Polyester resin composition and preparation method thereof
By introducing specific components and advanced processing techniques, a topological cross-linking network and a collaborative defense mechanism were constructed, solving the aging and mechanical property problems of polyester materials under extreme environments and achieving improved high toughness and aging resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANGZHOU XINBAO RESIN
- Filing Date
- 2026-03-19
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional polyester materials have poor aging resistance and mechanical properties under extreme environments, especially after aging, the mechanical properties drop sharply, and conventional modification methods have problems with poor compatibility and migration and precipitation of small molecule additives.
Using components such as poly(1,4-cyclohexanedimethyl terephthalate), polybutylene succinate, reactive toughening agent, modified titanium dioxide, and modified nanotubes, a topological cross-linked network is constructed through supercritical carbon dioxide-assisted twin-screw extrusion and gradient vacuum devolatilization. This network, combined with nanotubes loaded with antioxidants, forms a synergistic defense mechanism of physical shielding and chemical quenching.
It significantly improves the impact strength and aging resistance of polyester materials, solves the aging problem of traditional polyester materials in extreme environments, and ensures that the materials maintain excellent mechanical stability and anti-aging performance under high temperature and high humidity conditions.
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Figure CN122011702A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyester resin composition technology, specifically to a polyester resin composition and its preparation method. Background Technology
[0002] Polyester resins play an indispensable role in high-tech fields such as lightweight automotive components, electronic and electrical housings, 5G communication base stations, and aerospace due to their excellent processability, electrical insulation, and chemical corrosion resistance. As application scenarios continue to extend to extreme environments such as outdoor, high temperature, and high humidity, the end market is placing extremely stringent requirements on the overall service life of polyester resin compositions, which traditional single polyester materials can no longer meet.
[0003] Current technical challenges primarily stem from poor aging resistance and mechanical properties (especially the precipitous decline in mechanical properties after aging). On one hand, the ester bonds in the polyester macromolecular chain are highly susceptible to photo-oxidative and thermo-oxidative degradation under prolonged exposure to light, heat (ultraviolet radiation), and oxygen, leading to chain breakage and a decrease in molecular weight. On the other hand, conventional physical blending modifications (such as adding elastomers or antioxidants) often suffer from poor compatibility and the easy migration and precipitation of small-molecule additives. This not only fails to maintain long-term anti-aging effects but also causes severe phase separation in the material, macroscopically manifested as material embrittlement and a significant reduction in notched impact strength, severely restricting the high-end applications of polyester materials.
[0004] To this end, a polyester resin composition and its preparation method are proposed. Summary of the Invention
[0005] The purpose of this invention is to design a polyester resin composition and its preparation method. The raw materials for preparing the polyester resin composition include: polybutylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate), polybutylene succinate, reactive toughening agent, modified titanium dioxide, modified nanotubes, and chain extender. The mixture is prepared by supercritical carbon dioxide-assisted twin-screw extrusion and gradient vacuum devouring pelletizing. This invention utilizes the steric hindrance effect of the alicyclic structure to compensate for the rigidity loss caused by toughening, and constructs a topological cross-linked network through multiple interfacial reactions, significantly improving impact resistance. Simultaneously, by combining titanium dioxide loaded with a dual antioxidant system with polydopamine-coated nanotubes, a synergistic defense mechanism of physical shielding and chemical quenching is formed, ultimately improving the overall mechanical properties and aging resistance.
[0006] To achieve the above objectives, the present invention provides the following technical solution: Unless otherwise specified, all the following parts are by weight.
[0007] This invention provides a method for preparing a polyester resin composition, comprising the following steps: Polyester material was obtained by pretreatment of polybutylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate) and polybutylene succinate; the polyester material, reactive toughening agent, modified titanium dioxide, modified nanotubes and chain extender were mixed and stirred, and then subjected to supercritical fluid-assisted extrusion and gradient vacuum devolatilization and pelletizing to obtain a polyester resin composition.
