High-impact-resistance and high-weather-resistance PVC (polyvinyl chloride) reinforced pipe and preparation method thereof

Abstract

The invention relates to the technical field of pipes, and particularly discloses a high-impact high-weather-resistance PVC (polyvinyl chloride) reinforced pipe and a preparation method thereof, and the high-impact high-weather-resistance PVC reinforced pipe comprises the following components: PVC resin (SG-5 type), multifunctional composite particles, a calcium-zinc stabilizer, modified titanium dioxide, modified montmorillonite, a castor oil-based plasticizer, a composite lubricant and an antioxidant. The preparation method comprises the following steps: firstly, preparing the multifunctional composite particles with the core-shell structure, then preparing a pipe mixture through three-stage temperature control mixing, and finally, carrying out twin-screw extrusion molding to obtain the pipe. The multifunctional composite particles and the modified montmorillonite form a complementary reinforcing system, the modified titanium dioxide, the calcium-zinc stabilizer and the like are matched to realize weather-resistant synergy, and a staged mixing process is combined to ensure that components are uniformly dispersed, so that the impact resistance and weather resistance of the pipe are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of pipe technology, specifically to a high-impact, high-weather-resistant PVC reinforced pipe and its preparation method. Background Technology

[0002] PVC pipes, with their advantages of being lightweight, corrosion-resistant, and inexpensive, are widely used in building water supply and drainage, municipal pipe networks, agricultural irrigation, and chemical fluid transportation, making them an indispensable key material in modern infrastructure construction. Their excellent processing performance and chemical stability allow them to maintain basic mechanical properties even in complex environments such as low temperatures and humidity, meeting the needs of various working conditions.

[0003] Traditional PVC pipe formulations typically use PVC resin as the base material, combined with lead salt stabilizers, calcium carbonate fillers, phthalate plasticizers, and stearic acid lubricants. In existing technologies, to improve pipe performance, elastomers such as chlorinated polyethylene (CPE) and acrylate copolymers (ACR) are often added for toughening, or inorganic fillers such as nano-calcium carbonate and talc are introduced to enhance rigidity.

[0004] However, traditional PVC pipes still have significant shortcomings in practical applications: specifically, they have insufficient impact resistance and poor weather resistance. When exposed to sunlight, rain and other natural environments for a long time, they are prone to aging, discoloration, and mechanical property degradation, which seriously affect the service life and safety of the pipes. Summary of the Invention

[0005] To address the technical deficiencies in the background art, this invention proposes a high-impact, high-weather-resistant PVC reinforced pipe and its preparation method, solving the aforementioned technical problems and meeting practical needs. The specific technical solution is as follows: A high-impact, high-weather-resistant PVC reinforced pipe comprises the following components by weight: 100 parts of PVC resin (SG-5 type), 12-18 parts of multifunctional composite particles, 4-6 parts of calcium-zinc stabilizer, 5-8 parts of modified titanium dioxide, 8-12 parts of modified montmorillonite, 3-5 parts of castor oil-based plasticizer, 1-2 parts of composite lubricant, and 0.8-1.2 parts of antioxidant.

[0006] As a further technical solution of the present invention, the average degree of polymerization of the PVC resin (SG-5 type) is 981-1135, and the modified titanium dioxide is modified titanium dioxide with nano-silica coated on the surface, wherein the coating amount of the nano-silica is 1.5-2.5% of the mass of the titanium dioxide; The modified montmorillonite is sodium-based montmorillonite that has undergone intercalation treatment with dioctadecyl dimethylammonium chloride.

[0007] As a further technical solution of the present invention, the multifunctional composite particle is a composite particle with a core-shell structure, wherein the core is a porous zinc oxide microsphere, the middle layer is a bio-based polyester elastomer, and the outer shell is a fluoropolymer. The specific surface area of ​​the porous zinc oxide microspheres is 35-50 m². 2 / g, with an average pore size of 15-30nm; The bio-based polyester elastomer is a condensation polymer of ricinoleic acid and adipic acid, with a number-average molecular weight of 6,000-10,000. The fluoropolymer is a polysiloxane layer formed by the hydrolysis and condensation of perfluorooctyltriethoxysilane.

[0008] As a further technical solution of the present invention, the castor oil-based plasticizer has a hydroxyl value ≤10mg KOH / g and an acid value ≤0.5mg KOH / g, and the composite lubricant is a mixture of PE wax and lignite ester in a mass ratio of 1:(1-1.5).

