Modified chlorinated polyvinyl chloride composition and method for producing the same

Abstract

This invention relates to the field of polymer composite materials technology, and discloses a modified chlorinated polyvinyl chloride (PVC) composition and its preparation method. The PVC resin, methyl tin heat stabilizer, epoxidized soybean oil, and antioxidant are mixed, followed by the addition of a borate and phosphate composite intercalated magnesium zinc aluminum layered double hydroxide-coated nano-titanium dioxide composite heat-stabilized flame-retardant compound, a zinc hydroxystannate and zinc molybdate in-situ anchored boehmite and hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, rutile titanium dioxide, nano-calcium carbonate, zinc borate, impact-resistant resin, and lubricating components. The mixture is then subjected to mixing, melt plasticizing, compounding, degassing, extrusion, and granulation to obtain the final composition. The resulting composition exhibits good thermal stability, flame retardancy, smoke suppression, impact resistance, and processing stability.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to modified chlorinated polyvinyl chloride compositions and their preparation methods. Background Technology

[0002] Chlorinated polyvinyl chloride (PVC) resin is a thermoplastic resin obtained by further chlorination of PVC resin. It possesses good heat resistance, chemical corrosion resistance, flame retardancy, and mechanical properties, and is therefore widely used in hot and cold water pipes, chemical corrosion-resistant pipe fittings, fire protection pipelines, electrical sheathing, heat-resistant sheets, and other plastic products requiring corrosion and heat resistance. Compared to ordinary PVC, chlorinated PVC has a higher chlorine content in its molecular chain, resulting in increased chain segment rigidity and a higher glass transition temperature. This leads to better dimensional stability and pressure retention at higher temperatures. However, chlorinated PVC resin also suffers from higher melt viscosity, greater plasticizing difficulty, and a narrower processing window. Improper temperature control or insufficient thermal stability during melt processing can easily lead to defects such as yellowing of the material, uneven melt flow, rough product surface, and performance degradation after thermal aging.

[0003] Existing chlorinated polyvinyl chloride (PVC) compositions typically improve processing and performance by adding heat stabilizers, impact-modified resins, lubricants, inorganic fillers, and flame-retardant and smoke-suppressing agents. Commonly used formulation components include methyl tin heat stabilizers, epoxidized soybean oil, calcium stearate, polyethylene wax, oxidized polyethylene wax, pentaerythritol stearate, nano-calcium carbonate, rutile titanium dioxide, zinc borate, and antioxidants, which can improve the thermal stability, lubricity, rigidity, and flame retardancy of PVC to some extent. However, conventional formulations often rely on a single heat-stabilizing system or ordinary inorganic fillers for modification, making it difficult to simultaneously achieve thermal stability, impact resistance, flame retardancy, smoke suppression, and processing fluidity. Furthermore, some inorganic fillers lack compatibility with PVC resin, easily agglomerating within the system, resulting in limited reinforcing effects and potentially affecting the appearance and long-term service stability of the product.

[0004] Furthermore, chlorinated polyvinyl chloride (PVC) is prone to dehydrochlorination during processing and thermal aging. The released acidic small molecules further promote resin segment degradation, leading to a darker color and reduced mechanical properties. While existing technologies utilize inorganic materials such as layered bimetallic hydroxides, zinc borate, metal stannates, metal molybdates, boehmite, and hexagonal boron nitride to improve the thermal stability, flame retardancy, and smoke suppression of PVC resins, these materials are typically added individually, making it difficult to form a stable synergistic structure. Moreover, their overall improvement in acid capture, smoke suppression, and heat resistance reinforcement within the chlorinated PVC system remains insufficient. Therefore, it is necessary to develop a method for preparing modified chlorinated PVC compositions. This method involves designing a composite intercalated layered bimetallic hydroxide and zinc hydroxystannate / zinc molybdate synergistically anchored layered composite inorganic system, which can be used in conjunction with conventional commercially available resin additives to improve the processing stability, thermal stability, flame retardancy, smoke suppression, and overall mechanical properties of the chlorinated PVC composition. Summary of the Invention

[0005] The purpose of this invention is to provide a modified chlorinated polyvinyl chloride composition and its preparation method, which solves the technical problems of insufficient thermal stability, easy degradation during processing, limited flame retardant and smoke suppression effects, poor filler dispersibility, and insufficient toughness of existing chlorinated polyvinyl chloride compositions.

[0006] The present invention achieves the above objectives through the following technical solutions: A method for preparing a modified chlorinated polyvinyl chloride composition, comprising the following steps: S1. By weight, 100.0-120.0 parts of chlorinated polyvinyl chloride resin, 1.5-3.5 parts of methyltin heat stabilizer, 1.0-3.0 parts of epoxidized soybean oil, 0.1-0.4 parts of antioxidant 1010 and 0.1-0.4 parts of antioxidant 168 are mixed at 70-80℃ to obtain a chlorinated polyvinyl chloride mixture; 3.0-8.0 parts of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite heat-stabilized flame retardant compound, 2.0-6.0 parts of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, and 1.0-4.0 parts of rutile dioxide are added to the chlorinated polyvinyl chloride mixture. Titanium, 5.0-15.0 parts of nano-calcium carbonate, and 1.0-4.0 parts of zinc borate are mixed at 90-100℃ to obtain a modified chlorinated polyvinyl chloride mixture; 5.0-10.0 parts of MBS resin and 3.0-8.0 parts of chlorinated polyethylene resin are added to the modified chlorinated polyvinyl chloride mixture, and the mixture is mixed at 100-110℃ to obtain a toughened modified chlorinated polyvinyl chloride mixture; 0.4-1.0 parts of calcium stearate, 0.3-0.8 parts of oxidized polyethylene wax, 0.2-0.7 parts of polyethylene wax, and 0.3-1.0 parts of pentaerythritol stearate are added to the toughened modified chlorinated polyvinyl chloride mixture, and the mixture is mixed at 110-120℃ and cooled to obtain a premix. S2. Add the premixed material to a twin-screw extruder and perform melt plasticization, mixing, degassing, extrusion and granulation at 160-195℃.