[0008] Preferably, the preparation method of modified titanium dioxide is as follows: 15-25 parts of nano titanium dioxide (rutile type, average particle size of 20-50 nm) are dispersed in 150 parts of ethanol aqueous solution (ethanol mass concentration of 95%), 1 part of silane coupling agent KH-550 is added dropwise, and the mixture is mechanically stirred and ultrasonically reacted at 55℃ for 1.5 h to obtain a dispersion; 5-10 parts of antioxidant 168, 5-7 parts of HALS 944 and 50 parts of anhydrous ethanol are added to the dispersion, and the mixture is ultrasonically dispersed in a water bath at a frequency of 40 kHz for 45 min, with the temperature controlled at 50-60℃. Then, the mixture is transferred to a vacuum drying oven and dried and desolventized at a vacuum degree of -0.09 MPa and 80℃ for 12 h. The mixture is then dispersed by an air jet mill to obtain modified titanium dioxide.
[0009] Preferably, the specific pretreatment process is as follows: 65-75 parts of polybutylene terephthalate (intrinsic viscosity of 0.8-1.0 dL / g), 15-20 parts of poly(1,4-cyclohexanediethanol terephthalate) (intrinsic viscosity of 0.6-0.8 dL / g) and 5-10 parts of polybutylene succinate are put into a forced-air drying oven and dried at 110-120℃ for 5 hours to reduce the moisture content of the mixture to below 0.02% to obtain polyester material.
[0010] Preferably, the specific mixing process is as follows: polyester material, 12-18 parts of reactive toughening agent (ethylene-methyl acrylate-glycidyl methacrylate terpolymer, brand name Arkema, epoxy group content of 8wt%), 3-5 parts of modified titanium dioxide, 2-3 parts of modified nanotubes and 1.5 parts of chain extender polycarbodiimide (CAS No.: 151-51-9) are added to a high-speed mixer, the speed is set to 400 rpm, and the mixture is mixed for 3-5 minutes to obtain the blended material.
[0011] Preferably, the modified nanotubes are prepared as follows: natural halloysite nanotubes are added to a 2 mol / L hydrochloric acid solution (solid-liquid ratio of 1 g: 10-20 mL) and stirred at 55 °C for 3 h; after cooling, the precipitate is washed by centrifugation with deionized water until the supernatant is neutral; finally, the precipitate is vacuum dried at 70 °C for 18 h and then ground and sieved to obtain purified halloysite nanotubes; 2-3 parts of the purified halloysite nanotubes are dispersed in 150 parts of Tris-HCl buffer solution (concentration of 10-50 mmol / L, pH value of 8.5), 0.2-0.4 parts of dopamine hydrochloride are added, and the surface is coated by stirring in the dark at room temperature for 18 h; after centrifugation, washing, and vacuum drying, the modified nanotubes are obtained.
[0012] Preferably, the specific process of supercritical fluid-assisted extrusion is as follows: The blended material is fed into a co-rotating twin-screw extruder with a length-to-diameter ratio (L / D) of 45:1. The temperature range is set (from the feed port to the die head): Zone 1 (feeding section): 170-180℃; Zones 2 to 3 (melt mixing section): 230-240℃; Zone 4: 245℃; Zones 5 to 6 (reaction and Sc-CO2 injection section): 210-220℃ (inhibiting thermo-oxidative degradation). The Sc-CO2 injection pressure needs to be stabilized at 12MPa, the injection temperature is 50℃, and the injection amount accounts for 1.8wt% of the total material flow rate; the die head temperature is 230℃; and the screw speed is maintained at 400rpm.
[0013] Preferably, the specific process of gradient vacuum devolatilization and pelletizing is as follows: two-stage exhaust ports are set at the tail of the extruder. The first stage is atmospheric pressure exhaust (releasing most of the Sc-CO2 to initiate micro-foaming), and the second stage is vacuum exhaust, with the vacuum degree reaching -0.08MPa to -0.09MPa. Finally, underwater pelletizing is performed (water temperature controlled at 45℃), followed by centrifugal dehydration and drying to obtain a polyester resin composition.