[0009] A method for preparing high-impact, high-weather-resistant PVC reinforced pipe includes the following steps: (1) Preparation of multifunctional composite particles: S1. Preparation of porous zinc oxide microspheres; S2. Coating the porous zinc oxide microspheres with a bio-based polyester elastomer; S3. A fluoropolymer is deposited on the surface of the coated composite particles to obtain the multifunctional composite particles; (2) Preparation of pipe material mixture: First stage: Mix PVC resin, modified titanium dioxide, and calcium-zinc stabilizer at 100℃ and 1200rpm for 5 minutes; Second stage: Add multifunctional composite particles and modified montmorillonite, heat to 115℃ and mix at 1200rpm for 10min; Third stage: Add castor oil-based plasticizer, compound lubricant and antioxidant, transfer to low-speed cooling mixer and mix to below 45°C to obtain dry mix; (3) Pipe extrusion molding: The dry mixture is melted, plasticized, extruded, sized, cooled, drawn and cut by a twin-screw extruder to obtain pipes; the temperature of each section of the twin-screw extruder is 170℃ in zone 1, 175℃ in zone 2, 180℃ in zone 3, 175℃ in zone 4 and 170℃ in zone 5, the die temperature is 185℃ and the main screw speed is 25-30 rpm.

[0010] As a further technical solution of the present invention, the preparation of the porous zinc oxide microspheres in step (1) S1 includes: adding 0.5 mol / L zinc acetate solution and 0.5 mol / L ammonium oxalate solution in a volume ratio of 1:1 to the reactor at 60°C in parallel flow, controlling the pH to 6.5-7.0, stirring and co-precipitating for 2 hours, aging for 12 hours, filtering, washing and drying to obtain zinc oxalate precursor; placing the precursor in a muffle furnace and calcining it at 5°C / min to 500°C for 2 hours, and grinding it after natural cooling.

[0011] As a further technical solution of the present invention, the bio-based polyester coating in step (1) S2 includes: dissolving castor oil-based polyester prepolymer with a number average molecular weight of 6000-10000 in anhydrous ethanol to prepare a 15wt% solution, adding the porous zinc oxide microspheres obtained in step (1) S1 at a polyester to zinc oxide mass ratio of 1:(0.8-1.2), ultrasonically dispersing at 40kHz and 300W for 30min, and then spray drying at an inlet temperature of 160±5℃, an outlet temperature of 80±5℃, and a feed rate of 10mL / min.

[0012] As a further technical solution of the present invention, the fluorine-containing vapor deposition in step (1) S3 includes: spreading the composite particles obtained in step (1) S2 on a vacuum reactor, evacuating to -0.095MPa and heating to 120°C, introducing perfluorooctyltriethoxysilane (PFOTES) with nitrogen as a carrier, the mass ratio of PFOTES to composite particles being 1:(15-20), reacting at 120°C for 4 hours, purging with nitrogen for 1 hour, and cooling to obtain multifunctional composite particles.

[0013] As a further technical solution of the present invention, in the second stage of step (2), the modified montmorillonite is added in three equal amounts, with an interval of 2 minutes between each addition; in step (3), the sizing is performed using a vacuum sizing box with a sizing pressure of -0.06 to -0.08 MPa and a cooling water temperature of 12-16℃.

[0014] The beneficial effects of this invention are as follows: The core-shell structure of the multifunctional composite particles (porous zinc oxide microsphere core, bio-based polyester elastomer intermediate layer, and fluoropolymer shell) combined with intercalated modified montmorillonite synergistically enhances the impact strength of the pipe and improves its impact resistance. The fluoropolymer shell of the multifunctional composite particles, together with the modified titanium dioxide coated with nano-silica, synergistically shields ultraviolet rays and significantly improves weather resistance. Calcium-zinc stabilizers and antioxidants enhance material stability, while castor oil-based plasticizers and composite lubricants optimize processing performance, giving the product both high impact resistance, high weather resistance, and good processability. Detailed Implementation

[0015] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0016] A high-impact, high-weather-resistant PVC reinforced pipe comprises the following components by weight: 100 parts of PVC resin (SG-5 type), 12-18 parts of multifunctional composite particles, 4-6 parts of calcium-zinc stabilizer, 5-8 parts of modified titanium dioxide, 8-12 parts of modified montmorillonite, 3-5 parts of castor oil-based plasticizer, 1-2 parts of composite lubricant, and 0.8-1.2 parts of antioxidant.

[0017] The components of this invention achieve multiple performance enhancements through synergistic effects. The core-shell structure of the multifunctional composite particles forms a complementary reinforcement system with the modified montmorillonite, the porous zinc oxide microspheres provide rigid support, the bio-based polyester elastomer intermediate layer enhances impact toughness through energy dissipation, the fluoropolymer shell enhances interfacial compatibility, and together with the intercalated modified montmorillonite, a three-dimensional network structure is formed, significantly improving the impact resistance of the pipe.

