Polybutylene terephthalate, preparation method and application thereof

Abstract

The present invention relates to the technical field of polybutylene terephthalate production, specifically polybutylene terephthalate, its preparation method, and application. The preparation method comprises: catalyzing esterification, polycondensation, and erucic acid grafting reactions using a composite catalyst A (titanium-germanium catalyst) and B (yttrium-cerium-tetrabutyl titanate), combining carbon nanotubes, zinc oxide, and graphene to form a ternary conductive network, and adding maleic anhydride-grafted polypropylene, zinc stearate, and other additives for blending. The resulting material has a volume resistivity as low as 10²-10³Ω·cm, a water absorption rate of ≤0.3%, and an increased heat deformation temperature of 160-180°C. This material is used in intelligent driving sensor housings. After high-speed mixing, twin-screw extrusion, and injection molding, it exhibits strong hydrophobicity and excellent processing properties, meeting the requirements of precision electronic components in high-temperature and high-humidity environments.

Description

Technical Field

[0001] The invention relates to the technical field of polybutylene terephthalate production, in particular to polybutylene terephthalate and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT), a semi-crystalline thermoplastic engineering plastic, is widely used in the automotive parts field due to its excellent mechanical strength, chemical corrosion resistance, dimensional stability and good processing performance. However, the housing of intelligent driving sensors places higher requirements on the material: electrical conductivity: it must meet the requirements of electromagnetic shielding (≥30dB) and electrostatic discharge. The volume resistivity of traditional PBT is as high as 10 15 Ω·cm, unable to build an effective conductive path; Environmental tolerance: The high temperature and high humidity environment of the engine compartment (85℃ / 85%RH) requires the material to be resistant to hydrolysis and aging. Conventional PBT has a high water absorption rate (0.8%), and long-term service is prone to mechanical performance degradation due to ester bond hydrolysis; Precision processing: The sensor housing dimensional accuracy requirement is ±0.05mm. Conventional PBT has a low heat deformation temperature (60-80℃) and poor melt fluidity, making it difficult to meet the requirements of precision injection molding.

[0003] In the prior art, attempts to improve these properties of PBT have been made by adding conductive fillers (such as carbon nanotubes) or introducing hydrophobic groups, but a series of problems still exist. Chinese patent application CN117295784A, published on December 26, 2023, discloses a polybutylene terephthalate composition and product comprising (A) 40% to 99.8% by weight of polybutylene terephthalate, (B) 0.2% to 10% by weight of at least one conductive filler selected from the group consisting of carbon nanotubes, carbon nanostructures, and combinations thereof, and (C) 0% to 50% by weight of glass fiber, each based on the total weight of the polybutylene terephthalate composition, wherein each of the carbon nanostructures comprises a plurality of carbon nanotubes that are branched, cross-linked, and / or share a common wall. While carbon nanotubes enhance the conductivity of PBT, improving the material's electromagnetic shielding performance, this improvement only addresses conductivity without significantly improving the material's fundamental properties, particularly mechanical strength and hydrophobicity. Furthermore, the synergistic effect between the hydrophobic modification and the conductive filler in existing materials is insufficient, making it difficult to achieve both good conductivity and hydrophobicity. This makes it difficult to achieve a PBT material that effectively resists hydrolysis and exhibits good conductivity in practical applications. Summary of the Invention

[0004] In view of the above deficiencies in the prior art, the object of the present invention is to provide a polybutylene terephthalate, which, through compound catalysis, filler synergy and hydrophobic integrated design, achieves high conductivity, strong electromagnetic shielding, high hydrophobicity and environmental stability while maintaining excellent mechanical properties, and is suitable for precision electronic components in high temperature and high humidity environments.

[0005] The purpose of the present invention is to provide a method for preparing polybutylene terephthalate, which solves the limitations of traditional PBT and improves the overall performance of the material by optimizing raw material processing, reaction conditions and catalyst use.

[0006] The third object of the present invention is to provide an application of polybutylene terephthalate for the production of intelligent driving sensor housings.

[0007] The present invention is achieved by adopting the following technical solutions:

[0008] The preparation method of polybutylene terephthalate comprises the following steps:

[0009] (1) Add terephthalic acid and 1,4-butanediol into a reactor at a molar ratio of 1:1.2, add composite catalyst A, heat to 210-230°C, carry out esterification reaction, react for 2-4 hours, then heat to 240-260°C, carry out polycondensation reaction, react for 3-6 hours, and obtain polybutylene terephthalate base polymer;

[0010] (2) blending the antioxidant with the polybutylene terephthalate base polymer in a twin-screw extruder to obtain an intermediate, then mixing the surface-treated carbon nanotubes and the modified zinc oxide in a mass ratio of (1-3):1, and blending them with the intermediate in a twin-screw extruder, with the temperature of each section of the extruder set at 230-250°C and the screw speed at 200-400 r / min, to obtain a conductive polybutylene terephthalate base polymer;

[0011] (3) The product obtained in step (2) and erucic acid were added to a reactor in a mass ratio of 10:1, and then the composite catalyst B and phosphite were added. Nitrogen was introduced for protection, and the temperature was raised to 190-210°C under stirring. The reaction was carried out for 4-4.5 hours. The product was then washed and dried to obtain a hydrophobic polybutylene terephthalate base polymer;

[0012] (4) adding the product obtained in step (3), maleic anhydride, an organic phosphate nucleating agent, a fatty acid ester lubricant, an ultraviolet absorber, and a hindered amine light stabilizer to a twin-screw extruder for blending, and setting the temperature of each section of the extruder to 230-250° C. to obtain polybutylene terephthalate;

[0013] The compound catalyst A is a titanium-germanium compound catalyst; the compound catalyst B is a yttrium-cerium-tetrabutyl titanate compound catalyst.

[0014] The amount of the composite catalyst A added is 0.2-0.5% of the total mass of the reactants in step (1); the total amount of carbon nanotubes and zinc oxide added in step (2) is 3-7% of the total mass of the reactants in step (2); the amount of phosphite added is 0.1-0.3% of the total mass of the reactants in step (3); the amount of the antioxidant added is 0.3-1% of the mass of the polybutylene terephthalate base polymer in step (2); the amount of maleic anhydride added is 1-3% of the mass of the product obtained in step (3); the amount of the organic phosphate nucleating agent added is 0.5-2% of the mass of the product obtained in step (3); the amount of the fatty acid ester lubricant added is 0.3-1% of the mass of the product obtained in step (3); the amount of the ultraviolet absorber added is 0.5-1% of the mass of the product obtained in step (3); and the amount of the hindered amine light stabilizer added is 0.5-1% of the mass of the product obtained in step (3).

