A tear-resistant polyester composite film and a method for manufacturing the same

Abstract

This invention discloses a tear-resistant polyester composite film and its preparation method, relating to the field of thin film engineering technology. The tear-resistant polyester composite film comprises the following components by weight: 70-90 parts of a first polyester, 10-20 parts of a second polyester, 4-8 parts of an amide-functionalized polyester oligomer, and 0.2-0.6 parts of a multifunctional epoxy chain extender; wherein the intrinsic viscosity of the first polyester is 0.6-0.8 dL / g, and the main chain of the amide-functionalized polyester oligomer contains 15-35 mol% amide groups. The tear-resistant polyester composite film provided by this invention forms a multi-scale interpenetrating structure through the dynamic hydrogen bond network provided by the amide-functionalized polyester oligomer and the branched structure generated in situ by the multifunctional epoxy chain extender, driven by an ultrasonic-assisted process during its preparation. This structure effectively suppresses phase separation and provides a viscoelastic hysteresis dissipation mechanism, thereby significantly improving the tear resistance of the film.

Description

Technical Field

[0001] This invention relates to the field of thin film engineering technology, and in particular to a tear-resistant polyester composite film and its preparation method. Background Technology

[0002] Biaxially oriented polyester film (typically BOPET) is widely used in packaging, electronics, and optics. However, due to the high orientation of its molecular chains, it is prone to anisotropy, and tear cracks tend to propagate rapidly along the orientation direction, resulting in insufficient tear resistance. This severely restricts its application in high-stress packaging, flexible electronic substrates, and other high-reliability scenarios. Conventional modification methods include adding elastomer blends, inorganic fillers, or simple compatibilizers. However, these methods often suffer from poor compatibility, easy agglomeration, and stress concentration, leading to decreased transparency or deterioration in processing stability, making it difficult to achieve a balanced improvement in overall performance. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a tear-resistant polyester composite film and its preparation method, the specific technical solution being as follows: A tear-resistant polyester composite film, by weight, comprises the following components: 70-90 parts of a first polyester, 10-20 parts of a second polyester, 4-8 parts of an amide-functionalized polyester oligomer, and 0.2-0.6 parts of a multifunctional epoxy chain extender. The intrinsic viscosity of the first polyester is 0.6~0.8 dL / g, and the main chain of the amide-functionalized polyester oligomer contains 15~35 mol% amide groups.

[0004] Preferably: The first polyester is selected from at least one of polyethylene terephthalate or amide-modified polyester; The second polyester is polybutylene terephthalate.

[0005] Preferably, the multifunctional epoxy chain extender is an epoxy-functionalized styrene-acrylic acid copolymer.

[0006] Preferably, it further includes the following components by weight: 0.5 to 3 parts of functionalized polyhedral oligomeric silsesquioxane and 0.3 to 1 part of anhydride functionalized polyester compatibilizer.

[0007] Preferably: The functionalized polyhedral oligomeric silsesquioxane is an amino and / or epoxy bifunctionalized POSS. The anhydride-functionalized polyester compatibilizer is a maleic anhydride-grafted polyester oligomer.

[0008] The present invention also provides a method for preparing a tear-resistant polyester composite film as described in any one of the above claims, comprising the following steps: S1. Weigh each raw material component according to the proportion and mix them evenly; S2. Add the mixed raw materials to a twin-screw extruder and apply ultrasonic vibration treatment in the molten state; S3. The processed melt is extruded through a die and cooled to obtain a thick sheet; S4. The thick sheet is stretched longitudinally and laterally, and then heat-set to obtain the tear-resistant polyester composite film.

[0009] Preferably: In step S1, the mixing is high-speed stirring, with a stirring speed of 800~1500 rpm; In step S2, the temperature of the twin-screw extruder is 240~260℃, the screw speed is 200~300 rpm, the frequency of the ultrasonic vibration is 20~40 kHz, and the sound intensity is 5~15 W / cm². 2 The point of action is located in the metering section of the extruder or in the static mixer in front of the die; In step S3, the die head temperature is 255~265℃, and it is cooled to 30~50℃ to obtain a thick sheet; In step S4, the stretching process is synchronous biaxial stretching, with a longitudinal stretching ratio of 2.5 to 3.5 times and a stretching temperature of 85 to 95°C; a transverse stretching ratio of 3.0 to 4.0 times and a stretching temperature of 100 to 120°C; a heat setting temperature of 200 to 230°C and a heat setting time of 20 to 30 seconds.

[0010] Preferably, the first polyester comprises an amide-modified polyester, which is prepared by the following steps: S10. Mix 1,6-hexanediamine and ethylene carbonate at a mass ratio of 1:(1.6~1.8), react at 70~90℃ for 3~5 h in anhydrous ethanol solvent and sodium methoxide catalysis, and obtain bis(2-hydroxyethyl)hexanediamine by cooling crystallization, filtration and drying. S20. Terephthalic acid and ethylene glycol are subjected to an esterification reaction to obtain ethylene glycol terephthalate oligomers; S30. Add 0.5% to 5% (by weight) of bis(2-hydroxyethyl)hexamethylenediamide to the ethylene terephthalate oligomer, react at 240 to 250 °C under normal pressure for 1 h, and then carry out polycondensation at 270 to 285 °C and pressure < 100 Pa.