[0018] In terms of weather resistance, the low surface energy and UV resistance of the fluoropolymer shell, together with the modified titanium dioxide coated with nano-silica, form a synergistic shielding effect, effectively reflecting and absorbing ultraviolet rays and reducing photoaging. Calcium-zinc stabilizers replace traditional lead salts, and together with antioxidants, they delay oxidative degradation, significantly improving the weather resistance of the pipe. Castor oil-based plasticizers and composite lubricants (PE wax and lignite ester compound) optimize processing fluidity, ensuring uniform dispersion of each component without affecting mechanical properties.

[0019] As one of the preferred embodiments of the present invention, the PVC resin (SG-5 type) has an average degree of polymerization of 981-1135, the modified titanium dioxide is modified titanium dioxide with nano-silica coating on its surface, and the coating amount of nano-silica is 1.5-2.5% of the mass of titanium dioxide; the modified montmorillonite is sodium-based montmorillonite that has been intercalated with dioctadecyldimethylammonium chloride.

[0020] Specifically, the average degree of polymerization of the PVC resin (SG-5 type) is 1058; the coating amount of nano-silica is 2.0% of the titanium dioxide mass. The average degree of polymerization of PVC is 1058, which allows the molecular chains of PVC to form moderate entanglement. While ensuring the rigidity and tensile strength of the pipe, it also meets the plasticizing requirements of twin-screw extrusion and ensures the stability of the molding process. The uniform nano-silica layer on the surface of titanium dioxide not only improves the dispersion stability of titanium dioxide by utilizing the high hardness of silica, preventing it from agglomerating in the PVC matrix, but also enhances the ultraviolet reflection and absorption capacity through the synergistic effect of silica and titanium dioxide. Titanium dioxide itself can reflect ultraviolet light, while silica can scatter ultraviolet light. The combination of the two further reduces the photoaging rate.

[0021] Sodium-based montmorillonite treated with bis(octadecyl)dimethylammonium chloride intercalation has a long-chain alkyl structure that can effectively expand the interlayer spacing of montmorillonite, making it easier for PVC molecular chains to insert into the interlayer to form a nanocomposite structure. The hydrophobicity of bis(octadecyl)dimethylammonium chloride has good compatibility with PVC, which can reduce interface defects. While improving the rigidity of the pipe, it disperses impact energy through interlayer slip effect, and enhances impact resistance in combination with other toughening components.

[0022] As one of the preferred embodiments of the present invention, the multifunctional composite particle is a composite particle with a core-shell structure, wherein the core is a porous zinc oxide microsphere, the middle layer is a bio-based polyester elastomer, and the outer shell is a fluoropolymer. The specific surface area of ​​the porous zinc oxide microspheres is 35-50 m². 2 / g, with an average pore size of 15-30nm; The bio-based polyester elastomer is a condensation polymer of ricinoleic acid and adipic acid, with a number-average molecular weight of 6,000-10,000. The fluoropolymer is a polysiloxane layer formed by the hydrolysis and condensation of perfluorooctyltriethoxysilane.

[0023] Specifically, the specific surface area of ​​the porous zinc oxide microspheres is 45 m². 2 / g, with an average pore size of 25nm, 8000 of bio-based polyester elastomers.

[0024] The parameters of the multifunctional composite particles were set to maximize the synergistic enhancement effect. Porous zinc oxide microspheres with a diameter of 45 μm were selected. 2 With a specific surface area of ​​ / g and an average pore size of 25nm, this structure provides ample interfacial bonding sites, enhancing its interaction with the PVC matrix. At the same time, its porous properties effectively disperse impact energy, improving impact resistance.

[0025] The bio-based polyester elastomer is a ricinoleic acid-adipic acid condensate with a number average molecular weight of 8000. This molecular weight allows the elastomer to maintain good flexibility while forming a stable bond with zinc oxide microspheres and PVC matrix. It absorbs impact energy through elastic deformation, further optimizing its impact resistance.

[0026] The outer shell is made of a polysiloxane layer formed by the hydrolysis and condensation of perfluorooctyltriethoxysilane. Its low surface energy and UV resistance can improve the weather resistance of the pipe. At the same time, the siloxane structure can enhance the compatibility with the intermediate polyester layer, ensuring the stability of the core-shell structure and working synergistically with other components to achieve high impact resistance and high weather resistance.

[0027] As one of the preferred embodiments of the present invention, the castor oil-based plasticizer has a hydroxyl value ≤10mg KOH / g and an acid value ≤0.5mg KOH / g, and the composite lubricant is a mixture of PE wax and lignite ester in a mass ratio of 1:(1-1.5).

[0028] Specifically, the castor oil-based plasticizer can be epoxy methyl ricinoleate, and the composite lubricant is a mixture of PE wax and lignite ester at a mass ratio of 1:1.25.