[0015] The preparation method of the composite catalyst A comprises the following steps:

[0016] ① Dissolve 10g of hexadecyltrimethylammonium bromide in deionized water and stir at 40-60°C until completely dissolved; add aqueous ammonia to adjust the pH to 9-11, then add 40-60ml of ethyl orthosilicate dropwise and continue stirring for 2-6 hours; filter and wash the reaction product, then dry it at 110°C for 18 hours; and finally calcine it at 500-600°C for 4-6 hours to obtain a porous silica support;

[0017] ② According to the titanium:germanium molar ratio (3-8):1, tetrabutyl titanate is dissolved in anhydrous ethanol to form a titanium solution; germanium dioxide is placed in a container, 30-37% concentrated hydrochloric acid is added and heated to 50-80°C to dissolve it to form a germanium solution; under stirring, the germanium solution is added dropwise to the titanium solution and stirring is continued for 1-3 hours to obtain a titanium-germanium composite solution;

[0018] ③ Take the material according to the lithium: titanium molar ratio (0.01-0.1):1, dissolve it in deionized water to prepare a lithium solution;

[0019] ④ Premix the lithium solution and the titanium-germanium composite solution to obtain a mixed solution; add the porous silica support to the mixed solution and stir at room temperature for 6-12 hours; remove the solvent by vacuum distillation to obtain a solid product; dry the solid product at 105-110° C. for 15-20 hours, and then calcine at 300-500° C. for 2-4 hours to obtain a composite catalyst A.

[0020] The surface treatment method of the carbon nanotubes is as follows: placing the carbon nanotubes in a mixed acid of concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1, using 10-20 ml of the mixed acid per gram of carbon nanotubes, ultrasonically treating at 40-50° C. for 2-3 hours, and then washing with deionized water until neutral.

[0021] The zinc oxide modification method comprises the following steps:

[0022] a. The silane and solvent are taken in a ratio of 1-3wt% and added to an ethanol / water mixture, glacial acetic acid is added dropwise to adjust the pH to 4-5, and magnetic stirring is carried out for 30-60min;

[0023] b. Dry the zinc oxide powder at 100-120°C for 2-4h;

[0024] c. Add the dried zinc oxide to the mixture obtained in step a at a mass ratio of 1:(10-20) and ultrasonically treat at 40-50°C for 2-3h;

[0025] d. The mixture obtained in step c was centrifuged, the supernatant was removed, and the precipitate was washed with anhydrous ethanol 3-5 times. The washed ZnO was vacuum dried at 80-100 ° C for 6-12h to obtain silanized zinc oxide.

[0026] The preparation method of the composite catalyst B comprises the following steps:

[0027] Ⅰ. After calcining yttrium oxide and cerium oxide at 500-700℃ for 1-3h, add them to anhydrous ethanol and perform ultrasonic dispersion for 30-45min;

[0028] Ⅱ tetrabutyl titanate was added to a container, and then the resultant of step Ⅰ was added to a container containing tetrabutyl titanate, while stirring, the stirring speed was controlled at 300r / min, stirring for 1-1.5h to obtain a composite catalyst precursor solution;

[0029] III. The composite catalyst precursor solution is sealed and aged at room temperature for 20-24 hours. The total mass concentration of tetrabutyl titanate, yttrium oxide and cerium oxide in the aged solution is 10-20%, thereby obtaining composite catalyst B.

[0030] The mass ratio of tetrabutyl titanate, yttrium oxide and cerium oxide is 1: (0.1-1): 0.5; the active ingredients of the composite catalyst B are tetrabutyl titanate, yttrium oxide and cerium oxide, and the amount of the active ingredients added is 0.05-0.2% of the total mass of the reactants in step (3).

[0031] The silane coupling agent is one of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane; the antioxidant is obtained by compounding tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester and dilauryl thiodipropionate in a mass ratio of 2:1; the phosphite is one of tris(2,4-di-tert-butylphenyl)phosphite or tetrakis(2,4-di-tert-butylphenyl)biphenylbisphosphite; the organic phosphate nucleating agent is sodium phenylphosphinate; the fatty acid ester lubricant is obtained by mixing stearic acid monoglyceride and ethylene bisstearamide in a mass ratio of 5:3; the ultraviolet absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol; and the hindered amine light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

[0032] The polybutylene terephthalate is prepared by the above preparation method.

[0033] The polybutylene terephthalate is used for the production of intelligent driving sensor housings.

[0034] The method for preparing the intelligent driving sensor housing comprises the following steps:

[0035] A. Add 100 parts of PBT pellets to a high-speed mixer, preheat to 60°C, and stir for 5 minutes;

[0036] B. Add 1.5-2.25 parts of maleic anhydride grafted polypropylene, 0.5-0.75 parts of zinc stearate, 1-2 parts of modified MoS2, 1-3 parts of polypyrrole dispersion, and 0.3-0.5 parts of antioxidant 1010 in sequence, and continue stirring for 10 minutes;

[0037] C. Add it to a twin-screw machine for extrusion. Set the temperature of each section of the extruder to 225-250℃. Then place it in a mold with a barrel temperature of 240-250℃, a mold temperature of 70-80℃, an injection pressure of 90-110MPa, a holding pressure of 60-70MPa, hold pressure for 15-20s, and cool for 30-40s. This is the material used for the smart driving sensor housing.

[0038] When preparing the intelligent driving sensor housing, some raw materials need to be pretreated:

[0039] Modified MoS2: MoS2 nanosheets were dispersed in an oil-in-water emulsion containing 5% silane coupling agent (KH-570) and ultrasonically treated for 4 h (frequency 40 kHz, power 300 W); spray dried (inlet temperature 150°C, outlet temperature 80°C) to obtain modified MoS2 (particle size distribution 5-15 nm) with a surface grafting rate ≥90%.

[0040] Polypyrrole (PPy): PPy and carbon nanotubes were ball-milled in a 1:1 ratio (500 rpm, 2 h) to form a "CNT-PPy" core-shell structure. A 20% slurry was prepared with anhydrous ethanol and ultrasonically dispersed to form a uniform slurry.