[0011] Preferably, the amide-functionalized polyester oligomer is prepared by the following steps: S100. Polyethylene terephthalate and ethylene glycol are mixed at a mass ratio of 1:(2~4), and 0.1%~0.5% of zinc acetate by mass of polyethylene terephthalate is added. The mixture is stirred and reacted at 220~240℃ for 2~4 h to obtain hydroxyl-terminated polyester oligomers. S200. Add 10%~20% by weight of polyethylene terephthalate and 0.05%~0.2% by weight of titanate or tin catalyst to the hydroxyl-terminated polyester oligomer, and react at 230~250℃ for 0.5~1 h, followed by a further reaction at a pressure <100 Pa for 1~2 h.

[0012] Preferably, the raw material components further include functionalized polyhedral oligomeric silsesquioxanes and anhydride-functionalized polyester compatibilizers, wherein the functionalized polyhedral oligomeric silsesquioxanes are prepared by the following steps: S01. Mix 3-aminopropyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane at a mass ratio of 1:(1~1.5) and dissolve in 30~60 times their mass of anhydrous ethanol; S02. Add 10% (w / w) tetramethylsodium hydroxide methanol solution to adjust the pH to 10-11; S03. Stir and react at 25~35℃ in the dark for 48~72 h. After the reaction is completed, concentrate under reduced pressure, wash with deionized water and dry to obtain the product.

[0013] The tear-resistant polyester composite film provided by this invention utilizes a dynamic hydrogen-bonding network provided by amide-functionalized polyester oligomers and a branched structure generated in situ by a multifunctional epoxy chain extender. During its preparation process, a multi-scale interpenetrating structure can be formed through ultrasonic-assisted processing. This structure effectively suppresses phase separation and provides a viscoelastic hysteresis dissipation mechanism, thereby significantly improving the tear resistance of the film while maintaining excellent transparency and a wide processing window. This overcomes the technical challenges of poor compatibility and decreased transparency inherent in conventional rigid-flexible polyester blends. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0015] This embodiment provides a tear-resistant polyester composite film, which is made of the following components by weight: 70-90 parts of a first polyester, 10-20 parts of a second polyester, 4-8 parts of an amide-functionalized polyester oligomer, and 0.2-0.6 parts of a multifunctional epoxy chain extender.

[0016] The first polyester has an intrinsic viscosity of 0.6~0.8 dL / g, the amide-functionalized polyester oligomer has a number average molecular weight of 800~2500 g / mol, and its main chain contains 15~35 mol% amide groups.

[0017] Specifically, the first polyester mainly provides a rigid skeleton structure, while the second polyester introduces flexible segments to construct a rigid-flexible blend matrix. The amide groups on the main chain of the amide-functionalized polyester oligomer (Amide-PES) (mainly distributed at the chain ends and some side chains) can form a multiple hydrogen bond network, which has dynamic and reversible characteristics. The multifunctional epoxy chain extender extends / grafts the polyester end groups in situ through epoxy groups, generating branched or slightly cross-linked structures, thereby strengthening the interfacial bonding between the components.

[0018] The first polyester can be polyethylene terephthalate (PET) or an amide-modified polyester that introduces amide diol comonomers through a polycondensation stage; the second polyester is polybutylene terephthalate (PBT); the amide-functionalized polyester oligomer can be prepared by precise amidation / amide exchange reaction with diamines (such as 1,6-hexanediamine, m-phenylenediamine, etc.) after PET alcoholysis. The content of its main chain amide groups and the number-average molecular weight can be jointly controlled by the mass ratio of polyester to diamine, reaction time, and vacuum degree; the multifunctional epoxy chain extender can be epoxy-functionalized styrene-acrylic acid copolymer or other reactive chain extenders with multiple epoxy groups, which can undergo efficient ring-opening reactions with terminal hydroxyl / carboxyl groups in the molten state.

[0019] The tear-resistant polyester composite film provided in this embodiment utilizes a dynamic hydrogen-bonding network provided by amide-functionalized polyester oligomers and a branched structure generated in situ by a multifunctional epoxy chain extender. During its preparation process, a multi-scale interpenetrating structure can be formed through ultrasonic-assisted processing. This structure effectively suppresses phase separation and provides a viscoelastic hysteresis dissipation mechanism, thereby significantly improving the tear resistance of the film while maintaining excellent transparency and a wide processing window. This overcomes the technical challenges of poor compatibility and decreased transparency inherent in conventional rigid-flexible polyester blends.

[0020] Furthermore: The first polyester is selected from at least one of polyethylene terephthalate or amide-modified polyester.

[0021] The second polyester is polybutylene terephthalate.

[0022] Among them, polyethylene terephthalate (PET), as a rigid main chain component, provides excellent mechanical strength and thermal stability; amide-modified polyester introduces amide diol units through copolymerization during the PET polycondensation stage, so that the main chain contains covalently bonded amide groups, thereby achieving molecular-level hydrogen bond anchoring; polybutylene terephthalate (PBT), due to the flexibility of the butanediol segments, introduces dissipation domains, which helps to absorb energy through chain segment movement when subjected to force.

[0023] Specifically, the first polyester can be pure PET, or an amide-grafted-PET prepared by introducing amide diol comonomers such as bis(2-hydroxyethyl)hexamethylenediamide into the PET polycondensation system at a ratio of 0.5 to 2 mol%. This modification can further enhance the compatibility with Amide-PES oligomers. The second polyester is strictly selected from polybutylene terephthalate (PBT), whose intrinsic viscosity can be matched with PET to optimize blend flowability. In addition, the first polyester can also be any ratio of PET and amide-modified polyester to flexibly adjust the rigidity-flexibility balance according to the final film thickness or application scenario.