[0029] The castor oil-based plasticizer selected is methyl ricinoleate epoxy resin, which has low reactivity characteristics such as a hydroxyl value ≤10mg KOH / g and an acid value ≤0.5mg KOH / g. This reduces chemical reactions with calcium-zinc stabilizers, ensuring the stability of the system and preventing PVC degradation caused by high acid values. The epoxy groups have both plasticizing and heat-stabilizing effects, improving the flowability of PVC segments and capturing hydrogen chloride produced during degradation, synergistically enhancing the material's resistance to heat aging. Furthermore, it exhibits excellent compatibility with PVC and poses no risk of migration.

[0030] The composite lubricant uses a 1:1.25 ratio of PE wax and lignite ester. PE wax provides external lubrication, reducing friction between materials and equipment and preventing adhesion; lignite ester acts as an internal lubricant, promoting the slippage of PVC molecular chains and improving melt flowability. This ratio balances internal and external lubrication, avoiding insufficient plasticization due to excessive external lubrication or a decrease in melt strength due to excessive internal lubrication, ensuring a stable extrusion process, a smooth pipe surface, and uniform mechanical properties.

[0031] A method for preparing high-impact, high-weather-resistant PVC reinforced pipe includes the following steps: (1) Preparation of multifunctional composite particles: S1. Preparation of porous zinc oxide microspheres; S2. Coating the porous zinc oxide microspheres with a bio-based polyester elastomer; S3. A fluoropolymer is deposited on the surface of the coated composite particles to obtain the multifunctional composite particles; (2) Preparation of pipe material mixture: First stage: Mix PVC resin, modified titanium dioxide, and calcium-zinc stabilizer at 100℃ and 1200rpm for 5 minutes; Second stage: Add multifunctional composite particles and modified montmorillonite, heat to 115℃ and mix at 1200rpm for 10min; Third stage: Add castor oil-based plasticizer, compound lubricant and antioxidant, transfer to low-speed cooling mixer and mix to below 45°C to obtain dry mix; (3) Pipe extrusion molding: The dry mixture is melted, plasticized, extruded, sized, cooled, drawn and cut by a twin-screw extruder to obtain pipes; the temperature of each section of the twin-screw extruder is 170℃ in zone 1, 175℃ in zone 2, 180℃ in zone 3, 175℃ in zone 4 and 170℃ in zone 5, the die temperature is 185℃ and the main screw speed is 25-30 rpm.

[0032] The preparation method of this invention achieves synergistic optimization of material properties and processing stability through step-by-step control and precise parameter setting. In the staged preparation of multifunctional composite particles, the co-precipitation-calcination method precisely controls the pore structure of porous zinc oxide microspheres, ultrasonic dispersion and spray drying ensure uniform coating of bio-based polyester, and vacuum vapor deposition allows the fluoropolymer to form a dense shell. The stable combination of the three-layer structure ensures the synergistic performance of impact resistance and weather resistance.

[0033] The pipe mixture adopts a three-stage temperature-controlled mixing method: in the initial stage, the substrate and stabilizer are dispersed at medium temperature to avoid premature plasticization; after heating, modified montmorillonite is added in batches to break up agglomerates through multiple dispersions and form a uniform nano-intercalation structure; in the cooling stage, additives are added to prevent plasticizer volatilization and lubricant migration, and finally a uniformly dispersed dry mixture is obtained.

[0034] The gradient temperature setting (170-185℃) of the twin-screw extrusion system matches the melting characteristics of PVC, avoiding localized overheating and degradation. The main extruder speed control ensures sufficient plasticization and stable pressure. Vacuum sizing and cryogenic cooling work synergistically to quickly fix the pipe dimensions, reduce internal stress, and improve dimensional accuracy and uniformity of mechanical properties. The entire process maximizes the functionality of the components, ensuring that the pipe possesses high impact resistance, high weather resistance, and excellent processability.

[0035] As one of the preferred embodiments of the present invention, the preparation of the porous zinc oxide microspheres in step (1) S1 includes: adding 0.5 mol / L zinc acetate solution and 0.5 mol / L ammonium oxalate solution in a volume ratio of 1:1 to the reactor at 60°C in parallel flow, controlling the pH to 6.5-7.0, stirring and co-precipitating for 2 hours, aging for 12 hours, filtering, washing and drying to obtain zinc oxalate precursor; placing the precursor in a muffle furnace and calcining it at 5°C / min to 500°C for 2 hours, and grinding it after natural cooling.

[0036] Step (1) S1 preparation process achieved the controllable synthesis of porous zinc oxide microspheres by controlling the reaction conditions. Adding equal concentrations of zinc acetate and ammonium oxalate solutions avoids particle agglomeration caused by excessively high local concentrations. A reaction temperature of 60℃ promotes ion diffusion, resulting in uniform precipitate formation. The pH is controlled within a neutral range of 6.5-7.0 to ensure complete precipitation of zinc oxalate with high purity. Stirring the reaction for 2 hours ensures sufficient reaction time, while aging for 12 hours allows for slow crystal growth, forming a stable precursor structure and reducing impurity adsorption.