[0041] Titanium-germanium catalyst (compound A) and yttrium-cerium-tetrabutyl titanate (compound B) work synergistically. The former improves the esterification / polycondensation efficiency (reaction time is shortened by 20%), reduces the incidence of side reactions, and ensures the regularity of the polymer chain through the synergistic catalysis of titanium and germanium; the latter activates the erucic acid carboxyl group through rare earth metal sites, promotes hydrophobic grafting reaction, and the grafting rate reaches more than 85%. Carbon nanotubes (1D conductive pathways), zinc oxide (3D support structure) and graphene (2D sheets) form a multi-dimensional synergistic network. Carbon nanotubes provide efficient electron transport channels, zinc oxide inhibits filler agglomeration, and graphene enhances network continuity, reducing the volume resistivity by 2-3 orders of magnitude (as low as 10²-10³Ω·cm) compared to traditional modified PBT. Tetrabutyl titanate provides Lewis acid sites to accelerate the esterification reaction; germanium ions (Ge 4+ ) stabilizes intermediates through electron transfer, reducing side reactions. The titanium-germanium complex forms highly dispersed active centers on the porous silica support, improving polycondensation efficiency. The long alkyl chains of erucic acid bind to the organic layer of silanized ZnO through hydrophobic interactions, reducing interfacial defects.

[0042] Although zinc oxide (ZnO) is an insulator, after treatment with a silane coupling agent, an organic functional layer (such as amino or epoxy groups) forms on its surface, which then bonds to carbon nanotubes (CNTs) through chemical bonds or physical adsorption. ZnO nanoparticles (5-15 nm in diameter) act as "spacers," preventing CNT aggregation and promoting the formation of a three-dimensional conductive network. Furthermore, ZnO's semiconducting properties create a microcapacitive effect at the interface, enhancing local conductivity.

[0043] Dicumyl peroxide (DCP) initiates crosslinking of PBT molecular chains, increasing crystallinity by 15%, raising the heat distortion temperature to 160-180°C, and enhancing creep resistance. The carboxylic acid groups of maleic anhydride-grafted polypropylene (MAPP) react with the ester bonds of PBT to form covalent bonds. Combined with the van der Waals interactions between molybdenum disulfide (MoS2) modified with a silane coupling agent (KH-570) and carbon nanotubes, this significantly enhances the filler-matrix interface, reduces interfacial defects, and increases tensile strength by 25%. Zinc stearate (ZnSt) forms a lubricating film in the molten state, reducing molecular chain friction (melt viscosity decreases by 15%) and improving processing fluidity. The dual-stage "pre-dispersion-post-reinforcement" process of MAPP and premixed conductive fillers during the injection molding process ensures consistent conductive properties in the final product (resistivity fluctuation ≤±8%).

[0044] The long chain alkyl group of zinc stearate (C 18 H35- ) migrates to the surface of the material during processing to form a low surface energy layer; the lamellar structure of the modified MoS2 is dispersed in an exfoliated state in the PBT matrix, and its sulfur atom surface is entangled with the ZnSt alkyl chain through van der Waals force, hindering the penetration path of water molecules; polypyrrole, as a conductive polymer, wraps the carbon nanotubes and MoS2 surface to form a "CNT-PPy-MoS2" conductive network, reducing filler agglomeration; the high modulus and lamellar structure of the nanosheets hinder crack propagation and improve tensile strength.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The polybutylene terephthalate produced by this invention has a volume resistivity as low as 10²-10³Ω·cm, meeting the electromagnetic shielding requirements (≥40dB) for intelligent driving sensor housings. A crosslinking agent (DCP) and a nucleating agent (sodium phenylphosphinate) enhance crystallinity, resulting in a tensile strength of 60-65MPa and an impact strength of ≥13kJ / m², making it suitable for vehicle-mounted vibration environments.

[0047] (2) The polybutylene terephthalate produced by the present invention has a heat deformation temperature increased to 160-180°C and can withstand high temperatures of 150°C for a long time. Zinc stearate optimizes melt flowability, and the surface finish Ra is ≤ 1.2 μm. After aging for 1000 hours at 85°C / 85% RH, the performance fluctuation is less than 5%, and there is no hydrolysis cracking.

[0048] (3) The present invention achieves a comprehensive improvement in the electrical conductivity, mechanical strength, heat resistance and processing performance of PBT materials through compound catalysis, multi-dimensional conductive network design and dynamic cross-linking modification. DETAILED DESCRIPTION

[0049] In order to make the purpose and technical solution of the present invention more clear, the present invention is further described in detail below.

[0050] Test method:

[0051] Volume resistivity: ASTM D257 "Standard Test Method for DC Resistance or Conductance of Insulating Materials";

[0052] Electromagnetic Shielding Effectiveness (SE): ASTM D4935 "Test Method for Electromagnetic Shielding Effectiveness of Planar Materials";

[0053] Tensile strength: ISO 527-2 "Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and extruded plastics";

[0054] Flexural strength: ISO 178 "Plastics — Determination of flexural properties";

[0055] Impact strength (notched): ISO 179-1 "Plastics — Determination of impact properties of charpy beams — Part 1: Non-instrumented impact test";

[0056] Heat deflection temperature (HDT): ISO 75-2 "Plastics — Determination of temperature of deflection under load — Part 2: Plastics and hard rubber";

[0057] Water absorption: ISO 62 "Plastics - Determination of water absorption";

[0058] Surface finish (Ra): ISO 4287 “Geometrical product specifications (GPS) — Surface texture: Profilometry terms, definitions and surface texture parameters”.

[0059] Example 1

[0060] The preparation method of the composite catalyst A comprises the following steps:

[0061] ① Dissolve 10g of hexadecyltrimethylammonium bromide in deionized water and stir at 40°C until completely dissolved; add ammonia water dropwise to adjust the pH to 9, then add 40ml of ethyl orthosilicate dropwise and continue stirring for 2 hours; filter and wash the reaction product, then dry it at 110°C for 18 hours; finally, calcine it at 500°C for 4 hours to obtain a porous silica support;

[0062] ② According to the titanium:germanium molar ratio of 3:1, tetrabutyl titanate is dissolved in anhydrous ethanol to form a titanium solution; germanium dioxide is placed in a container, 30% concentrated hydrochloric acid is added and heated to 50°C to dissolve it to form a germanium solution; under stirring, the germanium solution is added dropwise to the titanium solution and stirring is continued for 1 hour to obtain a titanium-germanium composite solution;

[0063] ③ Take the material according to the lithium: titanium molar ratio of 0.01:1, dissolve it in deionized water to prepare a lithium solution;

[0064] ④ Premix the lithium solution and the titanium-germanium composite solution to obtain a mixed solution; add the porous silica support to the mixed solution and stir at room temperature for 6 hours; remove the solvent by vacuum distillation to obtain a solid product; dry the solid product at 105°C for 15 hours, and then calcine it at 300°C for 2 hours to obtain a composite catalyst A.