[0014] Another aspect of the present invention provides a polyester resin composition, the raw materials of which include polybutylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate), polybutylene succinate, reactive toughening agent, modified titanium dioxide, modified nanotubes and chain extender.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention effectively solves the traditional technical bottleneck of balancing toughness and strength in polyester materials by introducing poly(1,4-cyclohexanediethanol terephthalate) containing large-volume cyclohexyl groups, combined with flexible polybutylene succinate and a reactive toughening agent. The steric hindrance effect of the rigid alicyclic structure in poly(1,4-cyclohexanediethanol terephthalate) significantly restricts the internal rotation of the molecular chain, perfectly compensating for the loss of flexural modulus caused by the addition of large amounts of elastomer toughening agents, thus maintaining excellent rigidity while ensuring high toughness.
[0016] This invention utilizes the linear stitching effect of polycarbodiimide chain extender, combined with the abundant active groups (amino and hydroxyl groups) in the polydopamine coating layer on the modified nanotube surface and the epoxy groups of the toughening agent, to induce multiple in-situ interfacial crosslinking reactions during extrusion. These reactions construct a star-shaped hybrid topological network within the polyester matrix, with nanotubes as the rigid inorganic core and elastomers as the flexible chain segments. When the material is subjected to external impact, this network can not only absorb a large amount of impact energy through the efficient deformation of the rubber phase, but also resist the propagation of microcracks due to the rigidity of the nanotubes, significantly improving the material's impact resistance.
[0017] This invention utilizes rutile nano-titanium dioxide as an excellent physical UV shielding agent. Its surface is firmly loaded with antioxidant 168 (which decomposes hydrogen peroxide) and light stabilizer HALS 944 (which captures free radicals) through an ultrasonic reaction. This core-shell structure allows the material to simultaneously block UV penetration into its deeper layers and immediately quench polymeric free radicals caused by photodegradation. This achieves precise synergy between physical barrier and chemical antioxidant properties, effectively solving the problem of easy aging of conventional polyester materials after long-term outdoor exposure.
[0018] This invention employs polydopamine-coated halloysite nanotubes. Because the polydopamine layer is rich in natural catechol structures, it inherently possesses excellent intrinsic free radical quenching capabilities. More importantly, the polydopamine layer can react with toughening agents and polyesters, firmly anchoring these anti-aging nanotubes at the interface most susceptible to thermo-oxidative degradation. This interfacial site-specific antioxidant mechanism effectively inhibits polymer chain breakage during high-temperature processing and long-term thermal service, thereby improving the material's aging resistance.
[0019] This invention utilizes the powerful physical plasticizing and viscosity-reducing effect of Sc-CO2, combined with an atypical temperature field design of high-temperature high-shear followed by low-temperature reaction promotion. This ensures complete plasticization of high-viscosity polyethylene terephthalate-1,4-cyclohexanediethanol ester while preventing the reactive toughening agent from gelling due to localized overheating (resulting in dead material). Simultaneously, the micro-foaming induced by the first-stage natural venting at the extruder tail not only induces microcrystal nucleation in the polyester but also, combined with the second-stage powerful vacuum devouring, thoroughly removes residual volatiles, giving the polyester resin composition a dense, defect-free microstructure, further enhancing the material's mechanical stability and anti-aging properties. Attached Figure Description
[0020] Figure 1 The mechanical properties of Examples 1-5 and Comparative Examples 1-3 in this invention are shown in the diagram. Detailed Implementation
[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] For details, please refer to [link / reference]. Figure 1 This invention provides a polyester resin composition and its preparation method, the technical solution of which is as follows: Example 1
[0023] 20 parts of nano-titanium dioxide were dispersed in 150 parts of an aqueous ethanol solution (ethanol mass concentration of 95%), and 1 part of silane coupling agent KH-550 was added dropwise. The mixture was mechanically stirred and ultrasonically reacted at 55℃ for 1.5 h to obtain a dispersion. 7 parts of antioxidant 168, 6 parts of HALS 944 and 50 parts of anhydrous ethanol were added to the dispersion. The mixture was ultrasonically dispersed in a water bath at a frequency of 40 kHz for 45 min, with the temperature controlled at 55℃. Subsequently, it was transferred to a vacuum drying oven and dried and desolventized at a vacuum degree of -0.09 MPa and 80℃ for 12 h. The mixture was then dispersed using an air jet mill to obtain modified titanium dioxide.