[0024] Furthermore, the multifunctional epoxy chain extender is an epoxy-functionalized styrene-acrylic acid copolymer.

[0025] Among them, the epoxy-functionalized styrene-acrylic acid copolymer contains multiple epoxy groups, which can undergo ring-opening reactions with the terminal hydroxyl groups and / or terminal carboxyl groups of the polyester components (including the first polyester, the second polyester and the amide-functionalized polyester oligomer) at the melt blending temperature, thereby achieving in-situ chain extension and grafting, thus forming a branched or slightly cross-linked structure in the rigid-flexible blend matrix, strengthening interfacial adhesion and stabilizing the multiple hydrogen bond network.

[0026] Specifically, the preferred multifunctional epoxy chain extender is the BASF Joncryl® ADR series or other styrene-acrylic copolymers with similar epoxy functionality, and its epoxy equivalent can be matched according to the end group content of the system. Under the assistance of ultrasonic vibration, the reaction efficiency of this chain extender is significantly improved, and it can efficiently complete the in-situ reaction even at high temperature and short melt residence time.

[0027] Furthermore, it also includes the following components by weight: 0.5 to 3 parts of functionalized polyhedral oligomeric silsesquioxane and 0.3 to 1 part of anhydride-functionalized polyester compatibilizer.

[0028] Among them, functionalized polyhedral oligomeric silsesquioxanes (POSS), as nanoscale 0D hybrid particles, can form nanoscale anchoring points by chemically bonding with polyester matrix and amide-functionalized polyester oligomers through their amino and / or epoxy bifunctionalized groups; anhydride-functionalized polyester compatibilizers (such as maleic anhydride-grafted polyester oligomers) further enhance the dispersibility of nanoparticles and strengthen interfacial compatibility by undergoing in-situ grafting reactions with polyester end groups or amino groups through anhydride groups, thereby introducing additional crack bridging and tortuous path structures in multiscale interpenetrating networks.

[0029] Furthermore: Functionalized polyhedral oligomeric silsesquioxanes are amino and / or epoxy bifunctionalized POSSes.

[0030] The anhydride-functionalized polyester compatibilizer is a maleic anhydride-grafted polyester oligomer.

[0031] Among them, amino and / or epoxy bifunctionalized POSS forms a stable nano-polymer interface anchor by forming multiple chemical bonds with polyester segments, amide groups of amide-functionalized polyester oligomers and residual epoxy groups of chain extenders through its organic functional groups; maleic anhydride grafted polyester oligomers (MAH-g-PES) take advantage of the high reactivity of the anhydride groups in the molten state to rapidly undergo ring-opening or grafting reactions with polyester end groups, amino or hydroxyl groups, playing a role in reactive compatibility and dispersion, thereby firmly embedding nanoparticles into a multi-scale network structure.

[0032] This embodiment also provides a method for preparing a tear-resistant polyester composite film as described in any one of the above embodiments, comprising the following steps: S1. Weigh each raw material component according to the proportion and mix them evenly.

[0033] S2. Add the mixed raw materials into a twin-screw extruder and apply ultrasonic vibration treatment in the molten state.

[0034] S3. The processed melt is extruded through a die and cooled to obtain a thick sheet.

[0035] S4. The thick sheet is stretched longitudinally and laterally, and then heat-set to obtain a tear-resistant polyester composite film.

[0036] In step S1, premixing is used to achieve the initial dispersion of each component (including the first polyester, the second polyester, the amide-functionalized polyester oligomer, the multifunctional epoxy chain extender, and optional functionalized POSS and anhydride compatibilizer). In step S2, ultrasonic vibration is applied to the melting section of the twin-screw extruder to induce local shear thinning and molecular chain relaxation of the melt by high-frequency mechanical vibration, while accelerating the dynamic dissociation and reconstruction of amide hydrogen bonds and the in-situ reactive grafting of epoxy groups in the chain extender. In step S3, a thick sheet with a preliminary network structure is formed by die extrusion and cooling. In step S4, synchronous biaxial stretching promotes the synergistic orientation of rigid-flexible segments and nanoparticles, further improving the multi-scale interpenetrating network.

[0037] Benefically, this preparation method achieves a multi-dimensional synergy of "vibration acceleration-chemical anchoring-dynamic network formation" by precisely applying ultrasonic vibration treatment during the melt blending stage, which is strongly coupled with amide-functionalized polyester oligomers, multifunctional epoxy chain extenders, and optional nano-components. This process effectively overcomes the phase separation and interface weakening problems that easily occur in rigid-flexible polyester systems during conventional processing, forming a stable multi-scale interpenetrating structure after biaxial stretching, thereby significantly improving the tear resistance of the film while maintaining excellent transparency, processing stability, and a wide temperature window.

[0038] Furthermore: In step S1, the mixing is carried out by high-speed stirring at a speed of 800-1500 rpm.

[0039] In step S2, the temperature of the twin-screw extruder is 240~260℃, the screw speed is 200~300 rpm, the frequency of the ultrasonic vibration is 20~40 kHz, and the sound intensity is 5~15 W / cm². 2 The action point is located in the metering section of the extruder or in the static mixer in front of the die.

[0040] In step S3, the die head temperature is 255~265℃, and it is cooled to 30~50℃ to obtain a thick sheet.

[0041] In step S4, the stretching process is a simultaneous biaxial stretching, with a longitudinal stretching ratio of 2.5 to 3.5 times and a stretching temperature of 85 to 95°C. The transverse stretching ratio is 3.0 to 4.0 times and the stretching temperature is 100 to 120°C. The heat setting temperature is 200 to 230°C, and the heat setting time is 20 to 30 seconds.