[0065] The surface treatment method of carbon nanotubes is as follows: placing carbon nanotubes in a mixed acid of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, adding 20 ml of the mixed acid per gram of carbon nanotubes, ultrasonically treating at 40°C for 2 hours, and then washing with deionized water until neutral.

[0066] The modification method of zinc oxide comprises the following steps:

[0067] a. The silane and solvent were added to an ethanol / water mixture at a ratio of 1wt%, glacial acetic acid was added dropwise to adjust the pH to 4, and magnetic stirring was carried out for 30min;

[0068] b. Dry the zinc oxide powder at 100°C for 2h;

[0069] c. The dried zinc oxide was added to the mixture obtained in step a at a mass ratio of 1:10 and ultrasonically treated at 40 ° C for 3h;

[0070] d. The mixture obtained in step c was centrifuged, the supernatant was removed, and the precipitate was washed three times with anhydrous ethanol. The washed ZnO was vacuum dried at 80 ° C for 12 h to obtain silanized zinc oxide.

[0071] The preparation method of the composite catalyst B comprises the following steps:

[0072] Ⅰ. Yttrium oxide and cerium oxide were calcined at 500℃ for 1 hour, added to anhydrous ethanol, and ultrasonically dispersed for 30 minutes;

[0073] Ⅱ tetrabutyl titanate was added to a container, and then the resultant of step Ⅰ was added to a container containing tetrabutyl titanate, while stirring, the stirring speed was controlled at 300r / min, stirred for 1h to obtain a composite catalyst precursor solution;

[0074] III. The composite catalyst precursor solution was sealed and aged at room temperature for 20 h. The total mass concentration of tetrabutyl titanate, yttrium oxide and cerium oxide in the aged solution was 10%, thereby obtaining composite catalyst B.

[0075] The mass ratio of tetrabutyl titanate, yttrium oxide and cerium oxide is 1:0.1:0.5; the active ingredients of the composite catalyst B are tetrabutyl titanate, yttrium oxide and cerium oxide, and the amount of the active ingredients added is 0.05% of the total mass of the reactants in step (3).

[0076] The preparation method of polybutylene terephthalate comprises the following steps:

[0077] (1) Terephthalic acid and 1,4-butanediol were added to a reactor at a molar ratio of 1:1.2, and a composite catalyst A was added. The temperature was raised to 210°C for esterification reaction for 4 hours, and then the temperature was raised to 240°C for polycondensation reaction for 6 hours to obtain a polybutylene terephthalate base polymer;

[0078] (2) The antioxidant is blended with the polybutylene terephthalate base polymer in a twin-screw extruder to obtain an intermediate, and then the surface-treated carbon nanotubes and the modified zinc oxide are mixed in a mass ratio of 1:1 and blended with the intermediate in a twin-screw extruder. The temperature of each section of the extruder is set to 230°C and the screw speed is 200 r / min to obtain a conductive polybutylene terephthalate base polymer;

[0079] (3) The product obtained in step (2) and erucic acid were added to a reactor in a mass ratio of 10:1, and then the composite catalyst B and phosphite were added. Nitrogen was introduced for protection, and the temperature was raised to 190°C under stirring. The reaction was carried out for 4 hours, and then the product was washed and dried to obtain a hydrophobic polybutylene terephthalate base polymer;

[0080] (4) The product obtained in step (3), maleic anhydride, an organic phosphate nucleating agent, a fatty acid ester lubricant, an ultraviolet absorber, and a hindered amine light stabilizer are added to a twin-screw extruder for blending, and the temperature of each section of the extruder is set to 230° C. to obtain polybutylene terephthalate.

[0081] The amount of the composite catalyst A added is 0.2% of the total mass of the reactants in step (1); the total amount of the carbon nanotubes and zinc oxide added in step (2) is 3% of the total mass of the reactants in step (2); the amount of the phosphite added is 0.1% of the total mass of the reactants in step (3); the amount of the antioxidant added is 0.3% of the mass of the polybutylene terephthalate base polymer in step (2); the amount of maleic anhydride added is 1% of the mass of the product obtained in step (3); the amount of the organic phosphate nucleating agent added is 0.5% of the mass of the product obtained in step (3); the amount of the fatty acid ester lubricant added is 0.3% of the mass of the product obtained in step (3); the amount of the ultraviolet absorber added is 0.5% of the mass of the product obtained in step (3); and the amount of the hindered amine light stabilizer added is 0.5% of the mass of the product obtained in step (3).

[0082] The silane coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and dilauryl thiodipropionate in a mass ratio of 2:1; the phosphite is tris(2,4-di-tert-butylphenyl)phosphite; the organic phosphate nucleating agent is sodium phenylphosphinate; the fatty acid ester lubricant is a mixture of stearic acid monoglyceride and ethylene bisstearamide in a mass ratio of 5:3; the UV absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol; and the hindered amine light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

[0083] Example 2

[0084] The preparation method of the composite catalyst A comprises the following steps:

[0085] ① Dissolve 10g of hexadecyltrimethylammonium bromide in deionized water and stir at 50°C until completely dissolved; add ammonia water dropwise to adjust the pH to 10, then add 50ml of ethyl orthosilicate dropwise and continue stirring for 4 hours; filter and wash the reaction product, then dry it at 110°C for 18 hours; and finally calcine it at 550°C for 5 hours to obtain a porous silica support;

[0086] ② According to the titanium:germanium molar ratio of 5:1, tetrabutyl titanate was dissolved in anhydrous ethanol to form a titanium solution; germanium dioxide was placed in a container, 34% concentrated hydrochloric acid was added and heated to 65°C to dissolve it to form a germanium solution; under stirring, the germanium solution was added dropwise to the titanium solution, and stirring was continued for 2 hours to obtain a titanium-germanium composite solution;

[0087] ③ Take the material according to the lithium: titanium molar ratio of 0.05:1, dissolve it in deionized water to prepare a lithium solution;

[0088] ④ Premix the lithium solution and the titanium-germanium composite solution to obtain a mixed solution; add the porous silica support to the mixed solution and stir at room temperature for 9 hours; remove the solvent by vacuum distillation to obtain a solid product; dry the solid product at 108°C for 18 hours, and then calcine at 400°C for 3 hours to obtain a composite catalyst A.

