15 kg / h.

[0174] The final nano-polyester film had a water vapor permeability of 1.05 g / (m²). 2 • 24h); peel strength is 5.8 N / cm; FT-IR peak intensity coupling degree is 88%; XPS elemental binding energy shift is 0.45 eV; the antibacterial rate of the nanocomposite polyester film is 99.92%, and the antibacterial rate is 95.30% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.40%, and the oxidation induction time (OIT) is 20.8 min.

[0175] Example 5

[0176] A method for preparing a nanocomposite polyester film with high weather resistance, the specific steps of which are as follows:

[0177] (1) Synthesis of polyester resin matrix;

[0178] First, terephthalic acid and ethylene glycol were added to a reactor at a molar ratio of 1:1.15, along with antimony trioxide and triphenyl phosphite. The reaction was carried out at 235°C and atmospheric pressure for 3.5 hours until the water output reached more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, grade: T9318) with a grafting rate of 1.30% was added. The temperature was controlled at 249°C, the stirring speed at 90 r / min, and the reaction was carried out for 30 minutes to allow the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends. Finally, the system pressure was reduced to 180 Pa, the temperature was raised to 278°C, and the reaction was carried out for 2.25 hours until the intrinsic viscosity reached 0.69 dL / g, yielding a polyester resin matrix.

[0179] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 2% of the mass of polyester resin matrix.

[0180] (2) Multi-component gradient blending;

[0181] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0182] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0183] (2.3) The organically modified montmorillonite with an interlayer spacing of 2.9 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0184] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.12% of the mass of dioctyl phthalate relative to the polyester resin matrix has been added through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0185] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 70 r / min for 9 minutes to obtain mixture B;

[0186] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (70nm particle size), nano silver / titanium dioxide composite powder (32nm particle size) with stearic acid modified surface, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0187] The antioxidants consist of antioxidant 1010 (particle size 1.0 μm) and antioxidant 168 (particle size 1.1 μm) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 3%, and the mass percentage of the glass fiber treated with silane coupling agent is 30%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 1.5%, 1.0%, and 1.0%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 2:1, and the amount of ethylene propylene rubber added is 10% of the total mass of the polyester resin matrix.

[0188] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Use a metering pump to uniformly spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture. The amount of DOP is 0.3% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action, while avoiding high-speed shearing that would cause DOP to adsorb onto the glass fiber surface. After mixing, keep the paddle rotating at a low speed of 20 r / min and evacuate to remove the air entrained during the mixing process.

[0189] (3) Twin-screw extrusion molding;

[0190] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die and is cooled by a three-roll calender. The traction speed is controlled at 8 m / min, and the film is wound up to obtain a nano-composite polyester film with a thickness of 0.3 mm.

[0191] The co-rotating twin-screw extruder has an L / D ratio of 40:1 and a screw diameter of Φ = 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 5.5 MPa, and feeding speed 15 kg / h.

[0192] The final nano-polyester film had a water vapor permeability of 1.1 g / (m²). 2 • 24h); peel strength is 5.3 N / cm; FT-IR peak intensity coupling degree is 86%; XPS elemental binding energy shift is 0.35 eV; the antibacterial rate of the nanocomposite polyester film is 99.96%, and the antibacterial rate is 95.70% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.80%, and the oxidation induction time (OIT) is 21.3 min.

[0193] Example 6

[0194] A method for preparing a nanocomposite polyester film with high weather resistance, the specific steps of which are as follows:

[0195] (1) Synthesis of polyester resin matrix;