[0037] The calcination stage employs a slow heating rate of 5℃ / min to prevent particle breakage caused by sudden temperature increases. Calcination at 500℃ for 2 hours induces the decomposition of the zinc oxalate precursor, releasing gases that form porous channels within the crystals, ultimately yielding zinc oxide microspheres with controllable specific surface area and pore size. This process ensures the integrity of the microsphere's porous structure while removing residual organic matter through calcination, thus improving the crystallinity of zinc oxide and providing an ideal substrate for subsequent elastomer coating and functional layer deposition.

[0038] As one of the preferred embodiments of the present invention, the bio-based polyester coating in step (1) S2 includes: dissolving castor oil-based polyester prepolymer with a number average molecular weight of 6000-10000 in anhydrous ethanol to prepare a 15wt% solution, adding the porous zinc oxide microspheres obtained in step (1) S1 at a mass ratio of castor oil-based polyester prepolymer to zinc oxide of 1:(0.8-1.2), ultrasonically dispersing at 40kHz and 300W for 30min, and then spray drying at an inlet temperature of 160±5℃, an outlet temperature of 80±5℃, and a feed rate of 10mL / min.

[0039] Specifically, castor oil-based polyester prepolymer with a number average molecular weight of 8000 was dissolved in anhydrous ethanol to prepare a 15wt% solution. The porous zinc oxide microspheres obtained in step (1) S1 were added at a polyester to zinc oxide mass ratio of 1:1. After ultrasonic dispersion at 40kHz and 300W for 30min, the microspheres were spray-dried at an inlet temperature of 160℃, an outlet temperature of 80℃, and a feed rate of 10mL / min.

[0040] Step (1) S2 achieves uniform coating of zinc oxide microspheres with bio-based polyester through a combination of spray drying and impregnation. A 15wt% polyester ethanol solution ensures a moderate coating thickness and a 1:1 mass ratio to balance the core-shell structure. Ultrasonic dispersion at 40kHz and 300W breaks up microsphere aggregation, allowing polyester molecules to fully wet the zinc oxide surface and form a uniform adsorption layer. An inlet temperature of 160℃ accelerates ethanol evaporation, while an outlet temperature of 80℃ prevents high-temperature degradation of the polyester, ultimately forming a complete coated core-shell structure and providing a stable substrate for subsequent fluorine-containing layer deposition.

[0041] As one of the preferred embodiments of the present invention, the fluorine-containing vapor deposition in step (1) S3 includes: spreading the composite particles obtained in step (1) S2 on a vacuum reactor, evacuating to -0.095 MPa and heating to 120°C, introducing perfluorooctyltriethoxysilane (PFOTES) with nitrogen as a carrier, the mass ratio of PFOTES to composite particles being 1:(15-20), reacting at 120°C for 4 hours, purging with nitrogen for 1 hour, and cooling to obtain multifunctional composite particles.

[0042] Specifically, the mass ratio of PFOTES to composite particles is 1:17.5.

[0043] In step (1) S3, the fluorinated vapor deposition achieved a uniform and dense coating of the fluorinated polymer shell through precise control. The -0.095MPa vacuum environment can eliminate air interference, promote the diffusion of perfluorooctyltriethoxysilane (PFOTES), and avoid the introduction of impurities; the temperature of 120℃ provides suitable energy for the hydrolysis and condensation of PFOTES, promoting the formation of a polysiloxane network on the surface of the composite particles.

[0044] A PFOTES to composite particle mass ratio of 1:17.5 ensures the formation of a complete protective layer while preventing particle agglomeration due to excessive amounts. A 4-hour reaction ensures sufficient condensation, and nitrogen purging for 1 hour removes unreacted monomers, resulting in a pure and dense outer shell. This process ultimately forms a uniform fluorinated layer on the particle surface, enhancing weather resistance and interfacial compatibility.

[0045] As one of the preferred embodiments of the present invention, in the second stage of step (2), the modified montmorillonite is added in three equal amounts, with an interval of 2 minutes between each addition; in step (3), the sizing is performed using a vacuum sizing box with a sizing pressure of -0.06 to -0.08 MPa and a cooling water temperature of 12-16℃.

[0046] In step (2), the modified montmorillonite is added in three equal amounts, with a 2-minute interval between each addition. This avoids local agglomeration caused by adding it all at once. Through multiple dispersions, the montmorillonite sheets are inserted more evenly into the PVC matrix, giving full play to the nano-reinforcement effect and improving the uniformity of the pipe's mechanical properties.