[0089] The surface treatment method of carbon nanotubes is as follows: placing carbon nanotubes in a mixed acid of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, using 15 ml of the mixed acid for each gram of carbon nanotubes, ultrasonically treating at 45° C. for 3 hours, and then washing with deionized water until neutral.

[0090] The modification method of zinc oxide comprises the following steps:

[0091] a. The silane and solvent were added to an ethanol / water mixture at a ratio of 2 wt %, glacial acetic acid was added dropwise to adjust the pH to 4, and magnetic stirring was carried out for 45 min;

[0092] b. Dry the zinc oxide powder at 110°C for 3h;

[0093] c. The dried zinc oxide was added to the mixture obtained in step a at a mass ratio of 1:15 and ultrasonically treated at 45 ° C for 3h;

[0094] d. The mixture obtained in step c was centrifuged, the supernatant was removed, and the precipitate was washed four times with anhydrous ethanol. The washed ZnO was dried in vacuo at 90 ° C for 10 h to obtain silanized zinc oxide.

[0095] The preparation method of the composite catalyst B comprises the following steps:

[0096] Ⅰ. Yttrium oxide and cerium oxide were calcined at 600℃ for 2h, added to anhydrous ethanol, and ultrasonically dispersed for 40min.

[0097] Ⅱ tetrabutyl titanate was added to a container, and then the resultant of step Ⅰ was added to a container containing tetrabutyl titanate, while stirring, the stirring speed was controlled at 300r / min, stirred for 1h to obtain a composite catalyst precursor solution;

[0098] III. The composite catalyst precursor solution was sealed and aged at room temperature for 24 hours. The total mass concentration of tetrabutyl titanate, yttrium oxide and cerium oxide in the aged solution was 15%, thereby obtaining composite catalyst B.

[0099] The mass ratio of tetrabutyl titanate, yttrium oxide and cerium oxide is 1:0.5:0.5; the active ingredients of the composite catalyst B are tetrabutyl titanate, yttrium oxide and cerium oxide, and the amount of the active ingredients added is 0.1% of the total mass of the reactants in step (3).

[0100] The preparation method of polybutylene terephthalate comprises the following steps:

[0101] (1) Terephthalic acid and 1,4-butanediol were added to a reactor at a molar ratio of 1:1.2, and a composite catalyst A was added. The temperature was raised to 220°C for esterification reaction for 3 hours, and then the temperature was raised to 250°C for polycondensation reaction for 4 hours to obtain a polybutylene terephthalate base polymer;

[0102] (2) The antioxidant is blended with the polybutylene terephthalate base polymer in a twin-screw extruder to obtain an intermediate, and then the surface-treated carbon nanotubes and the modified zinc oxide are mixed in a mass ratio of 2:1 and blended with the intermediate in a twin-screw extruder. The temperature of each section of the extruder is set to 240°C and the screw speed is 300 r / min to obtain a conductive polybutylene terephthalate base polymer;

[0103] (3) The product obtained in step (2) and erucic acid were added to a reactor in a mass ratio of 10:1, and then the composite catalyst B and phosphite were added. Nitrogen was introduced for protection, and the temperature was raised to 200°C with stirring. The reaction was carried out for 4 hours, and then the product was washed and dried to obtain a hydrophobic polybutylene terephthalate base polymer;

[0104] (4) The product obtained in step (3), maleic anhydride, an organic phosphate nucleating agent, a fatty acid ester lubricant, an ultraviolet absorber, and a hindered amine light stabilizer are added to a twin-screw extruder for blending, and the temperature of each section of the extruder is set to 240° C. to obtain polybutylene terephthalate.

[0105] The amount of the composite catalyst A added is 0.3% of the total mass of the reactants in step (1); the total amount of the carbon nanotubes and zinc oxide added in step (2) is 5% of the total mass of the reactants in step (2); the amount of the phosphite added is 0.2% of the total mass of the reactants in step (3); the amount of the antioxidant added is 0.8% of the mass of the polybutylene terephthalate base polymer in step (2); the amount of maleic anhydride added is 2% of the mass of the product obtained in step (3); the amount of the organic phosphate nucleating agent added is 1.2% of the mass of the product obtained in step (3); the amount of the fatty acid ester lubricant added is 0.6% of the mass of the product obtained in step (3); the amount of the ultraviolet absorber added is 0.8% of the mass of the product obtained in step (3); and the amount of the hindered amine light stabilizer added is 0.7% of the mass of the product obtained in step (3).

[0106] The silane coupling agent is γ-glycidyloxypropyltrimethoxysilane; the antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and dilauryl thiodipropionate in a mass ratio of 2:1; the phosphite is tetrakis(2,4-di-tert-butylphenyl)biphenyl bisphosphite; the organic phosphate nucleating agent is sodium phenylphosphinate; the fatty acid ester lubricant is a mixture of stearic acid monoglyceride and ethylene bisstearamide in a mass ratio of 5:3; the UV absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol; and the hindered amine light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

[0107] Example 3

[0108] The preparation method of the composite catalyst A comprises the following steps:

[0109] ① Dissolve 10g of hexadecyltrimethylammonium bromide in deionized water and stir at 60°C until completely dissolved; add ammonia water dropwise to adjust the pH to 11, then add 60ml of ethyl orthosilicate dropwise and continue stirring for 6 hours; filter and wash the reaction product, then dry it at 110°C for 18 hours; finally, calcine it at 600°C for 4 hours to obtain a porous silica support;

[0110] ② According to the titanium:germanium molar ratio of 8:1, tetrabutyl titanate was dissolved in anhydrous ethanol to form a titanium solution; germanium dioxide was placed in a container, 37% concentrated hydrochloric acid was added and heated to 80°C to dissolve it to form a germanium solution; under stirring, the germanium solution was added dropwise to the titanium solution, and stirring was continued for 3 hours to obtain a titanium-germanium composite solution;

[0111] ③ Take the material according to the lithium: titanium molar ratio of 0.1:1, dissolve it in deionized water to prepare a lithium solution;

[0112] ④ Premix the lithium solution and the titanium-germanium composite solution to obtain a mixed solution; add the porous silica support to the mixed solution and stir at room temperature for 12 hours; remove the solvent by vacuum distillation to obtain a solid product; dry the solid product at 110°C for 15 hours, and then calcine it at 500°C for 2 hours to obtain a composite catalyst A.