[0196] First, terephthalic acid and ethylene glycol were added to a reaction vessel at a molar ratio of 1:1.15, followed by antimony trioxide and triphenyl phosphite. The reaction was carried out at 238°C and atmospheric pressure for 3.25 hours until the water output reached more than 95% of the theoretical value. Then, maleic anhydride-grafted ethylene-vinyl acetate copolymer (manufacturer: Arkema, France, brand name: [missing information]) with a grafting rate of 1.50% was added. 18307), the temperature was controlled at 250℃, the stirring speed was 95 r / min, and the reaction was carried out for 30 minutes to allow the anhydride groups of the maleic anhydride-grafted ethylene-vinyl acetate copolymer to undergo an esterification reaction with the hydroxyl groups at the end of the polyester chain; finally, the system pressure was reduced to 200 Pa, the temperature was raised to 280℃, and the reaction was carried out for 2 hours until the intrinsic viscosity reached 0.7 dL / g to obtain the polyester resin matrix;

[0197] The amount of antimony trioxide added is 3% of the mass of terephthalic acid, the amount of triphenyl phosphite added is 2% of the mass of terephthalic acid, and the amount of maleic anhydride-grafted ethylene-vinyl acetate copolymer added is 1.6% of the mass of polyester resin matrix.

[0198] (2) Multi-component gradient blending;

[0199] (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 80°C for 2 hours, then heated to 100°C and dried at a vacuum of -0.09MPa for 4 hours.

[0200] (2.2) The short glass fibers were immersed in a 2wt% aqueous solution of silane coupling agent (KH550) and ultrasonically treated for 15 minutes. After being taken out, they were dried in an oven at 120℃ for 2 hours to obtain glass fibers with silane coupling agent surface treatment.

[0201] (2.3) The organically modified montmorillonite with an interlayer spacing of 3 nm was placed in a vacuum drying oven and pre-dried at 60°C for 1 hour, then heated to 80°C and dried at a vacuum of -0.08 MPa for 3 hours.

[0202] (2.4) 60% of the total amount of the polyester resin matrix dried in step (2.1) is put into a dual planetary power mixer and run at a low speed of 50 r / min. At the same time, 0.1% of the mass of dioctyl phthalate relative to the polyester resin matrix has been added through an atomizing nozzle to form a lubricating layer on the resin surface. Then, the organic modified montmorillonite dried in step (2.3) is added into the dual planetary power mixer in three equal portions and mixed at 50 r / min for 5 minutes. Then, the speed is increased to 150 r / min, the vacuum system is turned on, and the mixture is continuously mixed for 12 minutes under a pressure of -0.08 MPa to obtain mixture A.

[0203] (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 90 r / min for 6 minutes to obtain mixture B;

[0204] (2.6) Mix A with Mix B in a horizontal ribbon mixer. Then add nano zinc oxide (particle size 90nm), nano silver / titanium dioxide composite powder (particle size 45nm) modified with stearic acid, and antioxidant. Mix at 120r / min for 10 minutes. Then add ethylene propylene rubber (manufacturer: Sinopec Beijing Yanshan Branch, grade: EPDM3092) and ethylene-methacrylate copolymer (manufacturer: Arkema, France, grade: Lotader AX8900). Mix at 60r / min for 15 minutes.

[0205] The antioxidants consist of antioxidant 1010 (particle size 1.8 μm) and antioxidant 168 (particle size 1.9 μm) in a mass ratio of 3:1. Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 4%, and the mass percentage of the glass fiber treated with silane coupling agent is 24%. Based on the total amount of mixture A and mixture B, the mass percentages of nano zinc oxide, nano silver / titanium dioxide composite powder with stearic acid modified surface, and antioxidant are 1.0%, 0.6%, and 0.7%, respectively. The mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1.6:1, and the amount of ethylene propylene rubber added is 7% of the total mass of the polyester resin matrix.

[0206] (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer. Use a metering pump to uniformly spray preheated dioctyl phthalate (DOP) at a rate of 5 mL / min onto the surface of the mixture. The amount of DOP is 0.4% of the total mass of the mixture. Mix at 40 r / min for 8 minutes (paddle blade linear velocity is 0.5 m / s) to allow DOP to penetrate into the resin particles through capillary action, while avoiding high-speed shearing that would cause DOP to adsorb onto the glass fiber surface. After mixing, keep the paddle rotating at a low speed of 20 r / min and evacuate to remove the air entrained during the mixing process.