[0007] In this invention, the preparation process of the modified chlorinated polyvinyl chloride composition mainly includes heat-stabilized premixing, inorganic synergistic modification, toughening compounding, and melt plasticizing. Chlorinated polyvinyl chloride resin is prone to dehydrochlorination during heat processing. Methyltin heat stabilizer can stabilize the unstable chlorine structure in the chlorinated polyvinyl chloride resin and inhibit continuous dehydrochlorination. The epoxy groups in epoxidized soybean oil can absorb the desorbed hydrogen chloride, improving processing stability. Antioxidant 1010 and antioxidant 168 synergistically reduce performance loss caused by thermo-oxidative aging. After the addition of the borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano-titanium dioxide composite heat-stabilized flame-retardant compound, the hydroxyl groups on the magnesium zinc aluminum layered double hydroxide layers can neutralize hydrogen chloride, and the interlayer phosphate and borate groups further participate in the fixation of acidic substances and promote the formation of phosphorus- and boron-containing inorganic protective structures at high temperatures. Nano-titanium dioxide, rutile titanium dioxide, nano-calcium carbonate, and zinc borate together improve the rigidity, thermal stability, and flame retardancy of the system. The addition of a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride lamellar composite smoke-suppressing and heat-resistant compound allows zinc hydroxystannate and zinc molybdate to synergistically promote carbon layer stability and reduce smoke release during pyrolysis. Boehmite, upon heating, loses bound water and transforms into alumina, absorbing heat and forming an inorganic shielding structure. The hexagonal boron nitride lamellars form a barrier pathway in the system, extending the diffusion path of heat and pyrolysis products. MBS resin and chlorinated polyethylene resin form a toughening dispersed phase with chlorinated polyvinyl chloride resin. Calcium stearate, oxidized polyethylene wax, polyethylene wax, and pentaerythritol stearate improve the internal and external lubrication and plasticization uniformity of the melt. After melt plasticizing, mixing, venting, extrusion, and granulation, each component forms a stable dispersion structure in the chlorinated polyvinyl chloride resin, resulting in a composition that combines thermal stability, flame retardancy and smoke suppression, processing stability, and toughness.

[0008] According to a preferred embodiment of the present invention, in step S1, the mixing time at 70-80°C is 1-3 minutes.

[0009] According to a preferred embodiment of the present invention, in step S2, the temperature of the twin-screw extruder is 160-170℃ in zone one, 170-180℃ in zone two, 180-190℃ in zone three, 185-195℃ in zone four, 183-193℃ in zone five, and 180-190℃ at the die head.

[0010] According to a preferred embodiment of the present invention, the preparation method of the borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano-titanium dioxide composite thermally stable flame retardant compound includes: A1. By weight, mix 18.0-22.0 parts of nano-titanium dioxide, 0.5-1.5 parts of sodium hexametaphosphate, and 750.0-850.0 parts of deionized water, and disperse by stirring and ultrasonication under nitrogen protection to obtain a pre-dispersion; dissolve 26.0-30.0 parts of magnesium nitrate hexahydrate, 16.0-20.0 parts of zinc nitrate hexahydrate, and 17.0-21.0 parts of aluminum nitrate nonahydrate in 200.0-240 mL of water. A metal salt solution was obtained by dissolving 12.0-16.0 parts of sodium tetraborate decahydrate, 1.0-2.5 parts of sodium dihydrogen phosphate, and 0.5-1.5 parts of disodium hydrogen phosphate in 160.0-200.0 parts of deionized water to obtain a composite anionic solution. The metal salt solution and the composite anionic solution were added to the pre-dispersion solution, and the pH was adjusted to 9.2-9.6 with sodium hydroxide aqueous solution to obtain the precursor slurry. A2. Crystallize the precursor slurry at 80-90℃, cool, wash, dry, crush, and sieve.

[0011] In this invention, the formation process of a thermally stable flame-retardant composite compound of borate / phosphate intercalated magnesium-zinc-aluminum layered double hydroxides coated nano-titanium dioxide mainly includes nano-titanium dioxide dispersion, synergistic hydrolysis of metal ions, composite anion intercalation, and crystallization coating. After stirring and ultrasonic dispersion in sodium hexametaphosphate and deionized water, sodium hexametaphosphate acts as a dispersion aid on the surface of nano-titanium dioxide, inhibiting particle aggregation and forming a relatively uniform pre-dispersion, providing heterogeneous nucleation sites for subsequent inorganic phase deposition. The dissolution of magnesium nitrate hexahydrate, zinc nitrate hexahydrate, and aluminum nitrate nonahydrate provides magnesium, zinc, and aluminum ions, while the dissolution of sodium tetraborate decahydrate, sodium dihydrogen phosphate, and disodium hydrogen phosphate provides borate and phosphate sources. After the metal salt solution and composite anion solution enter the pre-dispersion, in an alkaline environment adjusted by sodium hydroxide aqueous solution, magnesium, zinc, and aluminum ions undergo synergistic hydrolysis and co-precipitation, forming a magnesium-zinc-aluminum layered double hydroxide precursor structure on the surface of nano-titanium dioxide. Phosphate ions exhibit a strong affinity for the positive charges of the magnesium-zinc-aluminum layered double hydroxides, preferentially participating in interlayer charge balance. Borate ions partially participate in interlayer co-intercalation, while others are distributed at the layer edges and outer surfaces, forming a composite intercalation structure dominated by phosphate ions and synergistically supported by borate ions. Nitrogen protection reduces the competition for interlayer sites from carbonate ions formed after carbon dioxide enters the system, facilitating the participation of borate and phosphate ions in interlayer assembly. During the crystallization process of the precursor slurry, the layered structure becomes further ordered, forming a coated composite structure with nano-titanium dioxide particles as the core, ultimately yielding a thermally stable flame-retardant compound of borate / phosphate composite intercalated magnesium-zinc-aluminum layered double hydroxides coated with nano-titanium dioxide.