[0113] The surface treatment method of carbon nanotubes is as follows: placing carbon nanotubes in a mixed acid of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, using 10 ml of the mixed acid for each gram of carbon nanotubes, ultrasonically treating at 50° C. for 2 hours, and then washing with deionized water until neutral.

[0114] The modification method of zinc oxide comprises the following steps:

[0115] a. The silane: solvent was added to an ethanol / water mixture at a ratio of 3 wt %, glacial acetic acid was added dropwise to adjust the pH to 5, and magnetic stirring was carried out for 60 min;

[0116] b. Dry the zinc oxide powder at 120°C for 4 hours;

[0117] c. The dried zinc oxide was added to the mixture obtained in step a at a mass ratio of 1:20 and ultrasonically treated at 50 ° C for 2h;

[0118] d. The mixture obtained in step c was centrifuged, the supernatant was removed, and the precipitate was washed 5 times with anhydrous ethanol. The washed ZnO was vacuum dried at 100 ° C for 6 h to obtain silanized zinc oxide.

[0119] The preparation method of the composite catalyst B comprises the following steps:

[0120] Ⅰ. Yttrium oxide and cerium oxide were calcined at 700℃ for 1 hour, added to anhydrous ethanol, and ultrasonically dispersed for 45 minutes;

[0121] Ⅱ tetrabutyl titanate was added to a container, and then the resultant of step Ⅰ was added to a container containing tetrabutyl titanate, while stirring, the stirring speed was controlled at 300r / min, and stirred for 1.5h to obtain a composite catalyst precursor solution;

[0122] III. The composite catalyst precursor solution was sealed and aged at room temperature for 24 h. The total mass concentration of tetrabutyl titanate, yttrium oxide and cerium oxide in the aged solution was 20%, thereby obtaining composite catalyst B.

[0123] The mass ratio of tetrabutyl titanate, yttrium oxide and cerium oxide is 1:1:0.5; the active ingredients of the composite catalyst B are tetrabutyl titanate, yttrium oxide and cerium oxide, and the amount of the active ingredients added is 0.2% of the total mass of the reactants in step (3).

[0124] The preparation method of polybutylene terephthalate comprises the following steps:

[0125] (1) Terephthalic acid and 1,4-butanediol were added to a reactor at a molar ratio of 1:1.2, and a composite catalyst A was added. The temperature was raised to 230°C for esterification reaction for 2 hours, and then the temperature was raised to 260°C for polycondensation reaction for 3 hours to obtain a polybutylene terephthalate base polymer;

[0126] (2) The antioxidant is blended with the polybutylene terephthalate base polymer in a twin-screw extruder to obtain an intermediate, and then the surface-treated carbon nanotubes and the modified zinc oxide are mixed in a mass ratio of 3:1 and blended with the intermediate in a twin-screw extruder. The temperature of each section of the extruder is set to 250°C and the screw speed is 400 r / min to obtain a conductive polybutylene terephthalate base polymer;

[0127] (3) The product obtained in step (2) and erucic acid were added to a reactor in a mass ratio of 10:1, and then the composite catalyst B and phosphite were added. Nitrogen was introduced for protection, and the temperature was raised to 210° C. under stirring. The reaction was carried out for 4.5 hours. The product was then washed and dried to obtain a hydrophobic polybutylene terephthalate base polymer;

[0128] (4) The product obtained in step (3), maleic anhydride, an organic phosphate nucleating agent, a fatty acid ester lubricant, an ultraviolet absorber, and a hindered amine light stabilizer are added to a twin-screw extruder for blending, and the temperature of each section of the extruder is set to 250° C. to obtain polybutylene terephthalate.

[0129] The amount of the composite catalyst A added is 0.5% of the total mass of the reactants in step (1); the total amount of the carbon nanotubes and zinc oxide added in step (2) is 7% of the total mass of the reactants in step (2); the amount of the phosphite added is 0.3% of the total mass of the reactants in step (3); the amount of the antioxidant added is 1% of the mass of the polybutylene terephthalate base polymer in step (2); the amount of maleic anhydride added is 3% of the mass of the product obtained in step (3); the amount of the organic phosphate nucleating agent added is 2% of the mass of the product obtained in step (3); the amount of the fatty acid ester lubricant added is 1% of the mass of the product obtained in step (3); the amount of the ultraviolet absorber added is 1% of the mass of the product obtained in step (3); and the amount of the hindered amine light stabilizer added is 1% of the mass of the product obtained in step (3).

[0130] The silane coupling agent is γ-aminopropyltriethoxysilane; the antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and dilauryl thiodipropionate in a mass ratio of 2:1; the phosphite is tris(2,4-di-tert-butylphenyl)phosphite; the organic phosphate nucleating agent is sodium phenylphosphinate; the fatty acid ester lubricant is a mixture of stearic acid monoglyceride and ethylene bisstearamide in a mass ratio of 5:3; the UV absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol; and the hindered amine light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

[0131] Comparative Example 1

[0132] Compared with Example 1, the difference is that tetrabutyl titanate is used as catalyst A, and the added amount is 0.2% of the total mass of the reactants in step (1).

[0133] Comparative Example 2

[0134] Compared with Example 1, the difference is that the carbon nanotubes are directly mixed with zinc oxide without being treated with mixed acid.

[0135] Comparative Example 3

[0136] Compared with Example 1, the difference is that erucic acid grafting and phosphite addition are not performed.

[0137] Comparative Example 4

[0138] Compared with Example 1, the difference is that only carbon nanotubes are added, and the added amount is 7% of the total mass of the reactants in step (2).

[0139] The test data of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1.

[0140] Table 1: Test data of Examples 1-3 and Comparative Examples 1-4

[0141]

[0142] As shown in Table 1, the resistivity of comparative example 1 (using tetrabutyl titanate alone) is (10 4 Ω·cm) is much higher than that of the example (10²-10³Ω·cm), indicating that the composite catalyst A (titanium-germanium) significantly improves the polycondensation efficiency and conductivity. The conductivity of comparative example 2 (untreated carbon nanotubes) (2.7×10 5The water absorption rate of Comparative Example 3 (without erucic acid grafting) was as high as 1.8%, while that of the Examples was only 0.2-0.3%. Erucic acid grafting significantly improved hydrophobicity. The electromagnetic shielding effectiveness of Comparative Example 4 (carbon nanotubes only) (28 dB) was lower than that of the Examples (35-45 dB). The synergistic effect of zinc oxide and graphene strengthened the conductive network.