[0042] Furthermore, the first polyester comprises an amide-modified polyester, which is prepared by the following steps: S10. Mix 1,6-hexanediamine and ethylene carbonate at a mass ratio of 1:(1.6~1.8) until homogeneous. React at 70~90℃ for 3~5 h in anhydrous ethanol solvent and sodium methoxide as catalyst. After cooling and crystallization, filter and dry to obtain bis(2-hydroxyethyl)hexanediamine.

[0043] S20. Terephthalic acid and ethylene glycol are subjected to an esterification reaction to obtain ethylene glycol terephthalate oligomer.

[0044] S30. Add 0.5% to 5% (by weight) of bis(2-hydroxyethyl)hexamethylenediamide to the polyethylene terephthalate oligomer, react at 240 to 250 °C under normal pressure for 1 h, and then carry out polycondensation at 270 to 285 °C and pressure < 100 Pa.

[0045] In step S10, an amide diol comonomer (bis(2-hydroxyethyl)hexamethylenediamine) is precisely synthesized through the ring-opening reaction of 1,6-hexanediamine and ethylene carbonate. This monomer contains an amide group and two hydroxyl end groups. In step S20, a polyethylene terephthalate (BHET) oligomer is obtained as a polycondensation precursor. In step S30, the amide diol comonomer is introduced into the polycondensation system in a specific ratio, so that the amide group is grafted onto the PET main chain through covalent bonding, achieving molecular-level hydrogen bond anchoring, thereby enhancing the compatibility and dynamic network stability with the Amide-PES oligomer.

[0046] Specifically, the mass ratio, solvent, and catalyst dosage in S10 can be adjusted appropriately according to the reaction scale, and the reaction temperature and time ensure monomer purity and yield; the esterification reaction in S20 can adopt the conventional direct esterification process of terephthalic acid and ethylene glycol; the preferred amount of amide diol added in S30 is 0.5~2 mol% (relative to terephthalic acid), and the polycondensation conditions (temperature, pressure, and time) can be finely controlled by real-time monitoring of intrinsic viscosity to obtain Amide-grafted-PET with an intrinsic viscosity of 0.6~0.8 dL / g; in addition, other aliphatic or aromatic diamine-derived amide diol comonomers can be used for replacement, or the type of polycondensation catalyst (such as titanate esters) can be adjusted. As long as the covalent introduction of amide groups into the PET main chain can be achieved, amide-modified polyester with molecular anchoring reinforcement effect can be obtained.

[0047] Furthermore, the amide-functionalized polyester oligomer was prepared by the following steps: S100. Polyethylene terephthalate and ethylene glycol are mixed at a mass ratio of 1:(2~4), and 0.1%~0.5% of zinc acetate by mass of polyethylene terephthalate is added. The mixture is stirred and reacted at 220~240℃ for 2~4 h to obtain hydroxyl-terminated polyester oligomer.

[0048] S200. Add 10%~20% by weight of polyethylene terephthalate and 0.05%~0.2% by weight of titanate or tin catalyst to the hydroxyl-terminated polyester oligomer, and react at 230~250℃ for 0.5~1 h, followed by a further reaction at a pressure <100 Pa for 1~2 h.

[0049] In step S100, PET is depolymerized into hydroxyl-terminated polyester oligomers (mainly composed of BHET and short-chain oligomers) through an alcoholysis reaction, with precise control over the content of terminal hydroxyl groups. In step S200, amidation condensation is performed using diamines in a precise molar ratio, resulting in amide groups mainly distributed at the chain ends and some side chains, forming Amide-PES oligomers with a number-average molecular weight of 800-2500 g / mol and a main chain containing 15-35 mol% amide groups. This oligomer exhibits good high-temperature thermal stability, and its terminal groups are mainly hydroxyl and / or amide groups, facilitating subsequent reactive grafting with chain extenders and the formation of a dynamic hydrogen bond network.

[0050] Specifically, the mass ratio of PET to ethylene glycol, catalyst dosage, and reaction time in S100 can be optimized through viscosity or visual monitoring to ensure complete alcoholysis. In S200, the diamine feed ratio (1:0.85~1.05 relative to the total molar number of terminal hydroxyl groups) is key to controlling the molecular weight. 1,6-hexanediamine, m-phenylenediamine, or other aliphatic / aromatic diamines can be selected, and the catalyst can be tetrabutyl titanate or dibutyltin dilaurate, etc. The reaction process can be precisely controlled by periodically sampling and measuring acid value, hydroxyl value, or viscosity, as well as adjusting the vacuum degree. In addition, the obtained Amide-PES can be used directly in melt form or granulated and stored. As long as the number average molecular weight and amide content range are met, good compatibility with the polyester matrix can be achieved.

[0051] In this embodiment, the amide group content (mol%) refers to the molar percentage of amide structural units relative to all repeating units (ester bond units + amide units) in the oligomer molecular chain, calculated based on the raw material input amount using theoretical stoichiometry. The calculation formula is as follows: in, The molar number of 1,6-hexanediamine added in step S200. The total number of moles of the terephthalic acid segments corresponding to step S100; since the number of moles of TPA determines the total number of repeating units, and the diamine replaces part of the diol, the proportion of diamine to TPA is the degree of amidation.