[0012] According to a preferred embodiment of the present invention, in step A1, the ultrasonic dispersion time is 15-25 min.

[0013] According to a preferred embodiment of the present invention, in step A2, the crystallization time at 80-90°C is 10-14 hours.

[0014] According to a preferred embodiment of the present invention, the preparation method of the zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound includes: B1. By weight, mix 16.0-20.0 parts hexagonal boron nitride, 20.0-24.0 parts boehmite, and 550.0-650.0 parts deionized water, stir, and ultrasonically disperse to obtain a composite dispersion; dissolve 12.0-15.0 parts sodium stannate trihydrate and 4.0-7.0 parts sodium molybdate dihydrate in 140.0-180.0 parts deionized water to obtain a mixed solution; dissolve 22.0-26.0 parts zinc nitrate hexahydrate in 160.0-200.0 parts deionized water to obtain a zinc salt solution; add the zinc salt solution and the mixed solution sequentially to the composite dispersion, and adjust the pH to 7.0-8.0 with sodium hydroxide aqueous solution to obtain a composite precursor slurry; B2. Transfer the composite precursor slurry into a hydrothermal reactor and perform hydrothermal treatment at 140-160℃. Then, cool, wash, dry, pulverize, ball mill, and sieve.

[0015] In this invention, the formation process of the zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride lamellar composite smoke-suppressing and heat-resistant compound mainly includes lamellar dispersion, in-situ inorganic salt deposition, and hydrothermal crystallization. Hexagonal boron nitride and boehmite are dispersed in deionized water by stirring and ultrasonication to form a composite dispersion. Hexagonal boron nitride provides the lamellar barrier framework, while boehmite provides the hydroxyl-containing inorganic surface. The edges and defect sites of the hexagonal boron nitride lamellars can also participate in the adhesion of inorganic deposits. Sodium stannate trihydrate and sodium molybdate dihydrate are dissolved to form a mixed solution, providing stannate and molybdate ions respectively. Zinc nitrate hexahydrate is dissolved to form a zinc salt solution, providing zinc ions. The zinc salt solution and the mixed solution are sequentially added to the composite dispersion, and the pH is adjusted to weakly alkaline with sodium hydroxide aqueous solution. Zinc ions react with stannate ions to form zinc hydroxystannate, and zinc ions react with molybdate ions to form zinc molybdate. Both react in-situ on the surfaces of the boehmite and hexagonal boron nitride lamellars to nucleate and deposit. Maintaining a pH within a weakly alkaline range is beneficial for the formation of zinc hydroxystannate and zinc molybdate, while reducing the likelihood of zinc ions hydrolyzing alone to form free zinc hydroxide byproducts. After hydrothermal treatment, the deposited zinc hydroxystannate and zinc molybdate in the composite precursor slurry further crystallize and grow, forming a stable composite structure through hydroxyl coordination on the boehmite surface, electrostatic adsorption, and the confinement effect of hexagonal boron nitride sheets. Washing removes soluble sodium salts and unreacted ions, while drying, pulverizing, ball milling, and sieving improve the particle size distribution and dispersion, ultimately yielding a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound.

[0016] According to a preferred embodiment of the present invention, in step B1, the ultrasonic dispersion time is 20-30 min.

[0017] According to a preferred embodiment of the present invention, in step B2, the hydrothermal treatment at 140-160°C is carried out for 5-7 hours.

[0018] The present invention also provides a modified chlorinated polyvinyl chloride composition prepared according to the preparation method of the modified chlorinated polyvinyl chloride composition.

[0019] The beneficial effects of this invention are as follows: This invention improves the thermal stability of chlorinated polyvinyl chloride (PVC) resin during processing by adding a borate / phosphate composite intercalated magnesium-zinc-aluminum layered double hydroxide coating to a nano-titanium dioxide composite heat-stabilized flame-retardant compound. The magnesium-zinc-aluminum layered double hydroxide in the borate / phosphate composite coating can adsorb and neutralize acidic substances generated during the heating process of PVC resin. The borate and phosphate ions synergistically participate in the fixation of acidic substances and contribute to the formation of an inorganic flame-retardant protective structure. The nano-titanium dioxide, as the coating core, enhances the dispersion stability of the inorganic phase in the PVC resin, thereby reducing thermal degradation, discoloration, and performance degradation during processing.

[0020] This invention enhances the flame-retardant and smoke-suppressing properties and heat resistance of modified chlorinated polyvinyl chloride (PVC) compositions by incorporating a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride (HNB) layer composite smoke-suppressing and heat-resistant compound. In this compound, zinc hydroxystannate and zinc molybdate synergistically reduce the release of smoke and harmful pyrolysis products during thermal decomposition. Boehmite absorbs heat and forms an inorganic shielding structure upon heating, while the hexagonal boron nitride layers create barrier pathways within the PVC resin, delaying the transfer of heat and pyrolysis products. When combined with rutile titanium dioxide, nano-calcium carbonate, and zinc borate, this composite structure further improves the rigidity, dimensional stability, heat resistance, and flame-retardant and smoke-suppressing effects of the modified PVC compositions.