[0143] Application Example 1

[0144] Modified MoS2: MoS2 nanosheets were dispersed in an oil-in-water emulsion containing 5% KH-570 and ultrasonically treated for 4 h (frequency 40 kHz, power 300 W); spray dried (inlet temperature 150°C, outlet temperature 80°C) to obtain modified MoS2 (particle size distribution 10 nm) with a surface grafting rate ≥90%.

[0145] Polypyrrole (PPy): PPy and carbon nanotubes were ball-milled in a 1:1 ratio (500 rpm, 2 h) to form a "CNT-PPy" core-shell structure. A 20% slurry was prepared with anhydrous ethanol and ultrasonically dispersed to form a uniform slurry.

[0146] A method for preparing an intelligent driving sensor housing comprises the following steps:

[0147] A. Add 100 parts of the product obtained in Example 2 to a high-speed mixer, preheat to 60°C, and stir for 5 minutes;

[0148] B. Add 2.25 parts of maleic anhydride grafted polypropylene, 0.75 parts of zinc stearate, 2 parts of modified MoS2, 3 parts of polypyrrole dispersion, and 0.5 parts of antioxidant 1010 in sequence and continue stirring for 10 minutes;

[0149] C. Add it to a twin-screw extruder and extrude it. Set the temperature of each section of the extruder to 250°C. Then place it in a mold with a barrel temperature of 250°C, a mold temperature of 80°C, an injection pressure of 110 MPa, a holding pressure of 70 MPa, hold the pressure for 20 seconds, and cool for 40 seconds. This is the housing for the intelligent driving sensor.

[0150] Application Example 2

[0151] Modified MoS2: MoS2 nanosheets were dispersed in an oil-in-water emulsion containing 5% KH-570 and ultrasonically treated for 4 h (frequency 40 kHz, power 300 W); spray dried (inlet temperature 150°C, outlet temperature 80°C) to obtain modified MoS2 (particle size distribution 15 nm) with a surface grafting rate ≥90%.

[0152] Polypyrrole (PPy): PPy and carbon nanotubes were ball-milled in a 1:1 ratio (500 rpm, 2 h) to form a "CNT-PPy" core-shell structure. A 20% slurry was prepared with anhydrous ethanol and ultrasonically dispersed to form a uniform slurry.

[0153] A method for preparing an intelligent driving sensor housing comprises the following steps:

[0154] A. Add 100 parts of the product obtained in Example 1 to a high-speed mixer, preheat to 60°C, and stir for 5 minutes;

[0155] B. Add 1.5 parts of maleic anhydride grafted polypropylene, 0.5 parts of zinc stearate, 1 part of modified MoS2, 1 part of polypyrrole dispersion, and 0.3 parts of antioxidant 1010 in sequence and continue stirring for 10 minutes;

[0156] C. Add it to a twin-screw extruder and extrude it. Set the temperature of each section of the extruder to 225°C. Then place it in a mold with a barrel temperature of 240°C, a mold temperature of 70°C, an injection pressure of 90 MPa, a holding pressure of 60 MPa, hold the pressure for 15 seconds, and cool for 30 seconds. This is the housing for the smart driving sensor.

[0157] Application Example 3

[0158] Modified MoS2: MoS2 nanosheets were dispersed in an oil-in-water emulsion containing 5% KH-570 and ultrasonically treated for 4 h (frequency 40 kHz, power 300 W); spray dried (inlet temperature 150°C, outlet temperature 80°C) to obtain modified MoS2 (particle size distribution 5 nm) with a surface grafting rate ≥90%.

[0159] Polypyrrole (PPy): PPy and carbon nanotubes were ball-milled in a 1:1 ratio (500 rpm, 2 h) to form a "CNT-PPy" core-shell structure. A 20% slurry was prepared with anhydrous ethanol and ultrasonically dispersed to form a uniform slurry.

[0160] A method for preparing an intelligent driving sensor housing comprises the following steps:

[0161] A. Add 100 parts of the product obtained in Example 3 to a high-speed mixer, preheat to 60°C, and stir for 5 minutes;

[0162] B. Add 2 parts of maleic anhydride grafted polypropylene, 0.6 parts of zinc stearate, 2 parts of modified MoS2, 3 parts of polypyrrole dispersion, and 0.3 parts of antioxidant 1010 in sequence and continue stirring for 10 minutes;

[0163] C. Add it to a twin-screw machine for extrusion. Set the temperature of each section of the extruder to 240°C. Then place it in a mold with a barrel temperature of 245°C, a mold temperature of 75°C, an injection pressure of 100 MPa, a holding pressure of 65 MPa, hold the pressure for 18 seconds, and cool for 35 seconds. This is the material used for the intelligent driving sensor housing.

[0164] Comparative Application Example 1

[0165] Compared with Application Example 1, the difference is that maleic anhydride grafted polypropylene is not added.

[0166] Application Comparative Example 2

[0167] Compared with Application Example 2, the difference is that no modified MoS2 is added.

[0168] Application Comparative Example 3

[0169] Compared with Application Example 3, the difference is that zinc stearate is not added.

[0170] The test data of Application Examples 1-3 and Application Comparative Examples 1-3 are shown in Table 2.

[0171] Table 2: Test data of application examples 1-3 and application comparative examples 1-3

[0172]

[0173] It can be seen from Table 2 that the conductivity of Comparative Example 1 (1.2×10 4 The significant decrease in the Ω·cm (Ω·cm) indicates filler agglomeration due to insufficient interfacial bonding. The impact strength of Comparative Example 2 (11.5 kJ / m²) is lower than that of the Examples (13-14.5 kJ / m²), demonstrating that the layered structure of MoS2 improves toughness and dispersibility. The surface smoothness of Comparative Example 3 (3.0 μm) is much higher than that of the Examples (0.8-1.2 μm), demonstrating that zinc stearate optimizes melt flow and reduces processing defects.

[0174] This invention achieves comprehensive improvements in the electrical conductivity, mechanical strength, heat resistance, and processing properties of PBT materials through complex catalysis, multidimensional conductive network design, and dynamic cross-linking modification. Application examples demonstrate the key roles of maleic anhydride-grafted polypropylene, modified MoS2, and zinc stearate. The material meets the high standards required for intelligent driving sensor housings and has significant industrial potential.