[0052] Under the polycondensation process conditions of this embodiment, due to the decompression polycondensation promoting the expulsion of small molecule ethylene glycol, and the complete amidation / amide exchange reaction between the diamine and the terminal carboxyl or hydroxyl groups, the diamine component in the feed almost completely enters the oligomer backbone. Therefore, by precisely controlling the mass feed ratio of the raw materials, the molar content of the amide groups in the backbone (15~35 mol%) can be controlled.

[0053] Furthermore, the raw material components also include functionalized polyhedral oligomeric silsesquioxanes and anhydride-functionalized polyester compatibilizers. The functionalized polyhedral oligomeric silsesquioxanes are prepared through the following steps: S01. Mix 3-aminopropyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane at a mass ratio of 1:(1~1.5) and dissolve them in 30~60 times their mass of anhydrous ethanol.

[0054] S02. Add a 10% (w / w) tetramethylsodium hydroxide methanol solution to adjust the pH to 10-11.

[0055] S03. Stir and react at 25~35℃ in the dark for 48~72 h. After the reaction is completed, concentrate under reduced pressure, wash with deionized water and dry to obtain the product.

[0056] In step S01, amino and epoxy bifunctional groups are introduced into the POSS cage structure by mixing two silane coupling agents as co-hydrolysis-condensation precursors. Step S02 uses an alkaline catalyst to adjust the pH, promoting the hydrolysis and initial condensation of silanes. Step S03 completes the ordered assembly of the cage structure at a mild temperature, forming amino and / or epoxy bifunctional POSS nanoparticles. This POSS has a well-defined OD hybrid structure, which facilitates multiple chemical bonds with maleic anhydride-grafted polyester oligomers, amide-functionalized polyester oligomers, and chain extenders during melt blending.

[0057] Specific embodiments are provided below. These embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0058] In the following examples, in accordance with GB / T 14190-2017, phenol / 1,1,2,2-tetrachloroethane (mass ratio 1:1) was used as the solvent to prepare a test solution with a concentration of 0.5 g / dL. The outflow time of the solution and solvent was measured using an Ubbelohde viscometer in a constant temperature water bath at 25±0.05℃, and the intrinsic viscosity was calculated using the Billmeyer formula. Example 1

[0059] 5.0 g of polyethylene terephthalate (PET) particles were mixed thoroughly with 15.0 mL of ethylene glycol, and 0.015 g of zinc acetate was added. The mixture was mechanically stirred in an oil bath at 220 °C for 3 h. After the reaction was complete, hydroxyl-terminated polyester oligomers were obtained. After cooling to room temperature, 0.8 g of 1,6-hexanediamine and 0.005 g of tetrabutyl titanate were added to the oligomers, and the mixture was stirred at 230 °C for 45 min. Then, a vacuum pump was turned on to evacuate the system pressure to approximately 50 Pa, and the reaction was continued for 1.5 h. After the reaction was complete, heating was stopped, and the mixture was allowed to cool naturally to room temperature to obtain crude Amide-PES product for later use.

[0060] Weigh 80.0 g of polyethylene terephthalate (PET) with an intrinsic viscosity of 0.7 dL / g, 20.0 g of polybutylene terephthalate (PET), 6.0 g of the Amide-PES prepared above, and 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S. Place them in a high-speed mixer and mix at 1200 rpm for 15 min to obtain a uniform premix.

[0061] The premixed material was fed into a laboratory twin-screw extruder (L / D=44) via a hopper. The temperatures of each zone were set sequentially as follows: feeding section 230℃, compression section 245℃, metering section 255℃, and die section 260℃. The screw speed was set to 250 rpm. An ultrasonic device was installed in the metering section, applying an ultrasonic wave at a frequency of 30 kHz and a sound intensity of 10 W / cm². 2 The ultrasonic vibration. After the extruder is running stably, the melt is extruded from the die and cooled by traction under the condition that the cooling roller temperature is set at 40°C, to obtain a sheet with a thickness of about 1.0 mm and a width of about 120 mm.

[0062] A 100 mm × 100 mm sample was cut from a thick sheet and placed on a synchronous biaxial stretching machine. The temperature of the longitudinal stretching zone was set to 90°C, the temperature of the transverse stretching zone was set to 110°C, the longitudinal stretching ratio was set to 2.8 times (stretching speed 50 mm / min), the transverse stretching ratio was set to 3.5 times, the heat setting zone temperature was set to 220°C, and the heat setting time was 25 s. After stretching, the sample was allowed to cool naturally to room temperature to obtain a polyester composite film with a thickness of approximately 30 μm. Three parallel batches of samples were prepared in this embodiment, numbered 1-1, 1-2, and 1-3.

[0063] Tear strength was tested using the trouser tear test (GB / T 16578.1-2008); haze and transmittance were tested using an integrating sphere haze meter (GB / T2410-2008); water vapor transmission rate (GB / T 26253-2010) and oxygen transmission rate (GB / T 19789-2005) were tested using an air permeability tester; some samples were aged in a constant temperature and humidity chamber at 85%RH and 40℃ for 48 h and then the tear strength was tested again to calculate the wet retention rate. All tests were conducted at 23℃ and 50%RH.

[0064] The test results are shown in Table 1 below: Table 1: Test Data Table for Example 1 The three batches of parallel samples prepared in Example 1 all exhibited high tear strength, low haze, good water vapor barrier properties, and excellent wet performance retention. At the same time, no obvious yellowing was observed during processing at 240~260℃, indicating that the film prepared by this method has good tear resistance, transparency, and processing stability, and good batch repeatability. Example 2

[0065] 5.0 g of 1,6-hexanediamine was mixed with 8.5 g of ethylene carbonate, and 50 mL of anhydrous ethanol and 0.1 g of sodium methoxide were added. The mixture was stirred in an oil bath at 80 °C for 4 h. After the reaction was completed, the mixture was cooled to crystallize, filtered, washed twice with ethanol, and dried under vacuum at 60 °C to obtain bis(2-hydroxyethyl)hexanediamine for later use.