[0021] This invention employs methyltin heat stabilizer, epoxidized soybean oil, antioxidant 1010, antioxidant 168, MBS resin, chlorinated polyethylene resin, calcium stearate, oxidized polyethylene wax, polyethylene wax, and pentaerythritol stearate to jointly regulate the processing and mechanical properties of chlorinated polyvinyl chloride resin. Methyltin heat stabilizer and epoxidized soybean oil improve processing thermal stability; antioxidant 1010 and antioxidant 168 reduce the effects of thermo-oxidative aging; MBS resin and chlorinated polyethylene resin enhance the toughness and impact resistance of the modified chlorinated polyvinyl chloride composition; and calcium stearate, oxidized polyethylene wax, polyethylene wax, and pentaerythritol stearate improve melt lubricity and plasticization uniformity. This results in a modified chlorinated polyvinyl chloride composition that possesses good thermal stability, flame retardancy and smoke suppression, processing stability, a balance of rigidity and toughness, and molding adaptability. Detailed Implementation

[0022] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0023] Example 1 This embodiment provides a method for preparing a modified chlorinated polyvinyl chloride composition, the steps of which include: S1. Add 100.0g of chlorinated polyvinyl chloride resin, 1.5g of methyltin heat stabilizer, 1.0g of epoxidized soybean oil, 0.1g of antioxidant 1010 and 0.1g of antioxidant 168 to a high-speed mixer, start stirring at 800r / min, heat the material to 70℃, and mix at 70℃ for 1min to obtain a chlorinated polyvinyl chloride mixture; add 3.0g of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite heat-stabilized flame retardant compound, 2.0g of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, 1.0g of rutile titanium dioxide, and 5. 0g of nano-calcium carbonate and 1.0g of zinc borate were stirred and heated to 90°C, and mixed at 90°C for 3 minutes to obtain a modified chlorinated polyvinyl chloride mixture. 5.0g of MBS resin and 3.0g of chlorinated polyethylene resin were added to the modified chlorinated polyvinyl chloride mixture, and stirred and heated to 100°C, and mixed at 100°C for 3 minutes to obtain a toughened modified chlorinated polyvinyl chloride mixture. 0.4g of calcium stearate, 0.3g of oxidized polyethylene wax, 0.2g of polyethylene wax and 0.3g of pentaerythritol stearate were added to the toughened modified chlorinated polyvinyl chloride mixture, and stirred and heated to 110°C, and mixed at 110°C for 3 minutes. Then, cooling water was introduced to cool to 45°C to obtain a premix.

[0024] S2. The premix obtained in step S1 is added to a twin-screw extruder and subjected to melt plasticization, mixing, degassing, extrusion, and granulation at 160°C. The twin-screw extruder has a screw diameter of 25 mm, a length-to-diameter ratio of 40:1, a screw speed of 160 r / min, a zone temperature of 160°C in zone 1, a zone temperature of 170°C in zone 2, a zone temperature of 180°C in zone 3, a zone temperature of 185°C in zone 4, a zone temperature of 183°C in zone 5, a die head temperature of 180°C, and a vacuum degassing pressure of -0.08 MPa. After being extruded through the die head, the material enters a 25°C water bath for cooling. The cooled strip is then fed into a pelletizer for pelletizing, with a pellet length of 3 mm, to obtain the modified chlorinated polyvinyl chloride composition.

[0025] Preparation of a thermally stable flame retardant compound consisting of borate / phosphate intercalated magnesium-zinc-aluminum layered double hydroxides coated with nano-titanium dioxide: A1. Add 18.0g of nano-titanium dioxide, 0.5g of sodium hexametaphosphate, and 750.0g of deionized water to a glass reaction vessel. Turn on nitrogen protection at a flow rate of 100mL / min and start mechanical stirring at 500r / min for 20min to initially wet and disperse the nano-titanium dioxide. Then place the reaction vessel in an ultrasonic dispersion device at a frequency of 40kHz and a power of 500W for 15min to obtain a pre-dispersion. Add 26.0g of magnesium nitrate hexahydrate, 16.0g of zinc nitrate hexahydrate, and 17.0g of aluminum nitrate nonahydrate to 200.0g of deionized water and stir at 25℃ with a stirring speed of 400r / min. Stir at 400 r / min for 15 min until the solid is completely dissolved to obtain a metal salt solution. Add 12.0 g of sodium tetraborate decahydrate, 1.0 g of sodium dihydrogen phosphate, and 0.5 g of disodium hydrogen phosphate to 160.0 g of deionized water and stir at 400 r / min for 15 min at 25 °C until the solid is completely dissolved to obtain a composite anionic solution. Control the temperature of the pre-dispersion liquid at 50 °C and adjust the stirring speed to 600 r / min. Add the metal salt solution and the composite anionic solution to the pre-dispersion liquid, and simultaneously add a 1.0 mol / L sodium hydroxide aqueous solution dropwise to control the pH of the system at 9.2. After all the solution has been added, continue stirring for 50 min to obtain the precursor slurry.

[0026] A2. The precursor slurry obtained in step A1 was transferred into a polytetrafluoroethylene-lined crystallization container, sealed, and placed in a constant temperature oven for crystallization at 80°C for 10 hours. After crystallization, the mixture was allowed to cool naturally to 25°C. The slurry was then removed and centrifuged at 5000 r / min for 10 minutes. The solid was collected. The solid was washed five times with deionized water, with 500.0 g of deionized water added and stirred for 5 minutes each time, followed by centrifugation until the pH of the final washing solution was 7.0. The washed solid was placed in a vacuum drying oven and dried at 80°C for 12 hours under a vacuum of -0.08 MPa. The dried solid was then pulverized for 2 minutes and sieved through a 45 μm sieve to obtain a borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano-titanium dioxide composite thermally stable flame retardant compound.

[0027] Preparation of a smoke-suppressing and heat-resistant compound using zinc hydroxystannate-zinc molybdate-anchored boehmite-hexagonal boron nitride laminates: B1. Add 16.0g of hexagonal boron nitride, 20.0g of boehmite, and 550.0g of deionized water to a glass reaction vessel. Start mechanical stirring at 600r / min for 20min to fully wet the hexagonal boron nitride and boehmite. Then place the reaction vessel in an ultrasonic dispersion device at 40kHz and 600W for 20min to obtain a composite dispersion. Add 12.0g of sodium stannate trihydrate and 4.0g of sodium molybdate dihydrate to 140.0g of deionized water and stir at 400r / min for 15min at 25℃. The solid was completely dissolved to obtain a mixed solution. 22.0 g of zinc nitrate hexahydrate was added to 160.0 g of deionized water and stirred at 400 r / min for 10 min at 25 °C until the solid was completely dissolved to obtain a zinc salt solution. The temperature of the composite dispersion was controlled at 65 °C and the stirring speed was adjusted to 600 r / min. The zinc salt solution was added to the composite dispersion first, and then the mixed solution was added to the composite dispersion. During the addition process, a 1.0 mol / L sodium hydroxide aqueous solution was added dropwise to control the pH of the system at 7.0. After all the solution was added, stirring was continued for 1.5 h to obtain the composite precursor slurry.