Claims

1. A method for preparing polybutylene terephthalate, characterized in that: The following steps are involved: (1) Add terephthalic acid and 1,4-butanediol into a reactor at a molar ratio of 1:1.2, add composite catalyst A, heat to 210-230°C, carry out esterification reaction, react for 2-4 hours, then heat to 240-260°C, carry out polycondensation reaction, react for 3-6 hours, and obtain polybutylene terephthalate base polymer; (2) blending the antioxidant with the polybutylene terephthalate base polymer in a twin-screw extruder to obtain an intermediate, then mixing the surface-treated carbon nanotubes and the modified zinc oxide in a mass ratio of (1-3):1, and blending them with the intermediate in a twin-screw extruder, with the temperature of each section of the extruder set at 230-250°C and the screw speed at 200-400 r / min, to obtain a conductive polybutylene terephthalate base polymer; (3) The product obtained in step (2) and erucic acid were added to a reactor in a mass ratio of 10:1, and then the composite catalyst B and phosphite were added. Nitrogen was introduced for protection, and the temperature was raised to 190-210°C under stirring. The reaction was carried out for 4-4.5 hours. The product was then washed and dried to obtain a hydrophobic polybutylene terephthalate base polymer; (4) adding the product obtained in step (3), maleic anhydride, an organic phosphate nucleating agent, a fatty acid ester lubricant, an ultraviolet absorber, and a hindered amine light stabilizer to a twin-screw extruder for blending, and setting the temperature of each section of the extruder to 230-250° C. to obtain polybutylene terephthalate; The composite catalyst A is a titanium-germanium composite catalyst; the composite catalyst B is a yttrium-cerium-tetrabutyl titanate composite catalyst; The preparation method of the composite catalyst A comprises the following steps: ① Dissolve 10g of hexadecyltrimethylammonium bromide in deionized water and stir at 40-60°C until dissolved; add aqueous ammonia to adjust the pH to 9-11, then add 40-60ml of ethyl orthosilicate dropwise and continue stirring for 2-6 hours; filter and wash the reaction product, then dry it at 110°C for 18 hours; finally, calcine it at 500-600°C for 4-6 hours to obtain a porous silica support; ② According to the titanium:germanium molar ratio (3-8):1, tetrabutyl titanate is dissolved in anhydrous ethanol to form a titanium solution; germanium dioxide is placed in a container, 30-37% concentrated hydrochloric acid is added and heated to 50-80°C to dissolve it to form a germanium solution; under stirring, the germanium solution is added dropwise to the titanium solution and stirring is continued for 1-3 hours to obtain a titanium-germanium composite solution; ③ Take the material according to the lithium: titanium molar ratio (0.01-0.1):1, dissolve it in deionized water to prepare a lithium solution; ④ Premixing the lithium solution and the titanium-germanium composite solution to obtain a mixed solution; adding the porous silica support to the mixed solution and stirring at room temperature for 6-12 hours; removing the solvent by vacuum distillation to obtain a solid product; drying the solid product at 105-110° C. for 15-20 hours, and then calcining at 300-500° C. for 2-4 hours to obtain a composite catalyst A; The surface treatment method of the carbon nanotubes is as follows: placing the carbon nanotubes in a mixed acid of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, ultrasonically treating the carbon nanotubes at 40-50°C for 2-3 hours, and then washing with deionized water until neutral. The zinc oxide modification method is as follows: adding a silane coupling agent to an ethanol / water mixture, then adding zinc oxide powder, ultrasonically treating the mixture, centrifuging and drying, to obtain silanized zinc oxide. The preparation method of the composite catalyst B comprises the following steps: Ⅰ. After calcining yttrium oxide and cerium oxide at 500-700℃ for 1-3h, add them to anhydrous ethanol and perform ultrasonic dispersion for 30-45min; Ⅱ tetrabutyl titanate was added to a container, and then the resultant of step Ⅰ was added to a container containing tetrabutyl titanate, while stirring, the stirring speed was controlled at 300r / min, stirring for 1-1.5h to obtain a composite catalyst precursor solution; III. The composite catalyst precursor solution is sealed and aged at room temperature for 20-24 hours. The total mass concentration of tetrabutyl titanate, yttrium oxide and cerium oxide in the aged solution is 10-20%, thereby obtaining composite catalyst B.

2. The method for preparing polybutylene terephthalate according to claim 1, wherein The amount of the composite catalyst A added is 0.2-0.5% of the total mass of the reactants in step (1); the total amount of carbon nanotubes and zinc oxide added in step (2) is 3-7% of the total mass of the reactants in step (2); the amount of phosphite added is 0.1-0.3% of the total mass of the reactants in step (3); the amount of the antioxidant added is 0.3-1% of the mass of the polybutylene terephthalate base polymer in step (2); the amount of maleic anhydride added is 1-3% of the mass of the product obtained in step (3); the amount of the organic phosphate nucleating agent added is 0.5-2% of the mass of the product obtained in step (3); the amount of the fatty acid ester lubricant added is 0.3-1% of the mass of the product obtained in step (3); the amount of the ultraviolet absorber added is 0.5-1% of the mass of the product obtained in step (3); and the amount of the hindered amine light stabilizer added is 0.5-1% of the mass of the product obtained in step (3).

3. The method for preparing polybutylene terephthalate according to claim 1, wherein The mass ratio of tetrabutyl titanate, yttrium oxide and cerium oxide is 1: (0.1-1): 0.5; the active ingredients of the composite catalyst B are tetrabutyl titanate, yttrium oxide and cerium oxide, and the amount of the active ingredients added is 0.05-0.2% of the total mass of the reactants in step (3).

4. The method for preparing polybutylene terephthalate according to claim 1, wherein The silane coupling agent is one of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane; the antioxidant is obtained by compounding tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester and dilauryl thiodipropionate in a mass ratio of 2:1; the phosphite is one of tris(2,4-di-tert-butylphenyl)phosphite or tetrakis(2,4-di-tert-butylphenyl)biphenylbisphosphite; the organic phosphate nucleating agent is sodium phenylphosphinate; the fatty acid ester lubricant is obtained by mixing stearic acid monoglyceride and ethylene bisstearamide in a mass ratio of 5:3; the ultraviolet absorber is 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol; and the hindered amine light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

5. A polybutylene terephthalate, characterized in that The polybutylene terephthalate is prepared by the preparation method of any one of claims 1 to 4.

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