[0024] Natural halloysite nanotubes were added to a 2 mol / L hydrochloric acid solution (solid-liquid ratio 1 g: 10-20 mL) and stirred at 55 °C for 3 h. After cooling, the precipitate was washed with deionized water by centrifugation until the supernatant was neutral. Finally, the precipitate was vacuum dried at 70 °C for 18 h and then ground and sieved to obtain purified halloysite nanotubes. 2.5 parts of the purified halloysite nanotubes were dispersed in 150 parts of Tris-HCl buffer solution, and 0.2-0.4 parts of dopamine hydrochloride were added. The mixture was stirred at room temperature in the dark for 18 h to coat the surface. After centrifugation, washing, and vacuum drying, modified nanotubes were obtained.
[0025] 70 parts of polybutylene terephthalate, 18 parts of poly(1,4-cyclohexanedimethyl terephthalate) and 7 parts of polybutylene succinate were placed in a forced-air drying oven and dried at 115°C for 5 hours to reduce the moisture content of the mixture to below 0.02% to obtain a polyester material. Polyester material, 15 parts reactive toughening agent, 4 parts modified titanium dioxide, 2.5 parts modified nanotubes and 1.5 parts chain extender polycarbodiimide were added to a high-speed mixer, the speed was set to 400 rpm and mixed for 4 min to obtain a blend. The blended material is fed into a co-rotating twin-screw extruder with a length-to-diameter ratio (L / D) of 45:1. The temperature range is set (from the feed port to the die head): Zone 1 (feeding section): 175℃; Zones 2-3 (melt mixing section): 235℃; Zone 4: 245℃; Zones 5-6 (reaction and Sc-CO2 injection section): 215℃ (inhibiting thermo-oxidative degradation). The Sc-CO2 injection pressure needs to be stabilized at 12MPa, the injection temperature is 50℃, and the injection amount accounts for 1.8wt% of the total material flow rate. The die head temperature is 230℃, and the screw speed is maintained at 400rpm. Two-stage exhaust ports are set at the tail of the extruder. The first stage is atmospheric pressure exhaust and the second stage is vacuum exhaust, with a vacuum degree of -0.085MPa. Finally, underwater pelleting (water temperature controlled at 45℃) is used, followed by centrifugation and dehydration, and then drying to obtain a polyester resin composition.
[0026] Examples 2-5 refer to the parameter conditions in Example 1, with specific differences shown in Table 1.
[0027] Table 1 Parameters and conditions for Examples 1-5 Comparative Example 1 follows the same parameters and conditions as in Example 1, except that 1,4-cyclohexanediol terephthalate is not added, and it is replaced in equal amounts with polybutylene terephthalate.
[0028] Comparative Example 2 follows the same parameters and conditions as in Example 1, except that no reactive toughening agent is added.
[0029] Comparative Example 3 follows the same parameters and conditions as in Example 1, except that no chain extender is added.
[0030] Comparative Example 4 follows the same parameters and conditions as in Example 1, except that the nano-titanium dioxide is not modified.
[0031] Comparative Example 5 follows the same parameters and conditions as in Example 1, except that modified titanium dioxide is not added.
[0032] Comparative Example 6 follows the same parameters and conditions as in Example 1, except that no modification treatment is applied to the halloysite nanotubes.