[0047] In step (3), the pressure of the vacuum sizing box is controlled at -0.06~-0.08MPa, which can make the outer wall of the pipe fit tightly against the sizing sleeve through negative pressure, and accurately control the pipe diameter. The cooling water temperature of 12-16℃ can quickly solidify the pipe structure, reduce the accumulation of internal stress during the cooling process, avoid pipe deformation, and at the same time ensure the stability of the internal structure of the material and maintain excellent mechanical properties.

[0048] The present invention will be further described below through examples and comparative examples.

[0049] Example 1 A high-impact, high-weather-resistant PVC reinforced pipe is prepared by the following steps: (1) Preparation of multifunctional composite particles: S1. Preparation of porous zinc oxide microspheres: A 0.5 mol / L zinc acetate solution and a 0.5 mol / L ammonium oxalate solution were added concurrently to a reactor at a volume ratio of 1:1 at 60°C. The pH was controlled at 6.8, and the mixture was stirred for 2 hours. After aging for 12 hours, the mixture was filtered, washed three times with deionized water and anhydrous ethanol, and dried at 105°C for 12 hours to obtain a zinc oxalate precursor. The precursor was placed in a muffle furnace and calcined at 500°C for 2 hours at a rate of 5°C / min. After natural cooling, it was ground to obtain a specific surface area of ​​45 m². 2 / g porous zinc oxide microspheres with an average pore size of 25 nm.

[0050] S2. Bio-based Polyester Coating: A 15 wt% solution was prepared by dissolving a ricinoleic acid-adipic acid condensate (bio-based polyester elastomer prepolymer) with a number-average molecular weight of 8000 in anhydrous ethanol. The porous zinc oxide microspheres obtained in step S1 were added at a polyester to zinc oxide mass ratio of 1:1 and ultrasonically dispersed at 40 kHz and 300 W for 30 min. Subsequently, a spray dryer was used for coating, with an inlet temperature of 160℃, an outlet temperature of 80℃, and a feed rate of 10 mL / min, to obtain polyester-coated zinc oxide composite particles.

[0051] S3. Fluoropolymer vapor deposition: The composite particles obtained in step S2 were spread evenly in a vacuum reactor, evacuated to -0.095 MPa, and heated to 120°C. Perfluorooctyltriethoxysilane (PFOTES) was introduced using nitrogen as a carrier gas, controlling the mass ratio of PFOTES to composite particles to be 1:17.5. The reaction was carried out at 120°C for 4 h, and after the reaction was completed, the reactor was purged with nitrogen for 1 h. After cooling, multifunctional composite particles with a core-shell structure were obtained.

[0052] (2) Preparation of pipe material mixture: First stage: Add 100 parts of PVC resin (SG-5 type) with an average degree of polymerization of 1058, 7 parts of modified titanium dioxide with 2.0% nano silica coating, and 5 parts of calcium-zinc stabilizer to a high-speed mixer and mix for 5 min at 100℃ and 1200 rpm.

[0053] Second stage: Add 15 parts of the multifunctional composite particles prepared in step (1) to the above mixture. Add 10 parts of sodium montmorillonite intercalated with dioctadecyldimethylammonium chloride in three equal portions, with an interval of 2 min between each addition. Raise the mixer temperature to 115°C and continue mixing at 1200 rpm for 10 min.

[0054] Third stage: Add 4 parts of epoxy methyl ricinoleate with a hydroxyl value ≤10 mg KOH / g and an acid value ≤0.5 mg KOH / g, 1.5 parts of a composite lubricant made by compounding PE wax and lignite ester in a mass ratio of 1:1.25, and 1 part of antioxidant 1010 to the mixture. Transfer the material to a low-speed cooling mixer and mix until the temperature drops below 45°C to obtain a uniform dry mix.

[0055] (3) Pipe extrusion molding: The dry mixture is fed into a twin-screw extruder for extrusion molding. The extruder temperature is set to 170℃ in zone 1, 175℃ in zone 2, 180℃ in zone 3, 175℃ in zone 4, and 170℃ in zone 5, with a die temperature of 185℃ and a main screw speed of 28 rpm. The extruded pipe is sized in a vacuum sizing chamber (sizing pressure -0.07 MPa), cooled in a 14℃ water bath, drawn, and cut to obtain the high-impact, high-weather-resistant PVC reinforced pipe.

[0056] Comparative Example 1 The difference from Example 1 is that the core-shell structure of the multifunctional composite particles is omitted, and instead, an equal amount (15 parts) of ordinary zinc oxide (50 nm particle size) and an equal amount (5 parts) of commercially available ACR impact modifier are simply physically mixed and added. That is, in the second stage of step (2), 15 parts of ordinary zinc oxide + 5 parts of ACR impact modifier are added instead of 15 parts of multifunctional composite particles. The remaining components, amounts, and preparation process remain unchanged.