[0066] 66.0 g of terephthalic acid and 40.0 mL of ethylene glycol were added to a reaction vessel and esterified at 230 °C for 2 h to obtain ethylene glycol terephthalate oligomer.

[0067] 1.6 g of bis(2-hydroxyethyl)hexamethylenediamide was added to the above oligomers and reacted at 240~250℃ under normal pressure for 1 h. Then the temperature was raised to 270~285℃, and the pressure of the system was reduced to about 50 Pa by a vacuum pump. The polycondensation reaction continued until the intrinsic viscosity reached 0.7 dL / g to obtain Amide-grafted-PET.

[0068] The preparation of amide-functionalized polyester oligomers (Amide-PES) is the same as in Example 1.

[0069] Weigh out 80.0 g of Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), 6.0 g of Amide-PES, and 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S obtained above. The remaining operations are the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature 40℃, sheet preparation, 100 mm × 100 mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc. are all consistent). Three batches of parallel samples were prepared in this example, numbered 2-1, 2-2, and 2-3.

[0070] The performance testing method is the same as in Example 1, and the test results are shown in Table 2 below: Table 2: Test Data Table for Example 2 The three batches of parallel samples prepared in Example 2 all showed higher tear strength, better barrier properties and wet retention rate, while also exhibiting good processing stability. This indicates that the overall performance of the film was further improved by introducing Amide-grafted-PET on the basis of the basic components, and the batch repeatability was good. Example 3

[0071] The preparation of amide-grafted polyester (Amide-grafted-PET) was the same as in Example 2; the preparation of amide-functionalized polyester oligomer (Amide-PES) was the same as in Example 1.

[0072] 0.8 g of 3-aminopropyltrimethoxysilane and 1.0 g of 3-glycidyl etheroxypropyltrimethoxysilane were mixed and dissolved in 50 mL of anhydrous ethanol. A 10% (w / w) tetramethylsodium hydroxide methanol solution was added to adjust the pH to 10.5. The reaction was carried out at 30 °C with magnetic stirring in the dark for 60 h. After the reaction was completed, the solvent was removed by concentration under reduced pressure. The mixture was washed three times with deionized water and dried under vacuum at 60 °C to obtain amino / epoxy bifunctionalized POSS for later use.

[0073] Weigh out 80.0 g of Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), 6.0 g of Amide-PES, 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S, 1.5 g of functionalized POSS, and 0.6 g of maleic anhydride-grafted polyester oligomer (MAH-g-PES). The remaining operations are the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature 40℃, sheet preparation, 100mm×100mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc. are all consistent). Three batches of parallel samples were prepared in this example, numbered 3-1, 3-2, and 3-3.

[0074] The performance testing method is the same as in Example 1, and the test results are shown in Table 3 below: Table 3: Test Data Table for Example 3 The three batches of parallel samples prepared in Example 3 all showed further improved tear strength, lower haze and water vapor transmission rate, and higher wet retention rate, while exhibiting good processing stability. This indicates that the introduction of functionalized POSS and MAH-g-PES significantly improves the overall tear resistance, transparency, barrier properties, and wet durability of the film.

[0075] Comparative Example 1 100.0 g of commercially available polyethylene terephthalate with an intrinsic viscosity of 0.7 dL / g was weighed. The remaining procedures were the same as in Example 1, except that ultrasonic vibration treatment was not used (the temperatures of each zone of the twin-screw extruder, screw speed, cooling roller temperature of 40°C, sheet preparation, 100 mm × 100 mm sample cutting, parameters of the synchronous biaxial stretching machine, and heat setting were all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 4-1, 4-2, and 4-3.

[0076] The performance testing method is the same as in Example 1, and the test results are shown in Table 4 below: Table 4: Test Data Table for Comparative Example 1 The three batches of parallel samples prepared in Comparative Example 1 showed low tear strength and poor wet retention, and slight yellowing occurred during processing at 240~260℃, indicating that conventional pure PET biaxially oriented films have significant deficiencies in tear resistance and processing stability.

[0077] Comparative Example 2 Weigh out 80.0 g of polyethylene terephthalate (PET), 20.0 g of polybutylene terephthalate (PET), and 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S, all with an intrinsic viscosity of 0.7 dL / g. The remaining procedures were the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature of 40°C, sheet preparation, 100 mm × 100 mm sample cutting, simultaneous biaxial stretching machine parameters, heat setting, etc. were all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 5-1, 5-2, and 5-3.

[0078] The performance testing method is the same as in Example 1, and the test results are shown in Table 5 below: Table 5: Test Data Table for Comparative Example 2 The tear strength of the three batches of parallel samples prepared in Comparative Example 2 was significantly lower than that in Example 1, with higher haze, poorer barrier properties and wet retention, and moderate yellowing occurred during processing. This indicates that in the absence of Amide-PES, even with rigid-flexible blending, chain extenders, and ultrasonic treatment, the overall performance of the film is still difficult to improve effectively.

[0079] Comparative Example 3 The preparation of amide-functionalized polyester oligomers (Amide-PES) is the same as in Example 1.