[0028] B2. Transfer the composite precursor slurry obtained in step B1 into a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in an electrically heated drying oven for hydrothermal treatment at 140℃ for 5 hours. After hydrothermal treatment, allow it to cool naturally to 25℃, remove the slurry, and centrifuge it at 5000 r / min for 10 minutes. Collect the solid. Wash the obtained solid five times with deionized water, adding 400.0 g of deionized water each time and stirring for 5 minutes, then centrifuge again. The washing process continued until the pH of the final washing solution reached 7.0. The washed solid was placed in a vacuum drying oven and dried at 85°C for 10 hours under a vacuum of -0.08 MPa. The dried solid was then pulverized for 2 minutes and then ball-milled in a ball mill jar for 30 minutes at a ball-to-material mass ratio of 5:1 and a milling speed of 300 r / min. After milling, the solid was sieved through a 45 μm sieve to obtain a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound.

[0029] Example 2 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing a modified chlorinated polyvinyl chloride composition, the steps of which include: S1. Add 110.0g of chlorinated polyvinyl chloride resin, 2.5g of methyltin heat stabilizer, 2.0g of epoxidized soybean oil, 0.25g of antioxidant 1010 and 0.25g of antioxidant 168 to a high-speed mixer and mix at 75℃ for 2 minutes to obtain a chlorinated polyvinyl chloride mixture; add 5.5g of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite heat-stabilized flame retardant compound, 4.0g of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, and 2.5g of... Rutile titanium dioxide, 10.0 g of nano-calcium carbonate, and 2.5 g of zinc borate were mixed at 95 °C to obtain a modified chlorinated polyvinyl chloride mixture. 7.5 g of MBS resin and 5.5 g of chlorinated polyethylene resin were added to the modified chlorinated polyvinyl chloride mixture, and the mixture was further mixed at 105 °C to obtain a toughened modified chlorinated polyvinyl chloride mixture. 0.7 g of calcium stearate, 0.55 g of oxidized polyethylene wax, 0.45 g of polyethylene wax, and 0.65 g of pentaerythritol stearate were added to the toughened modified chlorinated polyvinyl chloride mixture, and the mixture was further mixed at 115 °C, followed by cooling to obtain a premix.

[0030] S2. The premix obtained in step S1 is added to a twin-screw extruder and subjected to melt plasticization, mixing, degassing, extrusion and granulation at 175°C. The temperature of the twin-screw extruder is 165°C in zone 1, 175°C in zone 2, 185°C in zone 3, 190°C in zone 4, 188°C in zone 5, and 185°C at the die head. After cooling and pelletizing, the extrudate is used to obtain a modified chlorinated polyvinyl chloride composition.

[0031] Preparation of a thermally stable flame retardant compound consisting of borate / phosphate intercalated magnesium-zinc-aluminum layered double hydroxides coated with nano-titanium dioxide: A1. Add 20.0g of nano-titanium dioxide, 1.0g of sodium hexametaphosphate, and 800.0g of deionized water to a reaction vessel equipped with a stirrer. Stir under nitrogen protection to initially wet and disperse the nano-titanium dioxide, then ultrasonically disperse for 20min to obtain a pre-dispersion. Add 28.0g of magnesium nitrate hexahydrate, 18.0g of zinc nitrate hexahydrate, and 19.0g of aluminum nitrate nonahydrate to 220.0g of deionized water and stir until completely dissolved to obtain a metal salt solution. Add 14.0g of sodium tetraborate decahydrate, 1.75g ​​of sodium dihydrogen phosphate, and 1.0g of disodium hydrogen phosphate to 180.0g of deionized water and stir until completely dissolved to obtain a composite anionic solution. Add the metal salt solution and the composite anionic solution to the pre-dispersion while stirring, and simultaneously add sodium hydroxide aqueous solution to adjust the pH of the system to 9.4 to obtain the precursor slurry.

[0032] A2. The precursor slurry obtained in step A1 is transferred into a crystallization container and crystallized at 85°C for 12 hours. After crystallization, it is cooled to room temperature and solid-liquid separation is performed. The obtained solid is washed with deionized water until the washing liquid is close to neutral and then dried. After drying, it is crushed and sieved to obtain a borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite thermally stable flame retardant compound.

[0033] Preparation of a smoke-suppressing and heat-resistant compound using zinc hydroxystannate-zinc molybdate-anchored boehmite-hexagonal boron nitride laminates: B1. Add 18.0g of hexagonal boron nitride, 22.0g of boehmite, and 600.0g of deionized water to a reaction vessel equipped with a stirrer. Stir to fully wet the hexagonal boron nitride and boehmite, then ultrasonically disperse for 25min to obtain a composite dispersion. Add 13.5g of sodium stannate trihydrate and 5.5g of sodium molybdate dihydrate to 160.0g of deionized water and stir until completely dissolved to obtain a mixed solution. Add 24.0g of zinc nitrate hexahydrate to 180.0g of deionized water and stir until completely dissolved to obtain a zinc salt solution. Add the zinc salt solution and the mixed solution sequentially to the composite dispersion while stirring. Adjust the pH to 7.5 with sodium hydroxide aqueous solution to obtain a composite precursor slurry.

[0034] B2. The composite precursor slurry obtained in step B1 is transferred into a hydrothermal reactor and hydrothermally treated at 150°C for 6 hours. After hydrothermal treatment, it is cooled to room temperature and solid-liquid separation is performed. The obtained solid is washed with deionized water until the washing liquid is close to neutral and then dried. After drying, it is crushed, ball-milled and sieved to obtain a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound.