[0033] Comparative Example 7 follows the same parameters and conditions as in Example 1, except that no modified nanotubes are added.
[0034] Comparative Example 8 follows the same parameters and conditions as in Example 1, except that there is no supercritical fluid (Sc-CO2) assistance.
[0035] Comparative Example 9 follows the same parameters and conditions as in Example 1, except that it is directly mixed and stirred without pretreatment.
[0036] Experimental Example 1: Mechanical Property Testing According to ISO 527-2 standard, dumbbell-shaped test specimens of polyester resin compositions were formed using an injection molding machine. Tensile tests were then performed on Examples 1-5 and Comparative Examples 1-3 using a Zwickau Roell Z020 universal testing machine. The impact toughness of Examples 1-5 and Comparative Examples 1-3 was tested according to GB / T 1043-1-2008 standard. The results are shown in Table 2. The mechanical properties of Examples 1-5 and Comparative Examples 1-3 are as follows: Figure 1 As shown.
[0037] Table 2 Mechanical properties of Examples 1-5 and Comparative Examples 1-3 From Table 2 and Figure 1 It can be observed that when comparative example 1 was completely replaced with polybutylene terephthalate instead of poly(1,4-cyclohexanediol) terephthalate, the impact toughness of the material decreased slightly, but the tensile strength decreased significantly. This is because the system contains a large amount of flexible polybutylene succinate and reactive toughening agent. Without the rigid support and steric hindrance effect of the large-volume cyclohexane alicyclic structure in the poly(1,4-cyclohexanediol) terephthalate molecular chain, the entire polyester matrix cannot offset the modulus loss caused by the elastomer. When comparative example 2 did not add reactive toughening agent, although the tensile strength of the composition increased to 72 MPa due to the lack of a soft rubber phase, its impact toughness plummeted to 6.5 kJ / m. 2 The material exhibits extremely typical brittle fracture characteristics; this is due to the lack of the core elastomer phase, the ethylene-methyl acrylate-glycidyl methacrylate terpolymer. When subjected to transient impacts, the material cannot absorb and dissipate impact energy significantly through cavitation of rubber particles and shear yielding of the matrix, leading to rapid microcrack propagation and fracture. Comparative Example 3, without the addition of the chain extender polycarbodiimide, shows that the material's tensile strength (54 MPa) and impact toughness (14.2 kJ / m) are... 2 Significant synchronous degradation was observed in all samples. This is because, in the high-temperature, high-shear environment of supercritical fluid-assisted extrusion, polyester molecular chains are highly susceptible to thermo-oxidative degradation and trace hydrolytic chain breakage. The lack of end-group suturing effect from chain extenders not only leads to a decrease in the molecular weight of the matrix, but more critically, it prevents the in-situ construction of a dense three-dimensional topological cross-linked network between the polyester phases and between the polyester and modified nanotube interfaces. The lack of effective stress transfer at these interfaces results in a comprehensive deterioration of the material's overall mechanical properties.
[0038] Experiment Example 2: Aging Resistance Test Referring to GB / T 7141-2008 standard, standard dumbbell-shaped specimens and notched impact specimens prepared using an injection molding machine were placed in a hot air aging test chamber. The test temperature was set at 120℃, and the aging time was 1000 hours. After the test, the specimens were removed and conditioned for 24 hours in a standard environment of 23℃ and 50% relative humidity. Subsequently, the tensile strength and impact toughness of Examples 1-5 and Comparative Examples 4-7 were tested, and the performance retention rate after aging was calculated. Referring to GB / T 16422.3 standard, a QUV accelerated ultraviolet aging tester was used for testing. The light source was a UVA-340 fluorescent ultraviolet lamp, and the irradiance was set to 0.76 W / (m²). 2 The light / condensation cycle was set as follows: 8 hours of light exposure (60℃) + 4 hours of condensation (50℃), with a total test time of 1000 hours. After aging, the change in yellow index (ΔYI) on the surface of the sample was measured using a colorimeter, and its impact toughness retention rate was also tested. The results are shown in Table 3.