[0080] Weigh out 80.0 g of polyethylene terephthalate (PET), 20.0 g of polybutylene terephthalate (PET), 6.0 g of the above-mentioned Amide-PES, and 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S. The remaining procedures were the same as in Example 1, but ultrasonic vibration treatment was not used (high-speed stirring premixing for 15 min, the temperature of each zone of the twin-screw extruder, screw speed, cooling roller temperature of 40℃, sheet preparation, 100 mm × 100 mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc., were all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 6-1, 6-2, and 6-3.

[0081] The performance testing method is the same as in Example 1, and the test results are shown in Table 6 below: Table 6: Test Data Table for Comparative Example 3 The tear strength, barrier properties and wet retention of the three batches of parallel samples prepared in Comparative Example 3 were all lower than those in Example 1, and slight yellowing occurred during processing. This indicates that even with Amide-PES, the synergistic effect between the components cannot be fully utilized without the assistance of ultrasonic vibration, and the overall performance of the film is significantly reduced.

[0082] Comparative Example 4 The preparation of amide-grafted polyester (PET) is the same as in Example 2.

[0083] Weigh out 80.0 g of the prepared Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), and 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S. The remaining procedures were the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature 40℃, sheet preparation, 100 mm × 100 mm sample cutting, simultaneous biaxial stretching machine parameters, heat setting, etc.). Three batches of parallel samples were prepared for this comparative example, numbered 7-1, 7-2, and 7-3.

[0084] The performance testing method is the same as in Example 1, and the test results are shown in Table 7 below: Table 7: Test Data Table for Comparative Example 4 The tear strength, barrier properties, and wet retention of the three batches of parallel samples prepared in Comparative Example 4 were significantly lower than those in Example 2, indicating that even with molecular anchoring modification of Amide-grafted-PET, the synergistic effect between components could not be effectively achieved in the absence of Amide-PES, and the overall performance improvement of the film was limited.

[0085] Comparative Example 5 The preparation of amide-grafted polyester (PET) was the same as in Example 2; the preparation of functionalized polyhedral oligomeric silsesquioxane (POSS) was the same as in Example 3.

[0086] Weigh out 80.0 g of the prepared Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S, 1.5 g of functionalized POSS, and 0.6 g of maleic anhydride-grafted polyester oligomer (MAH-g-PES). The remaining operations are the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature 40℃, sheet preparation, 100 mm × 100 mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc. are all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 8-1, 8-2, and 8-3.

[0087] The performance testing method is the same as in Example 1, and the test results are shown in Table 8 below: Table 8: Test Data Table for Comparative Example 5 The tear strength, barrier properties, and wet retention of the three batches of parallel samples prepared in Comparative Example 5 were significantly lower than those in Example 3. This indicates that even with molecular anchoring of Amide-grafted-PET and nano-modification of POSS+MAH-g-PES, the synergistic effect under ultrasonic assistance cannot be fully utilized in the absence of Amide-PES, resulting in limited improvement in the overall performance of the film.

[0088] Comparative Example 6 The preparation of amide-grafted polyester (Amide-grafted-PET) was the same as in Example 2; the preparation of amide-functionalized polyester oligomer (Amide-PES) was the same as in Example 1; and the preparation of functionalized polyhedral oligomeric silsesquioxane (POSS) was the same as in Example 3.

[0089] Weigh out 80.0 g of Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), 6.0 g of Amide-PES, 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S, 1.5 g of functionalized POSS, and 0.6 g of maleic anhydride-grafted polyester oligomer (MAH-g-PES). The remaining procedures are the same as in Example 1, except that ultrasonic vibration treatment was not used (high-speed stirring premixing for 15 min, the temperature of each zone of the twin-screw extruder, screw speed, cooling roller temperature of 40℃, sheet preparation, 100 mm × 100 mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc., were all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 9-1, 9-2, and 9-3.

[0090] The performance testing method is the same as in Example 1, and the test results are shown in Table 9 below: Table 9: Test Data Table for Comparative Example 6 Although the three batches of parallel samples prepared in Comparative Example 6 contained Amide-PES and nano-modified components, their tear strength, barrier properties and wet retention rate were significantly lower than those in Example 3 due to the lack of ultrasonic vibration assistance. Furthermore, slight yellowing occurred during the processing, indicating that Amide-PES must be coupled with ultrasound to fully exert the synergistic effect of the multi-component combination.

[0091] Comparative Example 7 The preparation of amide-grafted polyester (Amide-grafted-PET) was the same as in Example 2; the preparation of amide-functionalized polyester oligomer (Amide-PES) was the same as in Example 1; and the preparation of functionalized polyhedral oligomeric silsesquioxane (POSS) was the same as in Example 3.

[0092] Weigh out 80.0 g of Amide-grafted-PET, 20.0 g of polybutylene terephthalate (PBT), 6.0 g of Amide-PES, 0.4 g of the multifunctional epoxy chain extender Joncryl® ADR-4370S, and 1.5 g of functionalized POSS. The remaining operations are the same as in Example 1 (high-speed stirring premixing for 15 min, twin-screw extruder temperatures in each zone, screw speed, ultrasonic parameters, cooling roller temperature 40℃, sheet preparation, 100 mm × 100 mm sample cutting, synchronous biaxial stretching machine parameters, heat setting, etc. are all consistent). Three batches of parallel samples were prepared for this comparative example, numbered 10-1, 10-2, and 10-3.