[0035] Example 3 The specific implementation method is the same as in Example 1, except that this example provides a method for preparing a modified chlorinated polyvinyl chloride composition, the steps of which include: S1. Add 120.0g of chlorinated polyvinyl chloride resin, 3.5g of methyltin heat stabilizer, 3.0g of epoxidized soybean oil, 0.4g of antioxidant 1010, and 0.4g of antioxidant 168 to a high-speed mixer and mix at 80℃ for 3 minutes to obtain a chlorinated polyvinyl chloride mixture. Add 8.0g of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite heat-stabilized flame retardant compound, 6.0g of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, and 4.0g of gold to the chlorinated polyvinyl chloride mixture. Redstone-type titanium dioxide, 15.0 g of nano-calcium carbonate, and 4.0 g of zinc borate were mixed at 100 °C to obtain a modified chlorinated polyvinyl chloride mixture. 10.0 g of MBS resin and 8.0 g of chlorinated polyethylene resin were added to the modified chlorinated polyvinyl chloride mixture, and the mixture was further mixed at 110 °C to obtain a toughened modified chlorinated polyvinyl chloride mixture. 1.0 g of calcium stearate, 0.8 g of oxidized polyethylene wax, 0.7 g of polyethylene wax, and 1.0 g of pentaerythritol stearate were added to the toughened modified chlorinated polyvinyl chloride mixture, and the mixture was further mixed at 120 °C, followed by cooling to obtain a premix.

[0036] S2. The premix obtained in step S1 is added to a twin-screw extruder and subjected to melt plasticization, mixing, degassing, extrusion and granulation at 195°C. The temperature of the twin-screw extruder is 170°C in zone 1, 180°C in zone 2, 190°C in zone 3, 195°C in zone 4, 193°C in zone 5, and 190°C at the die head. After cooling and pelletizing, the extrudate is used to obtain a modified chlorinated polyvinyl chloride composition.

[0037] Preparation of a thermally stable flame retardant compound consisting of borate / phosphate intercalated magnesium-zinc-aluminum layered double hydroxides coated with nano-titanium dioxide: A1. Add 22.0g of nano-titanium dioxide, 1.5g of sodium hexametaphosphate, and 850.0g of deionized water to a reaction vessel equipped with a stirrer. Stir under nitrogen protection to initially wet and disperse the nano-titanium dioxide, then ultrasonically disperse for 25min to obtain a pre-dispersion. Add 30.0g of magnesium nitrate hexahydrate, 20.0g of zinc nitrate hexahydrate, and 21.0g of aluminum nitrate nonahydrate to 240.0g of deionized water and stir until completely dissolved to obtain a metal salt solution. Add 16.0g of sodium tetraborate decahydrate, 2.5g of sodium dihydrogen phosphate, and 1.5g of disodium hydrogen phosphate to 200.0g of deionized water and stir until completely dissolved to obtain a composite anionic solution. Add the metal salt solution and the composite anionic solution to the pre-dispersion while stirring, and simultaneously add sodium hydroxide aqueous solution to adjust the pH of the system to 9.6 to obtain the precursor slurry.

[0038] A2. The precursor slurry obtained in step A1 is transferred into a crystallization container and crystallized at 90°C for 14 hours. After crystallization, it is cooled to room temperature and solid-liquid separation is performed. The obtained solid is washed with deionized water until the washing liquid is close to neutral and then dried. After drying, it is crushed and sieved to obtain a borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite thermally stable flame retardant compound.

[0039] Preparation of a smoke-suppressing and heat-resistant compound using zinc hydroxystannate-zinc molybdate-anchored boehmite-hexagonal boron nitride laminates: B1. Add 20.0g of hexagonal boron nitride, 24.0g of boehmite, and 650.0g of deionized water to a reaction vessel equipped with a stirrer. Stir to fully wet the hexagonal boron nitride and boehmite, then ultrasonically disperse for 30min to obtain a composite dispersion. Add 15.0g of sodium stannate trihydrate and 7.0g of sodium molybdate dihydrate to 180.0g of deionized water and stir until completely dissolved to obtain a mixed solution. Add 26.0g of zinc nitrate hexahydrate to 200.0g of deionized water and stir until completely dissolved to obtain a zinc salt solution. Add the zinc salt solution and the mixed solution sequentially to the composite dispersion, keeping the mixture stirred during the addition process, and adjust the pH to 8.0 with sodium hydroxide aqueous solution to obtain a composite precursor slurry.

[0040] B2. The composite precursor slurry obtained in step B1 is transferred into a hydrothermal reactor and hydrothermally treated at 160°C for 7 hours. After hydrothermal treatment, it is cooled to room temperature and solid-liquid separation is performed. The obtained solid is washed with deionized water until the washing liquid is close to neutral and then dried. After drying, it is crushed, ball-milled and sieved to obtain a zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound.

[0041] Comparative Example 1 The specific implementation method is the same as in Example 2, except that 5.5g of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coating nano titanium dioxide composite thermally stable flame retardant compound is not added, and 5.5g of nano calcium carbonate is used instead, otherwise it is the same as in Example 2.

[0042] Comparative Example 2 The specific implementation method is the same as in Example 2, except that 4.0g of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound is not added, and 4.0g of nano calcium carbonate is used instead. The rest is the same as in Example 2.

[0043] Comparative Example 3 The specific implementation method is the same as in Example 2, except that 10.0g of nano calcium carbonate is not added, and 10.0g of chlorinated polyvinyl chloride resin is used instead. The rest is the same as in Example 2.

[0044] Performance testing The modified chlorinated polyvinyl chloride compositions prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following method, which included the following steps: The modified chlorinated polyvinyl chloride composition granules obtained in Examples 1-3 and Comparative Examples 1-3 were dried in an 80°C forced-air drying oven for 4 hours. After drying, they were immediately sealed and cooled to room temperature. Test samples were prepared using an injection molding machine with the following conditions: the barrel temperature was 175°C at the rear, 185°C at the middle, 190°C at the front, 190°C at the nozzle, 60°C at the mold, the injection pressure was 80 MPa, the holding time was 10 s, and the cooling time was 30 s. The obtained samples were placed at 23°C and 50% relative humidity for 24 hours before testing.