[0039] Table 3 Aging resistance of Examples 1-5 and Comparative Examples 4-7 Table 2 shows that in Comparative Example 4, without modification of nano-titanium dioxide, the yellow index (ΔYI) of the material after UV aging significantly increased to 12.5, and the impact resistance retention rate decreased to 71.3%. This is because unmodified titanium dioxide can only provide a certain degree of physical UV shielding, but cannot enrich antioxidants and light stabilizers in situ around it. When UV light excites the generation of polymeric free radicals on the material surface, the simple physical mixture system cannot achieve rapid in-situ quenching, leading to photo-oxidative degradation of the matrix. In Comparative Example 5, without any modified titanium dioxide, the material's UV aging resistance severely deteriorated. After 1000 hours of UV aging, the sample surface underwent severe photodegradation and yellowing, ΔYI increased significantly, and the impact resistance retention rate was only 45.2%, with the material exhibiting severe surface powdering and brittle fracture. This indicates that without the physical shielding effect of nano-titanium dioxide, high-energy UV light can directly penetrate and sever polyester molecular chains over a large area. In Comparative Example 6, when unmodified halloysite nanotubes were used directly, the tensile strength retention and impact resistance retention after thermo-oxidative aging at 120°C dropped significantly to 74.6% and 68.3%, respectively. On the one hand, due to the lack of a polydopamine biomimetic coating, the nanotube surface lacked a large number of catechol structures with extremely strong free radical scavenging capabilities, making it impossible to inhibit thermo-oxidative degradation from the inside. On the other hand, the interfacial bonding between the unmodified nanotubes and the polyester matrix was weak, and under long-term high-temperature thermal stress, interfacial debonding was very likely to occur, and microscopic defects were rapidly magnified, resulting in a significant loss of macroscopic mechanical properties. In Comparative Example 7, without any modified nanotubes, the material's thermo-oxidative aging retention rate was the lowest in the entire group (tensile retention rate was only 62.3%, and impact retention rate was only 55.7%). This indicates that conventional antioxidants, either external to the material or dispersed in the matrix, cannot resist the deep thermo-oxidative fracture of polymer chains caused by long-term high temperature of 120°C. Modified nanotubes, through cross-linking with chain extenders and toughening agents, construct a three-dimensional defense network within the matrix that can both transmit mechanical stress and target and quench free radicals. The absence of this network will lead to the complete disintegration of the internal structure at high temperatures.
[0040] Experiment Example 3: Mechanical Properties and Aging Resistance Testing The tensile strength, impact toughness, and performance retention of Examples 1-5 and Comparative Examples 8-9 were tested according to the test methods of Experimental Examples 1 and 2, and the results are shown in Table 4.
[0041] Table 4 Mechanical properties and aging resistance of Examples 1-5 and Comparative Examples 8-9 Table 4 shows that in Comparative Example 8, without the introduction of supercritical carbon dioxide (Sc-CO2) as an aid, the initial mechanical properties and aging retention rate of the material both exhibited a significant decline. This is because the system of this invention contains high-viscosity polyethylene terephthalate-1,4-cyclohexanediethanol resin, which generates significant frictional shear heat during conventional twin-screw extrusion. Lacking the strong physical plasticizing, viscosity-reducing, and heat-absorbing cooling effects of Sc-CO2, localized overheating leads to uncontrollable excessive cross-linking of the reactive toughening agent (forming gel dead material), hindering the effective transfer of stress. Simultaneously, continuous high thermal shear also causes a certain degree of thermal damage to the polydopamine active antioxidant layer on the surface of the nanotubes, resulting in a significant decrease in the subsequent heat resistance and oxygen aging retention rate. In Comparative Example 9, when materials were directly mixed and extruded without pretreatment, their various properties exhibited severe degradation. Polybutylene terephthalate, poly(1,4-cyclohexanediol) terephthalate, and polybutylene succinate are all condensation-type polyesters, and the ester bonds in their molecular chains are extremely sensitive to moisture. Under the high temperature and screw shearing action of the extruder, even trace amounts of residual moisture can trigger a violent chemical hydrolysis reaction, leading to the extensive breakage of polymer chains, a precipitous drop in molecular weight, and a severe loss of matrix strength. This renders subsequent additions of toughening agents and anti-aging networks ineffective, and the performance retention rate after aging also decreases. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a polyester resin composition, characterized in that, Includes the following steps: Polybutylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate), and polybutylene succinate were pretreated to obtain a polyester material. The polyester material, reactive toughening agent, modified titanium dioxide, modified nanotubes, and chain extender were mixed and stirred, and then subjected to supercritical fluid-assisted extrusion and gradient vacuum devolatilization and pelletizing to obtain the polyester resin composition. The modified titanium dioxide is prepared from nano-titanium dioxide, silane coupling agent, antioxidant and light stabilizer; the modified nanotubes are prepared from halloysite nanotubes and dopamine hydrochloride.