[0057] Comparative Example 2 The difference from Example 1 is that the modified montmorillonite treated with bis(octadecyldimethylammonium chloride) intercalation was replaced with an equal amount (10 parts) of untreated original sodium-based montmorillonite. The remaining components, amounts, and preparation process remain unchanged.

[0058] Comparative Example 3 The difference from Example 1 is that the mixing process is changed. All components (PVC resin, multifunctional composite particles, modified montmorillonite, modified titanium dioxide, calcium-zinc stabilizer, plasticizer, lubricant, and antioxidant) are added to a high-speed mixer at once and mixed for 15 minutes at 115°C and 1200 rpm, followed by cooling and discharge. The three-stage temperature-controlled mixing process is eliminated. The remaining components, dosages, and subsequent extrusion processes remain unchanged.

[0059] Performance testing The tensile properties of the pipes were tested according to GB / T 8804.2-2003 "Determination of tensile properties of thermoplastic pipes - Part 2".

[0060] The bending performance was tested according to GB / T 9341-2008 "Determination of bending properties of plastics".

[0061] Impact tests were conducted according to GB / T 18743.2-2022 "Determination of impact strength of simply supported beams of thermoplastic pipes - Part 2: Test conditions for pipes of different materials", with a test temperature of 23±2℃.

[0062] The surface color change ΔE after aging was determined according to GB / T 16422.2-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 2: Xenon Arc Lamp". The blackboard temperature was 65±3℃, the relative humidity was (50±5)%, and the test time was 200h. The aging surface was the visible surface of the pipe. The color detection used the CIE standard light source D65. Each sample underwent three color tests, and the average value was taken. Tensile strength, elongation, impact strength, and color change were tested for Examples 1 and Comparative Examples 1-3 according to the above test methods. The test results are shown in the table below:

[0063] By comparing the performance of Example 1 with that of the comparative examples, the following conclusions can be drawn: Compared to Comparative Example 1, Example 1 exhibited higher tensile strength (48.7 MPa vs 42.5 MPa), elongation (149.3% vs 125.6%), and impact strength, with less color change after aging (ΔE 2.7 vs 5.8). This indicates that a simple physical mixture of ordinary zinc oxide and ACR impact modifier cannot replace the role of multifunctional composite particles. In the multifunctional composite particles, porous zinc oxide microspheres disperse stress, bio-based polyester elastomer dissipates impact energy through deformation, and the fluoropolymer shell optimizes interfacial compatibility and enhances UV resistance. These three components synergistically form a "rigid-flexible-protective" system, improving both impact resistance and weather resistance.

[0064] Comparative Example 2 used unmodified raw sodium-based montmorillonite, and its mechanical properties were all lower than those of Example 1. This is because unmodified montmorillonite is highly hydrophilic, has poor compatibility with PVC, and is prone to agglomeration, making it difficult to form an effective nanocomposite structure. In contrast, montmorillonite treated with dioctadecyldimethylammonium chloride intercalation has increased interlayer spacing and enhanced hydrophobicity, enabling it to combine with PVC molecular chains to form a nanostructure. Through lamellar slip, it disperses impact energy and synergistically improves rigidity and impact resistance.

[0065] Comparative Example 3 employed a one-time mixing process, and all performance indicators were lower than those of Example 1. One-time mixing easily leads to the degradation of heat-sensitive additives and the agglomeration of solid fillers. In contrast, the three-stage process, through medium-temperature dispersion of the substrate and stabilizer, heating to promote montmorillonite intercalation, and the addition of liquid additives during the cooling stage, ensures uniform dispersion of each component, avoids agglomeration and additive failure, and allows the nano-effects of the multifunctional composite particles and modified montmorillonite to be fully utilized.

[0066] In summary, this invention achieves high impact resistance and high weather resistance in pipes through the synergistic effects of multifunctional composite particle structural design, modified montmorillonite intercalation treatment, and staged mixing process. The absence of any key component or process will disrupt the synergistic effect and lead to performance degradation.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-impact, high-weather-resistant PVC reinforced pipe, characterized in that, The product comprises the following components by weight: 100 parts PVC resin (SG-5 type), 12-18 parts multifunctional composite particles, 4-6 parts calcium-zinc stabilizer, 5-8 parts modified titanium dioxide, 8-12 parts modified montmorillonite, 3-5 parts castor oil-based plasticizer, 1-2 parts composite lubricant, and 0.8-1.2 parts antioxidant.