[0093] The performance testing method is the same as in Example 1, and the test results are shown in Table 10 below: Table 10: Test Data Table for Comparative Example 7 Although the three batches of parallel samples prepared in Comparative Example 7 contained Amide-grafted-PET, Amide-PES and POSS, the tear strength, haze control and wet retention rate were lower than those in Example 3 in the absence of MAH-g-PES. This indicates that MAH-g-PES significantly improved the dispersion uniformity and interfacial compatibility of nanoparticles through in-situ grafting reaction, and played an important role in aiding dispersion and anchoring the formation of multi-scale hybrid networks.

[0094] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be within the scope of protection of the present invention.

Claims

1. A tear-resistant polyester composite film, characterized in that, The product is made from the following components in parts by weight: 70-90 parts of a first polyester, 10-20 parts of a second polyester, 4-8 parts of an amide-functionalized polyester oligomer, and 0.2-0.6 parts of a multifunctional epoxy chain extender. The intrinsic viscosity of the first polyester is 0.6~0.8 dL / g, and the main chain of the amide-functionalized polyester oligomer contains 15~35 mol% amide groups.

2. The tear-resistant polyester composite film according to claim 1, characterized in that: The first polyester is selected from at least one of polyethylene terephthalate or amide-modified polyester; The second polyester is polybutylene terephthalate.

3. The tear-resistant polyester composite film according to claim 1, characterized in that, The multifunctional epoxy chain extender is an epoxy-functionalized styrene-acrylic acid copolymer.

4. The tear-resistant polyester composite film according to any one of claims 1 to 3, characterized in that, It also includes the following components by weight: 0.5 to 3 parts of functionalized polyhedral oligomeric silsesquioxane and 0.3 to 1 part of anhydride-functionalized polyester compatibilizer.

5. The tear-resistant polyester composite film according to claim 4, characterized in that: The functionalized polyhedral oligomeric silsesquioxane is an amino and / or epoxy bifunctionalized POSS. The anhydride-functionalized polyester compatibilizer is a maleic anhydride-grafted polyester oligomer.

6. A method for preparing a tear-resistant polyester composite film as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Weigh each raw material component according to the proportion and mix them evenly; S2. Add the mixed raw materials to a twin-screw extruder and apply ultrasonic vibration treatment in the molten state; S3. The processed melt is extruded through a die and cooled to obtain a thick sheet; S4. The thick sheet is stretched longitudinally and laterally, and then heat-set to obtain the tear-resistant polyester composite film.

7. The preparation method according to claim 6, characterized in that: In step S1, the mixing is high-speed stirring, with a stirring speed of 800~1500 rpm; In step S2, the temperature of the twin-screw extruder is 240~260℃, the screw speed is 200~300 rpm, the frequency of the ultrasonic vibration is 20~40 kHz, and the sound intensity is 5~15 W / cm². 2 The point of action is located in the metering section of the extruder or in the static mixer in front of the die; In step S3, the die head temperature is 255~265℃, and it is cooled to 30~50℃ to obtain a thick sheet; In step S4, the stretching process is synchronous biaxial stretching, with a longitudinal stretching ratio of 2.5 to 3.5 times and a stretching temperature of 85 to 95°C; a transverse stretching ratio of 3.0 to 4.0 times and a stretching temperature of 100 to 120°C; a heat setting temperature of 200 to 230°C and a heat setting time of 20 to 30 seconds.

8. The preparation method according to claim 6, characterized in that, The first polyester comprises an amide-modified polyester, which is prepared by the following steps: S10. Mix 1,6-hexanediamine and ethylene carbonate at a mass ratio of 1:(1.6~1.8), react at 70~90℃ for 3~5 h in anhydrous ethanol solvent and sodium methoxide catalysis, and obtain bis(2-hydroxyethyl)hexanediamine by cooling crystallization, filtration and drying. S20. Terephthalic acid and ethylene glycol are subjected to an esterification reaction to obtain ethylene glycol terephthalate oligomers; S30. Add 0.5% to 5% (by weight) of bis(2-hydroxyethyl)hexamethylenediamide to the ethylene terephthalate oligomer, react at 240 to 250 °C under normal pressure for 1 h, and then carry out polycondensation at 270 to 285 °C and pressure < 100 Pa.

9. The preparation method according to claim 6, characterized in that, The amide-functionalized polyester oligomer was prepared by the following steps: S100. Polyethylene terephthalate and ethylene glycol are mixed at a mass ratio of 1:(2~4), and 0.1%~0.5% of zinc acetate by mass of polyethylene terephthalate is added. The mixture is stirred and reacted at 220~240℃ for 2~4 h to obtain hydroxyl-terminated polyester oligomers. S200. Add 10%~20% by weight of polyethylene terephthalate and 0.05%~0.2% by weight of titanate or tin catalyst to the hydroxyl-terminated polyester oligomer. React at 230~250℃ for 0.5~1 h, and then continue the reaction for 1~2 h under pressure <100Pa.

10. The preparation method according to claim 6, characterized in that, The raw material components also include functionalized polyhedral oligomeric silsesquioxanes and anhydride-functionalized polyester compatibilizers. The functionalized polyhedral oligomeric silsesquioxanes are prepared through the following steps: S01. Mix 3-aminopropyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane at a mass ratio of 1:(1~1.5) and dissolve in 30~60 times their mass of anhydrous ethanol; S02. Add 10% (w / w) tetramethylsodium hydroxide methanol solution to adjust the pH to 10-11; S03. Stir and react at 25~35℃ in the dark for 48~72 h. After the reaction is completed, concentrate under reduced pressure, wash with deionized water and dry to obtain the product.

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