2. The method for preparing a polyester resin composition according to claim 1, characterized in that, The modified titanium dioxide is prepared as follows: the nano-titanium dioxide is dispersed in an ethanol aqueous solution, a silane coupling agent is added dropwise, and the mixture is stirred and ultrasonically reacted to obtain a dispersion; antioxidant 168, hindered amine light stabilizer and anhydrous ethanol are added to the dispersion, and the mixture is dispersed in a water bath under ultrasonication at a temperature controlled at 50-60℃, followed by vacuum drying and dispersion by an air jet mill to obtain the modified titanium dioxide; the modified nanotubes are prepared as follows: natural halloysite nanotubes are added to a hydrochloric acid solution, and after stirring and reacting, the precipitate is washed with deionized water by centrifugation until the supernatant is neutral; finally, the mixture is vacuum dried, ground and sieved to obtain purified halloysite nanotubes; the halloysite nanotubes are dispersed in a Tris-HCl buffer solution, dopamine hydrochloride is added, and the mixture is stirred and reacted at room temperature in the dark, followed by centrifugation, washing, and vacuum drying to obtain the modified nanotubes.
3. The method for preparing a polyester resin composition according to claim 1, characterized in that, The specific process of the pretreatment is as follows: the polybutylene terephthalate, the poly(1,4-cyclohexanediethanol) terephthalate and the polybutylene succinate are placed in a forced-air drying oven and dried at 110-120°C to obtain the polyester material.
4. The method for preparing a polyester resin composition according to claim 1, characterized in that, The specific process of mixing and stirring is as follows: the polyester material, the reactive toughening agent, the modified titanium dioxide, the modified nanotubes, and the chain extender polycarbodiimide are added to a high-speed mixer and mixed for 3-5 minutes to obtain a blended material.
5. The method for preparing a polyester resin composition according to claim 1, characterized in that, The specific process of the supercritical fluid-assisted extrusion treatment is as follows: the blended material is fed into a co-rotating twin-screw extruder, and the temperature range is set as follows: Zone 1: 170-180℃; Zones 2 to 3: 230-240℃; Zone 4: 245℃; Zones 5 to 6: 210-220℃.
6. The method for preparing a polyester resin composition according to claim 1, characterized in that, The specific process of gradient vacuum devolatilization and pelletizing is as follows: two exhaust ports are set at the tail of the extruder, the first stage is atmospheric pressure exhaust and the second stage is vacuum exhaust. Finally, underwater pelletizing is used, followed by centrifugal dehydration and drying to obtain the polyester resin composition.
7. A polyester resin composition, characterized in that, The polyester resin composition is prepared by the preparation method according to any one of claims 1-6; the raw materials for preparing the polyester resin composition include polybutylene terephthalate, poly(1,4-cyclohexanedimethyl terephthalate), polybutylene succinate, reactive toughening agent, modified titanium dioxide, modified nanotubes and chain extender.