[0207] (3) Twin-screw extrusion molding;

[0208] The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die and is cooled by a three-roll calender. The traction speed is controlled at 8 m / min, and the film is wound up to obtain a nano-composite polyester film with a thickness of 0.2 mm.

[0209] The co-rotating twin-screw extruder has an L / D ratio of 40:1 and a screw diameter of Φ = 50 mm. The extrusion process parameters are: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 245℃, and die temperature 250℃; screw speed 180 r / min, melt pressure 6.5 MPa, and feeding speed 15 kg / h.

[0210] The final nano-polyester film had a water vapor permeability of 1 g / (m 2 • 24h); peel strength is 5.6 N / cm; FT-IR peak intensity coupling degree is 87%; XPS elemental binding energy shift is 0.4 eV; the antibacterial rate of the nanocomposite polyester film is 99.91%, and the antibacterial rate is 95.20% after 50 UV aging cycles; the tensile strength retention rate of the nanocomposite polyester film after 1000h UV aging is 85.30%, and the oxidation induction time (OIT) is 20.5 min.

Claims

1. A method for preparing a nanocomposite polyester film with high weather resistance, characterized in that: First, maleic anhydride graft copolymer is added to the system after the polyester esterification reaction, causing the anhydride groups of the maleic anhydride graft copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends, followed by a polycondensation reaction to obtain a polyester resin matrix. Then, a portion of the polyester resin matrix is ​​premixed with organically modified montmorillonite, allowing the organically modified montmorillonite to form a layered dispersion structure in the polyester resin matrix, resulting in mixture A. The remaining portion of the polyester resin matrix is ​​then mixed and dispersed with glass fibers whose surfaces have been treated with a silane coupling agent, resulting in mixture B. Finally, mixture A and mixture B are mixed, and ethylene propylene rubber and ethylene-methacrylate copolymer are added. The mixture is then extruded using a twin-screw extruder to obtain a nanocomposite polyester film.

2. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 1, characterized in that, The specific steps are as follows: (1) Synthesis of polyester resin matrix; First, terephthalic acid and ethylene glycol are added to a reactor at a molar ratio of 1:1.08–1.22, along with a catalyst and heat stabilizer. The reaction is carried out at 230–240°C and atmospheric pressure for 3–4 hours until the water output reaches more than 95% of the theoretical value. Then, maleic anhydride graft copolymer is added, and the temperature is controlled at 245–250°C with a stirring speed of 80–100 r / min. The reaction is carried out for 30–35 minutes to allow the anhydride groups of the maleic anhydride graft copolymer to undergo an esterification reaction with the hydroxyl groups at the polyester chain ends. Finally, the system pressure is reduced to 100–200 Pa, the temperature is raised to 270–280°C, and the reaction is carried out for 2–3 hours to obtain the polyester resin matrix. (2) Multi-component gradient blending; (2.1) The polyester resin matrix synthesized in step (1) is placed in a vacuum oven and pre-dried at 75-90°C for 2-2.5 hours, then heated to 90-105°C and dried at a vacuum of -0.085--0.095MPa for 3.5-4.5 hours. (2.2) Immerse the short glass fibers in an aqueous solution of silane coupling agent and sonicate for 15 to 18 minutes. After removing them, dry them in an oven at 110 to 130°C for 1.5 to 2.5 hours to obtain glass fibers with a surface treated with silane coupling agent. (2.3) Place the organically modified montmorillonite in a vacuum drying oven and pre-dry it at 55-65℃ for 0.8-1.2 hours, then raise the temperature to 75-85℃ and dry it at a vacuum of -0.075--0.085MPa for 2.5-3.5 hours; (2.4) Add 60% of the total amount of the polyester resin matrix dried in step (2.1) to a dual planetary power mixer and run it at a low speed of 45-55 r / min. At the same time, spray 0.08%-0.12% by mass of dioctyl phthalate relative to the added polyester resin matrix through an atomizing nozzle to form a lubricating layer on the resin surface. Then, add equal amounts of the organic modified montmorillonite dried in step (2.3) to the dual planetary power mixer in three batches and mix at 45-55 r / min for 4-6 minutes. Then, increase the speed to 150 r / min, turn on the vacuum system, and continue mixing for 12-15 minutes under a pressure ≤ -0.08 MPa to obtain mixture A. (2.5) Add the remaining 40% of the polyester resin matrix and the glass fiber treated with silane coupling agent in step (2.2) to a horizontal ribbon mixer and mix at a speed of 70-90 r / min for 6-9 minutes to obtain mixture B; (2.6) Mix A with mixture B in a horizontal ribbon mixer. Then add anti-aging agent, antibacterial agent and antioxidant first, and mix at high speed of 110-130 r / min for 8-12 minutes. Then add ethylene propylene rubber and ethylene-methacrylate copolymer, and mix at low speed of 50-70 r / min for 12-18 minutes. (2.7) Transfer the mixture obtained in step (2.6) to a paddle mixer, and uniformly spray preheated dioctyl phthalate (DOP) at a rate of 4-6 mL / min onto the surface of the mixture using a metering pump. The amount of DOP is 0.2-0.5% of the total mass of the mixture. Mix at a speed of 35-45 r / min for 7-9 minutes. After mixing, keep the paddle rotating at a low speed of 18-25 r / min and evacuate to remove the air entrained during the mixing process. (3) Twin-screw extrusion molding; The mixture obtained in step (2.7) is fed into a co-rotating twin-screw extruder. The extruded melt flows out through a T-die, is cooled by a three-roll calender, and the traction speed is controlled at 7-9 m / min. The mixture is then wound up to obtain a nano-composite polyester film.

3. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (1), the catalyst is antimony trioxide, and the amount of catalyst added is 0.02% to 0.08% of the mass of terephthalic acid. The heat stabilizer is triphenyl phosphite, and the amount of heat stabilizer added is 0.05% to 0.2% of the mass of terephthalic acid.

4. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (1), the maleic anhydride graft copolymer is a maleic anhydride-grafted ethylene-vinyl acetate copolymer with a grafting rate of 1.2-1.5%; the amount of maleic anhydride graft copolymer added is 1-2% of the mass of the polyester resin matrix.

5. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (2.3), the interlayer spacing of the organically modified montmorillonite is ≥2.5nm.

6. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, Based on the total amount of the dried polyester resin matrix, the mass percentage of the dried organic modified montmorillonite is 2-5%, and the mass percentage of the glass fiber treated with silane coupling agent is 20-30%.

7. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (2.6), the anti-aging agent is nano zinc oxide, the antibacterial agent is nano silver / titanium dioxide composite powder with a surface modified by stearic acid, and the antioxidant is composed of hindered phenolic phosphites. Based on the total amount of mixture A and mixture B, the mass percentages of the anti-aging agent, antibacterial agent and antioxidant are 0.5-1.5%, 0.3-1.0% and 0.5-1.0%, respectively.

8. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (2.6), the mass ratio of ethylene propylene rubber to ethylene-methacrylate copolymer is 1 to 2:1, and the amount of ethylene propylene rubber added is 5 to 10% of the total mass of polyester resin matrix.

9. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, In step (3), the length-to-diameter ratio of the co-rotating twin-screw extruder is L / D = 35:1 to 45:1, and the screw diameter is Φ = 45 to 55 mm.

10. The method for preparing a nanocomposite polyester film with high weather resistance according to claim 2, characterized in that, The extrusion process parameters in step (3) are: zone 1 temperature 220~240℃, zone 2 temperature 230~250℃, zone 3 temperature 240~260℃, zone 4 temperature 235~255℃, die temperature 240~260℃; screw speed 160~200r / min, melt pressure 5~8MPa, and feeding speed 12~18kg / h.

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