2. The high-impact, high-weather-resistant PVC reinforced pipe according to claim 1, characterized in that, The PVC resin (SG-5 type) has an average degree of polymerization of 981-1135, and the modified titanium dioxide is modified titanium dioxide with a surface coating of nano-silica, wherein the coating amount of nano-silica is 1.5-2.5% of the mass of titanium dioxide. The modified montmorillonite is sodium-based montmorillonite that has undergone intercalation treatment with dioctadecyl dimethylammonium chloride.

3. The high-impact, high-weather-resistant PVC reinforced pipe according to claim 1, characterized in that, The multifunctional composite particle is a composite particle with a core-shell structure, wherein the core is a porous zinc oxide microsphere, the middle layer is a bio-based polyester elastomer, and the outer shell is a fluoropolymer. The specific surface area of ​​the porous zinc oxide microspheres is 35-50 m². 2 / g, with an average pore size of 15-30nm; The bio-based polyester elastomer is a condensation polymer of ricinoleic acid and adipic acid, with a number-average molecular weight of 6,000-10,000. The fluoropolymer is a polysiloxane layer formed by the hydrolysis and condensation of perfluorooctyltriethoxysilane.

4. The high-impact, high-weather-resistant PVC reinforced pipe according to claim 1, characterized in that, The castor oil-based plasticizer has a hydroxyl value ≤10mg KOH / g and an acid value ≤0.5mg KOH / g. The composite lubricant is a mixture of PE wax and lignite ester in a mass ratio of 1:(1-1.5).

5. A method for preparing high-impact, high-weather-resistant PVC reinforced pipe as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of multifunctional composite particles: S1. Preparation of porous zinc oxide microspheres; S2. Coating the porous zinc oxide microspheres with a bio-based polyester elastomer; S3. A fluoropolymer is deposited on the surface of the coated composite particles to obtain the multifunctional composite particles; (2) Preparation of pipe material mixture: First stage: Mix PVC resin, modified titanium dioxide, and calcium-zinc stabilizer at 100℃ and 1200rpm for 5 minutes; Second stage: Add multifunctional composite particles and modified montmorillonite, heat to 115℃ and mix at 1200rpm for 10min; Third stage: Add castor oil-based plasticizer, compound lubricant and antioxidant, transfer to low-speed cooling mixer and mix to below 45°C to obtain dry mix; (3) Pipe extrusion molding: The dry mixture is melted, plasticized, extruded, sized, cooled, drawn and cut by a twin-screw extruder to obtain pipes; the temperature of each section of the twin-screw extruder is 170℃ in zone 1, 175℃ in zone 2, 180℃ in zone 3, 175℃ in zone 4 and 170℃ in zone 5, the die temperature is 185℃ and the main screw speed is 25-30 rpm.

6. The method for preparing high-impact, high-weather-resistant PVC reinforced pipe according to claim 5, characterized in that, The preparation of porous zinc oxide microspheres in step (1) S1 includes: adding 0.5 mol / L zinc acetate solution and 0.5 mol / L ammonium oxalate solution in a volume ratio of 1:1 to the reactor at 60°C in a co-current manner, controlling the pH to 6.5-7.0, stirring and co-precipitating for 2 hours, aging for 12 hours, filtering, washing and drying to obtain zinc oxalate precursor; placing the precursor in a muffle furnace and calcining it at 500°C for 2 hours at a rate of 5°C / min, and grinding it after natural cooling.

7. The method for preparing high-impact, high-weather-resistant PVC reinforced pipe according to claim 5, characterized in that, The bio-based polyester coating in step (1) S2 includes: dissolving castor oil-based polyester prepolymer with a number average molecular weight of 6000-10000 in anhydrous ethanol to prepare a 15wt% solution, adding the porous zinc oxide microspheres obtained in step (1) S1 at a polyester to zinc oxide mass ratio of 1:(0.8-1.2), ultrasonically dispersing at 40kHz and 300W for 30min, and then spray drying at an inlet temperature of 160±5℃, an outlet temperature of 80±5℃, and a feed rate of 10mL / min.

8. The method for preparing high-impact, high-weather-resistant PVC reinforced pipe according to claim 5, characterized in that, The fluorine-containing vapor deposition in step (1) S3 includes: spreading the composite particles obtained in step (1) S2 on a vacuum reactor, evacuating to -0.095 MPa and heating to 120°C, introducing perfluorooctyltriethoxysilane (PFOTES) with nitrogen as a carrier, the mass ratio of PFOTES to composite particles being 1:(15-20), reacting at 120°C for 4 h, purging with nitrogen for 1 h, and cooling to obtain multifunctional composite particles.

9. The method for preparing high-impact, high-weather-resistant PVC reinforced pipe according to claim 5, characterized in that, In step (2), the modified montmorillonite is added in three equal amounts, with a 2-minute interval between each addition. In step (3), a vacuum sizing box is used for sizing, with a sizing pressure of -0.06 to -0.08 MPa and a cooling water temperature of 12-16℃.

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