[0045] During the thermal stability time test, 60.0g of dried granules were weighed and added to the mixing chamber of the torque rheometer. The mixing chamber temperature was set to 190℃ and the rotor speed was set to 60r / min. The torque change curve after the material was added was recorded, and the color change of the material was observed simultaneously. The time when the torque showed a continuous and rapid increase and the material changed from light color to dark color was taken as the thermal stability time. Each sample was tested in parallel 3 times, and the average value was taken. The unit is min.

[0046] During the Vicat softening temperature test, the injection-molded sample is processed into a sample with a thickness of 4.0 mm, a smooth surface and no bubbles. The sample is placed under the indenter of the Vicat softening temperature tester, with the indenter in perpendicular contact with the sample surface. A load of 50 N is applied, and the temperature is increased at a rate of 50 °C / h. The temperature when the indenter penetrates 1.0 mm into the sample is recorded. Five samples are tested for each sample, and the average value is taken. The unit is °C.

[0047] For notched impact strength testing, injection-molded specimens are machined into notched impact strips with a notch depth of 2.0 mm. The bottom of the notch is smooth and crack-free. Before testing, the strips are placed at 23℃ for 2 hours. The impact breaking energy is measured using a cantilever beam impact testing machine. The notched impact strength is calculated based on the effective cross-sectional area at the notch. Ten specimens are tested for each sample. After discarding data with obvious abnormal fractures, the average value is taken. The unit is kJ / m². 2 .

[0048] For tensile strength testing, the injection-molded specimens were made into dumbbell-shaped tensile specimens and placed at 23℃ and 50% relative humidity for 24 hours before testing. The test was conducted using an electronic universal testing machine with the clamp spacing set to 50mm and the tensile speed set to 50mm / min. The maximum load that the specimen could withstand before fracture was recorded, and the tensile strength was calculated based on the effective cross-sectional area of ​​the specimen. Five specimens were tested for each sample, and the average value was taken. The unit is MPa.

[0049] During the limiting oxygen index test, the injection-molded sample is made into a vertically burning sample with a smooth surface free of gaps and obvious bubbles. The sample is vertically fixed in the combustion chamber of the oxygen index tester, and a mixture of oxygen and nitrogen is introduced. After igniting the upper part of the sample, the oxygen volume fraction is adjusted, and the lowest oxygen volume fraction at which the sample just maintains the specified combustion state is recorded. Five samples are tested for each sample, and the average value is taken. The unit is .

[0050] During the smoke density level test, the injection-molded sample is cut into sheet-shaped samples of the same size, placed in the combustion chamber of the smoke density tester, the sample is ignited and the attenuation of light flux by the smoke during the combustion process is recorded, and the smoke density level is calculated according to the maximum light attenuation. Each sample is tested 3 times and the average value is taken. The lower the smoke density level value, the better the smoke suppression performance.

[0051] During the melt flow rate test, the dried granules were added to the barrel of the melt flow rate tester. The test temperature was set to 190℃, the load was set to 5.0kg, and the preheating time was 5min. After the material melted and stabilized, the samples were cut at 30s intervals. The mass of each extruded section was weighed and converted into the melt outflow mass within 10min. Each sample was tested 5 times and the average value was taken. The unit is g / 10min.

[0052] Test results: Table 1: Test results of each embodiment and comparative example ; As can be seen from Table 1, Examples 1-3 show comprehensive improvement in thermal stability, flame retardancy and smoke suppression, mechanical properties and processing stability compared to Comparative Examples 1-3. This indicates that the present invention effectively solves the problems of insufficient thermal stability, easy degradation during processing, limited flame retardancy and smoke suppression effect, and difficulty in balancing filler reinforcement and toughness in existing modified chlorinated polyvinyl chloride compositions.

[0053] The thermal stabilization times of Examples 1-3 were 36.8 min, 42.5 min, and 45.3 min, respectively, which were significantly higher than the 25.6 min of Comparative Example 1. This indicates that the addition of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coating nano titanium dioxide composite thermally stabilized flame retardant compound can significantly delay the thermal degradation of chlorinated polyvinyl chloride resin during processing.

[0054] The limiting oxygen indices of Examples 1-3 were 36.5%, 38.7%, and 40.2%, respectively, and the smoke density grades were 58, 51, and 47, respectively. In contrast, the limiting oxygen index of Comparative Example 2 was only 33.1%, and the smoke density grade was as high as 79. This indicates that the zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound plays a key role in improving flame retardancy and reducing smoke release.

[0055] The Vicat softening temperatures of Examples 1-3 were 113.6℃, ​​116.8℃, and 118.5℃, respectively, and the tensile strengths were 54.8MPa, 57.6MPa, and 59.2MPa, respectively, all higher than those of Comparative Examples 1-3. This indicates that the two inorganic modified compounds (borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite thermally stable flame retardant compound and zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound) can improve the heat resistance, rigidity, and load-bearing capacity of the material when synergistically combined with rutile titanium dioxide, nano calcium carbonate, and zinc borate.

[0056] The notched impact strength of Examples 1-3 is 12.6 kJ / m. 2 14.3 kJ / m 2 and 15.1 kJ / m 2 The comparative example 3 was only 10.2 kJ / m³. 2 This indicates that the combination of nano-calcium carbonate with MBS resin and chlorinated polyethylene resin can improve the retention of toughness after the addition of rigid fillers. The melt mass flow rates of Examples 1-3 were 5.8 g / 10 min, 6.3 g / 10 min, and 6.6 g / 10 min, respectively, which are within a relatively stable processing range. However, Comparative Example 3 reached 7.2 g / 10 min, but the impact strength and tensile strength decreased. This shows that simply increasing the resin ratio can improve flowability, but it cannot simultaneously maintain mechanical and flame-retardant smoke-suppressing properties.

[0057] This invention achieves a good balance between thermally stable flame-retardant compounds (composite magnesium zinc aluminum layered double hydroxides coated with nano-titanium dioxide), smoke-suppressing and heat-resistant compounds (in-situ anchored boehmite-hexagonal boron nitride sheets), and nano-calcium carbonate through the synergistic effect of boehmite / phosphate composite intercalated magnesium zinc aluminum layered double hydroxides, zinc hydroxystannate-zinc molybdate in situ anchored boehmite-hexagonal boron nitride layered composites, and nano-calcium carbonate. Examples 1-3 demonstrate that this invention can effectively improve the thermal stability, flame retardancy and smoke suppression, processing stability, mechanical strength, and toughness of modified chlorinated polyvinyl chloride compositions.

[0058] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a modified chlorinated polyvinyl chloride composition, characterized in that the steps include... include: S1. By weight, 100.0-120.0 parts of chlorinated polyvinyl chloride resin, 1.5-3.5 parts of methyltin heat stabilizer, 1.0-3.0 parts of epoxidized soybean oil, 0.1-0.4 parts of antioxidant 1010 and 0.1-0.4 parts of antioxidant 168 are mixed at 70-80℃ to obtain a chlorinated polyvinyl chloride mixture; 3.0-8.0 parts of borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite heat-stabilized flame retardant compound, 2.0-6.0 parts of zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride layered composite smoke-suppressing and heat-resistant compound, and 1.0-4.0 parts of rutile dioxide are added to the chlorinated polyvinyl chloride mixture. Titanium, 5.0-15.0 parts of nano-calcium carbonate, and 1.0-4.0 parts of zinc borate are mixed at 90-100℃ to obtain a modified chlorinated polyvinyl chloride mixture; 5.0-10.0 parts of MBS resin and 3.0-8.0 parts of chlorinated polyethylene resin are added to the modified chlorinated polyvinyl chloride mixture, and the mixture is mixed at 100-110℃ to obtain a toughened modified chlorinated polyvinyl chloride mixture; 0.4-1.0 parts of calcium stearate, 0.3-0.8 parts of oxidized polyethylene wax, 0.2-0.7 parts of polyethylene wax, and 0.3-1.0 parts of pentaerythritol stearate are added to the toughened modified chlorinated polyvinyl chloride mixture, and the mixture is mixed at 110-120℃ and cooled to obtain a premix. S2. Add the premixed material to a twin-screw extruder and perform melt plasticization, mixing, degassing, extrusion and granulation at 160-195℃.

2. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 1, characterized in that, In step S1, the mixing time at 70-80℃ is 1-3 minutes.

3. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 1, characterized in that, In step S2, the temperature of the twin-screw extruder is 160-170℃ in zone one, 170-180℃ in zone two, 180-190℃ in zone three, 185-195℃ in zone four, 183-193℃ in zone five, and 180-190℃ at the die head.

4. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The preparation method of the borate / phosphate composite intercalated magnesium zinc aluminum layered double hydroxide coated nano titanium dioxide composite thermally stable flame retardant compound includes: A1. By weight, mix 18.0-22.0 parts of nano-titanium dioxide, 0.5-1.5 parts of sodium hexametaphosphate, and 750.0-850.0 parts of deionized water, and disperse by stirring and ultrasonication under nitrogen protection to obtain a pre-dispersion; dissolve 26.0-30.0 parts of magnesium nitrate hexahydrate, 16.0-20.0 parts of zinc nitrate hexahydrate, and 17.0-21.0 parts of aluminum nitrate nonahydrate in 200.0-240 mL of water. A metal salt solution was obtained by dissolving 12.0-16.0 parts of sodium tetraborate decahydrate, 1.0-2.5 parts of sodium dihydrogen phosphate, and 0.5-1.5 parts of disodium hydrogen phosphate in 160.0-200.0 parts of deionized water to obtain a composite anionic solution. The metal salt solution and the composite anionic solution were added to the pre-dispersion solution, and the pH was adjusted to 9.2-9.6 with sodium hydroxide aqueous solution to obtain the precursor slurry. A2. Crystallize the precursor slurry at 80-90℃, cool, wash, dry, crush, and sieve.

5. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 4, characterized in that, In step A1, the ultrasonic dispersion time is 15-25 minutes.

6. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 4, characterized in that, In step A2, the crystallization time at 80-90℃ is 10-14 hours.

7. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 1, characterized in that, The preparation method of the zinc hydroxystannate-zinc molybdate in-situ anchored boehmite-hexagonal boron nitride sheet composite smoke-suppressing and heat-resistant compound includes: B1. By weight, mix 16.0-20.0 parts hexagonal boron nitride, 20.0-24.0 parts boehmite, and 550.0-650.0 parts deionized water, stir, and ultrasonically disperse to obtain a composite dispersion; dissolve 12.0-15.0 parts sodium stannate trihydrate and 4.0-7.0 parts sodium molybdate dihydrate in 140.0-180.0 parts deionized water to obtain a mixed solution; dissolve 22.0-26.0 parts zinc nitrate hexahydrate in 160.0-200.0 parts deionized water to obtain a zinc salt solution; add the zinc salt solution and the mixed solution sequentially to the composite dispersion, and adjust the pH to 7.0-8.0 with sodium hydroxide aqueous solution to obtain a composite precursor slurry; B2. Transfer the composite precursor slurry into a hydrothermal reactor and perform hydrothermal treatment at 140-160℃. Then, cool, wash, dry, pulverize, ball mill, and sieve.

8. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 7, characterized in that, In step B1, the ultrasonic dispersion time is 20-30 minutes.

9. The method for preparing the modified chlorinated polyvinyl chloride composition according to claim 7, characterized in that, In step B2, the hydrothermal treatment at 140-160℃ takes 5-7 hours.

10. A modified chlorinated polyvinyl chloride composition, characterized in that, The modified chlorinated polyvinyl chloride composition is prepared by the method according to any one of claims 1-9.